HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content Social Bookmarking                      What's this?

Musculoskeletal

Jan E.; Parasu N.; Harish S.; Finlay K.; Friedman L.; O'Neill J.; Jurriaans E. Department of Radiology, McMaster University, Hamilton, Canada

Address correspondence to E. Jan (ed.jan{at}utoronto.ca)

Background: There are many dedicated planes of imaging described in musculoskeletal MRI recently, such that it is difficult for the busy radiologist to keep track of them all. These planes are not used routinely, but offer value in specific instances, as problem-solving tools (especially when faced with a specific clinical question). A single one-stop resource would be useful to summarize such sequences.

Key Issues: We will not be using specific data, but will offer our perspective on the use of dedicated imaging planes in musculoskeletal MRI. Experience gained by us from using various dedicated imaging planes and positions in different joints of the body (especially, some of which we have been using consistently over a period of time) will be used to emphasize and reinforce key concepts, by way of illustrative examples

Format: The exhibit will be in didactic format. The organization will be as follows: A. Upper limb 1. Shoulder a. AC joint b. Glenohumeral joint–labrum (e.g., double oblique sequences), glenohumeral ligaments (e.g., ABER, ADIR sequences) 2. Elbow a. Collateral ligaments (e.g., posterior oblique sequence) b. Distal biceps tendon (e.g., FABS) c. Neurovascular bundle 3. Hand and wrist a. Ligaments of the proximal carpal row (e.g., oblique through scapholunate and lunotriquetral ligaments) b. Ulnar collateral ligament of the thumb. B. Lower limb 1. Hip - labrum 2. Knee a. Anterior cruciate ligament (e.g., para-coronal and parasagittal sequences) b. Posterolateral and posteromedial corners (e.g., posterior oblique) 3. Ankle and foot a. Lateral collateral ligament complex b. Spring ligament c. Lisfranc's joint C. Miscellaneous 1. Brachial plexus 2. Sacroiliac joint 3. Groin

Teaching Points: 1. To be aware of the gamut of dedicated/tailored imaging sequences described in musculoskeletal MRI. 2. To understand the indications for use of such sequences and optimize the examination to achieve best results, when faced with such indications. 3. To illustrate the methodology of performing such sequences by using images to illustrate the base sequence and patient position to plan the planes, and also demonstrate the anatomy in the images obtained as a result of such planning. 4. To provide some illustrative examples to show how such sequences help reveal anatomy and abnormalities better than on conventional sequences.

E263. MRI Pictorial Review of Bursal Anatomy and Pathology

Matin A.¹; Masih S.³; Freitas A. D.³; Modarresi S.³; Learch T. J.² 1. UCLA Medical Center, Los Angeles, CA; 2. University of Southern California University Hospital, Los Angeles, CA; 3. Veterans Administration of Greater Los Angeles, Los Angeles, CA

Address correspondence to A. Matin (amatin{at}gmail.com)

Background: Bursae are found throughout the body at points of friction or stress to enhance motion between the opposing tissues. When bursae are located near joints, the synovial membrane of the bursa may be continuous with that of the joint cavity. Inflammation of the bursa is called bursitis, a response to the irritation of mechanical stress from pressure or friction, although some bursae may also be involved along with the joints and tendon sheaths in rheumatoid arthritis and gout. Bursae may also be affected by traumatic processes.

Key Issues: Examples of important bursae are those around the ankle (retrocalcaneal bursa), elbow (olecranon bursa), glenohumeral joint (subacromial and subdeltoid bursae), hip (iliopsoas and trochanteric bursae), and knee (prepatellar, suprapatellar, pes anserine and other bursae). The most useful aspects of bursal anatomy and pathology relevant to diagnostic imaging will be depicted in this pictorial review with examples of various entities affecting the bursae on MR imaging. Anatomic diagrams will also be utilized where helpful.

Format: This exhibit will provide a pictorial review of bursal anatomy and pathology commonly encountered on MR imaging, organized by location (e.g., shoulder, hip, knee, ankle).

Teaching Points: The viewer will learn: 1) the normal anatomy and locations of various bursae, 2) to identify common forms of bursal pathology on MR imaging.

E264. High Resolution Magnetic Resonance Imaging Anatomy of the Ankle and the Foot Ligaments on a 3.0-T Magnet

Rao A. T.; Stanton D.; Krampert S.; Kramer L. A. University of Texas Health Science Center–Houston, Houston, TX

Address correspondence to A. Rao (anuradha.t.rao{at}uth.tmc.edu)

Background: Magnetic resonance imaging is the modality of choice for the diagnosis of ligamentous and soft tissue injuries of the ankle and the foot. A firm grasp of the complex anatomy of this region is essential to make an accurate diagnosis of ankle pathology. 3.0-T magnetic resonance imaging with its superb and enhanced signal to noise ratio and superior resolution is fast becoming the gold standard for imaging the joints especially the smaller joints as the small field of view minimizes the sensitivity to artifacts and field inhomogeneities. A much detailed study of the complex ligaments of the ankle and intrinsic ligaments of the foot is now feasible and practical with the advent of higher Tesla magnets. Revisiting the ankle and foot magnetic resonance imaging anatomy with a high resolution 3.0-T magnet would make us better understand the attachments of the ligaments, their complex relationships with one another and the surrounding tendons and bones and hence the mechanism of injury in this region.

Key Issues: We discuss and present the technique, imaging planes and the appearances of the complex ligamentous anatomy around the ankle, the hind foot and the midfoot on a high resolution 3.0-T magnet. We will present a detailed high resolution pictorial exhibit of the anatomy of the: 1) Lateral collateral ligament complex including the anterior and posterior talofibular and the calcaneofibular ligaments, anterior and posterior tibiofibular ligaments, the intermalleolar ligament and the interosseous ligament. 2) Medial deltoid ligament including the three superficial talotibial, the calcaneotibial and the navicular tibial ligaments and the two deep anterior and posterior talotibial ligaments. 3) Spring ligament complex which includes the supermedial calcaneonavicular ligament, the medioplantar oblique and the inferoplantar longitudinal ligaments. 4) Lis Franc ligament including the dorsal and plantar components.

Format: Didactic presentation. We will discuss the imaging plane, the MR sequence used and the clinical significance of each image. We will present a cross-sectional correlative image wherever possible.

Teaching Points: 1. Detailed anatomy including the individual components of the intrinsic ligaments of the ankle, hind and midfoot. 2. Clinical significance and where possible pathology in this region. 3. Inter-relationships of the ligaments and with the surrounding osseous structures and tendons.

E265. Secondary Search Pattern in Evaluation of Ankle Trauma Radiographs

Pham H.; Hunter J.; Escobedo E. UC Davis Medical Center, Sacramento, CA

Address correspondence to H. Pham (huanphamusc{at}hotmail.com)

Background: Ankle injuries including sprain ankles and ankle fractures are very common affecting everyone including athletes, people involved in active outdoor activities, and normal people with accidents. Ankle joint is one of the most injured joints in sports. Plain radiographs are usually the first imaging studies obtained, and careful evaluation of ankle radiographs is crucial in patient management.

Key Issues: Evaluation of ankle radiographs involves the primary search pattern, which includes looking for injuries involving the soft tissue, the maleoli, and ligaments and ankle mortise alignment. However, additional and more subtle injuries in or near the ankle joint should also be evaluated including the base of the fifth metatarsus, the lateral process of the calcaneous and the talus, and talar dome injury such as osteochondral defect. The secondary search pattern involves evaluating these areas after the initial primary search pattern.

Format: This is a didactic PowerPoint display of the above mentioned ankle injuries by plain radiographs with cross-sectional images correlation.

Teaching Points: When evaluating ankle injury with plain radiographs, using the secondary search pattern after the primary search pattern will help identify more subtle injury in or near the ankle joint.

E266. "Foot Faults"

Sones W. D.; Derr D. University of Mississippi Medical Center, Jackson, MS

Address correspondence to W. Sones (wsones{at}medicine.umsmed.edu)

Background: The foot's anatomic structure is composed of multiple bones with complex articulations; consequently, both congenital and acquired deformities commonly occur. The complex interaction of bones, joints and connective tissue makes accurate evaluation of deformities challenging. However, numerous useful quantitative methods have been devised to reliably measure the effect of varying degrees of osseous subluxation on the mechanics of the foot.

Key Issues: The approach to foot deformities must begin with recognizing the normal anatomy of the foot under correct radiographic technique. Proper positioning assures that deformities are not mimicked on routine radiographs. When evaluating radiographs, several key angles are easily added to the radiologist's routine search pattern. These give quantitative measurements of an abnormality and are applicable for common problems like pes planus to more obscure disorders such as skewfoot.

Format: This exhibit reviews useful measurements available for the evaluation of the foot with a review of normal ranges and variations. Treatment options for specific abnormalities are also discussed. Postsurgical images are utilized to illustrate how intervention can improve the abnormal alignment of the deformed foot.

Teaching Points: Teaching points include: 1. Helping the viewer integrate important angle measurements into his/her routine radiographic search pattern to improve the accuracy of the evaluation of the foot 2. Understanding the normal range of anatomy as well as the clinical significance of the misaligned foot 3. Giving appreciate for how the severity of the disorder contributes to clinical management.

