André Plass

Low-Dose CT Coronary Angiography in the Step-and-Shoot Mode: Diagnostic Performance

Objective: To investigate the performance of low-dose, dual-source computed tomography (DSCT) coronary angiography in the step-and-shoot (SAS) mode for the diagnosis of significant coronary artery stenoses in comparison with conventional coronary angiography (CCA). Design, setting and patients: Prospective, single-centre study conducted in a referral centre enrolling 120 patients (71 men, mean (SD) age 68 (9) years, mean (SD) body mass index 26.2 (3.2) kg/m2). All study participants underwent DSCT in the SAS mode and CCA within 14 days. Twenty-seven patients were given intravenous β blockers for heart rate reduction before CT. Patients were excluded if a target heart rate ⩽70 bpm could not be achieved by β blockers or when the patients were in non-sinus rhythm. Two blinded readers independently evaluated coronary artery segments for assessability and for the presence of significant (>50%) stenoses. Sensitivity, specificity, negative (NPV) and positive predictive values (PPV) were determined, with CCA being the standard of reference. Radiation dose values were calculated. Results: DSCT coronary angiography in the SAS mode was successfully performed in all 120 patients. Mean (SD) heart rate during scanning was 59 (6) bpm (range 44–69). 1773/1803 coronary segments (98%) were depicted with a diagnostic image quality in 109/120 patients (91%). The overall patient-based sensitivity, specificity, PPV and NPV for the diagnosis of significant stenoses were 100%, 93%, 94% and 100%, respectively. The mean (SD) effective dose of the CT protocol was 2.5 (0.8) mSv (range 1.2–4.4). Conclusions: DSCT coronary angiography in the SAS mode allows, in selected patients with a regular heart rate, the accurate diagnosis of significant coronary stenoses at a low radiation dose.

Dual-source CT in step-and-shoot mode: noninvasive coronary angiography with low radiation dose.

PURPOSE To prospectively investigate computed tomographic (CT) image quality parameters by using different protocols and to calculate radiation dose estimates for noninvasive coronary angiography performed with dual-source CT in the step-and-shoot (SAS) mode. MATERIALS AND METHODS This study was local ethics board approved; written informed consent was obtained from all patients. In the preliminary portion of the study, 40 patients underwent CT coronary angiography in the SAS mode: at 100 kV (protocol A) in 22 patients with a body mass index (BMI) of less than 25 kg/m(2) and at 120 kV (protocol B) in 18 patients with a BMI of 25-30 kg/m(2). Both protocols involved use of an attenuation-based tube current and 1 mL of contrast material per kilogram of body weight. The final portion of the study involved 50 additional patients: 21 patients with a BMI of 25-30 kg/cm(2) assigned to protocol B and 29 patients with a BMI of less than 25 kg/cm(2) assigned to protocol C, which was performed with 100 kV, an attenuation-based tube current, and a reduced contrast material dose of 0.8 mL/kg. Image quality was independently assessed. Attenuation in the aorta and coronary arteries and image noise were measured. Radiation dose was estimated. RESULTS Mean image noise was similar with protocols A and B. Mean attenuation in the aorta and coronary arteries with protocol A (444 HU) was significantly (P < .001) higher than that with protocol B (358 HU). The reduced contrast material dose in protocol C yielded attenuation similar to that with protocol B. Diagnostic image quality was achieved with all protocols in 1237 (97.9%) of 1264 coronary segments. No significant differences in image quality between the 100- and 120-kV protocols were found. Mean heart rate had a significant effect on motion artifacts (area under receiver operating characteristic curve [AUC] = 0.818; 95% confidence interval [CI]: 0.723, 0.892; P < .001), whereas heart rate variability had a significant effect on stair-step artifacts (AUC = 0.79; 95% CI: 0.687, 0.865; P < .001). The mean estimated effective dose was 1.2 mSv +/- 0.2 for protocols A and C and 2.6 mSv +/- 0.5 for protocol B. CONCLUSION Dual-source SAS-mode CT coronary angiography yielded diagnostic image quality for 97.9% of coronary segments at a low radiation dose.

