Quantification of aortic regurgitant fraction and volume with multi-detector computed tomography comparison with echocardiography.

RATIONALE AND OBJECTIVES: Evaluate quantification of the aortic regurgitant fraction and volume with computed tomography (CT). MATERIALS AND METHODS: Fifty-three patients with aortic regurgitation (AR) and 29 controls were examined with 64-multi-detector CT coronary angiography and transthoracic echocardiography (TTE). A dedicated software algorithm employing three-dimensional segmentation of left ventricle (LV) and right ventricle (RV) volumes and LV mass was applied. AR volume and fraction was calculated based on RV and LV stroke volumes (SV) and compared with echocardiography. The aortic regurgitant orifice area (ROA) was measured by CT. RESULTS: A good correlation of the AR fraction and AR volume determined by CT compared to echocardiography was found for mild, moderate, and severe AR with 14.2% ± 9, 28.8% ± 8, and 57.9% ± 9 (r = 0.95, P < .001) for AR fraction, and 15.7 mL ± 11.33 mL ± 14, and 98.9 mL ± 36 for AR volume (r = 0.92, P < .0001), respectively. CT correctly classified severity of AR in 93% of patients based of AR-fraction, and in 89% based on AR volume. The sensitivity and specificity of CT were 98% and specificity 90.3%. The specificity improved to 97%, if the ROA by CT was added as diagnostic criterion. CONCLUSION: Aortic regurgitation fraction and volume can be accurately quantified from CT coronary angiography datasets. These parameters can assist clinical management, e.g. in case of pending cardiac surgery decision.

Radiation dose reduction by using 100-kV tube voltage in cardiac 64-slice computed tomography: a comparative study.

OBJECTIVE: To evaluate a 100-kilovoltage (kV) tube voltage protocol regarding radiation dose and image quality, in comparison with the standard 120 kV setting in cardiac computed tomography angiography (CCTA). METHODS: 103 patients undergoing retrospective ECG-gated helical 64-slice CCTA were enrolled (100 kV group: 51 patients; 120 kV group: 52 patients). Inclusion criteria were: (1) BMI <28 kg/m(2); (2) weight <85 kg; (3) coronary calcium score <300 Agatston Units (AU). Quantitative image quality parameters were calculated [image noise, contrast-to-noise ratio (CNR), intracoronary CT-attenuation (HU)]. Each coronary artery segment (AHA/ACC-16-segments-classification) was evaluated for image quality on a 4-point scale. RESULTS: There was no statistical difference in age, gender, BMI and eff. tube current (mAs), and the use of ECG-tube current modulation (50.9% vs. 50% of patients) between both groups. 84.2% of patients in the 100 kV group had zero calcium score or less than 100 AU, the remaining had between 100 and 300 AU. The effective radiation dose was significantly lower in the 100 kV group with mean 7.1 mSv+/-2.4 (range, 3.4-11.1) compared to the 120 kV group with 13.4 mSv+/-5.2 (range, 6.3-22.7) (p<0.001) (dose reduction, 47%). In the 100 kV group, the use of ECG-dependent tube current modulation reduced the radiation exposure (by 44.8%) to 5.3 mSv+/-1.1 (range, 3.4-8.5 mSv) (p<0.001), the dose without was 9.6 mSv+/-1.1 (range, 6.3-11.1). Image noise in the coronary arteries was not different between both groups with 29.8 and 30.5 SD [HU], respectively. CNR in the 100 kV group was with 20.9+/-6.8 for the coronary arteries and with 19.9+/-5.9 for the aorta similar to the 120 kV group. Intraluminal CT-attenuation (HU) of the coronary arteries were higher in the 100 kV group (p<0.001). Image quality on 100 kV scans was excellent in 86.3%, good in 9.2%, acceptable in 3.1% of coronary segments; 1.4% were non-interpretable (in 1/4 due to increased image noise because of BMI >25 kg/m(2)). CONCLUSIONS: The 100 kV protocol significantly reduces the radiation dose in CCTA in patients with a low BMI <25 kg/m(2) and a low calcium load while maintaining high image quality and the advantages of helical scan algorithm.

Evaluation of left ventricular function by 64-multidetector computed tomography in patients undergoing totally endoscopic coronary artery bypass grafting.

OBJECTIVES: The goal of this study was to quantify left ventricular (LV) function with automated 3-dimensional volume segmentation by 64-slice computed tomography (CT) in patients undergoing totally endoscopic coronary artery bypass grafting (CABG). METHODS: We used 64-multidetector CT coronary angiography to examine 63 patients with >70% coronary stenosis who were undergoing totally endoscopic CABG for single-vessel disease (left internal mammary artery to left anterior descending coronary artery) or multivessel disease with the da Vinci robotic surgical device (arrested heart approach). CT measurements were compared with cineventriculography results in 20 patients. RESULTS: The intraobserver variability values for the end-systolic volume (ESV) and the end-diastolic volume (EDV) were excellent (7.2% and 5.2%, respectively). Bland-Altman plots showed good upper and lower limits of agreement (ESV, +9% and -3.3%, respectively; EDV, +17% and -5.9%). Intraobserver variability for the LV ejection fraction (LVEF) was 4.8% with narrow limits of agreement (+7.8%, -2.2%). The mean postprocessing time was 6.5 minutes. Mean values (+/-SD) were 62.7% +/- 12% (range, 23%-86%) for LVEF, 98.4 mL +/- 29 mL for EDV, and 38.3 mL +/- 23 mL for ESV. The LVEF obtained via CT was moderately but significantly correlated with the invasive cineventriculogram (r = 0.51; P = .02; limits of agreement, +18.7% and -18.4%). CONCLUSION: . Through the use of automated LV volume segmentation, 64-slice CT permits fast quantification of LV function in patients with coronary artery disease undergoing totally endoscopic CABG grafting, enabling a comprehensive evaluation of coronary arteries and bypass grafts.