E267. Multimodality Imaging of Achilles Tendon Pathology

Mariano M. N.²; Gentili A.¹; Hughes T.²; Chung C. B.² 1. San Diego VA Medical Center, La Jolla, CA; 2. University of California, San Diego, San Diego, CA

Address correspondence to M. Mariano (mmariano{at}ucsd.edu)

Background: Injury to the Achilles tendon is a common cause of heel pain. Direct trauma or overuse causes the majority of Achilles tendon pathology. However, metabolic disorders, crystal deposition diseases and inflammatory arthritis are also important, although less common, etiologies. It is important to evaluate the degree of tendinous injury as well as concurrent involvement of the osseous attachments, adjacent paratenon, bursae and musculature to help guide intervention.

Key Issues: We will review conventional radiography, ultrasound and MR imaging findings of injury to the Achilles tendon including paratendonitis, insertional tendinosis, interstitial, partial and complete tears. We will also present subsequent follow-up studies focusing on nonsurgical versus postoperative imaging characteristics. Lastly, we will discuss differential diagnoses for heel pain such as tennis-leg, Haglund's disease, and calcaneal stress fracture.

Format: The format will be didactic organized by pathology with corresponding imaging findings on conventional radiography, ultrasound and MRI.

Teaching Points: 1. Demonstrate Achilles tendon pathology on conventional radiography, ultrasound and MR imaging. 2. Evaluate the degree of tendinous injury and concurrent involvement of the osseous attachments, adjacent paratenon, bursae and musculature to help guide intervention. 3. Distinguish follow-up nonsurgical from postoperative imaging characteristics. 4. Describe clinical mimickers of Achilles tendon pathology.

E268. Accessory Muscles of the Ankle

Mariano M. N.²; Gentili A.¹; Chung C. B.¹; Hughes T.² 1. San Diego VA Medical Center, La Jolla, CA; 2. University of California, San Diego, San Diego, CA

Address correspondence to M. Mariano (mmariano{at}ucsd.edu)

Background: Several accessory muscles about the ankle have been described. The four most recognized muscles are the peroneus quartus, flexor digitorum accessorius longus, accessory soleus and peroneocalcaneus internus muscles. Most commonly the accessory muscles are asymptomatic and are found as incidental findings on MRI obtained for other reasons. Occasionally an accessory muscle can present clinically as a soft tissue mass. Rarely an accessory muscle can cause nerve entrapment or pain.

Key Issues: We will demonstrate MR and conventional radiography imaging characteristics of these accessory muscles to delineate their anatomy including the origins, insertions and relation to adjacent neurovascular and normal muscular structures.

Format: The presentation will be didactic organized according to anatomy and MR imaging findings.

Teaching Points: 1. To review imaging appearance of accessory muscles around the ankle. 2. To explain how to distinguish different accessory muscles. 3. To discuss common presentations of accessory muscles.

E269. Imaging Soft Tissue Tumors of the Foot

Smyth K.; Di Primio G.; Rakhra K.; Sheikh A. University of Ottawa, Ottawa, Canada

Address correspondence to K. Smyth (smythkr{at}hotmail.com)

Background: Soft tissue tumors of the foot are rare and difficult to diagnose as malignant or benign on clinical grounds alone. Imaging characteristics of benign tumors such as plantar fibromatosis, ganglion cysts and giant cell-tumors of the tendon sheath are important to recognize in order to avoid exposing patients to unnecessary surgical risk. Findings associated with malignant lesions such as synovial sarcoma and chondrosarcoma are important diagnostically and for determining resectability and preoperative planning.

Key Issues: Multiple imaging modalities are employed to identify soft tissue tumors of the foot. Detection and evaluation of soft tissue tumors is performed by recognizing their appearance on radiographs, CT and MR images.

Format: This electronic exhibit combines descriptive text with radiographs, CT, and MR images of soft tissue tumors of the foot.

Teaching Points: 1. To recognize abnormal radiograph, CT, and MRI findings consistent with soft tissue tumors. 2. To review the findings most commonly associated with malignant tumors. 3. To emphasize important anatomic structures relevant to surgical planning.

E270. Fractures Around the Ankle—How Orthopedic Surgeons Decide What They Do

El-Sherief A.; Huang B.; Azodo U.; Maragh M.; Seo G.; Monu J. U. University of Rochester School of Medicine and Dentistry, Rochester, NY

Address correspondence to A. El-Sherief (ahmed_elsherief{at}urmc.rochester.edu)

Background: Ankle fractures are common injuries and vary in degrees of severity. The reasoning guiding the management options of the surgeon are at times not immediately obvious. The existence of numerous classification schemes for ankle fractures tends to confuse issues further for the inexperienced. The purpose of this presentation is to clarify some of the reasoning behind management decisions of the surgeon.

Key Issues: The exhibit will use annotated images and schematics to illustrate the anatomy of the ankle joint. The various landmarks including the malleoli, the mortice and the syndesmosis will be defined using plain radiographs, CT and MRI images. Various classification schemes for ankle fractures will be presented. The limitations and advantages of each scheme will be highlighted using material from our database.

Format: Using an interactive format, an appropriate classification scheme for various fractures using are discussed. CT and MR images will be used to buttress and support the observations and inferences drawn from plain radiographs. The final management of the injury will be presented to validate the classification used.

Teaching Points: The viewer will 1. Review the radiographic anatomy of the ankle joint 2. Review some of the more common classifications of ankle fractures 3. Appreciate the use of each classification and when it can be applied 4. Learn the reasoning behind management options available to and utilized by the surgeons.

E271. Ankle Fractures: Classification Systems and Imaging Pearls

Skanes M.¹; Pike E.² 1. Memorial University, St. John's, Canada; 2. St. Clare's Mercy Hospital, St. John's, Canada

Address correspondence to M. Skanes (melissaskanes{at}hotmail.com)

Background: The ankle is the most commonly injured joint in the body. It has been reported that approximately 10% of all radiographs requested by the emergency room involve the ankle joint. Early recognition of ankle fractures leads to the proper management of these injuries and decreases long-term disability. The plain radiograph is still considered the most important study for the initial evaluation of ankle injuries. Other modalities such as CT scanning or MR imaging, may prove useful in the demonstration of intra-articular fractures or in preoperation assessments.

Key Issues: Historically, there have been many classification systems in use regarding ankle fractures. This exhibit/module will briefly review some of these classification schemes, with a focus on the most commonly used system- the AO classification. Various radiographic findings will be presented to help demonstrate the spectrum of ankle fractures, including minor injuries such as avulsion or isolated fractures, to more complex injuries such as comminuted intra-articular fractures and fracture-dislocations.

Format: The format of this exhibit will include both didactic and interactive components. Radiographic findings will be shown to demonstrate the spectrum of ankle fractures according to commonly used classification systems.

Teaching Points: Physicians reviewing this exhibit will gain an important understanding of ankle fractures, the use of adjuvant studies, and pearls in fracture and injury recognition.

E273. Postoperative Evaluation of the Total Ankle Arthroplasty with an Emphasis on CT Imaging

Bestic J. M.; Peterson J. J.; DeOrio J. K.; Bancroft L. W.; Berquist T. H.; Kransdorf M. J. Mayo Clinic, Jacksonville, FL

Address correspondence to J. Bestic (bestic.joseph{at}mayo.edu)

Background: Initially introduced in the 1970s, first-generation ankle arthroplasties were plagued with significant complications and have been largely abandoned. Second-generation total ankle arthroplasty devices have since addressed many of the initial concerns with innovative designs and technical advancements. Encouraging results with second-generation devices has lead to their increasing popularity and total ankle arthroplasty has emerged as a viable alternative to ankle arthrodesis. Imaging continues to play an important role in the postoperative evaluation of total ankle arthroplasties. Thus, a thorough understanding of the normal and abnormal postoperative imaging features of these devices is of considerable value.

Key Issues: Two basic designs of second-generation prostheses are commonly employed. Two-component systems consist of a tibial component with an attached polyethylene articular surface and a talar component. Three-component systems consist of a polyethylene core sandwiched between the tibial and talar components. Postoperative radiographic evaluation effectively demonstrates component positioning and surrounding osseous architecture. Multidetector CT allows for alterations in technique which can minimize metallic artifact and facilitate more precise evaluation of prosthetic components and associated complications. Such complications include mechanical loosening, subsidence, polyethylene osteolysis, periprosthetic fractures, and infection.

Format: In this didactic exhibit, we will illustrate the components of the total ankle arthroplasty and their appropriate anatomic positioning. Radiographic and CT characteristics of the ankle prostheses will be presented with an emphasis on CT imaging. Sample cases illustrating normal postoperative appearance as well as prosthesis-related complications will be depicted. To better localize abnormalities about the components, we introduce a zonal system similar to that developed for the hip.

Teaching Points: After viewing the exhibit, the participant will identify the expected postoperative imaging appearance of the total ankle arthroplasty. He or she will be able to describe both the normal and common abnormal imaging features of such devices and will define the utility of CT for more precise evaluation in equivocal cases. Lastly, the participant will recognize a new zonal system which serves to more precisely localize abnormalities, thereby facilitating more effective communication between radiologist and clinician.

