SUBJECTS AND METHODS. We performed cardiac MDCT at rest and stress/rest ²⁰¹Tl myocardial perfusion scintigraphy (MPS) in 34 patients with suspected coronary artery disease. We reconstructed 2D long- and short-axis cardiac images in diastolic and systolic phases using raw data from coronary CT angiography. The attenuation value (in Hounsfield units) in the myocardium was used as an estimate of myocardial perfusion. We measured the subendocardial intensity of 17 segments according to the American Heart Association classification. Systolic perfusion or diastolic perfusion was calculated by dividing the subendocardial intensity at systole or diastole, respectively, for each segment by the mean value across all segments for each patient. We used stress/rest MPS to evaluate the variation in myocardial perfusion at systole and diastole for the segments diagnosed as ischemic or nonischemic.

RESULTS. Systolic perfusion for ischemic segments was significantly lower than that for nonischemic segments in 15 of 17 segments. The difference between systolic perfusion and diastolic perfusion in ischemic segments was significantly lower than that in nonischemic segments (14 of 17 segments). There was no significant difference in diastolic perfusion between ischemic and nonischemic segments (15 of 17 segments).

CONCLUSION. Our results suggest that a pattern of subendocardial hypoperfusion at systole and normal perfusion at diastole characterizes ischemic myocardium.

MATERIALS AND METHODS. Twenty sequential patients with 23 mechanical prosthetic valves were evaluated with an ECG-gated 40- or 64-MDCT scanner. Multiplanar reformation, maximal-intensity-projection, volume-rendering, and volume-averaging techniques were used for visualization of valve leaflets in systole and diastole. The visibility of each mechanical valve was evaluated by consensus of a radiologist and a cardiologist using a subjective 5-point scale (0–4). MDCT findings were correlated with fluoroscopic opening and closing angle measurements and echocardiographic pressure gradient measurements in 11 and 19 valves, respectively.

RESULTS. The series included 18 bileaflet and five single-leaflet mechanical valves. The visibility score for the bileaflet mechanical valves was excellent (score of 4) in all 18 cases, but it was lower for single-leaflet valves (mean score, 2.8; range, 1–4) (p = 0.04). Bland-Altman plots showed high agreement between MDCT and fluoroscopy for measurements of opening and closing angles of bileaflet mechanical valves. In four patients, a stuck valve was seen on MDCT and was confirmed by fluoroscopy. Doppler echocardiography showed increased transvalvular pressure in two of the four patients with a stuck mitral valve and increased transaortic pressure in four patients with normal prosthetic aortic valve motion.

CONCLUSION. Our preliminary results suggest that MDCT is a promising technique for functional evaluation of bileaflet mechanical valves, allowing reliable measurements of opening and closing leaflet angles. However, the role of MDCT in the evaluation of single-leaflet valves might be limited.

MATERIALS AND METHODS. We evaluated nine consecutive patients, age range 35–60 years, who had been treated for Hodgkin's lymphoma by radiation therapy between the ages of 11 and 27 years. The total mediastinal dose ranged from 34 to 45 Gy. All patients were evaluated with 64-MDCT with calcium scoring followed by CT angiography of the coronary arteries. Imaging findings and clinical follow-up were analyzed.

RESULTS. Eight of nine patients had coronary artery disease. CT showed long segments of diffuse disease; areas of stenosis from soft plaque; and calcification in the proximal right coronary, left anterior descending, and left circumflex arteries. Calcium scores were significantly higher than in other patients of this age group. Additional tests, including selective coronary angiography, were necessary in patients with diffuse disease with calcifications. CT evaluation led to bypass surgery and angioplasty in two patients.

CONCLUSION. Coronary CT angiography and calcium scores are useful tools for evaluation of irradiation-related coronary artery disease. Complementary tests might be necessary in selected patients. Prospective larger studies are needed to better define the role of coronary CT angiography and calcium scores and to establish an algorithm for evaluation and treatment of these patients.

SUBJECTS AND METHODS. The right and left coronary arteries of 20 subjects were imaged with axial whole-heart acquisition and two oblique targeted-volume acquisitions.

RESULTS. Both whole-heart and targeted-volume acquisitions were completed with similar navigator efficiencies ( 50%) and depicted similar coronary artery diameters ( 3 mm) (p ≥ 0.06). The lengths of the coronary arteries were not significantly different (p = 0.07–0.45) for the whole-heart and targeted-volume approaches. Depiction of the sharper coronary arteries (p ≤ 0.04) and overall image quality (p < 0.02) were better with the targeted-volume approach.