Multislice Computed Tomography in Infective Endocarditis Comparison With Transesophageal Echocardiography and Intraoperative Findings

OBJECTIVES The aim of this study was to assess the value of multislice computed tomography (CT) for the assessment of valvular abnormalities in patients with infective endocarditis (IE) in comparison with transesophageal echocardiography (TEE) and intraoperative findings. BACKGROUND Multislice CT has recently shown promising data regarding valvular imaging in a 4-dimensional fashion. METHODS Thirty-seven consecutive patients with clinically suspected IE were examined with TEE and 64-slice CT or dual-source CT. Twenty-nine patients had definite IE and underwent surgery. RESULTS The diagnostic performance of CT for the detection of evident valvular abnormalities for IE compared with TEE was: sensitivity 97%, specificity 88%, positive predictive value (PPV) 97%, and negative predictive value (NPV) 88% on a per-patient basis (n = 37; excellent intermodality agreement kappa = 0.84). CT correctly identified 26 of 27 (96%) patients with valvular vegetations and 9 of 9 (100%) patients with abscesses/pseudoaneurysms compared with the intraoperative specimen. On a per-valve-based analysis, diagnostic accuracy for the detection of vegetations and abscesses/pseudoaneurysms compared with surgery was: sensitivity 96%, specificity 97%, PPV 96%, NPV 97%, and sensitivity 100%, specificity 100%, PPV 100%, NPV 100%, respectively, without significant differences as compared with TEE. Vegetation size measurements by CT correlated (r = 0.95; p <0.001) with TEE (mean 7.6 +/- 5.6 mm). The mobility of vegetations was accurately diagnosed in 21 of 22 (96%) patients with CT, but all of 4 leaflet perforations (<or=2 mm) were missed. CT provided more accurate anatomic information regarding perivalvular extent of abscess/pseudoaneurysms than TEE. CONCLUSIONS Multislice CT shows good results in detecting valvular abnormalities in IE and could be applied in pre-operative planning and exclusion of coronary artery disease before surgery.

Image quality and reconstruction intervals of dual-source CT coronary angiography: recommendations for ECG-pulsing windowing.

Purpose:To evaluate reconstruction intervals and image quality in dual-source computed tomography (DSCT) coronary angiography for optimal placement of the ECG-pulsing window. Materials and Methods:DSCT coronary angiography was performed in 60 patients. Thirteen datasets were reconstructed in 5% increments from 20–80%. Two readers independently assessed image quality of each segment in each percentage-interval, using scores ranging from 1 (no motion artifacts) to 4 (nonevaluable). Results:Mean heart rate (HR) was 69.0 ± 18.9 beats per minute (bpm) (range, 35–117 bpm). Diagnostic image quality (scores 1–3) was found in 97.8% of all segments (763 of 780). The 70% RR-interval provided best image quality in all patients and all HRs. The narrowest reconstruction window providing diagnostic image quality was 60–70% for HR <60 bpm, 60–80% for 60–70 bpm, 55–80% for 70–80 bpm, and 30–80% for HR >80 bpm. Conclusions:DSCT coronary angiography provides best image quality for various HRs at 70%. The ECG-pulsing window can be adapted according to the HR while maintaining diagnostic image quality.

Dual-source computed tomography coronary angiography: influence of obesity, calcium load, and heart rate on diagnostic accuracy

AIMS To prospectively investigate the diagnostic accuracy of dual-source computed tomography coronary angiography (CTCA) to diagnose coronary stenoses in relation to body mass index (BMI), Agatston score (AS), and heart rate (HR) as compared with catheter coronary angiography (CCA). METHODS AND RESULTS Hundred and fifty consecutive patients (47 female, mean age 62.9 +/- 12.1 years) underwent dual-source CTCA without HR control. Patients were divided into subgroups depending on the median of their BMI (26.0 kg/m2), AS (194), and HR (66 b.p.m.). CCA was considered the standard of reference. Mean BMI was 26.5 +/- 4.2 kg/m2 (range 18.3-39.1 kg/m2), mean AS was 309 +/- 408 (range 0-4387), and HR was 68.5 +/- 12.6 b.p.m. (range 35-102 b.p.m.). Diagnostic image quality was found in 98.1% of all segments (2020/2059). Considering not-evaluative segments at CTCA as false-positive, overall per-patient sensitivity, specificity, positive, and negative predictive value were 96.6%, 86.8%, 82.6%, and 97.5%, respectively. High HR did not deteriorate diagnostic accuracy of CTCA. High BMI and AS were associated with a decrease in per-patient specificity to 84.1% and 77.8%, respectively, while sensitivity and negative predictive value remained high. CONCLUSION Dual-source CTCA provides high diagnostic accuracy irrespective of the HR and serves as a modality to rule-out coronary artery stenoses even in patients with high BMI and AS.