E274. MRI Evaluation of Bone Marrow Abnormalities

Aagesen M.; Jacobson J.; Morag Y.; Brigido M.; Schuetze S.; Baker L. University of Michigan, Ann Arbor, MI

Address correspondence to M. Aagesen (maagesen{at}gmail.com)

Background: MRI is the primary imaging modality currently used in evaluation of bone marrow. Normal adult marrow is normally characterized by the presence of fat-predominant yellow marrow and hematopoietic red marrow. There are multiple pathologic and iatrogenic causes for alterations in normal marrow signal, including proliferative disorders, marrow replacing disorders, and loss of the normal cellular elements.

Key Issues: This exhibit will review the features of normal adult bone marrow, and then focus on the different presentations of marrow disorders. Normal yellow marrow has high T1 signal, intermediate T2 signal, and low signal on fat-suppressed sequences. Normal red marrow usually demonstrates intermediate signal on all pulse sequences. Heterogeneous signal in the bone marrow can be a normal finding, but is sometimes difficult to differentiate from pathologic conditions. Low T1 signal is a common feature of abnormalities in marrow pathologies, while T2 signal changes can be more variable. The imaging characteristics of diseases such as red marrow reconversion, leukemias, multiple myeloma, primary tumors, metastasis, lymphoma, aplastic anemia, chemotherapy, radiation changes, myelofibrosis, Paget's, and Gaucher's disease are presented in this exhibit.

Format: The format of this presentation will be a pictorial review of multiple individual conditions, benign and malignant, causing signal alteration in the marrow spaces on MRI. Attention will be placed on the evaluation of the marrow signal and signal changes in the axial skeleton. In and out of phase MRI will also be discussed, as well as the role of intravenous gadolinium.

Teaching Points: The features of normal marrow on MRI are presented with respect to different pulse sequences. This presentation will focus on the signal alterations present in different benign and malignant marrow pathologies in the adult patient.

E275. MRI Assessment of Bone Marrow

Roberts C. C.¹; Chew F. S.² 1. Mayo Clinic College of Medicine, Scottsdale, AZ; 2. University of Washington, Seattle, WA

Address correspondence to C. Roberts (roberts.catherine{at}mayo.edu)

Background: Bone marrow can have a widely varied appearance on MRI. The signal characteristics reflect the composition of the marrow. Differing quantities of red and yellow bone marrow can make normal marrow appear pathologic. Erythropoiesis-stimulating drugs administered to chemotherapy patients can lead to complex marrow changes, which sometimes can complicate the interpretation of serial imaging to evaluate for metastatic disease.

Key Issues: There are three main characteristics that help differentiate benign from malignant bone marrow changes. The first characteristic is the presence of macroscopic fat within the marrow. If foci of fat signal remain present throughout the marrow then any inhomogeneity of the marrow is likely benign. The second characteristic is the intensity of the marrow on T1-weighted images. If the marrow signal intensity on T1-weighted images is higher than adjacent muscle, then the marrow changes are likely benign. The final characteristic is the appearance of the marrow on in- and out-of-phase imaging. Similar to imaging of adrenal masses, bone marrow that demonstrates signal drop out on out-of-phase images contains microscopic fat and thus is most likely benign.

Format: This electronic exhibit combines didactic teaching of the above principles, combined with interactive pathologically proven cases of varying bone marrow lesions, and a self-assessment quiz.

Teaching Points: By completing this educational activity, the participant will: 1. Exercise, self-assess, and improve his or her understanding of the normal and abnormal appearances of bone marrow on MRI; 2. Exercise, self-assess, and improve his or her understanding of the use of in and out-of-phase sequences in the evaluation of bone marrow with MRI.

E276. Femoral Head Trabeculae and Bone Marrow: Correlation Between CT Findings and Histologic Features

Kim J.¹; Park G.¹; Lee J.²; Han Y.¹; Lee S.¹ 1. Chonbuk National University Medical School, Jeonju, South Korea; 2. The Catholic University of Korea, Daejeon St. Mary's Hospital, Daejeon, South Korea

Address correspondence to J. Kim (greem{at}freechal.com)

Objective: By using a point to point comparison we tried to correlate the histopathologic findings of the resected femoral head with those of CT images especially focused on bony trabeculae and bone marrow.

Materials and Methods: Six resected femoral heads were harvested and used according to institutional guidelines and with institutional approval and consent from the donors with a mean age of 54 years (41–65 years). Before CT imaging of the resected femoral head, sectioning of the femoral head with 2 mm in thickness was performed by use of diamond blade. CT images of individual sections were obtained with 16 MDCT with an ultra-high resolution protocol provided by the manufacturer. After decalcification of the bone sections with formic acids, giant slides including whole specimen of the femoral head section were made and stained with Hematoxylin-eosin. Histopathologic findings of bony trabeculae and bone marrow were correlated with those of CT images by a point-to-point approach.

Results: Various changes of bony trabeculae on histopathologic slides were exactly represented on corresponding CT images. Newly formed trabeculae appeared as foggy appearance on CT images. Destructed trabeculae by osteoclast in fibrotic tissue of the bone marrow appeared abrupt cut-off trabeculae on CT images. Changes of bone marrow in histopathologic slides were not classified on CT images. However, various bone marrow changes were associated with those of bony trabeculae.

Conclusion: The new developed method provides an exact comparison between the histopathologic and CT image findings.

E277. MR Features of Benign and Malignant Soft Tissue Masses of the Hand and Wrist

Winger D.⁴; Luchs J. S.⁴; Teplitz G.⁴; Finzel K.³; Math K.¹; Kenan S.² 1. Beth Israel Medical Center, New York, NY; 2. NYU Medical Center, New York, NY; 3. ProHealth Care Associates, Lake Success, New York; 4. Winthrop-University Hospital, Mineola, NY

Address correspondence to D. Winger (dwinger{at}winthrop.org)

Background: The purpose of this exhibit is: 1. To review the imaging features of both benign and malignant soft tissue tumors of the hand and wrist and demonstrate pathological correlation when available. MR will be the primary imaging modality discussed, with limited discussion of other modalities: plain film, ultrasound. 2. To briefly discuss the symptoms, physical exam findings, natural history, diagnosis, prognosis, and management of selected soft tissue lesions of the hand and wrist. 3. To explain the utility of MRI in the diagnosis of selected lesions.

Key Issues: 1. List of benign and malignant soft tissue lesions of the hand and wrist 2. MR images of selected benign and malignant lesions of hand and wrist, with corresponding plain film, ultrasound images and pathology images when available. Selected cases from our institution and other collaborating institutions will be used. 3. Brief discussion of symptoms, physical exam findings, natural history, diagnosis, prognosis, and management of selected soft tissue lesions of the hand. This will be in bullet format below the corresponding images. 4. Brief discussion of the utility of MR in the diagnosis of selected lesions.

Format: We will be using case material to illustrate these imaging findings. This will be a didactic format and organized by case. Each case will have a different diagnosis and bullet points regarding the pathology and imaging findings demonstrated.

Teaching Points: The major teaching points of this exhibit are: 1. MR features of benign and malignant soft tissue tumors of hand and wrist. 2. Physical exam findings, natural history, diagnosis, prognosis, and management of selected soft tissue lesions of the hand. 3. Utility of MR in the diagnosis of selected lesions.

E278. Demystifying MRI of the Wrist

Whitlock M.²; Chew F. S.²; Richardson M. L.²; Roberts C. C.¹ 1. Mayo Clinic, Scottsdale, AZ; 2. University of Washington, Seattle, WA

Address correspondence to M. Whitlock (swhitlock{at}comcast.net)

Background: Interpreting an MRI scan of the wrist can be an intimidating task for the general radiologist because of the complex anatomy, the intricate biomechanics, and the broad range of pathology. This educational exhibit demystifies this difficult region and presents an approach to interpretation that builds on general radiologic principles.

Key Issues: The normal appearance of osseous, articular, ligamentous, muscle-tendon, neurovascular, and soft tissue anatomy of the wrist on MRI is reviewed. Case examples are used to illustrate the range of disease processes that may be seen, and the locations in which those conditions may occur.

Format: This computer-based educational exhibit presents an approach to interpretation of MRI of the wrist so that the practicing radiologist can recognize and accurately describe a variety of disease conditions. Participants may take an interactive self-assessment quiz to test their learning.

Teaching Points: The objectives of this educational activity are for the participant to: 1.) Review the normal MRI appearance of the wrist 2.) To learn an approach to interpretation 3.) To review the MRI appearance of a variety of disease conditions.

E279. Review of Wrist Pain: An Interactive Quiz

Han R.; Sarno R. Tufts - New England Medical Center, Boston, MA

Address correspondence to R. Han (rhan{at}tufts-nemc.org)

Background: Many causes of wrist pain, including trauma, arthritis, metabolic disease, infection, and congenital conditions may present with findings in the wrist. This exhibit shows radiologists a collection of interesting multimodality (X ray, CT, and MRI) cases involving the wrist with associated teaching points, differential diagnosis, imaging pearls, and pitfalls to help improve the understanding of radiologic findings and clinical correlation.

