64 slice

In COPDGene, the CT acquisition protocol used was as follows: 120kVp, 200mAs, and 0.5 s rotation time for General Electric (GE) LightSpeed-16, GE VCT-64, Siemens Sensation-16, Siemens Sensation-64, Philips 40-slice, and Philips 64-slice scanners. Images were reconstructed using a standard algorithm at 0.625 mm slice thickness and 0.625 mm intervals for GE scanners. Siemens CT images were reconstructed using a B31f algorithm at 0.625 (Sensation-16) or 0.75 mm slice thickness and 0.5 mm intervals. Reconstruction of Philips images was performed by using B algorithm at 0.9 mm slice thickness and 0.45 mm intervals. In the FHS, CT images were acquired with a General Electric Discovery VCT 64-slice PET/CT scanner (GE Healthcare) using a MA determined by subject weight (300 mA for subjects less than 220 lbs, 350mG for subjects equal to or greater than 220 lbs) 120 Kv, and a gantry rotation time of 0.35 s. Raw data was collected using a 210° scan reconstruction algorithm and a detector width of 0.625 mm. Images were reconstructed with a 50 cm field of view (FOV).

Two 64-slice and one 16-slice spiral CT scanners (Siemens Healthineers 64-slice, Forchheim, Germany; or Philips Medical Systems 64 and 16-slice, Cleveland, OH, USA) were used for abdominal nonenhanced CT examinations. The scanning parameters were as follows: tube voltage, 120 kVp; tube current, 220 mA; field of view, 350 × 350 mm; pitch 0.8 and 1.2; slice thickness, 2 mm; and slice interval, 2 mm. Patients were imaged in a supine position, and the scan range is from 2 cm above the xiphoid process to the lower border of the pubic symphysis.
CT signs, including periappendiceal fat stranding, mural calcification, periappendiceal free fluid, luminal fluid attenuation, short-axis diameter of the luminal fluid area, thin line mural, and mural thickening of the cecum, were analysed by two abdominal radiologists who had 12 and 32 years of experience and were blinded to the clinical and pathological details. The conclusions of the 32-year-old abdominal radiologist were used in cases of data discrepancies.