Preserved diagnostic performance of dual-source CT coronary angiography with reduced radiation exposure and cancer risk.

PURPOSE: To evaluate the effects of standard and optimal electrocardiographic (ECG) pulsing on diagnostic performance, radiation dose, and cancer risk in symptomatic patients in a "real-world" clinical setting. MATERIALS AND METHODS: The institutional review board approved the study, and all patients gave informed consent. Dual-source computed tomographic (CT) coronary angiography was performed in 436 symptomatic patients (301 men, 135 women; mean age, 61.6 years +/- 10.6 [standard deviation]; age range, 23-89 years) referred for conventional coronary angiography. Standard and optimal ECG pulsing was performed in 327 and 109 patients, respectively. The diagnostic performance of dual-source CT coronary angiography for detection of significant stenosis (>or=50 luminal diameter reduction), with quantitative coronary angiography as the reference standard, was reported as sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios. The mean effective radiation dose, additional fatal cancer risk, and age- and sex-specific cancer risks related to one CT coronary angiographic examination were determined from data averaged over the study population. RESULTS: Mean effective doses with standard and optimal ECG pulsing were 14.2 mSv +/- 3.2 and 10.7 mSv +/- 3.6, respectively. Optimal ECG pulsing resulted in a 43% overall reduction in mean effective radiation dose and cancer risk compared with a nonpulsing protocol (18.8 mSv +/- 3.5) and a 25% overall reduction in mean effective dose compared with the standard pulsing protocol. At patient-by-patient analysis, CT coronary angiography with standard ECG pulsing yielded sensitivity, specificity, and positive and negative predictive values of 100% (95% confidence interval [CI]: 99%, 100%), 85% (95% CI: 81%, 88%), 94% (95% CI: 91%, 96%), and 99% (95% CI: 98%, 100%), respectively, for detection of significant stenosis. Optimal ECG pulsing yielded similar results: Sensitivity, specificity, and positive and negative predictive values were 100% (95% CI: 100%, 100%), 88% (95% CI: 82%, 94%), 97% (95% CI: 93%, 100%), and 100%, respectively. CONCLUSION: Compared with a nonpulsing protocol, optimal ECG pulsing resulted in significant (P < .001) reductions in patient radiation dose and cancer risk (up to 55% reduction in patients with high heart rates) while preserving the diagnostic performance of dual-source CT coronary angiography.

Left ventricular remodelling and systolic function measurement with 64 multi-slice computed tomography versus second harmonic echocardiography in patients with coronary artery disease: a double blind study.

The present study evaluated LV volumes, ejection fraction (LVEF) and stroke volume (SV) obtained by 64-MDCT and to compare these data with those obtained by second harmonic 2D Echo, in patients referred for non-invasive coronary vessels evaluation. The most common technique in daily clinical practice used for determination of LV function is two-dimensional echocardiography (2D-TTE). Multi-detector computed tomography (MDCT) is an emerging new technique to detect coronary artery disease (CAD) and was recently proposed to assess LV function. 93 patients underwent to 64-MDCT for LV function and volumes assessment by segmental reconstruction algorithm (Argus) and compared with recent (2 months) 2D-TTE, all images were processed and interpreted by two observers blinded to the Echo and MDCT results. A close correlation between TTE and 64 MDCT was demonstrated for the ejection fraction LVEF (r=0.84), end-diastolic volume LVEDV (r=0.80) and end-systolic volume LVESV (r=0.85); acceptable correlation was recruited for stroke volume LVSV (r=0.58). Optimal results were recruited for inter-observer variability for 64-MDCT measured in 45 patients: LVESV (r=0.82, p<0.001), LVEDV (r=0.83, p<0.001), LVEF (r=0.69, p<0.002) and SV (r=0.66, p<0.001). Our results, showed that functional and temporal information contained in a coronary 64-MDCT study can be used to assess left ventricular (LV) systolic function and LV dimensions with good reproducibility and acceptable correlation respect to 2D-TTE. The combination of non-invasive coronary artery imaging and assessment of global LV function might became in the future a fast and conclusive cardiac work-up in patients with CAD.