CONCLUSION. For current 3-T navigator parallel-imaging coronary MR angiography, targeted-volume acquisition yields sharper coronary images than does whole-heart acquisition.

MATERIALS AND METHODS. A pulsating cardiac phantom was used to simulate the beating heart and coronary arteries of 5 and 3 mm in diameter with three degrees of stenosis (25%, 50%, and 75%) at a heart rate of 55 beats per minute. Coronary vascular enhancement had four attenuation levels: low, 200 H; moderately low, 300 H; moderately high, 350 H; and high, 500 H. Cardiac scans were obtained with 64-MDCT. Percentage stenosis, plaque area, and plaque density were measured on axial images.

RESULTS. For 50% and 75% stenosis in 5-mm vessels, there were no significant differences among the four attenuation groups. For 50% and 75% stenosis in 3-mm vessels, significant underestimation of percentage stenosis occurred in the high-attenuation group compared with the moderate- and low-attenuation groups (p < 0.05). For 25% stenosis in 5-mm vessels, low attenuation led to significant overestimation of degree of stenosis compared with the moderate and high attenuation levels (p < 0.05). None of the instances of 25% stenosis in 3-mm vessels were detected in the high-attenuation group. Underestimation was found only for 3-mm vessels. For 75% stenosis, all plaques were detected irrespective of contrast attenuation and vessel size.

CONCLUSION. Use of higher attenuation leads to a significant underestimation of stenosis in smaller vessels. Lower attenuation leads to slight and clinically acceptable overestimation of stenosis. The optimal vascular attenuation for stenosis detection in coronary 64-MDCT angiography is approximately 350 H.

MATERIALS AND METHODS. Data from 794 consecutive coronary CTA examinations performed between February 2005 and May 2007 were reviewed. The calcium scores were determined as part of coronary CTA examinations, and calcium was quantified according to the Agatston method. Patients underwent coronary CTA because of high risk for coronary artery disease (53%) or atypical symptoms or abnormal stress test results (47%). On coronary CTA, plaque was characterized as mild disease without hemodynamically significant stenosis, moderate disease without hemodynamically significant stenosis, moderate stenosis (50–70% luminal narrowing), or severe stenosis (> 70% luminal narrowing).

RESULTS. Of the 729 patients included in the study, 325 (45%) had a normal calcium score. Of these, 167 (51%) had noncalcified plaque on coronary CTA. Twelve (3.7%) of those with a normal calcium score had at least moderate stenosis, five (1.5%) of whom had severe stenosis. Eight of the 12 patients with significant stenosis underwent invasive angiography and coronary stenting.

CONCLUSION. A considerable atheroma burden including significant stenoses may be present in patients with no coronary calcification. Although the calcium score does add prognostic value to standard risk factors and serum markers, imaging the vessel wall directly may be helpful to identify noncalcified plaque and guide therapy.

SUBJECTS AND METHODS. Thirty-five consecutively registered patients (10 women, 25 men; mean age, 65 years) with 48 stents were examined prospectively without heart rate controlling agents. Observers evaluating image quality and patency of the stents were blinded to the results of invasive coronary angiography. In-stent restenosis was defined as more than 50% narrowing of the lumen.

RESULTS. All stents were considered assessable for diagnosis with dual-source CT. In 85% (41/48) of the stents, image quality was good. Only two patent stents were misidentified as being stenotic. All other stents with stenosis and occlusion were correctly diagnosed. The sensitivity, specificity, positive and negative predictive values, and accuracy of dual-source CT in the detection of in-stent restenosis and occlusion were 100%, 94%, 89%, 100%, and 96%, respectively. The McNemar test result showed no statistically significant difference between the diagnostic performance of dual-source CT and that of invasive coronary angiography. The kappa indexes showed excellent intraobserver and interobserver agreement.

CONCLUSION. The high temporal resolution of dual-source CT is helpful for evaluation of coronary stents without heart rate control. Further confirmation of our preliminary results may broaden the clinical indications for CT angiography as a diagnostic test for the exclusion of in-stent restenosis.

CONCLUSION. Radiologists should be familiar with the protocol design and comprehensive interpretation of cardiac MDCT to provide comprehensive treatment suggestions for the patients.

