Individually adapted, interactive multiplanar reformations vs. semi-automated coronary segmentation and curved planar reformations for stenosis detection in coronary computed tomography angiography.

OBJECTIVE: To evaluate, whether semi-automated vessel extraction and curved planar reformations ("automated vessel extraction") increases diagnostic accuracy in the detection of relevant coronary artery lesions compared to manual, interactive multiplanar interpretation ("manual approach"). MATERIALS AND METHODS: 50 coronary CT angiography datasets were evaluated by four independent readers (two experienced, two novice) for the presence of stenoses exceeding 50% diameter reduction. One experienced and one novice reader each used the "manual approach" for cases 1-25 and "automated vessel extraction" for cases 26-50, while the other two readers used the complementary method. Results were compared to those of invasive coronary angiography. RESULTS: Using the "manual approach", 37 of 42 stenoses were correctly detected by experienced as well as novice readers. 14 vs. 17 lesions were false positive (sensitivity 88%, specificity 91% vs. 89%, PPV 73% vs. 69%, NPV 97%, n.s.). Using "automated vessel extraction", experienced readers detected 35/42 stenoses compared to 31/42 for novice readers. 7 vs. 11 lesions were missed and 17 vs. 15 false-positive lesions reported (sensitivity 83% vs. 74%, specificity 89% vs. 90%, PPV 67%, NPV 95% vs. 93%, n.s.).In patient-based analysis, for novice readers sensitivity was higher using the "manual approach" (97%, 29/30 pts. vs. 80%, 24/30 pts., p=0.069). CONCLUSIONS: Semi-automated vessel extraction and curved multiplanar reconstructions do not improve the diagnostic accuracy of coronary CT angiography compared to the use of interactive multiplanar reformations. Especially for less experienced readers, the use of automatically rendered curved multiplanar reconstructions alone cannot be recommended.

Comparison of dual-source computed tomography for the quantification of the aortic valve area in patients with aortic stenosis versus transthoracic echocardiography and invasive hemodynamic assessment.

We compared the measurements of the aortic valve area (AVA) using dual-source computed tomography (DSCT) in patients with mid to severe aortic stenosis to measurements using transthoracic echocardiography (TTE) and invasive hemodynamic assessment. A total of 50 patients (mean age 73 +/- 10 years) with suspected aortic stenosis were included. The computed tomographic data were acquired using DSCT with standardized scan parameters (2 x 64 x 0.6 mm collimation, 330-ms rotation, 120-kV tube voltage, 560 mA/rot tube current). After injection of 35 ml contrast agent (flow rate 5 ml/s), a targeted volume data set, ranging from the top of the leaflets to the infundibulum, was acquired. Ten cross-sectional data sets (slice thickness 1 mm, no overlap, increment 0.6 mm) were reconstructed during systole in 5% increments of the R-R interval. The AVA determined in systole by planimetry was compared to the calculated AVA values using the continuity equation on TTE and the Gorlin formula on catheterization. DSCT allowed the planimetry of the AVA in all patients. The mean AVA using DSCT was 1.16 +/- 0.47 cm(2) compared to a mean AVA of 1.04 +/- 0.45 cm(2) using TTE and 1.06 +/- 0.45 cm(2) using catheterization, with a significant correlation between DSCT/TTE (r = 0.93, p <0.001) and DSCT/cardiac catheterization (r = 0.97, p <0.001). However, DSCT demonstrated a slight, but significant, overestimation of the AVA compared to TTE (+0.12 +/- 0.17 cm) and catheterization (+0.10 +/- 0.12 cm(2)). In conclusion, DSCT permits one to assess the AVA with a high-image quality and diagnostic accuracy compared to TTE and invasive determination.

Assessment of changes in non-calcified atherosclerotic plaque volume in the left main and left anterior descending coronary arteries over time by 64-slice computed tomography.

Multidetector computed tomography (MDCT) permits the visualization of the coronary arteries and of coronary atherosclerotic plaques. The natural course of noncalcified plaque is not known. This study was conducted to measure the change in noncalcified coronary plaque volume in the left main coronary artery and in the proximal left anterior descending coronary artery over time using 64-slice MDCT. Fifty patients in whom noncalcified lesions had been detected on baseline MDCT received follow-up scans after an interval of 17 +/- 6 months. Plaque areas were traced manually in serial multiplanar reconstructions to determine overall volume. The mean plaque volumes were 92 +/- 81 mm(3) on baseline MDCT and 115 +/- 110 mm(3) on follow-up MDCT (p <0.001). The mean annualized volume change was 22% (95% confidence interval 14.7% to 29.7%). A weak but significant correlation with low-density lipoprotein cholesterol level was observed for the amount of baseline plaque volume (r = 0.37, p <0.001). In conclusion, the quantification of noncalcified plaque volume is possible on repeated 64-slice MDCT. A significant increase of the amount of noncalcified plaque was observed over a mean interval of 17 months. Contrast-enhanced MDCT may therefore be a tool to study the progression of coronary atherosclerosis.

Randomized comparison of 64-slice single- and dual-source computed tomography coronary angiography for the detection of coronary artery disease.

