Biomedical subjects
Publications and source records attributed to Suhny Abbara.
OBJECTIVE: The objective of our study was to evaluate FDG uptake in patients with cardiac lipomatous hypertrophy of the interatrial septum (LHIS). CONCLUSION: Increased FDG uptake occurs in LHIS, a benign fatty infiltration of the interatrial septum. Increased uptake in the right heart on FDG PET warrants correlation with additional imaging to assess for LHIS and avoid false interpretation of malignancy.
In 26 patients, 16-slice multidetector computed tomography (MDCT) with 0.75-mm collimation and intravascular ultrasound (IVUS) of 1 coronary artery were performed. At 100 sites within the coronary arteries, the measurement of cross-sectional luminal area and, if detectable, the cross-sectional area of atherosclerotic plaque was performed independently with IVUS and MDCT. The mean luminal area (r = 0.92), measured at 100 sites, and plaque area (r = 0.55), measured at 65 sites, were significantly correlated (p <0.001) between MDCT and IVUS. The mean luminal area and mean plaque area were slightly but significantly overestimated with MDCT. MDCT permits the noninvasive measurement of coronary cross-sectional luminal and plaque areas with moderate accuracy.
BACKGROUND: In this study, we investigated the diagnostic value and limitations of multidetector computed tomography (MDCT)-based noninvasive detection of significant obstructive coronary artery disease (CAD) in a consecutive high-risk patient population with inclusion of all coronary segments. METHODS AND RESULTS: In a prospective, blinded, standard cross-sectional technology assessment, a cohort of 33 consecutive patients with a positive stress test result underwent 16-slice MDCT and selective coronary angiography for the detection of significant obstructive CAD. We assessed the diagnostic accuracy of MDCT in a segment-based and a patient-based model and determined the impact of stenosis location and the presence of calcification on diagnostic accuracy in both models. Analysis of all 530 coronary segments demonstrated moderate sensitivity (63%) and excellent specificity (96%) with a moderate positive predictive value of 64% and an excellent negative predictive value (NPV) of 96% for the detection of significant coronary stenoses. Assessment restricted to either proximal coronary segments or segments with excellent image quality (83% of all segments) led to an increase in sensitivity (70% and 82%, respectively), and high specificities were maintained (94% and 93%, respectively). In a patient-based model, the NPV of MDCT for significant CAD was limited to 75%. Coronary calcification was the major cause of false-positive findings (94%). CONCLUSIONS: For all coronary segments included, 16-slice MDCT has moderate diagnostic value for the detection of significant obstructive coronary artery stenosis in a population with a high prevalence of CAD. The moderate NPV of patient-based detection of CAD suggests a limited impact on clinical decision-making in high-risk populations.
The epidemiology of and association between vascular and valvular calcium as quantified by multidetector computed tomography (MDCT) were studied in 416 elderly subjects with no history of coronary artery disease. Coronary calcium (CC), descending thoracic aortic calcium (DTAC), aortic valve calcium (AVC), and mitral valve calcium (MVC) were present in 282 (68%), 214 (51%), 152 (37%), and 68 (16%) subjects, respectively. Multiple logistic regression analysis showed that after adjusting for age and gender, subjects with AVC (odds ratio [OR] 2.3), MVC (OR 2.81), and DTAC (OR 2.79) were independently and significantly more likely to have CC. Further evidence is provided for the notion that calcifications in those regions are associated and that MDCT can be used as a tool for the global assessment of vascular and valvular calcium.
We systematically studied the thickness of the myocardium in the left ventricular apical region in patients without a history of myocardial infarction and with no hemodynamically significant coronary artery disease, using contrast-enhanced multidetector spiral computed tomography with submillimeter collimation. We confirmed previous pathology data and reliably detected a small confined region of the normal apical myocardium with a thickness of <or=3 mm, i.e., the left ventricular thin point.