Low-dose, 128-slice, dual-source CT coronary angiography: accuracy and radiation dose of the high-pitch and the step-and-shoot mode

Objective To compare the diagnostic accuracy and radiation doses of two low-dose protocols for coronary artery imaging with second-generation, dual-source CT in comparison with catheter angiography (CA). Design, setting and patients Prospective, single-centre study conducted in a referral centre enrolling 100 patients with low-to-intermediate risk and suspicion of coronary artery disease. All patients underwent contrast-enhanced, 128-slice, dual-source CT coronary angiography and CA. Patients were randomly assigned to two different low-dose CT protocols (each 100 kV/320 mA): in group A (n=50), CT was performed using the prospectively electrocardiography (ECG)-gated step-and-shoot (SAS) mode; in group B (n=50), CT was performed using the prospectively ECG-gated high-pitch mode (pitch 3.4). The image quality and presence or absence of significant coronary stenosis in all coronary segments were evaluated by two blinded and independent observers. CA served as the standard of reference. Results Sixty-one significant stenoses were found in group A, and 69 in group B. There was no significant difference in age (group A, 62±8yrs; group B, 63±8yrs; p=0.72), body mass index (group A, 26.4±3.1kg/m2; group B, 25.9±2.8kg/m2; p=0.41) and heart rate (HR) (group A, 58±8bpm; group B, 56±10bpm; p=0.66) between the groups. Diagnostic image quality was obtained in 98.6% (651/660) of segments in group A and in 98.9% (642/649) in group B, with no significant differences between groups. Sensitivity, specificity and positive and negative predictive values were 94%, 91%, 85% and 97% per-patient in group A, and 93%, 94%, 89% and 97% per-patient in group B (no significant differences). The effective radiation dose in group B (0.9±0.1 mSv) was significantly (p<0.01) lower than that in group A (1.4±0.4 mSv). Conclusions Both the high-pitch and the SAS mode for low-dose CT coronary angiography provide high accuracy for the assessment of significant coronary stenoses, while the high-pitch mode further significantly lowers the radiation dose.

Adenosine stress high-pitch 128-slice dual-source myocardial computed tomography perfusion for imaging of reversible myocardial ischemia: comparison with magnetic resonance imaging.

Background— Coronary computed tomography angiography (CTA) enables accurate anatomic evaluation of coronary artery stenosis but lacks information about hemodynamic significance. The aim of this study was to evaluate 128-slice myocardial CT perfusion (CTP) imaging with adenosine stress using a high-pitch mode, in comparison with cardiac MRI (CMR). Methods and Results— Thirty-nine patients with intermediate to high coronary risk profile underwent adenosine stress 128-slice dual source CTP (128×0.6 mm, 0.28 seconds). Among those, 30 patients (64±10 years, 6% women) also underwent adenosine stress CMR (1.5T). The 2-step CTP protocol consisted of (1) adenosine stress-CTP using a high-pitch factor (3.4) ECG-synchronized spiral mode and (2) rest-CTP/coronary-CTA using either high-pitch (heart rate <63 bpm) or prospective ECG-triggering (heart rate >63 bpm). Results were compared with CMR and with invasive angiography in 25 patients. The performance of stress-CTP for detection of myocardial perfusion defects compared with CMR was sensitivity, 96%; specificity, 88%; positive predictive value (PPV), 93%; negative predictive value (NPV), 94% (per vessel); and sensitivity, 78%; specificity, 87%; PPV, 83%; NPV, 84% (per segment). The accuracy of stress-CTP for imaging of reversible ischemia compared with CMR was sensitivity, 95%; specificity, 96%; PPV, 95%; and NPV, 96% (per vessel). In 25 patients who underwent invasive angiography, the accuracy of CTA for detection of stenosis >70% was (per segment): sensitivity, 96%; specificity, 88%; PPV, 67%; and NPV, 98.9%. The accuracy improved from 84% to 95% after adding stress CTP to CTA. Radiation exposure of the entire stress/rest CT protocol was only 2.5 mSv. Conclusions— Adenosine-induced stress 128-slice dual-source high-pitch myocardial CTP allows for simultaneously assessment of reversible myocardial ischemia and coronary stenosis, with good diagnostic accuracy as compared with CMR and invasive angiography, at a very low radiation exposure.

Radiation dose of cardiac dual-source CT: The effect of tailoring the protocol to patient-specific parameters