OBJECTIVES: The purpose of this study was to analyze the influence of a systematic approach to lower heart rate for coronary computed tomography (CT) angiography on diagnostic accuracy of 64-slice single- and dual-source CT. BACKGROUND: Coronary CT angiography is often impaired by motion artifacts, so that routine lowering of heart rate is usually recommended. This is often conceived as a major limitation of the technique. It is expected that higher temporal resolution, such as with dual-source 64-slice CT, would allow diagnostic imaging even without systematic pre-treatment for lowering the heart rate. METHODS: Two hundred patients with suspected coronary artery disease were first randomized to either 64-slice single-source CT (n = 100) or dual-source CT (n = 100) for contrast-enhanced coronary artery evaluation. In each group, patients were further randomized to either receive systematic heart rate control (oral and intravenous beta-blockade for a target heart rate < or =60 beats/min) or receive no premedication. Evaluability of datasets and diagnostic accuracy were compared between groups against the results obtained from invasive angiography. RESULTS: Systematic pre-treatment lowered heart rate during CT coronary angiography by 10 beats/min. Heart rate control significantly improved evaluability in single-source CT (93% vs. 69% on a per-patient basis, p = 0.005), whereas it did not in dual-source CT (96% vs. 98%). In evaluable patients, sensitivity to detect the presence of at least 1 coronary stenosis by single-source CT was 86% and 79%, respectively, with and without heart rate control (p = NS). For dual-source CT, it was 100% and 95%, respectively (p = NS). The rate of correctly classified patients, defined as evaluable and correct classification as to the presence or absence of at least 1 coronary artery stenosis, was significantly improved by heart rate control in single-source CT (78% vs. 57%, p = 0.04), whereas there was no such influence in dual-source CT (87% vs. 93%). CONCLUSIONS: Systematic heart rate control significantly improves image quality for coronary visualization by 64-slice single-source CT, whereas image quality and diagnostic accuracy remain unaffected in dual-source CT angiography. Improved temporal resolution obviates the need for heart rate control.

Influence of heart rate on the diagnostic accuracy of dual-source computed tomography coronary angiography.

OBJECTIVES: We evaluated the influence of heart rate on image quality and diagnostic accuracy of dual-source computed tomography (DSCT) coronary angiography. BACKGROUND: Multidetector computed tomography (MDCT) coronary angiography has demonstrated an inverse relationship between heart rate and image quality. Dual-source CT provides a higher temporal resolution. METHODS: One hundred patients were studied by DSCT (DEFINITION, Siemens Medical Solutions, Forchheim, Germany). A contrast-enhanced volume dataset was acquired (two tubes, 120 kV, 400 mAs/rot, collimation 64 x 0.6 mm). Datasets were evaluated concerning the presence of significant coronary stenoses and validated against invasive coronary angiography. RESULTS: In 44 patients with a heart rate > or =65 beats/min, 566 of 616 coronary segments were evaluable (92%), whereas in 56 patients with a heart rate <65 beats/min, 777 of 778 coronary segments were evaluable (100%, p < 0.001). On a per-patient basis, 93% of patients (> or =65 beats/min) and 100% of patients (<65 beats/min) were considered evaluable. By classifying unevaluable segments as positive for stenosis, per-patient sensitivity was 95% (19 of 20) for heart rates > or =65 beats/min and 100% (22 of 22) for heart rates <65 beats/min. Specificity was 87% (21 of 24) versus 76% (26 of 34), and overall diagnostic accuracy was 91% (40 of 44) versus 86% (48 of 56). None of these differences were statistically significant. Similarly, no difference in diagnostic accuracy was found in per-vessel and -segment analyses. CONCLUSIONS: In 100 patients studied without beta-blocker pre-medication, DSCT demonstrated slightly lower per-segment evaluability for high heart rates but no decrease in diagnostic accuracy for the detection of coronary artery stenoses.

Assessment of coronary artery stent restenosis by 64-slice multi-detector computed tomography.

AIMS: We investigated the feasibility of assessing coronary artery stent restenosis using a new generation 64-slice multi-detector computed tomography-scanner (MDCT) in comparison to conventional quantitative angiography. METHODS AND RESULTS: MDCT was performed in 64 consecutive patients (mean age 58+/-10 years) with previously implanted coronary artery stents (102 stented lesions: mean stent diameter 3.17+/-0.38 mm). Each stent was classified as 'evaluable' or 'unevaluable', and in evaluable stents, the presence of in-stent restenosis (diameter reduction >50%) was determined visually. Results were verified against invasive, quantitative coronary angiography. Fifty-nine stented lesions (58%) were classified as evaluable in MDCT. The mean diameter of evaluable stents was 3.28+/-0.40 mm, whereas the mean diameter of non-evaluable stents was 3.03+/-0.31 mm (P=0.0002). Overall, six of 12 in-stent restenoses were correctly detected by MDCT [50% sensitivity (confidence interval 22-77%)] and in 51 of 90 lesions, in-stent restenosis was correctly ruled out [57% specificity (46-67%)]. In evaluable stents, six of seven in-stent restenoses were correctly detected, and the absence of in-stent stenosis was correctly identified in 51 of 52 cases [sensitivity 86% (42-99%) and specificity 98% (88-100%)]. CONCLUSION: Stent type and diameter influence evaluability concerning in-stent restenosis by MDCT. The rate of assessable stents is low, but in evaluable stents, accuracy for detection of in-stent restenosis can be high.