| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Clinical Observations |
1 Department of Radiology, Affiliated Hospital of North Sichuan Medical College,
Wenhua Road 63, Nanchong, Sichuan 637000, P.R. China.
2 Department of Anatomy, North Sichuan Medical College, Nanchong, Sichuan
637000, P.R. China.
3 Department of Pathology, North Sichuan Medical College, Nanchong, Sichuan
637000, P.R. China.
Received November 14, 2004;
accepted after revision March 22, 2005.
Supported by grant 30370436 from the National Nature Science Foundation of
China.
Abstract
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
CONCLUSION. MRI can show the celiac ganglia accurately in cadavers when the ganglia are large and labeled with gadolinium. The findings in cadavers can be a reference for identifying the celiac ganglia in vivo.
Keywords: abdomen • anatomy • celiac ganglia • MRI
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Neural invasion is an important prognostic factor in pancreaticobiliary malignancy [2]. Bhuiya et al. [3] reported that the overall incidence of perineural invasion in resected specimens was 81.4%. The respective 3- and 5-year survival rates were 80% and 67% in patients without perineural invasion and 41% and 32% in those with perineural invasion.
Involvement of pancreaticobiliary cancer in the celiac plexus or celiac ganglions results in intractable pain [4]. The use of a celiac plexus block to relieve intractable pain owing to upper abdominal malignancy is well established [5]. Significant relief of pain has been reported in 70-90% of patients, allowing a reduction in opioid use and in the occurrence of opioid-related side effects. The duration of relief varies, but most patients experience relatively pain-free deaths. Determining the exact location of the celiac ganglia by MRI might be helpful for guiding therapeutic neurolysis of the celiac plexus.
The celiac ganglia are small, and earlier abdominal MRI for celiac ganglia was limited by motion (respiratory and other) and the large size of the abdomen. The spatial resolution of abdominal MR images is likely to improve with strategies for improved registration of breathing or multiple-breath-hold acquisitions [6] or with more efficient data acquisition [7-9]. We believe that high-resolution imaging of the abdomen will become possible soon and that it is helpful to know the MRI characteristics of the celiac ganglia.
We therefore conducted this investigation on cadavers to determine whether the celiac ganglia can be depicted by commercial MRI software and current MRI protocols. Our purpose was to facilitate the in vivo identification of the celiac ganglia on MRI by using current MRI techniques to identify the celiac ganglia in cadavers.
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
From three of the 12 cadavers marked with MRI contrast medium, the six celiac ganglia were removed for histologic analysis. Sections were cut with a Hacker-Bright Micro Cryostat (Hacker Instruments and Industries, Inc.) at 5-µm thickness and placed on glass slides for histologic analysis.
|
0.5 mm); number of signals
acquired, one; and sampling bandwidth, 31 or 62 kHz. All 3D spoiled
gradient-echo images were acquired as follows: TR range/TE range,
4-7.5/1.5-2.2; flip angle, 15°; matrix, 256 x 256; field of view,
26-32 cm; section thickness, 5 mm; and number of signals acquired, one. MR
images were reconstructed at 2.5-mm increments.
Image Analysis
Our methods were similar to those of Dal Pozzo et al.
[10], who marked the celiac
ganglia with opaque contrast medium to show their position, morphology, and
dimensions on CT in an anatomic specimen. We used gadolinium chelate to mark
the celiac ganglia so that, on T1-weighted images, they would have a more
intense signal than would other viscera, such as liver, pancreas, adrenal
gland, and crura. A single radiologist attempted to identify these ganglion
zones according to the changes in signal intensity and the location of the
celiac ganglia.
The original MRI data were loaded onto a workstation (GE AW4.1, Sun Microsystems), and the MR images of the 12 cadavers were reviewed. The location, morphology, and dimensions of the celiac ganglia, and their relationship to abutting structures, were noted.
Statistics
Results are given as the mean (± SD) dimension for the celiac
ganglia on each side. Two-tailed Student's t test and analysis of
variance were used to calculate differences between dissection- and
MRI-derived measurements. The difference between them in location and in
morphology was analyzed by Fisher's exact chi-square test. Values of
p less than 0.05 were considered significantly different.
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
In the 12 cadavers marked with MRI contrast medium, the long (left-right) diameter of the right ganglia was 21.43 ± 5.53 mm, and the short (anteroposterior) diameter was 2.08 ± 0.46 mm. In the left ganglia, the long and short diameters were 20.02 ± 10.13 mm and 2.83 ± 0.45 mm, respectively.