Key Issues: Images will be presented as multipart multimodality unknown cases, with the key findings illustrated, discussion, and differential diagnoses. Cases include causes of posttraumatic wrist pain, snuffbox tenderness, chronic wrist pain, decreased range of motion, and pain with passive dorsiflexion of various fingers.

Format: This presentation will be presented as a PowerPoint presentation in quiz format. Multimodality cases will be presented, along with scan findings, discussion, differential diagnosis, and pearls and pitfalls. Cases will be organized by pathologic classification of disease.

Teaching Points: Many conditions of the wrist which cause pain have characteristic findings and associated clinical presentations. A better understanding of the disease processes at work in the wrist can greatly aid a radiologist's interpretation of images.

E280. Analysis of Median Nerve Motion on Ultrasound

Hadjiev O.; Hulen R.; Craig J.; van Holsbeeck M. Henry Ford Hospital, Detroit, MI

Address correspondence to O. Hadjiev (orlinh{at}rad.hfh.edu)

Background: Static and dynamic criteria for median nerve imaging in carpal tunnel syndrome (CTS) have been suggested in literature, however, median nerve (MN) motion analysis has been difficult to standardize. It has generally been accepted that repetitive trauma from regular use of the keyboard can lead to symptoms of carpal tunnel syndrome. Our limited analysis has shown that repetitive motion involving opposition of the thumb to the index finger (i.e. pinch) during supination/pronation can lead to CTS from entrapment of the MN. This hypothesis gives insight into why the condition is prevalent among sonographers, dental hygienists and a number of persons whose occupations do not require frequent use of the keyboard but where pinch maneuver is common. Furthermore, while most current MN evaluation focuses on ultrasound (US) diagnosis of CTS based on MN cross-sectional area, our study evaluates dynamic motion as anatomic etiology for compression of the median nerve within the carpal tunnel with supination/pronation during pinch maneuvers.

Key Issues: The hands of 10 asymptomatic volunteers (normals) were examined in both axial and sagittal planes for MN motion. The median nerve distance with respect to flexor policis longus (FPL) and carpal tunnel bones was measured in supination, pronation and with pinch maneuver. These measurements were compared to values in symptomatic patients who have CTS clinically. The MN cross-sectional area was measured using oval approximation. Imaging was conducted using General Electric Logiq 9 with M12L and i12L transducers.

Format: Didactic electronic exhibit with AVI files and static grayscale images in which normal median nerve mobility on US is contrasted with abnormal sagittal and transverse tissue movement in patients with CTS, detailing normal relationship between MN and FPL both statically, dynamically and with pinch maneuver.

Teaching Points: This electronic exhibit will demonstrate the normal relationship between MN, FPL, carpal tunnel bones and transverse ligament on US. It will also demonstrate that during supination/pronation of the forearm, there is normal lateral motion of the median nerve. We will show that individuals who are more susceptible to development of CTS seem to demonstrate an increased sagittal motion, predisposing the median nerve to compression during repetitive pinch maneuvers (e.g., use of computer mouse, scanning with US probe) leading to edema and classic symptoms of CTS.

E281. Significance of Vascularities Within the Median Nerve in Patient With Carpal Tunnel Syndrome: Assessment of Color Doppler Imaging

Yoon C.¹; Kwon S.¹; Sohn E.²; Jeon J.¹; Shin H.³ 1. Department of Diagnostic Radiology, Chungnam National University Hospital, Daejeon, South Korea; 2. Department of Neurology, Chungnam National University Hospital, Daejeon, South Korea; 3. Department of Orthopaedic Surgery, Chungnam National University Hospital, Daejeon, South Korea

Address correspondence to C. Yoon (ycd7804{at}cnuh.co.kr)

Objective: To analyze the visible vascularity of median nerve in the patient with carpal tunnel syndrome and to compare with clinical symptom and sign.

Materials and Methods: Among the patients with physical examinations and nerve conduction tests of carpal tunnel syndrome, 29 hands with increased vascularities within the median nerve on ultrasonography of 21 patients (2 men, 19 women; mean age, 55 years; range, 39–76 years) were enrolled. Transverse and longitudinal scan of the median nerve was done at two levels; inlet of carpal tunnel and proximal to carpal tunnel near the proximal wrist crease (total 37 hands). The presence of vascularity including the location within median nerve and its peak systolic velocity was analyzed and compared with clinical symptoms and its degree.

Results: The location of the vascularities within the median nerve was proximal to carpal tunnel in 17 cases (59%), the inlet of carpal tunnel in seven cases (24%), within carpal tunnel in one case (3%), both inlet of carpal tunnel and proximal to carpal tunnel in four cases (14%). Mean peak systolic velocity was 0.05 m/sec. Among 32 cases with clinical symptoms of carpal tunnel syndrome, 29 cases with increased vascularities within the median nerve were detected (90.6%). Those with symptoms in both hands (11 patients), the vascularities were found at the more severe symptomatic hand (100%). And those with vascularities within both hands (eight cases) the higher peak systolic velocity in more severe symptomatic hand was found in four cases (50%).

Conclusion: The vascularities within the median nerve in patient with carpal tunnel syndrome have high correlation with the clinical symptoms and its degree.

E282. Acute Calcific Periarthritis of the Hand: An Underappreciated Disease in Radiology

Vazirani R.¹; Clifford P.¹; Doumas C.²; Owens P.¹ 1. University of Miami Miller School of Medicine, Miami, FL; 2. University of Pennsylvania, Philadelphia, PA

Address correspondence to R. Vazirani (vazirani{at}hotmail.com)

Background: Acute calcific periarthritis (ACP) is an acute periarticular inflammation associated with juxta-articular deposits of mineral. Acute symptoms may include pain, erythema, swelling and restricted motion at the involved joint. Clinical findings may suggest infection. Well described in the rheumatology literature, ACP is little discussed in recent radiology literature. The recognition of this disease process on imaging studies may circumvent unnecessary diagnostic tests and therapy in patients having this self-limited process. We present a pictorial review of several patients with acute calcific periarthritis of the hand, discussing the pathophysiology, imaging findings, differential considerations as well as the clinical presentation and course of this interesting disease.

Key Issues: We present several patients with ACP of the hand. There will be a discussion of the clinical and radiographic findings, differential diagnosis, pathophysiology and outcome of this disease. The discussion will have application to other joints about the body where ACP may occur.

Format: The format will be didactic. The organization will be by way of clinical examples and pictorial display.

Teaching Points: The participant/reader will be made aware of acute calcific periarthritis, its pathophysiology as well as its clinical and imaging characteristics. Recognition of ACP by the radiologist may prevent unnecessary procedures and therapy. The participant/reader will learn the differential diagnosis of acute calcific periarthritis and how to differentiate each entity by clinical and radiologic findings.

E283. Benign Wrist Masses Diagnosed on Radiologic Studies

Huang B.; El-Sherief A.; Timberlake J. C.; Maragh M.; Seo G.; Monu J. U. University of Rochester School of Medicine and Dentistry, Rochester, NY

Address correspondence to B. Huang (brady_huang{at}urmc.rochester.edu)

Background: Evaluation of the wrist joint is performed for various reasons, but more commonly for diagnosis of painful or mass lesions. Plain radiographs are rarely sufficient to diagnose mass lesions. However, additional imaging such CT, US and MRI can be used to make a definite diagnosis. The purpose of this exhibit is to illustrate some usual and unusual imaging findings in the diagnosis of wrist mass lesions.

Key Issues: Various masses in the wrist including soft tissue and bony mass lesions with characteristic radiologic features will be presented using a multimodality approach. The clinical presentations, radiologic evaluations, differential diagnosis and the basis for imaging diagnosis for these various conditions will be illustrated.

Format: The presentation will be interactive and a combination of plain radiographs and CT, US, and MR images will be used to illustrate appropriate work-up for wrist mass lesions. Leading questions will be used to advance the learning process to an appropriate and correct diagnosis

Teaching Points: The viewer will: 1. Learn a simple working anatomy of the wrist 2. Develop a systematic approach to the work-up and evaluation of wrist masses 3. Become familiar with some wrist mass lesions with characteristic features, locations they tend to occur and diagnostic features.

E284. Plain Radiograph, CT, US, and MRI Features of the Normal and Abnormal Proximal Rectus Femoris Musculotendinous Unit

Gyftopoulos S.¹; Rosenberg. S.³; Miller T. T.²; Schweitzer M. E.³ 1. Beth Israel Medical Center, New York, NY; 2. North Shore University Hospital, Manhasset, NY; 3. NYU Hospital for Joint Diseases, New York, NY

Address correspondence to S. Gyftopoulos (Soterios20{at}gmail.com)

Background: The unusual anatomy of the proximal rectus femoris (PRF) musculotendinous unit (MTU) has only been minimally explored in the literature. The PRF has 2 proximal tendinous origins and 3 proximal musculotendinous junctions which are susceptible to 5 distinct injury patterns affecting different age groups. Distinguishing these patterns of injury is paramount in making the correct diagnosis and applying the appropriate treatment.

