The Diagnostic Accuracy of the 64-slice Multi-detector CT Coronary Angiography for the Assessment of Coronary Artery Stenosis in Symptomatic Patients

PURPOSE: We evaluated the diagnostic accuracy of a 64-slice multi-detector CT (MDCT) coronary angiography against a conventional coronary angiography (CCA) for the detection of significant stenosis (> or =50% lumen diameter narrowing). MATERIALS AND METHODS: Sixty-four patients underwent a MDCT and a subsequent CCA to evaluate the presence of atypical chest pain or suspected coronary artery disease (CAD). A MDCT angiography was performed using a 64-slice MDCT-scanner (Sensation 64, slice collimation 32x0.6 mm). The coronary artery segments were classified according to a 15-segment model. The sensitivity, specificity, and diagnostic accuracy of the 64-slice MDCT for the detection or exclusion of significant CAD were calculated on a per-segment and per-patient basis. RESULTS: Fifty-nine of the 64 (92%) coronary CT angiograms were of diagnostic image quality with 93.5% (809 of 865) of the coronary segments assessable by CT angiography. One-hundred two (12.6%) segments showed significant stenosis by CCA. Stenosis of 50% or greater was detected by sensitivity, specificity, accuracy, positive predictive valve, and negative predictive value on a per segment basis (89%, 99%, 97%, 90%, and 98%, respectively) and a per-patient basis (96%, 69%, 90%, 92%, and 82%, respectively). CONCLUSION: The 64-slice MDCT coronary angiography demonstrated a high diagnostic accuracy for both the per-segment and per-patient analyses for this symptomatic patient group.

Comparison of Transaxial Source Images and 3-Plane, Thin-Slab Maximal Intensity Projection Images for the Diagnosis of Coronary Artery Stenosis with Using ECG-Gated Cardiac CT

OBJECTIVE: We wanted to compare the transaxial source images with the optimized three plane, thin-slab maximum intensity projection (MIP) images from electrocardiographic (ECG)-gated cardiac CT for their ability to detect hemodynamically significant stenosis (HSS), and we did this by means of performing a receiver operating characteristic (ROC) analysis. MATERIALS AND METHODS: Twenty-eight patients with a heart rate less than 66 beats per minute and who were undergoing both retrospective ECG-gated cardiac CT and conventional coronary angiography were included in this study. The contrast-enhanced CT scans were obtained with a collimation of 16x0.75-mm and a rotation time of 420 msec. The transaxial images were reconstructed at the mid-diastolic phase with a 1-mm slice thickness and a 0.5-mm increment. Using the transaxial images, the slab MIP images were created with a 4-mm thickness and a 2-mm increment, and they covered the entire heart in the horizontal long axis (4 chamber view), in the vertical long axis (2 chamber view) and in the short axis. The transaxial images and MIP images were independently evaluated for their ability to detect HSS. Conventional coronary angiograms of the same study group served as the standard of reference. Four radiologists were requested to rank each image with using a five-point scale (1 = definitely negative, 2 = probably negative, 3 = indeterminate, 4 = probably positive, and 5 = definitely positive) for the presence of HSS; the data were then interpreted using ROC analysis. RESULTS: There was no statistical difference in the area under the ROC curve between transaxial images and MIP images for the detection of HSS (0.8375 and 0.8708, respectively; p > 0.05). The mean reading time for the transaxial source images and the MIP images was 116 and 126.5 minutes, respectively. CONCLUSION: The diagnostic performance of the MIP images for detecting HSS of the coronary arteries is acceptable and this technique's ability to detect HSS is comparable to that of the transaxial source images.