INTRODUCTION: Pulmonary vein (PV) isolation for atrial fibrillation (AF) currently is performed using either an ostial or an extra-ostial approach. The objective of this study was to analyze by three-dimensional (3D) magnetic resonance angiography (MRA) the anatomy of the PVs in order to detect structural variability that would impact the choice of ablation approach. METHODS AND RESULTS: Three-dimensional MRA was performed in 105 patients undergoing PV isolation. The ostial diameter, branching pattern, and PV angulation were analyzed. Fifty-nine (56%) patients had the typical pattern of 4 PVs with 4 separate ostia, 30 (29%) patients had an additional PV, and 18 (17%) patients had a left common PV trunk. In two patients, there were three right-sided veins and a common left-sided trunk, giving rise to four ostia: three on the right and one on the left. Two different populations of right middle PVs were noted: one where the additional vein projected anteriorly to drain the right middle lobe and one posterior to drain the superior portion of the right lower lobe. The average intrapatient variability in PV diameter was 7.9 +/- 4.2 mm. The PV ostium was <10 mm in 26 (25%) patients and >25 mm in 15 (14%) patients. The first branch originated 6.7 +/- 2.3 mm from the ostium. The left superior, right superior, right inferior, and left inferior PVs were found to enter the left atrium at the following angles: 32 +/- 13 degrees, 131 +/- 11 degrees, 206 +/- 16 degrees, and 329 +/- 14 degrees, respectively. Forty-nine patients (47%) had at least one funnel shaped PV. CONCLUSION: This largest PV imaging study to date demonstrates that MRA is a valuable tool that allows detection of marked intrapatient and interpatient anatomic variability of the PVs. These findings suggest that, at least in some patients, circumferential extra-ostial left atrial encirclement of the PVs may be preferable to ostial PV isolation. These findings also may have significant implications on the future development of coil- and balloon-based catheter ablation designs for AF ablation.
OBJECTIVE: Arrhythmogenic right ventricular dysplasia (ARVD) is characterized by intramyocardial fibrofatty change. Fat suppression performed during conventional spin-echo imaging has been used to confirm fatty infiltration. The utility of fat suppression for enhancing the interpretation of studies of suspected ARVD has not previously been formally tested. We investigated the value of fat suppression for enhancing the interpretation of intramyocardial fatty infiltration. MATERIALS AND METHODS: Twenty-six consecutive patients clinically referred for evaluation of possible ARVD underwent cardiac MRI. Two independent observers reviewed the images retrospectively. Intramyocardial areas (n = 101) that had increased signal intensity relative to normal surrounding myocardium on T1-weighted conventional spin-echo images ("index areas") were identified. The index areas were interpreted for presence of fatty infiltration using two sets of images: The first set was obtained without fat suppression, and the second set was obtained with fat suppression. Agreement between reviewers and confidence of interpretation were determined and compared. RESULTS: Interobserver agreement was measured using a 5-point scale: 1, definitely not fat; 2, probably not fat; 3, equivocal; 4, probably fat; and 5, definitely fat. The resulting kappa values were 0.35 for non-fat-suppressed images and 0.55 for fat-suppressed images. Interobserver kappa increased from 0.67 without fat suppression to 0.90 with fat suppression using a 3-point scale: 1, not fat; 2, equivocal; and 3, fat. Confidence in the diagnosis increased from 7.2 without fat suppression to 8.8 with fat suppression (p < 0.0001) on a 10-point scale ranging from 1, not confident, to 10, very confident. CONCLUSION: The use of fat-suppressed in addition to non-fat-suppressed conventional T1-weighted spin-echo imaging increased interobserver agreement and confidence in diagnosis and evaluation of intramyocardial fatty infiltration in patients who were suspected to have ARVD.