Key Issues: Normal Anatomy-The rectus femoris muscle has 2 proximal tendinous origins, a direct head arising from the anterior inferior iliac spine and an indirect head arising from the superior acetabulum. The direct and indirect heads coalesce a few centimeters below their origin and form the proximal MTU. Subsequently, the direct head blends with the anterior rectus femoris fascia forming a superficial MTU while the indirect head dives into the belly of the muscle forming the deep MTU. Pathology-Five distinct patterns of injury occur at the PRF. 1. Osseous avulsion injuries in adolescents, prior to closure of the apophysis. 2. Avulsion of the direct tendinous head off the anterior inferior iliac spine. 3. Avulsion of the indirect head off the acetabular insertion. 4. Avulsion at the proximal musculotendinous junction and 5. Strain at the deep musculotendinous junction. This exhibit will demonstrate the unusual anatomy of PRF and its associated injury patterns utilizing plain radiographs, US, CT, and MRI.

Format: The exhibit will be a didactic presentation divided into 3 sections: A. The first section will focus on the anatomy and imaging appearance of the normal proximal rectus femoris musculotendinous unit. B. The second section will discuss the 5 distinct injuries of the proximal rectus femoris musculotendinous unit as illustrated by plain radiographs, US, CT, and MRI. C. The third section will compare the utility of the various imaging modalities applied for assessing injuries of the proximal rectus femoris musculotendinous unit.

Teaching Points: Familiarize the radiologist with: 1. The normal anatomy and the clinical presentations of the 5 patterns of injury of the proximal rectus femoris. 2. The plain radiography, US, CT, and MRI imaging features of normal and abnormal proximal rectus femoris musculotendinous units. 3. The merits and disadvantages of the various imaging modalities in illustrating pathology of the proximal rectus femoris.

E285. Flexor Femoris Muscle Complex (FFMC): Spectrum of Injury

Hancock C. R.²; Sanders T.¹; Zlatkin M. B.¹; Clifford P. D.²; Pevsner D.² 1. National Musculoskeletal Imaging Inc., Weston, FL; 2. University of Miami Department of Radiology, Miami, FL

Address correspondence to C. Hancock (chancock50{at}gmail.com)

Background: The flexor femoris muscle complex (FFMC) or flexor group of the thigh is also known as the hamstring muscle complex and more commonly as the "hamstrings". Three muscles comprise this group: biceps femoris, semitendinosis, and semimembranosis. The FFMC is a frequent site for injury being recognized more often in today's imaging climate; thought to be attributed to the increase in our society's pursuit of high energy athletic activities and to the greater mobility of our active seniors. Athletes who participate in running, jumping, and kicking are prone to strain-type injuries, while avulsion-type injuries are more commonly seen in those who hurdle, ice-skate, dance, waterski, or weight lift. The FFMC crosses both the hip and knee joints. This anatomic requisite is thought to account for the increased prevalence of injury to the FFMC relative to the injury rate of muscles which cross only a single joint. A three tiered grading system has been described, depicting the severity of muscular injury: Grade I - strain, Grade II - partial tear, Grade III - complete tear. The tendons of the members of the FFMC may demonstrate tendinosis, partial tear, or complete tear. The tendons may also avulse from their proximal origin on the ischial tuberosity with or without an osseous fragment or from their distal insertion on the tibia. Correctly identifying and grading FFMC muscular, tendinous and apophyseal avulsion injuries is critical for planning effective management. The decision to treat injured patients with conservative medical management versus surgical correction often rests upon the musculoskeletal radiologist's correct interpretation and subsequent characterization. The following cases represent the full spectrum of FFMC injuries, with examples of proximal, mid and distal injuries.

Key Issues: This exhibit will allow the viewer to become proficient in the correct and precise interpretation of flexor femoris muscle complex injuries. The entirety of the FFMC will be covered from the origin at the ischial tuberosity to the insertion on the proximal tibia. MRI is used extensively in this analysis.

Format: The format will entail a case-based system with a short didactic summary following each case. This exhibit will cover the gamut of flexor femoris muscle injuries from origin to insertion.

Teaching Points: The viewer will be able to correctly identify the location, extent, degree, and chronicity of the spectrum of flexor femoris muscle complex injuries after completion of this exhibit.

E286. Femoral Acetabular Impingement Syndrome: Indirect MR Arthrographic Correlation with Arthroscopy

Hancock C. R.²; Sanders T. G.¹; Zlatkin M. B.¹; Pevsner D.² 1. National Musculoskeletal Imaging Inc., Weston, FL; 2. University of Miami Department of Radiology, Miami, FL

Address correspondence to C. Hancock (chancock50{at}gmail.com)

Objective: Femoral acetabular impingement (FAI) may be surgically corrected and its early diagnosis is crucial in preventing the severe degenerative sequelae that may accompany long standing repetitive impingement. The purpose of this study was to determine if there is a significant difference in the diagnostic accuracy of FAI, labral tear, and chondromalacia between conventional and indirect MR arthrography with arthroscopic evaluation.

Materials and Methods: 14 patients with conventional and indirect MR arthrography with arthroscopic intervention were collected over a period of 18 months. MR studies were performed with a 1.5-T magnet consisting of sagittal T2, axial T2 fat sat, and coronal T1 fat sat. Whole pelvis coronal T1 and STIR sequences were also obtained. Patients were then injected with gadolinium contrast intravenously and were instructed to exercise for 15 minutes. Post-gadolinium fat saturated T1 sequences were then obtained in three planes. Arthroscopic procedures were performed by 2 orthopedic surgeons familiar with the hip. These cases were retrospectively reviewed by consensus by two musculoskeletal radiologists blinded to the arthroscopic findings. Cases were examined for femoral acetabular impingement changes, labral tears, and chondromalacia. Pre and post-gadolinium images of the labrum were compared for differences and/or change in diagnosis. Comparison was made to the operative and MR findings for statistical analysis.

Results: Femoral acetabular impingement (FAI) syndrome changes were seen in all patients evaluated by MR with the distribution of 11/14 cam type (prominent anterior bump) 1/14 pincer type (osteophytic), and 2/14 combination pincer and cam type. Conventional MR demonstrated 11/14 labral tears while indirect MR revealed 100%, 14/14 labral tears (one tear confirmed on MR not confirmed on arthroscopy). The extent of the labral tears were correctly identified in 12/14 patients (a second site was identified in one patient as seen on arthroscopy). Chondromalacia to the femoral head was correctly identified in 8/14 and for both the femoral head and acetabulum in 6/14 patients. Moderate to high grade chondromalacia was missed in 4 of 14 patients with labral tears.

Conclusion: Indirect MR arthrography is a highly valuable adjunct for the evaluation of FAI and improves the diagnostic accuracy and interpretive confidence for the presence of labral pathology. Indirect MR arthrography did not significantly improve the detection of chondromalacia.

E287. Ultrasound Characteristics of Morel-Lavallée Lesions

Neal C.; Jacobson J.; Brandon C.; Kalume Brigido M.; Morag Y.; Girish G. University of Michigan, Ann Arbor, MI

Address correspondence to C. Neal (hawleyc{at}med.umich.edu)

Objective: To characterize and describe the variable ultrasound appearances of Morel-Lavallée lesions.

Materials and Methods: IRB approval was obtained. Retrospective search of radiology records identified 21 ultrasound examination reports from 15 patients that described a fluid collection about the hip or thigh after trauma. Ultrasound images and available ultrasound video clips were retrospectively reviewed and each fluid collection was characterized with regard to shape, echogenicity, uniformity, borders, location, compressibility, and flow on color or power Doppler imaging. Correlation was made to clinical data.

Results: The 15 patients (11 male, 4 female) had an average time interval from trauma to ultrasound examination of 13 months (range 1 week to 4 years). The average largest dimension of the fluid collection was 8 cm (range 3–17 cm) and all were located between the deep fat and adjacent fascia over the hip and thigh region. With regard to shape, 60% (12/20) were fusiform, 25% (5/20) were flat, and 15% (3/20) were lobular; all lobular collections were < 2 weeks old and flat collections were > 6 months old. With regard to echogenicity, 71% (15/21) were hypoechoic and 39% (6/21) were anechoic, with no trend relative to age of fluid collection. The fluid collections were heterogeneous in 62% (13/21) and homogeneous in 38% (8/21); while homogeneous collections were all at least 6 months old. One case showed septations while another showed nodularity within the fluid collection. With regard to borders, 71% were smooth and 39% were irregular; most of the irregular collections were < 4 weeks old while smooth collections were > 18 months old. All fluid collections were compressible. Minimal blood flow was detected at the periphery of one fluid collection.

Conclusion: Although Morel-Lavallée lesions have a characteristic location, a variable sonographic appearance exists. Fluid collections < 1 month old tend to be lobular, heterogeneous, with an irregular border, which may simulate other fluid collections or abscess. Fluid collections at least several months old are more likely flat or fusiform in shape and homogeneous with a smooth border characteristic of a Morel-Lavallée lesion.