The Significance of Perfusion Defect at Myocardial Perfusion MR Imaging in a Cat Model of Acute Reperfused Myocardial Infarction

OBJECTIVE: To determine whether the size of a perfusion defect seen at myocardial perfusion MR imaging represents the extent of irreversibly damaged myocardium in acute reperfused myocardial infarction. MATERIALS AND METHODS: In nine cats, reperfused myocardial infarction was induced by occlusion of the left anterior descending coronary artery for 90 minutes and subsequent reperfusion for 90 minutes. At single-slice myocardial perfusion MR imaging at the midventricular level using a turbo-FLASH sequence, 60 short-axis images were sequentially obtained with every heart beat after bolus injection of gadomer-17. The size of the perfusion defect was measured and compared with both the corresponding unstained area seen at triphenyl tetrazolium chloride (TTC) staining and the hyperenhanced area seen at gadophrin-2-enhanced MR imaging performed in the same cat six hours after myocardial perfusion MR imaging. RESULTS: The sizes of perfusion defects seen at gadomer-17-enhanced perfusion MR imaging, unstained areas at TTC staining, and hyperenhanced areas at gadophrin-2-enhanced MR imaging were 20.4+/-4.3%, 29.0+/-9.7%, and 30.7+/-10.6% of the left ventricular myocardium, respectively. The perfusion defects seen at myocardial perfusion MR imaging were significantly smaller than the unstained areas at TTC staining and hyperenhanced areas at gadophrin-2-enhanced MR imaging (p < .01). The sizes of both the perfusion defect at myocardial perfusion MR imaging and the hyperenhanced area at gadophrin-2- enhanced MR imaging correlated well with the sizes of unstained areas at TTC staining (r = .64, p = .062 and r = .70, p = .035, respectively). CONCLUSION: In this cat model, the perfusion defect revealed by myocardial perfusion MR imaging underestimated the true size of acute reperfused myocardial infarction. The defect may represent a more severely damaged area of infarction and probably has prognostic significance.

Distribution of Coronary Calcium Score in Healthy Middle-aged Korean

PURPOSE: To determine the prevalence and degree of CAC (coronary artery calcification) in appearently healthy middle-aged Koreans, and the relation of CAC to risk factors for atherosclerosis. MATERIALS AND METHODS: A total of 289 apparently healthy personnel at Yonsei University (male: 170, female: 119, age: mean(SD=54.9 +/-7.1 years) underwent EBT (electron bean tomography). The risk factors for atherosclerosis, which included diabetes mellitus, hypertension, smoking, a family history of precocious onset, obesity, hyperlipidemia, and high intraperitoneal fat, were scrutinized. One hundred and sixty-eight subjects (58 % ) had at least one risk factor. The CAC score was calculated for all subjects and for each coronary artery separately and was then analyzed by age and sex and in relation to the risk factors. RESULTS: The prevalence of CAC was 40% in men and 18.5% in women (mean score: 29.7 vs. 9.9). The number of individuals who had one, two, or more than two risk factors was 141, 41, and 19, respectively. The number of risk factors and the prevalence and score of CAC were significantly correlated (p=0.01, 0.02 respectively). The number of individuals with no risk factor, with without CAC, was 58(20.1%) and 103(35.6% ) , respectively, while the number with some risk factor, with or without CAC, was 38(13.1%) and 90(31.1%), respectively. The CAC score was significantly higher in the presence of hypertension, low HDL, or obesity (p=0.001, 0.049, and 0.068, respectively). Smoking appeared to have a borderline effect on the calcium score (p=0.118). CONCLUSION: This study should provide useful information for interpreting CAC scores and establishing a treatment strategy for Koreans. The comparison of our results with other studies will enable a better understanding of the process and risk factors of atherosclerosis in Koreans.

Accuracy of Three-dimensional Coronary Arteriography by Electron-Beam Tomography

PURPOSE: To evaluate the diagnostic accuracy of non-invasive coronary angiography by electron beam tomography(EBT) for the depiction of coronary artery stenosis, as compared with conventional coronary angiography. MATERIALS AND METHODS: In 20 patients with no history of coronary artery disease, EBT (Imatron C-150) study was performed with EKG-gating. Forty images were obtained in each patient from the pulmonary trunk to the cardiac base at 80% R-R interval, and data were reconstructed into a three-dimensional coronary angiography. The interval between conventional coronary arteriograpy and EBT was less than 30 (mean, 9) days. Coronary arteries were divided into seven segments, and stenosis was defined as a narrowing of the luminal diameter of the coronary artery of more than 50 %. The results of EBT and of conventional angiography were compared for diagnostic accuracy. RESULTS: Conventional argiography revealed significant stenosis of the coronary artery in 12 of the 20 patients, while the use of three-dimensional coronary angiography by EBT revealed this in 16. The sensitivity and specificity of EBT were relatively high in the depiction of stenosis in the proximal left anterior descending (LAD), left circumflex (LCx), and right coronary artery (RCA) and middle LAD, but low sensitivity in the middle LCx and RCA. In the left main coronary artery, sensitivity was 50%. The sensitivity, specificity, accuracy, and positive and negative predictive values for the depiction of coronary artery stenosis with three-dimensional coronary arteriography by EBT were 79%, 95 %, 93 %, 71%, and 97 %, respectively. CONCLUSION: Three-dimensional coronary angiography by EBT is a non-invasive diagnostic modality for the depiction of proximal epicardial coronary artery stenosis and appears to be useful for excluding the probability of ischemic heart disease in a selected patient group.