Multidetector computed tomography (MDCT) permits visualization of the coronary arteries, but limited spatial and temporal resolution can lead to artifacts. We quantitatively evaluated the image quality that can be obtained with the latest generation of MDCT scanners with submillimeter collimation and increased gantry rotation speed. Thirty patients with angiographically proved absence of significant coronary artery stenoses (mean age 56 +/- 13 years, mean heart rate 62 +/- 13 beats/min) were studied by MDCT (12 x 0.75 mm collimation, 420-ms tube rotation, 210-ms temporal resolution, 500 mA, 120 kVp, retrospective electrocardiographic gating). In multiplanar reconstructions of the 4 major coronary arteries (left main, left anterior descending, left circumflex, and right coronary artery), the overall visualized vessel length and the length of segments without motion artifacts were measured. Vessel diameters at 8 predefined locations were measured in MDCT maximum intensity projections and in corresponding invasive angiograms. The mean lengths of visualized coronary arteries were left main 13 +/- 6 mm, left anterior descending 138 +/- 39 mm, left circumflex 84 +/- 34 mm, and right coronary artery 155 +/- 41 mm. On average, 93 +/- 13% of the total visualized vessel length was depicted without motion artifacts (left main 100 +/- 0%, left anterior descending 93 +/- 12%, left circumflex 91 +/- 17%, and right coronary artery 87 +/- 14%). The percentage of vessel length visualized free of motion artifacts was significantly higher in patients with a heart rate </=60 beats/min compared with patients with a heart rate >60 beats/min (96 +/- 8% vs 89 +/- 17%, p <0.05). Vessel diameters in MDCT correlated closely to quantitative coronary angiography (R(2) 0.83 to 0.87). In conclusion, MDCT with submillimeter collimation and improved temporal resolution permits reliable visualization of the vessel lumen and accurate measurements of vessel dimensions.
RATIONALE AND OBJECTIVES: To compare scoring threshold and calibration method-dependent accuracy and variability of coronary calcium measurements by multidetector computed tomography (MDCT). METHODS: Ninety-five subjects were scanned with MDCT. We calculated Agatston score and volume score. Mineral mass (MM) was calculated using patient-based and scanner-based calibration methods. Accuracy of calibration was validated using artificial calcium cylinders. RESULTS: Patient-based and scanner-based calibration permitted accurate quantification of artificial calcium cylinders (bias: 0 mg and -2 mg). In the subjects, the mean relative difference of MM measurements performed at 90 and 130 Hounsfield units threshold (59%) was lower than for Agatston score (94%) and volume score (109%; P < 0.05). Patient-based and scanner-based calibration yielded systematically different MM measurements (bias: 22%). CONCLUSIONS: MM lowers threshold-dependent variability of coronary calcium measurements. Patient-based and scanner-based calibration allows accurate calcium quantification ex vivo but reveal systematic differences in subjects. Patient-based calibration may better account for subject size and composition.
PURPOSE: To determine whether a transient hypercoagulable state is induced by the uterine artery embolization (UAE) procedure. MATERIALS AND METHODS: Serial periprocedure blood samples were obtained from 27 patients undergoing the UAE procedure. Five blood samples were obtained from each patient at set time intervals: before the procedure (for baseline determination), immediately before and after embolization of the uterine arteries, 90 minutes after conclusion of the procedure, and between 18 and 24 hours later. Each blood sample was analyzed for the peripheral levels of the following parameters: thrombin-antithrombin complex (TAT), prothrombin fragment 1.2 (F1.2), platelet factor 4 (PF4), D-dimer, and plasmin-alpha(2)-antiplasmin complex (PAP). For each parameter, the baseline values were statistically compared with the pre- and postembolization values for each individual to detect change over time. Overall and global occasion effects for continuous variables were assessed with the Friedman statistic and individual comparisons between occasions with the Wilcoxon signed-rank test. RESULTS: No evidence was found for a difference in coagulability among the five occasions for D-dimer (P =.7645) or PF4 (P =.09). All three of the remaining measures were found to have statistically significant differences (P <.0001 for F1.2, P =.0026 for PAP, and P =.0006 for TAT). No evidence was found for a difference between preprocedure and preembolization levels for these three latter parameters (P =.595 for F1.2, P =.128 for PAP, P =.9705 for TAT). Hypercoagulability potential as measured by prothrombinase and F1.2 generation increased between preembolization samples and each of the successive postprocedure samples (P <.0001, P <.0001, P =.0082), whereas PAP increased at 90 minutes (P =.0023) and TAT increased immediately after embolization (P <.0001). No clinically apparent thrombotic complications occurred among any of the patients studied. CONCLUSIONS: Surrogate markers of hypercoagulability increase as a result of UAE, suggesting that a prothrombotic state may result after the procedure.