Anatomy of Celiac Ganglia on MRI
On the T1-weighted MR images of 12 cadavers, all right and left ganglia
were identified and were hyperintense relative to liver and spleen
(Fig. 2). One celiac ganglion
was on each side.
In the 12 cadavers scanned by MRI, 18 (75%) of 24 celiac ganglia were at the level between the celiac artery and the SMA, in front of the diaphragmatic crura, and close to and medial to the aorta (Fig. 3). Six (25%) of 24 celiac ganglia were at the level of the SMA. Both the right and the left celiac ganglia were depicted at the same level on MR images in 10 (83.33%) of 12 cadavers. Almost all celiac ganglia could be seen at the level of the pancreas. At the level of the head and body of the pancreas, the right celiac ganglia were seen in 41.67% (5/12) and the left in 58.33% (7/12); at the level of the head of the pancreas, the right celiac ganglia were seen in 25% (3/12) and the left in 16.67% (2/12); and at the level of the body and tail of the pancreas, the right celiac ganglia were seen in 33.33% (4/12) and the left in 25% (3/12). The level of the pancreas at which the celiac ganglia could be seen did not significantly differ between the right and left ganglia (Fisher's exact chi-square, p > 0.05).
|
Ten (83.33%) of 12 right celiac ganglia were located at the space formed by the IVC, right adrenal gland or kidney, right diaphragmatic crura, SMA, and pancreas. Eleven (91.67%) of 12 left ganglia were located at the open space formed by the left adrenal gland or kidney, left diaphragmatic crura, and SMA (Fig. 3).
Ten right ganglia were in front of the right diaphragmatic crura, and the other two right ganglia were in front of the aorta. Eight and four left ganglia were in front of the left diaphragmatic crura and the aorta, respectively (p = 0.22).
On the MR images, the celiac ganglia of the 12 cadavers were lamina-shaped in 66.67% (16/24), nodule-shaped in 16.67% (4/24), and sickle-shaped in 16.67% (4/24).
The long and short diameters on MR images were 24.75 ± 10.97 mm and 2.58 ± 0.77 mm, respectively, for the right ganglia and 20.23 ± 6.16 mm and 3.05 ± 0.97 mm, respectively, for the left ganglia. The diameters of the ganglia measured on MR images did not significantly differ from those measured at dissection (p > 0.05). The diameters derived from MR images were larger than those derived from dissection; however, only the short diameter of the right celiac ganglia was significantly different (p < 0.001).
Histology of Celiac Ganglia
In the six gadolinium-marked celiac ganglia taken from three cadavers,
histologic analysis confirmed the presence of ganglion cells. Sparse nerve
fibers were present among the ganglion cells
(Fig. 4).
|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The celiac plexus comprises a diffuse network of nerve fibers and multiple ganglia that lie over the anterolateral surface of the aorta at the T12 or L1 vertebral level [1]. The network of nerve fibers is fine and is difficult to identify in the dissection of cadavers. Dal Pozzo et al. [10] reported that during anatomic dissections, the celiac ganglia were identified because of their relation to the diaphragmatic crura and adrenal glands; furthermore, the right ganglia are close to the IVC. In our study, the ganglia were at the T12 or L1 level in 93.85% of the 65 cadavers. These ganglia were found in front of the diaphragmatic crura, medial to the adrenal glands, and close to the aorta between the origin of the celiac trunk and the SMA. Most left ganglia were between the left adrenal gland and the left diaphragmatic crura, and most right ganglia were at the superior angle resulting from entrance of the left renal vein into the IVC and frequently were covered partly or completely by the IVC.
We also measured the dimensions of the celiac ganglia at dissection. The largest dimensions were 21.43 ± 5.53 mm and 20.02 ± 10.13 for the right and left celiac ganglia, respectively. These measurements were similar to those reported by Ward et al. [1].
Celiac plexus block is used for palliation of severe upper abdominal pain caused by pancreatitis or tumors of the pancreas. The block can be guided by bony landmarks, fluoroscopy, sonography, or CT. To avoid severe complications, the preferred methods are those such as CT or MRI, which can reveal soft tissue, especially the celiac plexus.
Dal Pozzo et al. [10] performed CT at the level of the celiac trunk and SMA to identify the celiac ganglia. The celiac ganglia appeared as small oval or laminar structures lower in density than the diaphragm. CT of the specimen showed that the celiac ganglia thus indicated corresponded exactly—by position, morphology, and dimensions—to the anatomic structures previously described in vivo. Fukuda et al. [11] reported the CT findings of neural plexus invasion in common bile duct carcinoma. Those authors found that increased attenuation of the fat between the common bile duct and the proper hepatic artery was associated with neural plexus invasion in the hepatoduodenal ligament.