First-pass Perfusion Disturbance of Coronary Artery Stenosis: An Experimental Study Using MR Imaging with Gd-DTPA Enhancement

PURPOSE: In order to determine the value of first-pass MR imaging in the diagnosis of myocardial ischemia, first-pass perfusion abnormality of coronary artery stenosis was observed in MRI after gadopentate dimeglumine (Gd-DTPA) enhancement. MATERIALS AND METHODS: The left anterior descending (LAD) coronary arteries of six dogs were subjected to approximately 70% stenosis confirmed by coronary angiography. Half an hour after adenosine and 99mTc-sestamibi infusion, Gd-DTPA (0.2 mmol/kg) and methylene blue were administered and termination was induced with potassium chloride. SE T1-weighted and single-photon emission computed tomography (SPECT) images were subsequently obtained and the findings of perfusion defect compared with specimen stain. Three dimensionally reconstructed MR images were used to measure signal intensity (SI) of normal myocardium and perfusion defect from their sectional and total volume. RESULTS: Five of six dogs with LAD artey stenosis ranging from 66% to 73% displayed perfusion defect on MRI, SPECT, and specimen stain, but the remaining dog with stenosis of 58% showed no such defect. MRI showed the perfusion defect as distinct low SI, enabling the measurement of percentage perfusion defect (24.4+/-5.4%), which increased inferiorly. SI of normal myocardium and perfusion defect decreased inferiorly; their difference indicated stenosis-induced perfusion loss according to section location. Volumetric SI of normal myocardium and perfusion defect were 3.42+/-0.52 and 2.16+/-0.45, respectively (p < 0.05). CONCLUSION: Gd-DTPA enhanced MRI displayed first-pass perfusion abnormality of coronary artery stenosis as perfusion defect with distinct low SI ; this enabled the measurement of its volume and SI changes according to section location, and thus indicated the value of first-pass MR imaging in the diagnosis of myocardial ischemia.

Utility of Quantification of Coronary Artery Calcification Using Spiral CT

PURPOSE: To evaluate the utility of quantification of coronary artery calcification using spiral CT. MATERIALS AND METHODS: Spiral CT scans of the heart were obtained in 25 patients with coronary artery disease diagnosed by coronary angiography and in six controls without coronary artery disease. Spiral CT was performedwith 3 mm collimation at 3 mm/sec table speed and the obtained volume data of the heart was reconstructed at 2 mm intervals. Total calcium scores of the 30 contiguous slices of the proximal coronary artery were calculated basedon the areas and peak density. Two groups were compared for total scores and sensitivity, and specificity and positive predictive values were calculated. RESULTS: The number of subjects with coronary calcification(totalcalcium score>0) detected by spiral CT were 20(80%) of 25 with coronary artery disease and 2(33%) of 6 without coronary artery disease. The sensitivity, specificity, and positive predictive values were 80%, 67% and 91% respectively. Sensitivity was 64%, specificity was 80% in patients aged < or =60. Sensitivity was 76% and specificity was 83%(total calcium score 10). CONCLUSION: Quantification of coronary artery calcification using spiral CT haslow specificity in the older group and low sensitivity in the younger group ; the procedure is therefore may notbe useful as a non invase screening test to predict the prescence of coronary artery disease. In the younger group, however, a cardiac workup is strongly indicated if calcification is present.