E288. Pelvic Ring Insufficiency Fractures Revisited: Pitfalls in Diagnosis and How to Avoid Them

Peh W. C.¹; Muttarak M.² 1. Alexandra Hospital, Singapore; 2. Chiang Mai University, Chiang Mai, Singapore

Address correspondence to W. Peh (wilfred{at}pehfamily.per.sg)

Background: Insufficiency fractures of the sacrum and bony pelvis are now well-recognized entities that are typically seen in elderly women with post-menopausal osteoporosis. The diagnosis is usually made when bone scintiscans show the typical Honda-H sacral uptake pattern, sometimes with concomitant pubic uptake. Atypical scintiscan uptake patterns or the MR imaging appearances of these fractures are less easy to recognize and may be misdiagnosed. This exhibit highlights the diagnostic pitfalls of less common appearances of pelvic ring insufficiency fractures seen on various imaging modalities.

Key Issues: Radiographs may show lytic, sclerotic or mixed lesions mimicking tumors or infection, particularly in less common sites such as the acetabulum or ilium. Incomplete sacral scintiscan uptake patterns such as the partial-H, unilateral or bilateral bar and linear dot pattern may mimic metastases, particularly in patients who had undergone irradiation for pelvic cavity tumors. Metastases located close to an insufficiency fracture may be undetectable on scintiscans. On MR imaging, fractures with adjacent edema often appear as patchy T1-isointense and T2-hyperintense areas that may also enhance, mimicking metastases. Tips to avoid diagnostic pitfalls include: careful correlation with clinical history, looking for combination of concomitant pelvic ring scintiscan uptake, linear uptake pattern, fluid signal within fracture on MR imaging, and performing CT in doubtful cases.

Format: Didactic. Multimodality imaging of appearances of pelvic ring insufficiency fractures that may potentially cause diagnostic problems.

Teaching Points: 1. To be aware of the imaging features of insufficiency fractures of the pelvic ring that may result in misdiagnosis. 2. To recognize examples of these fractures on radiographs, bone scintiscans and MR imaging. 3. Know how the correct diagnosis can be made in these cases, hence avoiding potential diagnostic pitfalls.

E289. Traumatic and Stress Fractures of the Hip—A Review

Yadavalli S.; Vartanian S.; Koshy P. G. William Beaumont Hospital, Royal Oak, MI

Address correspondence to S. Yadavalli (yadavalli{at}comcast.net)

Background: Hip fractures are often seen in the elderly who present to the emergency department with inability to bear weight or with a painful hip after a fall. These are often occult on plain radiographs. Stress fractures are also a significant cause of hip pain in both the elderly and in the athletic patients. The causes of stress fractures of the proximal femur include fatigue fractures in the athletes, insufficiency fractures in osteoporotic patients, and pathologic fractures. The location of traumatic and stress fractures in the proximal femur can be varied. In addition these fractures may not be isolated. The benefits of MRI in the diagnosis of occult fractures have been discussed in both orthopedic and radiology literature. The key to a favorable outcome with reduction in associated morbidity and mortality and cost relies on early diagnosis and treatment.

Key Issues: To achieve a favorable outcome it is important to recognize the various presentations of occult fractures. This exhibit will review different types of traumatic proximal femoral fractures with a discussion of some of the classification systems. The discussion of stress fractures in the proximal femur will include the causes, locations and clinical implications of the different types of fractures. Examples of both traumatic and stress fractures of the proximal femur will be presented with radiographs, CT and MR images.

Format: The exhibit will be didactic with a quiz at the end. The didactic portion will be organized by pathology. Examples of each fracture type will be included along with a brief discussion. Radiographs, MRI, CT, and bone scintigraphy will be used to illustrate the pathology. The discussion will also include the clinical implications and complications related to delayed or no treatment.

Teaching Points: 1. Early diagnosis of occult hip fractures. 2. Recognition of other associated pathology.

E290. Isolated Fibular Fracture Without Overt Instability: Which Ligaments are Interrupted

Cheung Y. Y.; Goodwin D.; Koval K. J. Dartmouth-Hitchcock Medical Center, Lebanon, NH

Address correspondence to Y. Cheung (yvonne.cheung{at}hitchcock.org)

Objective: To retrospectively evaluate with magnetic resonance (MR) imaging, the pattern of ligamentous injury in patients with distal fibular fractures without overt instability

Materials and Methods: This HIPAA-compliant study had institutional board approval and patient consent was exempted. MR imaging of 23 patients (12 men; 11 women; mean age, 40.7 years; age range, 16–67 years) with acute isolated fibular fracture (Weber B) were retrospectively reviewed. Mean time to MR imaging was 7.4 days (range: 0–18 days). Selection criteria included widened medial clear space (MCS) only on stress radiographs but not on routine mortise ankle radiographs. Two musculoskeletal radiologists, by consensus, recorded the integrity (intact, partial tear, complete tear, indeterminate) of 4 sets of ligaments (syndesmotic, deltoid, lateral and sinus tarsi ligaments) seen on MR exams. The MCS distance on both mortise view of the ankle and stress radiographs were recorded. The MR findings were sequentially analyzed to determine the frequency of ligamentous injury.

Results: All anterior inferior tibiofibular (AITF) and deep deltoid (DD) ligaments are injured. The frequencies of ligamentous injuries (partial and complete tears) are: 100% of AITF, 47.8% of interosseous membrane (IOM), 60.9% of posterior inferior tibiofibular ligament (PITF), 100% of deep deltoid (DD), 82.6% of tibiospring ligament (TS), 82.6% of tibiocalcaneal ligament (TC), 69.6% of anterior talofibular ligament (ATAF), 21.7% of calcaneofibular ligament (CF), 26.1% of posterior talofibular ligament (PTAF), 34.8% of cervical ligament (CL) and 30.4% of interosseous talocalcaneal ligament (ITCL).

Conclusion: The management of isolated fibular fractures that are not overtly unstable remains controversial. The pathologic anatomy of this subset of patients has been inferred by cadavaric and outcome studies, but has never been reliably determined by imaging. For example, the integrity of the deep deltoid ligament, a prime stabilizer of the ankle, is indirectly inferred by the medial clear space (MCS) on radiography. Our investigation documented the integrity of deltoid ligaments along with injury to other sets of ligaments. Recognition of the extent of ligamentous injury as displayed on the MR images allows stratification of injury and may help to assess treatment outcome.

E291. Helical CT and 3D Reformations of Tibial Plateau Fractures: What the Orthopedic Surgeon Needs to Know

Kesala R. L.; Marcantonio D.; Fessell D. P.; Wiater B.; Wiater P.; Nowinski G.; William Beaumont Hospital, Royal Oak, MI

Address correspondence to R. Kesala (rkesala{at}pol.net)

Background: Tibial plateau fractures were originally termed `bumper' or `fender' fractures, based on the mechanism of injury. Additional mechanisms of injury for tibial plateau fractures involve axial loading or torque. Although severe fractures are often treated surgically, both surgically and nonsurgically treated fractures are at high risk for developing posttraumatic osteoarthritis from a combination of ligamentous injuries, alteration of mechanical forces, and cartilage damage.

Key Issues: Helical CT and 3D reformations provide high resolution, multiplanar imaging for the detection, classification, and preoperative planning of tibial plateau fractures. Key technical factors for optimizing helical CT and 3D reformations will be reviewed. The frequently utilized Schatzker classification will be illustrated with diagrams and CT cases, since the correct fracture classification directly impacts treatment. The quantification of depression and displacement of fracture fragments at the articular surfaces, which also impacts treatment, and their associated soft tissue injuries, will be illustrated in detail. In addition, the surgical treatment for each classification will be shown.

Format: The computer-based educational exhibit will be in an interactive format with the participant, and organized by the classification of tibial plateau fractures with helical CT imaging and illustrations.

Teaching Points: 1. Learn the technical factors necessary for optimal helical CT and 3D images. 2. Illustrate the classification of tibial plateau fractures by CT and by diagrammatic images. 3. Understand the significance of displacement and depression of fracture fragments involving the articular surfaces, and their impact on treatment. 4. Obtain a thorough understanding of the precise information required by the orthopedic surgeon for proper treatment planning.

E292. MR Imaging of Bone Bruising of the Knee and Associated Findings: Five Different Mechanisms of Knee Injury

Harada Y.; Tokuda O.; Matsunaga N. Yamaguchi University School of Medicine, Ube, Japan

Address correspondence to Y. Harada (yuuko-ygc{at}umin.ac.jp)

Background: The term "bone bruising" has been used synonymously and is thought to represent a spectrum of occult injuries, including bleeding and edema due to microscopic compression fractures of cancellous bone. The distribution of bone bruising often provides valuable clues to the associated soft-tissue injuries. Knee injury patterns are often divided into five types: pivot shift injury, dashboard injury, hyperextension injury, clip injury, and lateral patellar dislocation. The mechanism of injury can be determined by learning the distribution of bone bruising, which enables one to predict with accuracy the specific soft-tissue injuries.