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BACKGROUND: Fluorine 18 fluorodeoxyglucose (FDG) has been shown to accumulate in inflamed tissues. However, it is not known whether vascular inflammation can be measured noninvasively. The aim of this study was to test the hypothesis that vascular inflammation can be measured noninvasively by use of positron emission tomography (PET) with FDG. METHODS AND RESULTS: Inflamed atherosclerotic lesions were induced in 9 male New Zealand white rabbits via balloon injury of the aortoiliac arterial segment and exposure to a high cholesterol diet. Ten rabbits fed standard chow served as controls. Three to six months after balloon injury, the rabbits were injected with FDG (1 mCi/kg), after which aortic uptake of FDG was assessed (3 hours after injection). Biodistribution of FDG activity within aortic segments was obtained by use of standard well gamma counting. FDG uptake was also determined noninvasively in a subset of 6 live atherosclerotic rabbits and 5 normal rabbits, via PET imaging and measurement of standardized uptake values over the abdominal aorta. Plaque macrophage density and smooth muscle cell density were determined by planimetric analysis of RAM-11 and smooth muscle actin staining, respectively. Biodistribution of FDG within nontarget organs was similar between atherosclerotic and control rabbits. However, well counter measurements of FDG uptake were significantly higher within atherosclerotic aortas compared with control aortas (P < .001). Within the upper abdominal aorta of the atherosclerotic group (area of greatest plaque formation), there was an approximately 19-fold increase in FDG uptake compared with controls (108.9 +/- 55.6 percent injected dose [%ID]/g x 10(3) vs 5.7 +/- 1.2 %ID/g x 10(3) [mean +/- SEM], P < .001). In parallel with these findings, FDG uptake, as determined by PET, was higher in atherosclerotic aortas (standardized uptake value for atherosclerotic aortas vs control aortas, 0.68 +/- 0.06 vs 0.13 +/- 0.01; P < .001). Moreover, macrophage density, assessed histologically, correlated with noninvasive (PET) measurements of FDG uptake (r = 0.93, P < .0001). In contrast to this finding, FDG uptake did not correlate with either aortic wall thickness or smooth muscle cell staining of the specimens. CONCLUSION: These data show that FDG accumulates in macrophage-rich atherosclerotic plaques and demonstrate that vascular macrophage activity can be quantified noninvasively with FDG-PET. As such, measurement of vascular FDG uptake with PET holds promise for the noninvasive characterization of vascular inflammation.
A case of congenitally corrected transposition of the great arteries in a 64-old-woman is presented. Diagnosis was missed by invasive angiocardiography. Electrocardiographic-gated multislice computed tomography not only demonstrated switching of the aortic root and pulmonary trunk but clearly identified fine morphologic details of the cardiac chambers, including the atypical coronary artery pattern.
Current strategies for the triage of patients who have chest pain but normal initial cardiac enzyme levels and nondiagnostic electrocardiograms do not permit efficient risk stratification. The potentially fatal consequences and high malpractice costs of missed acute coronary syndromes lead every year to the unnecessary hospital admission of about 2.8 million patients who present with acute chest pain in emergency departments in the United States. Most of these patients are at very low risk for an acute coronary syndrome. However, the standard clinical work-up does not provide information about the presence and extent of coronary artery disease. In most patients (80%-94%) with an acute coronary syndrome, a significant coronary artery stenosis can be detected with selective coronary angiography. High levels of diagnostic accuracy also have been established for the detection of significant coronary artery stenosis with the use of 16- and 64-section multidetector computed tomography (CT) in patients with stable angina. Preliminary data indicate that multidetector CT also can help quantify and characterize coronary atherosclerotic plaque and that the CT findings are in good agreement with those at intravascular ultrasonography. Although multidetector CT provides accurate information about the presence of coronary artery disease, large blinded observational studies are warranted to identify CT characteristics with high accuracy for diagnosis of acute coronary syndromes. Such information would enable the conduct of randomized controlled trials to determine whether the detection of coronary stenosis and plaque with multidetector CT improves triage and reduces the costs or increases the cost-effectiveness of management of acute chest pain.