CONCLUSION. Contrast-enhanced MRI is a useful noninvasive technique for determining the presence of microvascular obstruction. No-reflow phenomenon has important prognostic implications, and knowledge of the physiologic mechanism is important to understanding the distribution patterns of enhancement in correlation with the underlying pathologic process.

MATERIALS AND METHODS. Eighty-one consecutive patients were examined with ECG-gated CT coronary angiography using image reconstruction during end-diastole. The diagnostic criterion for aortic valve regurgitation by CT was an incomplete coadaptation of aortic valve leaflets, the central aortic regurgitation area (ARA), which was quantified. All patients underwent transthoracic echocardiography using semiquantitative grading of aortic valve regurgitation (i.e., mild, moderate, or severe).

RESULTS. Of the 81 patients, 45 had aortic valve regurgitation by transthoracic echocardiography. The diagnostic accuracy of CT in detecting aortic valve regurgitation was as follows: sensitivity of 73% (33/45), specificity of 97% (35/36), positive predictive value (PPV) of 97% (33/34), and negative predictive value (NPV) of 74% (35/47). All 12 false-negative findings by CT were graded as mild regurgitation by transthoracic echocardiography and were caused by severe valve calcification (mean, 3,053.1 ± 1,700 Agatston units; range, 937.7–5,632.5 Agatston units), bicuspid valves, or both. The sensitivity, specificity, PPV, and NPV of CT for the detection of moderate and severe aortic valve regurgitation were 95%, 100%, 100%, and 98%, respectively. Quantification of the ARA by CT (mean, 0.25 cm² ± 0.34 cm² [SD]) was significantly correlated with the severity of aortic valve regurgitation by trans thoracic echocardiography (p < 0.001).

CONCLUSION. Although 64-MDCT accurately detects moderate and severe aortic regurgitation in patients referred to coronary CT angiography, mild aortic regurgitation can be missed on 64-MDCT in the presence of severe valve calcification or bicuspid valves.

MATERIALS AND METHODS. Forty-one normal and eight abnormal arterial cross sections with noncalcified plaque selected from 40 patients undergoing MDCTA were analyzed for percentage of stenosis and plaque volume using a voxel analysis technique.

RESULTS. Using voxel analysis, the normal arterial wall thickness was determined to be 0.8 ± 0.4 mm. Attenuation values (in Hounsfield units) for normal segments ranged between 30 and 175 H and for abnormal (plaque-containing) segments ranged from -49 to 139 H (p < 0.05). Plaque volume measurements varied from 0.90 to 156 mm³ with good interobserver correlation (R² = 0.9671). Percentage of stenosis correlated with quantitative coronary arteriography measurement (R² = 0.55). Voxel analysis underestimated the percentage of stenosis (Pearson's correlation coefficient, 1.2; p = 0.03).

CONCLUSION. The study shows that the voxel analysis technique appears to be an accurate and reproducible method to measure arterial wall thickness, noncalcified plaque, and degree of arterial stenosis using density values measured in Hounsfield units. The technique may be useful on further correlative studies.

SUBJECTS AND METHODS. Ninety-one patients with suspected coronary artery disease were scanned twice on retrospective ECG-gated helical scans. Images with 2.5-mm thickness and 1.25-mm interval at nine cardiac phases (center of cardiac phase: 40-80% in 5% increments) were reconstructed. The interscan variability of coronary artery scores (Agatston, volume, and mass) per patient and motion artifact scores per branch, subjectively assigned by motion artifact grading (1, none; 2, minor; and 3, major), were compared between cardiac phases for all patients, low (< 65 beats per minute [bpm]) and high (≥ 65 bpm) heart rate patient groups.

RESULTS. For all patients, two-factor factorial analysis of variance revealed that the interscan variability was different between cardiac cycles (p < 0.01); however, this was not statistically significant between scoring algorithms (p = 0.46). The least variability was obtained at 70% on Agatston (8%) and volume (7%) and at 75% on mass (7%). Adjacent categories logit model analysis revealed that the motion artifact score was the least at 75% (left anterior descending coronary artery, 1.3; left circumflex coronary artery, 1.4; and right coronary artery, 1.9 in all patients) and that a smaller difference in calcium scores between the scans led to a smaller motion artifact score (p < 0.05).

CONCLUSION. Middiastole reconstruction (center of cardiac phase: 70-75%), with the least interscan variability and the least motion artifacts, is recommended on 64-MDCT.

MATERIALS AND METHODS. Coronary CT angiograms of 250 patients (152 men, 98 women; mean age, 60 ± 12 [SD] years) were retrospectively analyzed for identification of the origin, number, anatomic course, mode of termination, and S-shaped variant of the SAN artery.