Anatomical and functional assessment of single left internal mammary artery versus arterial T-grafts 12 years after surgery.

We determined whether ultrasonographic left internal mammary artery (LIMA) findings correspond with 64 multislice computed tomography (MSCT) in patients 12 years after coronary artery bypass grafting. We included 34 patients (63.2+/-9.2 years), 16 with conventional single LIMA (group I) and 18 arterial T-grafts (group II), in a cross-sectional study. Patients underwent transthoracic proximal LIMA ultrasonography at rest and during the Azoulay maneuver, transthoracic echocardiography of the left ventricle and 64-MSCT, 11.5+/-1.4 years postoperatively. MSCT scans showed three string sign LIMA grafts (19%) in group I and three distal string sign LIMA grafts (17%) and 16 occluded T-graft anastomoses (22%) in group II. LIMA diameters and areas are significantly larger in group II in the origin, 3.5+/-0.7 vs. 2.5+/-0.5 mm, P=0.00007 and 0.09+/-0.04 vs. 0.05+/-0.02 cm(2), P=0.00019 and in the third intercostal space, 3.4+/-0.7 vs. 2.5+/-0.5 mm, P=0.00009 and 0.09+/-0.03 vs. 0.05+/-0.02 cm(2), P=0.000047. Most ultrasonographic LIMA findings do not differ between the groups. Thus, proximal LIMA diameters and areas are significantly larger in T-grafts and ultrasonographic variables equalize between the groups at rest and during the Azoulay maneuver 12 years after surgery.

Diagnostic accuracy of computed tomography angiography in patients after bypass grafting: comparison with invasive coronary angiography.

OBJECTIVES: We sought to evaluate the contribution of noninvasive dual-source computed tomography angiography (CTA) in the comprehensive assessment of symptomatic patients after coronary artery bypass grafting (CABG). BACKGROUND: Assessment of bypass grafts and distal runoffs by invasive coronary angiography is cumbersome and often requires extra procedure time, contrast load, and radiation exposure. METHODS: Dual-source CTA was performed in 52 (41 men, mean age 66.6 +/- 13.2 years) symptomatic post-CABG patients scheduled for invasive coronary angiography. No oral or intravenous beta blockers or sedation were administered before the scan. Mean interval between CABG surgery and CTA was 9.6 +/- 7.2 (range 0 to 20) years. Mean heart rate during scanning was 64.5 +/- 13.2 (range 48 to 92) beats/min. Seventy-five percent of patients had both arterial and venous grafts. A total of 152 graft segments and 142 distal runoffs vessels were analyzed. Native coronary segments were divided into nongrafted (n = 118) and grafted segments (n = 289). A significant stenosis was defined as >or=50% lumen diameter reduction, and quantitative coronary angiography served as reference standard. RESULTS: The diagnostic accuracy of CTA for the detection or exclusion of significant stenosis in arterial and venous grafts on a segment-by-segment analysis was 100%. Sensitivity, specificity, positive predictive value, and negative predictive value to detect significant stenosis were 95% (95% confidence interval [CI]: 73% to 100%), 100% (95% CI: 96% to 100%), 100% (95% CI: 79% to 100%), 99% (95% CI: 95% to 100%) in distal runoffs respectively; 100% (95% CI: 97% to 100%), 96% (95% CI: 90% to 98%), 97% (95% CI: 93% to 99%), 100% (95% CI: 95% to 100%) in grafted native coronary arteries respectively; and 97% (95% CI: 83% to 100%), 92% (95% CI: 83% to 96%), 83% (95% CI: 67% to 92%), 99% (95% CI: 92% to 100%) in nongrafted native coronary arteries, respectively. CONCLUSIONS: Noninvasive CTA is successful for evaluating bypass grafts in symptomatic post-CABG patients, whereas invasive coronary angiography is still required for the assessment of significant stenosis in distal runoffs and native coronary arteries.

Follow-up of internal mammary artery stent with 64-slice CT.