OBJECTIVE To determine the radiation doses and image quality of different dual-source computed tomography coronary angiography (CTCA) protocols tailored to the heart rate (HR) and body mass index (BMI) of the patients. MATERIALS AND METHODS Two hundred consecutive patients (68 women; mean age 61+/-9 years) underwent either helical CTCA with retrospective ECG-gating or sequential CT with prospective ECG-triggering: 50 patients (any BMI, any HR) were examined with a standard, non-tailored protocol (helical CTCA, 120 kV, 330 mAs), whereas the other 150 patients were examined with a tailored protocol: 40 patients (group A, BMI<or=25 kg/sqm, HR<or=70 bpm) with sequential CTCA (100 kV, 190 mAs(ref)), 43 patients (group B, BMI</=25 kg/sqm, HR>70 bpm) with helical CTCA (100 kV, 220 mAs), 28 patients (group C, BMI>25 kg/sqm, HR<or=70 bpm) with sequential CTCA (120 kV, 330 mAs(ref)), and 39 patients (group D, BMI>25 kg/sqm, HR>70 bpm) with helical CTCA (120 kV, 330 mAs). The effective radiation dose estimates were calculated from the dose-length-product for each patient. Image quality was classified as being diagnostic or non-diagnostic in each coronary segment. RESULTS Image quality was diagnostic in 2403/2460 (98%) and non-diagnostic in 57/2460 (2%) of all coronary segments. No significant differences in image quality were found among all five CTCA protocols (p=0.78). The non-tailored helical CTCA protocol was associated with a radiation dose of 9.0+/-1.0 mSv, being significantly higher compared to that using sequential CTCA (group A: 1.3+/-0.3 mSv, p<0.001; group C: 2.9+/-0.6 mSv, p<0.001), and helical CTCA at reduced tube voltage and tube current (group B: 4.2+/-0.6 mSv, p<0.01). No significant differences were found compared to the non-tailored CTCA protocol in patients with HR>70 bpm (group D: 8.5+/-0.9 mSv, p=0.51). CONCLUSIONS Dual-source CTCA is associated with radiation doses ranging between 1.3 and 9.0 mSv, depending on the protocol used. Tailoring of the CTCA protocol to the HR and BMI of the individual patient results in dose reductions of up to 86%, while maintaining a diagnostic image quality of the examination.

Left atrial appendage clip occlusion: Early clinical results

OBJECTIVE Atrial fibrillation puts patients at significant risk for embolic stroke originating from the left atrial appendage. Few means are available for safe, effective, and durable left atrial appendage occlusion. A new clip device was evaluated with regard to safety and effectiveness for epicardial left atrial appendage occlusion. METHODS Patients with atrial fibrillation undergoing elective cardiac surgery through a median sternotomy were enrolled for concomitant epicardial clip placement. Early postoperative and 3-month follow-up computed tomography studies were used to assess clip stability and left atrial appendage perfusion. RESULTS From September 2007 to December 2008, 34 patients underwent successful clip placement. No device-related complications occurred. Operative mortality was 8.8% and not study or device related. Deployment was rapid, and left atrial appendage occlusion was confirmed by intraoperative transesophageal echocardiography in all patients. In addition to excellent clinical outcomes (no stroke/transient ischemic attack), serial computed tomography demonstrated stable clip location and appendage perfusion at 3 months in all patients. CONCLUSION Safe, effective, and durable left atrial appendage occlusion can easily be achieved with this new clip. Further trials are necessary to evaluate the role of the left atrial appendage occlusion in stroke prevention.

Myocardial Bridging: Depiction Rate and Morphology at CT Coronary Angiography—Comparison with Conventional Coronary Angiography

PURPOSE To prospectively assess the depiction rate and morphologic features of myocardial bridging (MB) of coronary arteries with 64-section computed tomographic (CT) coronary angiography in comparison to conventional coronary angiography. MATERIALS AND METHODS Patients were simultaneously enrolled in a prospective study comparing CT and conventional coronary angiography, for which ethics committee approval and informed consent were obtained. One hundred patients (38 women, 62 men; mean age, 63.8 years +/- 11.6 [standard deviation]) underwent 64-section CT and conventional coronary angiography. Fifty additional patients (19 women, 31 men; mean age, 59.2 years +/- 13.2) who underwent CT only were also included. CT images were analyzed for the direct signs length, depth, and degree of systolic compression, while conventional angiograms were analyzed for the indirect signs step down-step up phenomenon, milking effect, and systolic compression of the tunneled segment. Statistical analysis was performed with Pearson correlation analysis, the Wilcoxon two-sample test, and Fisher exact tests. RESULTS MB was detected with CT in 26 (26%) of 100 patients and with conventional angiography in 12 patients (12%). Mean tunneled segment length and depth at CT (n = 150) were 24.3 mm +/- 10.0 and 2.6 mm +/- 0.8, respectively. Systolic compression in the 12 patients was 31.3% +/- 11.0 at CT and 28.2% +/- 10.5 at conventional angiography (r = 0.72, P < .001). With CT, a significant correlation was not found between systolic compression and length (r = 0.16, P = .25, n = 150) but was found with depth (r = 0.65, P < .01, n = 150) of the tunneled segment. In 14 patients in whom MB was found at CT but not at conventional angiography, length, depth, and systolic compression were significantly lower than in patients in whom both modalities depicted the anomaly (P < .001, P < .01, and P < .001, respectively). CONCLUSION The depiction rate of MB is greater with 64-section CT coronary angiography than with conventional coronary angiography. The degree of systolic compression of MB significantly correlates with tunneled segment depth but not length.