Lightspeed vct xt

Examinations were performed on a 64-slice CT scanner (LightSpeed VCT XT; GE Healthcare, Milwaukee, WI, USA). A prospectively ECG-triggered scan protocol was used: detector configuration 64×0.625 mm, rotation time 350 ms, tube potential 120 kV, tube current 450–650 mA (according to patient size). The scans were performed in diastole, in general at 70–75% of the RR interval, with a padding of 100–200 ms, depending on heart rate and variability. The contrast agent used was iodixanol 320 mg I/ml (Visipaque, GE Healthcare, Stockholm, Sweden), which was administered using a dual-head injector (Medrad, Stellant Dual Head Injector, Pittsburgh, PA, USA) and a triple-phase protocol. The contrast agent was individually dosed, based on body weight (400 mg I/kg, 75–100 ml iodixanol), with a fixed injection time (15 s), resulting in an injection rate of 5–7 ml/s. This was followed by a 50 ml mixture of 40% iodixanol and 60% saline and finally by a 50 ml saline chaser. In the absence of contraindications and depending on the initial heart rate, patients received metoprolol (25–100 mg) per os prior to the examination. Patients also received sublingual nitroglycerine (0.4 mg) 4 minutes before the scan.
To assess the coronary calcium score, a non-enhanced scan was performed, using a prospectively ECG-triggered scan protocol: tube potential 120 kV, tube current 200 mA.

CT scans were acquired using a 64-detector row CT scanner (LightSpeed VCT XT; GE Medical Systems, Milwaukee, Wisconsin, USA). Images were reconstructed using a high spatial resolution algorithm. A volumetric scan was performed with 0.625 mm slice thickness at an interval of 0.625 mm.

Protocols for contrast-enhanced head and neck CT varied moderately between studies. Images were obtained on either a 128-row CT scanner (Somatom Definition Flash, Siemens) or a 64-row CT scanner (Lightspeed VCT XT, GE Healthcare, Chicago, IL, USA) available at our institution. Patients received 80 mL of CA, and the iodine concentration was either 350 or 400 mg/mL. The bolus of CA (1.0 mL/s) was followed by a flush of 30 mL of normal saline (3.0 mL/s). The acquisition started 90 s after the initiation of the CA bolus. Images were acquired in the arteriovenous phase. The helical acquisition of 0.6 or 0.625 mm collimated images with a pitch of 0.53–0.8 was used. The kilovoltage was within a range of 100 to 140 kV with a standard reference output of 110 mAs up to 280 mAs. The automated dose reduction programs were performed on both scanners. The reconstruction field of view ranged from 240 to 280 mm, and the reconstruction matrix was 512 × 512, resulting in pixel size from 0.47 to 0.55 mm. Reconstruction slice thickness was from 0.6 to 1.5 mm, depending on the reconstruction algorithm. Images were reconstructed with soft tissue algorithms provided by manufacturers.

While all children underwent chest X-Ray as routine part for the evaluation of a suspected TB case, chest CT scan was performed on medical decision of every single case.
Images were reviewed by three radiologists, one with 20 years and two with 5 years experience, respectively, in thoracic imaging. This review is not a normal clinical practice, but it was only performed during the study.
Chest X-rays examinations were obtained with computed radiography (CXR), in supine position. CT examinations were performed with a 64-detector-row helical CT scanner (Light Speed VCT XT, GE Medical Systems, Milwaukee, WI, USA). The following parameters were used: acquisition 64 × 0.6 mm, rotation time 0.5 s; pitch 1.20; kV 80–100; ref. mAs 45/85; reconstruction 1 mm; lter B30f/B60f. Median CTDIvol32 was 1.35. CT examination were performed with sedated patient in younger ones, in supine position, after injection of a low-osmolality, non-ionic contrast agent (370 mgI/ml) at 2 ml/kg up to 125 ml: contrast injection was mainly used to establish the mediastinal involvement of tuberculosis.