RESULTS. At least one SAN artery was detected in 244 patients. The S-shaped variant was seen in 35 (14.3%) of these patients. Thirty-four of the variants (30.6% of all left SAN arteries) arose from the proximal to middle portion of the left circumflex artery (mean distance between the ostium of the left circumflex artery and the origin of S-shaped variant, 28.7 ± 13.1 mm). The other variant (0.7% of all right SAN arteries) originated from the distal right coronary artery. The S-shaped variant was the only artery supplying the SAN in 28 (11.4%) of the patients. In patients with two arteries supplying the SAN, the right SAN artery and the S-shaped variant of the left SAN artery were seen together in seven patients. The S-shaped SAN artery (mean distance from atrial wall, 2.43 ± 0.992 mm) had a predictable proximal course, lying in the posterior aspect in a groove between the orifices of the left superior pulmonary vein and the left atrial appendage close to the left atrial wall. The terminal segment of the artery approached the nodal tissue posterior to the superior vena cava in 22 patients, anterior to the vena cava in 10 patients, and through branches surrounding the vena cava in two patients.

CONCLUSION. The S-shaped variation of the SAN artery is common and has a characteristic anatomic course. MDCT can be used to plan surgical and catheter-based left atrial interventions in which this artery is at risk of injury.

SUBJECTS AND METHODS. Before and after treatment, 15 patients with acromegaly underwent myocardial T2 mapping with an experimental single-breath-hold black-blood fast spin-echo sequence. Myocardial T2 mapping with both a multiple-breath-hold fast spinecho sequence and the experimental sequence also was performed on 14 volunteers. T2 relaxation times were calculated with a standard linear least-squares fit applied to myocardial signal intensity. The T2 relaxation times of patients were compared with those of volunteers and correlated with levels of serum growth hormone and insulinlike growth factor 1. Left ventricular function and mass index were determined with cine MRI.

RESULTS. T2 values before treatment were higher in patients (71 ± 12 milliseconds) than in volunteers (55.9 ± 3.6 milliseconds) (p = 0.0003). These T2 values in patients decreased soon after treatment (57.6 ± 6.6 milliseconds, p = 0.0007). This reduction correlates with successful reduction of levels of serum growth hormone and insulinlike growth factor 1. In volunteers, myocardial T2 values did not vary significantly between the single-breath-hold sequence and the multiple-breath-hold fast spin-echo sequence. In patients, myocardial mass and left ventricular function did not differ significantly before and after treatment.

CONCLUSION. Patients with acromegaly have increased myocardial T2 values, which decrease soon after treatment, reflecting reversible myocardial edema. T2 value is more sensitive than left ventricular mass index in the detection of early reversal of acromegalic cardiomyopathy. These results highlight the potential role of MRI in direct assessment of the tissular effects of growth hormone and insulinlike growth factor 1 and in evaluation of the efficacy of treatment.

SUBJECTS AND METHODS. CT and invasive coronary angiography were performed on 114 patients (mean age, 62 years) referred for known coronary artery disease (n = 26), atypical chest pain (n = 58), and presurgical exclusion of coronary artery disease before abdominal aortic (n = 14) or cardiac valve (n = 16) surgery. The population was divided into two groups depending on median average heart rate (60.0 beats/min) and median heart rate variability (2.7 beats/min) during scanning. Heart rate variability was calculated as SD from the mean heart rate. Two blinded observers using a 4-point scale independently assessed the quality of images of each coronary artery segment and classified each segment as being stenosed (luminal diameter narrowing > 50%) or not. Invasive coronary angiography was used as the reference standard.

RESULTS. In 71 (62.3%) of the patients, 241 significant coronary artery stenoses were identified with invasive coronary angiography. In 11 (9.7%) of the patients, 1.6% (26/1,672) of the segments were not evaluable with CT. Overall sensitivity, specificity, and positive and negative predictive values in a patient-based analysis were 97%, 81%, 90%, and 95%, respectively. Image quality was better (p < 0.05) in the low average heart rate group than in the high average heart rate group, but diagnostic accuracy was comparable for the two groups. In contrast, image quality and diagnostic accuracy were significantly better (p < 0.01) among patients in the low heart rate variability group than in the high heart rate variability group.

CONCLUSION. Lower heart rate variability is associated with higher diagnostic accuracy of 64-MDCT coronary angiography.