Israel Medical Association Journal

Background: Coronary computed tomography angiography (CCTA) is an established modality for ruling out coronary artery disease. However, it has been suggested that CCTA may be a source of non-negligible radiation exposure.

Objectives: To evaluate the potential degradation in coronary image quality when using prospective gated (PG) CCTA as compared with retrospective gated (RG) CCTA in chest pain evaluation.

Methods: The study cohort comprised 216 patients: 108 consecutive patients in the PG CCTA arm and 108 patients matched for age, gender and heart rate in the RG CCTA arm. Scans were performed using a 64-slice multidetector CT scanner. All 15 coronary segments were evaluated subjectively for image quality using a 5-point visual scale. Dose-length product was recorded for each patient and the effective radiation dose was calculated

Results: The PG CCTA technique demonstrated a significantly higher incidence of step artifacts in the middle and distal right coronary artery, the distal left anterior descending artery, the second diagonal, the distal left circumflex artery, and the second marginal branches. Nevertheless, the diagnostic performance of these scans was not adversely affected. The mean effective radiation doses were 3.8 ± 0.9 mSv vs.17.2 ± 3 mSv for PG CCTA and RG CCTA, respectively (P < 0.0001).

Conclusions: Artifacts caused by the PG CCTA technique (64 MDCT) scanners tended to appear in specific coronary segments but did not impair the overall diagnostic quality of CCTA and there was a marked reduction in radiation exposure. We conclude that 64-slice PG CCTA is suitable for clinical use, especially for acute chest pain "fast track" evaluation targeted at relatively young subjects in a chest pain unit.
 

Background: Coronary CT angiography is an accurate imaging modality; however, its main drawback is the radiation dose. A new technology, the "step and shoot," which reduces the radiation up to one-eighth, is now available.

Objectives: To assess our initial experience using the "step-and-shoot" technology for various vascular pathologies.

Methods: During a 10 month period 125 consecutive asymptomatic patients (111 men and 14 women aged 25–82, average age 54.9 years) with various clinical indications that were appropriate for step-and-shoot CCTA[1] (regular heart rate < 65 beats/minute and body weight < 115 kg) were scanned with a 64-slice multidetector computed tomography Brilliance scanner (Philips, USA). The preparation protocol for the scan was the same as for the regular coronary CTA. All examinations were interpreted by at least one experienced radiologist and one experienced interventional cardiologist. The quality of the examinations was graded from 1 (excellent imaging quality of all coronary segments) to 4 (poor quality, not diagnostic). There were 99 patients without a history of coronary intervention, 13 after coronary stent deployment (19 stents), and 3 after coronary artery bypass graft.

Results: Coronary interpretation was obtained in 122 examinations (97.6%). The imaging quality obtained was as follows: 103 patients scored 1 (82.4%), 15 scored 2 (12%), 4 scored 3 (3.2%) and 3 scored 4 (2.4%). The grades were unrelated to cardiac history or type of previous examinations. Poor image quality occurred because of sudden heart rate acceleration during the scan (one patient), movement and respiration (one patient), and arrhythmia and bad scan timing (in one). Two patients were referred to percutaneous coronary intervention based on the CCTA findings, which correlated perfectly.

Conclusions: Step-and-shoot CCTA is a reliable technique and CCTA algorithm comparable to the regular CCTA. This technique requires the lowest radiation dose, as compared to other coronary imaging modalities, that can be used for all CCTA indications based on the inclusion criteria of low (> 65 bpm) and stable heart rate.

Background: Cardiac computed tomography angiography is a relatively new imaging modality to detect coronary atherosclerosis.

Objectives: To explore the diagnostic value of CTA[1] in assessing coronary artery disease among asymptomatic patients.

Methods: In this retrospective single-centered analysis, 622 consecutive patients underwent CTA of coronary arteries between November 2004 and May 2006 at the Mor Institute for Cardiovascular Imaging in Bnei Brak, Israel. All patients were asymptomatic but had at least one risk factor for atherosclerotic CAD[2]. The initial 244 patients were examined with the 16-slice Brilliance CT scanner (Philips, Cleveland, OH, USA), and in the remaining 378 patients the 64-slice scanner (GE Healthcare, The Netherlands) with dedicated cardiac reconstruction software and electrocardiography triggering was used. Scanning was performed in the cranio-caudal direction. Images reconstructed in different phases of the cardiac cycle using a retrospective ECG-gated reconstruction algorithm were transferred to a dedicated workstation for review by experienced CT radiologists and cardiologists.

Results: Of 622 patients, 52 (8.4%) had severe obstructive atherosclerosis (suspected ≥ 75% stenosis) according to CTA interpretation. Invasive coronary angiography was performed in 48 patients while 4 patients had no further procedure. A non-significant CAD (e.g., diameter stenosis < 70%) was identified in 6 of 48 patients (12%) by selective coronary angiography. Forty-two patients showed severe CAD with at least one lesion of ≥ 70% stenosis. Percutaneous coronary intervention was performed in 35 patients and coronary artery bypass grafting surgery in the other 4 patients. Angioplasty procedures were successful in all 35 patients and stents were utilized in all cases without complications. No further complications occurred among the study cohort undergoing either PCI[3] or surgery. The 6 month survival rate in these patients was 100%.

Conclusions: Non-invasive coronary CTA appears to be a reliable technique, with reasonably high accuracy, to detect obstructive atherosclerosis in asymptomatic high risk patients for atherosclerotic CAD.