Dual-source CT coronary angiography: prospective versus retrospective acquisition technique.

PURPOSE: The aim of our work was to compare image quality and radiation dose in a group of patients who underwent cardiac dual-source computed tomography (DSCT) with prospective electrocardiographic (ECG) gating with those of a control group studied with retrospective gating. MATERIALS AND METHODS: Sixty patients were randomly assigned to two groups of 30 individuals each. Patients with heart rates >70 bpm and body mass index (BMI) >30 kg/m(2) were excluded. Group A was examined with prospective ECG gating and group B with retrospective gating. The dose-length product (DLP) was recorded to calculate the radiation dose, whereas the effective dose was normalised to a standard 12-cm scan of the heart. RESULTS: Applying the best reconstruction interval, 98.6% of segments in the prospective group and 99.3% in the retrospective group were diagnostic. No significant difference (p>0.05) in image quality was observed between groups. Mean normalised radiation dose was 4.91 ± 0.4 mSv in the prospective-gating group and 14.62 mSv ± 4.36 in the retrospective-gating group (p<0.01). CONCLUSIONS: Coronary CT with prospective ECG gating, a standard feature on new scanners, allows for a significant reduction in radiation dose without causing any significant decrease in image quality or in the number of segments assessed. The prospective technique is thus recommended for patients with heart rates £70 bpm and BMI £30 kg/m(2).

Preliminary experience with abdominal dual-energy CT (DECT): true versus virtual nonenhanced images of the liver.

PURPOSE: The aim of this work was to compare the quality and noise of true non-enhanced (TNE) and virtual non-enhanced (VNE) images in patients undergoing dual-energy computed tomography (DECT) of the liver. MATERIALS AND METHODS: Twenty consecutive patients (mean age 54.7±19.9 years) prospectively underwent abdominal DECT to assess the liver using a triphasic protocol consisting of precontrast, arterial-phase and portal-phase acquisitions. Exclusion criteria were allergy to iodinated contrast material, impaired renal function and a body mass index (BMI) >35 kg/m(2). The DE portal-phase acquisition was performed with automatic dose modulation (CARE Dose 4D). Nonionic iodinated contrast material (Iomeron 400) was administered at 0.625 gI/kg with a flow rate of 3.5 ml/s. Axial VNE images were reconstructed based on the portal data set using a collimation and an increment of 5 mm and were compared with TNE images reconstructed with the same parameters. The average image quality and noise were analysed by two radiologists in separate reading sessions. RESULTS: No statistically significant difference (p>0.05) in image quality was observed between VNE (4.00±0.85) and TNE images (4.35±0.58). A sufficient diagnostic quality was found in 95.0% (19/20) of VNE images and in 100% of TNE images. No statistically significant difference (p<0.05) was observed in the average image noise of VNE (9.5±0.7) and TNE (12.3±1.1) images. CONCLUSIONS: Abdominal DECT allows acquisition of liver VNE images with similar image quality and lower noise than TNE. Nevertheless, a few technical limitations related to the small field of view of the second detector in patients with a high BMI and heterogeneous iodine subtraction restrict the application of this technique to selected patients only.

Preoperative coronary risk assessment with dual-source CT in patients undergoing noncoronary cardiac surgery.

PURPOSE: The aim of our work was to assess the role of dual-source computed tomography (DSCT) in the preoperative evaluation of coronary artery disease in patients scheduled for noncoronary cardiac surgery. MATERIALS AND METHODS: One hundred patients were prospectively evaluated. Patients negative for coronary disease at DSCT (n=81) underwent surgery without coronary angiography. Patients positive for significant lesions or with nondiagnostic image quality due to artefacts or severe calcifications underwent coronary angiography (n=19) and were excluded from the study. In patients who underwent surgery with only a DSCT diagnosis, we evaluated the frequency of major adverse cardiac events (MACEs) during the perioperative period and at 3 months follow-up. RESULTS: No MACEs were recorded during the perioperative period; three noncardiac complications (one surgical revision for bleeding, one cardiac tamponade and one respiratory insufficiency) and one death related to severe respiratory insufficiency were observed. None of the 80 patients had MACEs during the 3-month follow-up period. CONCLUSIONS: Coronary evaluation with DSCT is able to rule out the presence of coronary disease in patients scheduled for cardiac surgery, without the need for coronary angiography confirmation. Patients with significant stenosis or nondiagnostic image quality should be referred for coronary angiography.