We present a case of 81-year-old woman complaining chest pain after minimal efforts who underwent multiple coronary artery bypass grafts (CABGs) during the last 15 years. A significant in-stent re-stenosis was found at ostium of left internal mammary artery (LIMA). A non-invasive CT coronary angiography (CT-CA) was performed after 6-month follow-up. CT-CA is a reliable non-invasive technique for the follow-up of stents in coronary artery bypass grafts.

Adjunctive value of CT coronary angiography in the diagnostic work-up of patients with typical angina pectoris.

AIMS: To determine the adjunctive value of CT coronary angiography (CTCA) in the diagnostic work-up of patients with typical angina pectoris. METHODS AND RESULTS: CTCA was performed in 62 consecutive patients (45 male, mean age 58.8 +/- 7.7 years) with typical angina undergoing diagnostic work-up including exercise-ECG and conventional coronary angiography. Only patients with sinus heart rhythm and ability to breath hold for 20 s were included. Patients with initial heart rates >/=70 beats/min received beta-blockers. We determined the post-test likelihood ratios, to detect or exclude patients with significant (>/=50% lumen diameter reduction) stenoses, of exercise-ECG and CTCA separately, and of CT performed after exercise-ECG testing. The prevalence of patients with significant coronary artery disease (CAD) was 74%. Positive and negative likelihood ratios for exercise-ECG were 2.3 [95% confidence interval (CI): 1.0-5.3] and 0.3 (95% CI: 0.2-0.7) and for CTCA 7.5 (95% CI: 2.1-27.1) and 0.0 (95% CI: 0.0-8), respectively. CTCA increased the post-test probability of significant CAD after a negative exercise-ECG from 58 to 91%, and after a positive exercise-ECG from 89 to 99%, while CT correctly identified patients without CAD (probability 0%). CONCLUSION: Non-invasive CTCA is a potentially useful tool, in the diagnostic work-up of patients with typical angina pectoris, both to detect and to exclude significant CAD.

Diagnostic accuracy of multislice computed tomography coronary angiography is improved at low heart rates.

PURPOSE: Assess the effect of heart rate on diagnostic accuracy for the detection of significant coronary artery stenosis using 16-row multislice computed tomography (MSCT). MATERIAL AND METHODS: About 120 patients (105 males; 59+/-11 years) with suspected coronary artery disease who underwent conventional coronary angiography (CA) and MSCT-CA were retrospectively enrolled for the study. Patients underwent a MSCT-CA (Sensation 16, Siemens, Germany), with the following protocol: collimation 16 x 0.75 mm, gantry rotation time 420 ms, feed/rotation 3.0 mm, kV 120, mAs 400-500. The protocol for contrast material administration was 100 ml of Iodixanol (Visipaque 320 mg l/ml, Amersham, UK) at 4 ml/s and the delay was defined with a bolus tracking technique. In all patients the mean heart rate (HR) during the scan was used as a criteria to divide the population in two groups of 60 patients each. In one group (Low HR) the 60 patients with lower heart rates, and in the other group (High HR) the patients with higher heart rates. In the two groups diagnostic accuracy (per coronary segment) for the detection of significant stenosis (>or=50% lumen reduction) was evaluated in vessels >or=2 mm of diameter using quantitative CA as reference standard. The difference in diagnostic accuracy were compared with a Chi(2) test and a p<0.05 was considered significant. RESULTS: There was no significant difference between the two groups regarding age, gender, weight, mean intravascular attenuation, and calcium score. Overall 1,310 (652 for Low HR and 658 for High HR) segments with 219 (105 for Low HR and 114 for High HR) significant lesions were available for the analysis. The average heart rate was 52+/-4 HU and 63+/-5 HU for Low HR and High HR, respectively (p<0.001). The sensitivity and specificity were 92 and 96% for Low HR and 90 and 92% for High HR (p<0.05). There were 22 vs. 44 false positives, and 8 vs. 12 false negatives in the Low HR and High HR, respectively. CONCLUSION: Increasing HR significantly deteriorates diagnostic accuracy in MSCT-CA.