CT sometimes is used to localize the celiac plexus for neurolytic blocks in patients with advanced pancreatic carcinoma and other intraabdominal malignancies. Hol et al. [12] described celiac plexus blocks performed in an open MRI scanner, offering needle guidance with an optical tracking system and nearly real-time image acquisition. Placement of the needle was easily guided with MRI in all patients. The MRI technique ensures good visualization of soft tissue and direct monitoring of needle movement and avoids exposure to ionizing radiation. Celiac plexus blocks can be performed safely in an open MRI scanner. To our knowledge, however, no reports have described the normal anatomy of the celiac plexus or ganglia on MRI.
The celiac ganglia are about 2 cm in long-axis measurement. Detailed in vivo MRI has been impeded thus far by motion (respiratory and other) and the large size of the abdomen. The spatial resolution of abdominal MR images is likely to improve, however, with strategies for better registration of breathing or multiple-breath-hold acquisitions [6] or with more efficient data acquisition [7-9]. Mitchell et al. [13] reported that adrenal corticomedullary contrast medium could be depicted on high-resolution T2-weighted images by using current MRI techniques. In our study, the celiac ganglia in cadavers were recognized using commercial MRI protocols, such as gradient-refocused-echo T1-weighted in-phase and out-of-phase imaging and 3D fast spoiled gradient-echo fat-suppressed T1-weighted imaging.
We confirmed the MRI patterns of the celiac ganglia by isolating and marking with T1-shortening contrast medium the ganglia in cadavers. Six celiac ganglia from the 12 cadavers scanned by MRI were sectioned and observed under light microscopy to confirm the presence of ganglion cells. For unclear reasons, the signal intensity of the celiac ganglia on MRI T1-weighted images was higher than that of liver and spleen. A possible explanation is that the celiac ganglia of cadavers lost water or that gadolinium chelate infiltrated the surfaces of the celiac ganglia, shortening their T1 time.
Our results showed that most celiac ganglia were at the level between the celiac artery and the SMA, in front of the diaphragmatic crura and medial to the aorta. Almost all celiac ganglia could be seen at the level of the pancreas on axial T1-weighted MR images. Most right celiac ganglia were located at the space formed by the IVC, right kidney, right diaphragmatic crura, and SMA, and most left ganglia were located at the open space formed by the left adrenal gland or kidney, left diaphragmatic crura, and SMA.
We measured both the long and the short diameters of the celiac ganglia on axial MR images. These two diameters were comparable to the right-left diameters and anteroposterior diameters, respectively, of the ganglia at dissection. Because the superior-inferior diameters of the ganglia are difficult to measure on MR images, we omitted that measurement. The long and short diameters of the celiac ganglia measured on MR images did not significantly differ from those measured at dissection (p > 0.05).
The dimensions of the celiac ganglia were slightly but not significantly (p > 0.05) larger in the 12 cadavers marked with gadopentetate dimeglumine than in the other 53 cadavers. A possible reason was that, when we dissected the celiac ganglia, we selected larger ganglia for easier dissection and marking with contrast medium. Another possibility is that marking the celiac ganglia with contrast medium enlarged them.
Our findings are limited by our method of selecting cadavers for dissection and MRI. To our knowledge, however, ours is the first report indicating that current clinical MRI techniques can depict the celiac ganglia in cadavers when larger ganglia are selected and labeled with gadolinium. The dimensions and morphology of the celiac ganglia may be different in cadavers from those in vivo. Moving the viscus, dissecting and isolating the celiac ganglia, and marking the celiac ganglia with MRI contrast medium before performing MRI on cadavers may cause the location, morphology, and dimensions of the celiac ganglia to differ between cadaveric MR images and in vivo MR images. In future studies, a better test of the capability of MRI would be to image cadavers before dissection—attempting to identify the celiac ganglia—and then to prove or disprove the identification at dissection. This change would remove the limitations of this study (selection of larger ganglia and use of labeling).
Our results show that, in cadavers, current MRI techniques not only can depict the location and morphology of the celiac ganglia (if larger ganglia are selected and labeled with gadolinium) but also can be used to measure the dimensions of the ganglia. These findings can be a reference for identifying the celiac ganglia in vivo.
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