Key Issues: The pivot shift injury occurs when a valgus load is applied to the knee in flexion combined with external rotation of the tibia or internal rotation of the femur. With pivot shift injury, the bone bruising involved the posterior aspect of the lateral tibial plateau and the midportion of the lateral femoral condyle, and anterior cruciate ligament (ACL) tear was found. Dashboard injury occurs when force is applied to the anterior aspect of the proximal tibia in a flexed position. With dashboard injury, the bone bruising was seen at the anterior aspect of the tibia, and posterior cruciate ligament (PCL) tear was found. With hyperextension injury, the anterior aspect of the tibial plateau strikes the anterior aspect of the femoral condyle. The kissing contusion pattern of bone injury was found. PCL and meniscal tear was found in this type. The clip injury is a contact injury that occurs after a valgus stress is applied to the knee with mild flexion. With clip injury, bone bruising was seen in the lateral femoral condyle, and medial collateral ligament tear was found. With lateral patellar dislocation, bone bruising involved the anterolateral aspect of the lateral femoral condyle and the inferomedial aspect of the patella, and medial patellofemoral ligament tear was found.

Format: The format will be a didactic PowerPoint presentation. Five specific injury patterns of the knee will be described. MR imaging will provide examples of each specific injury pattern.

Teaching Points: To know the typical patterns of bone bruising and associated abnormal soft-tissue findings resulting from five mechanisms of knee injuries. By learning the distribution of the bone bruising on MR images, the radiologists can determine the type of injury and efficiently evaluate associated soft-tissue injuries.

E293. Medial Patellofemoral Ligament in Tibiofemoral Dislocation: The Forgotten Connection?

Kreeger M.; Oostveen R. J.; Wissman R. University of Cincinnati Department of Radiology, Cincinnati, OH

Address correspondence to M. Kreeger (kreegermc{at}yahoo.com)

Objective: Identify the MRI findings of medial patellofemoral ligament (MPFL) injuries and injury to other medial soft tissue restraint of the patella in the setting of tibiofemoral dislocations.

Materials and Methods: After institutional review board approval was obtained, a retrospective search of all radiology reports at our institution was performed looking for patients with a history of knee dislocations and magnetic resonance (MR) imaging of the knee over a five year period. MR images were independently reviewed by two radiologists. The medial soft tissue restraints of the patella were evaluated using previously described criteria for patients with prior patellofemoral dislocations. This included identifying disruptions and/or irregularity of the MPFL, and vastus medialis oblique (VMO), as well as edema and elevation. Associated findings were also identified.

Results: The majority of patients showed evidence of some irregularity of the MPFL, ranging from waviness and irregularity, to frank disruption. Most tears occurred at the femoral origin, similar to that seen in patellofemoral dislocations. Although previously suggested to be continuations of medial collateral ligament (MCL) tears, MPFL injuries can occur with an intact MCL. VMO elevation and edema increased with increasing MPFL injury.

Conclusion: MPFL tears are not uncommon in the setting of tibiofemoral dislocations. Ligament failure usually occurs at the femoral attachment, similar to that seen in patellofemoral dislocations. Additional studies are needed to quantify the morbidity associated with this injury especially since patellofemoral dislocations have occurred in the setting of tibiofemoral dislocation and can and have gone unrecognized. MPFL is a major stabilizer of the patella. There is increasing interest in repair/reconstruction. Preoperative identification of location and extent of injury is essential.

E294. 1.5-T MRI Evaluation of Patients with Lateral Meniscal Tears for Subsequent Knee Cartilage Abnormalities

Kamireddi A.²; Higgins L.¹; Major N.² 1. Brigham and Women's Hospital/Department of Orthopedics - Chief of Sports Medicine, Boston, MA; 2. Duke University Hospital/Department of Radiology - Musculoskeletal Division, Durham, NC

Address correspondence to A. Kamireddi (ak3{at}duke.edu)

Objective: Retrospective analysis of patients with acute lateral meniscal (LM) tears to evaluate the rate of follow-up adequate to evaluate cartilage damage in the postinjury period and note evidence of subsequent cartilage damage in those that received follow-up.

Materials and Methods: Thirty-two patients (71.9% male) formed the study population. Inclusion criteria were patients with acute LM tears < 40 years of age with arthroscopic confirmation of LM tears. These patients were then analyzed to see if they received follow-up (an MRI or arthroscopy) adequate to evaluate cartilage status in the lateral compartment of the knee in the postoperative period. Patients were evaluated for degenerative chondral lesions in this period.

Results: 8 of 32 patients (25.0%) received follow-up as defined above. Of those patients, 7 of 8 (87.5%) showed a deteriorating cartilage status in the postoperative period. These new cartilage defects presented at a mean interval of 1.7 years. 4 of 7 (57.1%) patients initially presented with radial tears. 6 of 7 (85.7%) patients and 3 of 7 (42.9%) patients had focal defects in the lateral femoral condyle and the lateral tibial plateau, respectively.

Conclusion: Retrospective analysis demonstrated that patients with acute LM tears have a low rate of follow-up adequate to evaluate cartilage damage in the postinjury period. Our series indicates that patients < 40 years of age with acute LM tears can develop degenerative cartilage lesion progression in the postoperative period. A prospective study with increased follow-up rates will help identify patients with a deteriorating cartilage status allowing for potential cartilage therapies.

E295. Don't Be Afraid of the Knee MRI

Nutter K.; Derr D.; Oliver J. University of Mississippi Medical Center, Jackson, MS

Address correspondence to K. Nutter (katnutter{at}aol.com)

Background: Interpretation of an MRI examination of a joint can be a daunting task without a well-organized, inclusive but succinct, pattern approach. Following a concise normal dictation as a template for interpretation of each exam is a helpful way for radiology residents in training to thoroughly evaluate the entire study without risk of omission of important findings. The use of such a dictation provides a reproducible search pattern for reliable evaluation of normal anatomy as well as accurate identification of normal variants and pathologic findings. Additionally, this approach provides a predictable, organized report for referring clinicians who will learn to scan the report for a pattern of key findings the way the dictating radiologist scans the images for patterns of abnormality.

Key Issues: This exhibit will provide a recommended basic dictation for a knee MRI examination just as we routinely give the residents rotating in the musculoskeletal division at our institution. The exhibit will include examples of normal anatomy and pertinent abnormal findings to correlate with each sentence in the normal dictation. Tips will also be included concerning a basic utilization of MR sequences for the best definition of anatomy and typical pathology encountered in the knee.

Format: This exhibit will be formatted as a didactic lecture outlined by "sentences" of the recommended dictation for a knee MRI examination with normal findings.

Teaching Points: The objective of this exhibit is to provide a basic, easily memorizable, dictation for a knee MRI examination that can be used as a template for efficient, complete interpretation of this study. This exhibit will be useful to residents in training as well as radiologists in practice in need of such an organized, pattern approach.

E296. Assessment of Knee Joint with Ultrasound and Power Doppler Sonography

Abdel Razek A.; Fouda N. Mansoura Faculty of Medicine, Mansoura, Egypt

Address correspondence to A. Abdel Razek (arazek{at}mans.eun.eg)

Background: The knee joint is a common site for various traumatic and nontraumatic pathologic conditions. Assessment of different structures of the knee lesions is essential for treatment planning. MR imaging is commonly used for imaging of knee joints; however, ultrasound with power Duplex is a simple noninvasive, cheap method for evaluation of the knee joint.

Key Issues: High resolution ultrasound and power Doppler sonography of the knee joint were done for 129 patients. The injured ligaments appeared as thickened and hypoechoic. Collateral ligaments were better delineated than cruciate ligaments. It differentiates tendenopathy from tendon tear and detection muscle contusion. Meniscal tear uncommonly differentiated from meniscal degeneration. It can detect extent and delineate cystic lesions around the knee joint. It shows synovial thickening and hyperemia in rheumatoid arthritis, cartilage thinning in osteoarthritis, and helped to differentiate infective from noninfective synovitis. It can detect vascularity within bony and soft tissue tumors around the knee. We conclude that ultrasound with power Doppler sonography is a safe, inexpensive, noninvasive imaging method for assessment of knee joint.

Format: The information will be in didactic format. First describing normal ultrasound anatomy, and then ultrasound examination technique. Pathologic conditions for each area will follow the didactic format.

Teaching Points: The reviewer will: 1. Be able to understand normal ultrasound of the knee joint 2. Be able to perform ultrasound and power Duplex examination of the knee joint 3. Be familiar with ultrasound features of common pathology involving the knee joint.

E297. Interactive Computer-Based Magnetic Resonance Imaging of the Knee with Emphasis on MR Anatomy, Pathology and Arthroscopic Correlation

Robbin M. R.¹; Zenooz N. A.¹; Victoroff B.¹; Oneton J.²; Zell S.²; Bugnone A.² 1. Case Western Reserve University, Cleveland, OH; 2. Mount Sinai Medical Center, Miami Beach, FL

Address correspondence to M. Robbin (robbin{at}uhrad.com)

Background: While radiographic imaging of the knee is an essential component of the evaluation of patients with knee pain and trauma, MRI has become the most accurate noninvasive method for diagnosing intra-articular pathology. Meniscal and ligamentous tears are rather common among athletes and predispose the joint to early osteoarthritis. In addition to history and physical examination, diagnosis of knee pathology is often made or confirmed with imaging studies. The high sensitivity and specificity of MRI for diagnosis of soft tissue abnormalities has made it the modality of choice for assessing articular cartilage, meniscal and ligamentous injuries. MRI is also considered the most useful imaging tool for the evaluation of muscular injuries, bone marrow contusion, and radiographically occult fractures.

