Brightspeed ct

Non-contrast CT was performed with contiguous 6-mm sequentially acquired axial slices. The CT angiography studies were performed on a 64 slice CT scanner (Brightspeed CT; General Electric Medical Systems, Little Chalfont, Buckinghamshire, United Kingdom) with the gantry angled to the orbitomeatal line, with 64 1-s rotations of 1.25-mm collimation and a table speed of 23 mm/s, 512 × 512 matrix, 16 cm field of view, 120 kV of variable tube current (mA) with a mean of 100 mA at the level of the circle of Willis. For CTA imaging, 50 cc of Visipaque iodine contrast material (320 mg iodine/ml) (General Electric healthcare, Little Chalfont, Buckinghamshire, United Kingdom) was injected intravenously at a rate of 6 cc/s using an automated power injector. Automated triggering of image acquisition was used at the time of contrast passage through the aortic arch, followed by a chaser bolus of saline. The CT angiographic source image data were post-processed creating coronal and axial 3-mm thick maximum intensity on a computer workstation (Advantage Workstation 4.4; Global Electronics Medical Systems).

The following CT scanning instruments were used: Optima CT660, BrightSpeed CT, Revolution CT, Discovery CT750 (GE Medical System, Milwauke, WI) and Toshiba Aquilion 64 -slice spiral CT. Before scanning, the patient performed breathing training. The patient was placed in a supine position, with the head or feet advanced, and a breath-hold scan was performed after deep inhalation. All patients underwent an enhanced CT scan; the tube voltage was 120 kVp, the tube current was 200–350 mAs, the generated images were 5 mm thick, and some images were reconstructed with 1.25 mm layer thickness. The contrast agent used for enhanced scanning was iopromide injection (iodine concentration of 300 mg/ml) at a dose of 80 to 90 ml and a flow rate of 2.5 to 3.0 ml/s. Standard algorithms and high-resolution algorithms were used for image reconstruction and parallel multiplane reconstruction. The lung window (window width 1500 HU, window level -550 HU) and mediastinal window (window width 350 HU, window level 50 HU) were selected for image observation.