The purpose of this study was to investigate whether spectral computed tomography (CT) has the potential to improve luminal depiction by differentiating among intravascular gadolinium-based contrast agent, calcified plaque, and stent material by using the characteristic k edge of gadolinium. A preclinical spectral CT scanner with a photon-counting detector and six energy threshold levels was used to scan a phantom vessel. A partially occluded stent was simulated by using a calcified plaque isoattenuated to a surrounding gadolinium chelate solution. The reconstructed images showed an effective isolation of the gadolinium with subsequent clear depiction of the perfused vessel lumen. The calcified plaque and the stent material are suppressed.

To assess image quality and radiation exposure with prospectively gated axial CT coronary angiography (PGA) compared to retrospectively gated helical techniques (RGH). Forty patients with suspected coronary artery disease (CAD) and a stable heart rate below 65 bpm underwent CT coronary angiography (CTCA) using a 64-channel CT system. The patient cohort consisted of 20 consecutive patients examined using a PGA technique and 20 patients examined using a standard RGH technique. Both groups were matched demographically according to age, gender, body mass index, and heart rate. For both groups, two independent observers assessed image quality for all coronary segments on an ordinal scale from 1 (nonassessable) to 5 (excellent quality). Image quality and radiation exposure were compared between patient groups. There were no significant differences in vessel-based image quality between the two groups (P > 0.05). Mean (+/- SD) effective radiation exposure in the PGA group was 3.7 +/- 0.8 mSv compared to 18.9 +/- 3.8 mSv in the RGH group without ECG-based tube current modulation (P < 0.001). Preliminary experience shows PGA technique to be a promising approach for CTCA resulting in a substantial reduction in radiation exposure with image quality comparable to that of standard RGH technique.

The purpose of this study was to evaluate the accuracy of multi-detector row helical CT (MDCT) for detection and localization of acute upper and lower gastrointestinal (GI) hemorrhage or intraperitoneal bleeding. Thirty-six consecutive patients with clinical signs of acute bleeding underwent biphasic (16- or 40-channel) MDCT. MDCT findings were correlated with endoscopy, angiography or surgery. Among the 36 patients evaluated, 26 were examined for GI bleeding and 10 for intraperitoneal hemorrhage. Confirmed sites of GI bleeding were the stomach (n = 5), duodenum (n = 5), small bowel (n = 6), large bowel (n = 8) and rectum (n = 2). The correct site of bleeding was identifiable on MDCT in 24/26 patients with GI bleeding. In 20 of these 24 patients, active CM extravasation was apparent during the exam. Among the ten patients with intraperitoneal hemorrhage, MDCT correctly identified the bleeding source in nine patients. Our findings suggest that fast and accurate localization of acute gastrointestinal and intraperitoneal bleeding is achievable on MDCT.

Purpose of this study was the evaluation of the thoracic aortic wall thickness as a potential identifier of patients at increased risk for future cardiac events. Thoracic aortic wall thickness was measured with MDCT in 160 patients. The CT-scans were implemented as non-invasive coronary angiography studies. Relationships between aortic wall thickness, sex, age, major risk factors and atherosclerotic plaque burden of the coronary arteries were explored. Higher values of maximum aortic wall thickness of the descending aorta (women P = 0.02, men P = 0.01) were found in patients with coronary atherosclerosis, compared to patients with same gender but excluded atherosclerosis. Aortic wall thickness of the mid-portion of the descending aorta of 3.0 mm is associated with coronary artery disease (CAD) with a specificity of 96.6% (sensitivity 27.5%) and a positive predictive value (PPV) of 93.3%. For patients with two or more major risk factors and a maximum wall thickness of equal or more than 2.6 mm we found a PPV of 100%. We conclude that measurements of maximum wall thickness of the descending aorta are a potential tool for detecting patients with coronary atherosclerosis. The potential effect of combining measurements of aortic wall thickness at routine chest CT studies with a possible cardiovascular screening is substantial and merits further study.

Multidetector computed tomography has been progressively used for evaluation of coronary artery disease, so the knowledge about the anatomy of coronary arteries and veins is of fundamental importance.