Key Issues: This computer-based exhibit will provide a comprehensive review, in an interactive format, of MR anatomy and mechanisms of injury, with emphasis on the MR appearance of common meniscal and ligamentous injuries. A discussion of reviewed cases with arthroscopic and radiographic correlation will be presented.

Format: More than 1000 MRI cases of the knee were reviewed and analyzed. Images were uploaded into an interactive exhibit to display the normal anatomy classified into three broad categories: Examples of normal anatomy, sports-related injuries, and internal derangement. Cases will be presented in an interactive format with explanations of the imaging findings and pathology.

Teaching Points: (1) To review normal MR anatomy of the knee joint with correlation to common pathology. (2) To depict common sports-related injuries and internal derangements of the knee. (3) To correlate MR findings with radiographic abnormalities.

E298. Magnetic Resonance Imaging of Instability of the Anterior Cruciate Ligament

Nutter K.; Derr D.; Oliver J. University of Mississippi Medical Center, Jackson, MS

Address correspondence to K. Nutter (katnutter{at}aol.com)

Background: The normal anterior cruciate ligament (ACL) demonstrates a variable MRI appearance due to the oblique course of the ligament and the configuration of the two fiber bundles and intermixed fat within the substance of the ligament. Developing an eye for the normal ACL takes review of many cases. In the same way, characterizing injury of the ACL can be difficult due to the variety of abnormal appearances of the ligament which include thickened morphology to complete transection with a large gray area of "partial tears" in between. Attempting to date an injury of the ACL as acute or chronic adds an even deeper layer of complexity. Assessing for secondary signs of ACL insufficiency on MRI can be a helpful way of determining clinical significance of an ACL injury despite the variability in MRI appearance with injury.

Key Issues: This exhibit will define and provide MRI examples of the various normal presentations of the anterior cruciate ligament. Additionally, this exhibit will include a review of the spectrum of abnormalities encountered in the injured ACL. We will emphasize the importance of evaluation for secondary signs of ACL insufficiency including, but not limited to, anterior tibial translation, overhanging of the posterior horns of the menisci, and straightening of the normal obliquity of the lateral collateral ligament.

Format: This exhibit is structured in didactic format with numerous imaging examples illustrating the spectrum of normal to abnormal findings in the anterior cruciate ligament. Additionally, this exhibit will contain instruction about and illustration of secondary signs of anterior cruciate ligament insufficiency which may help determine the clinical significance of the imaging findings in the ACL.

Teaching Points: Objectives: 1. Review MR appearance of normal anterior cruciate ligament. 2. Review spectrum of imaging abnormalities encountered with ACL injury including intrinsic findings in the ligament and secondary signs within the knee suggestive of clinically significant insufficiency of the ligament.

E299. ABC's of the ACL

Bining H. J.; Andrews G.; Forster B. B. University of British Columbia, Vancouver, Canada

Address correspondence to H. Bining (hjsbining{at}yahoo.ca)

Background: The anterior cruciate ligament (ACL) is a critical structure in maintaining knee stability. The mainstay of imaging evaluation of the ACL and supportive ligamentous structures is magnetic resonance (MR) imaging, which is routinely used to direct surgical intervention. Knowledge of the normal appearance of the ACL, variants and the breadth of pathologic processes is important for radiologists in order to ensure appropriate patient management.

Key Issues: The normal MRI appearance of the ACL will be described, along with typical imaging pitfalls. The typical MR appearance of acute and chronic full thickness tears will be reviewed. The controversial entity of partial tears will be discussed, as will indirect signs of an ACL tear and posterolateral corner injury. ACL cystic mucoid degeneration and ACL-related ganglia will be addressed. Another important aspect of ACL imaging is evaluation of the postoperative ACL neoligament. The normal appearance of this structure will be reviewed with relationship to current surgical techniques. Neoligament tears will be illustrated. As well, "cyclops" lesion and the rare tibial tunnel cyst will be demonstrated.

Format: Didactic/pictorial essay.

Teaching Points: Both the native and reconstructed ACL very commonly undergo traumatic injury. Knowledge of the MR appearance of the normal ligament and the breadth of pathology it can harbor will assist radiologists in providing optimum patient care.

E300. Relationship Between Mucoid Hypertrophy of the Anterior Cruciate Ligament (ACL) and Morphology of the Intercondylar Notch: MRI and Arthroscopy Correlation

Cha J.; Lee S.; Shin M.; Choi B.; Bin S. Asan Medical Center, Seoul, South Korea

Address correspondence to J. Cha (cha0409{at}hanmail.net)

Objective: The purpose of this study was to evaluate the relationship between mucoid hypertrophy of the ACL and morphologic change of the intercondylar notch.

Materials and Methods: We retrospectively reviewed 47 patients with arthroscopic notchplasty during 27 months; all of them had a knee MRI. We also reviewed 33 patients with knee arthroscopy without ACL lesion for the arthroscopic control group and 25 patients with normal MRI for the normal control group. The arthroscopy findings were divided into four groups as follows: group 1. 18 patients of mucoid hypertrophy of the ACL with notchplasty, group 2. 29 patients of degeneration of the ACL with notchplasty, group 3. 33 patients of arthroscopy without ACL lesion or notch narrowing, and group 4. 25 patients had no abnormality on knee MRI. 2 musculoskeletal radiologists retrospectively reviewed all MRI exams. The intercondylar notch width, angle and area were recorded on axial MRI at the mid line of the Blumensaat's line as identified on the sagittal view. Furthermore the diameter of the ACL was recorded on coronal MRI at the posterior end of the Blumensaat's line. Intercondylar notch width, angle, area, and diameter of the ACL were compared between each group

Results: Mean diameter of the intercondylar notch width, angle and area and diameter of the ACL: group 1–15.16 mm/49.51/236.47 mm²/8.88 mm; group 2–16.42 mm/50.43/255.93 mm²/6.88 mm; group 3–9.25 mm/52.88/323.44 mm²/4.75 mm; and group 4–20.34 mm/51.35/350.77 mm²/4.53 mm. Notch width, area and ACL diameter were significantly different between group 1, group 2, group 3 or group 4 (p < 0.05). Notch angle was not significant between each group.

Conclusion: Narrow notch width and area play an important role of the impingement of ligament to the roof and lateral wall of the notch. It could be one of the important factors developing the mucoid hypertrophy of the ACL.

E301. Popliteal Artery Assessment on Routine Knee MRI: Comparison with Angiography

Inampudi R.; Jacobson J. A.; Dasika N.; Sabb B.; Girish G.; Kim S.; Caoili E. University of Michigan, Ann Arbor, MI

Address correspondence to R. Inampudi (radhai{at}umich.edu)

Objective: To determine whether popliteal artery abnormalities are identified with routine MRI of the knee.

Materials and Methods: IRB approval was obtained. Radiology report search from 1998 through March 2006 identified 61 consecutive subjects who had MRI of the knee and lower extremity angiography. After excluding MRI examinations with artifact or nonroutine knee imaging, 35 knees from 35 subjects remained. Angiograms from these subjects were retrospectively reviewed by an interventional radiologist and categorized as normal, stenosis, occlusion, deviation, dissection, and aneurysm as the gold standard. MRI examinations were retrospectively reviewed by four musculoskeletal radiologists in consensus for similar abnormalities. At MRI, the criteria were as follows: stenosis = narrowing of the normal popliteal flow void; occlusion = loss of flow void; deviation = popliteal artery location lateral or medial to the femoral notch; dissection = visualization of an intimal flap; aneurysm = dilation greater than 7 mm. Correlation was assessed with Fisher's exact test.

Results: Angiography confirmed the popliteal artery in the 35 subjects as normal in 24, stenosis in three, occlusion in four, dissection in two, and aneurysm in two. There was a significant positive correlation between MRI results and angiography results (p = 0.0004). MRI correctly identified the popliteal artery as normal in 20/24 (83%), stenosis in 1/3 (33%), occlusion in 3/4 (75%), deviation in 0/2 (0%), and aneurysm in 0/2 (0%). Of the four occluded popliteal arteries at angiography, MRI diagnosed three as occluded, one as dissection, and none as normal.

Conclusion: There was positive correlation between MRI and angiographic evaluation of the popliteal artery with routine knee MRI, with highest correlation in diagnosis of normal popliteal artery and occlusion. The popliteal artery should be routinely assessed, especially after trauma when there may be concern for occlusion.

E302. Signal Abnormality of Hoffa's Fat Pad as a Sign of Knee Synovitis

Gleason J. D.; Jacobson J. A.; Brandon C.; Kim S.; Caoili E.; Wojtys E. University of Michigan, Ann Arbor, MI

Address correspondence to J. Gleason (johnglea{at}med.umich.edu