Aw version 4

All subjects fasted for at least 6 hours and were verified to have blood glucose < 200 mg/dL at the time of the ¹⁸F-FDG injection. PET/CT scanning was performed using the Discovery LS (GE Healthcare, Milwaukee, WI, USA). A whole-body CT scan was performed with a continuous spiral technique using an 8-slice helical CT with a gantry rotation speed of 0.8 seconds. CT scan data were collected at 40–120 mAs adjusted to patient body weight, 140 keV, a section width of 5 mm, and a table feed of 5 mm per rotation. No intravenous or oral contrast material was used. After the CT scan, an emission scan was obtained from the thighs to the head, at 4 minutes per frame over 60 minutes, following an intravenous injection of up to 370 MBq ¹⁸F-FDG. Attenuation-corrected PET images from the CT data were reconstructed using an ordered-subsets expectation maximization algorithm (28 subsets and 2 iterations). The standardized uptake value (SUV) was calculated by adjusting for patient body weight and the actual dose of ¹⁸F-FDG. Commercial software (AW version 4.4, GE Healthcare) was used to co-register the separate CT and PET scan data.

The section thickness was reconstructed with 0.75 mm. A medium smooth convolution kernel (I26f) and an iterative algorithm with SAFIRE 3 (a medium strength level of 3, strength 1–5) were used for group A. Filter back projection with a medium smooth convolution kernel (B26f) was used for group B. Image processing and storage were performed with an advanced three-dimensional workstation (AW version 4.4; GE Healthcare). The curved planar reconstruction (CPR) technique was applied for the evaluation of the three types of coronary arteries, and image quality was evaluated on CPR as well as axial images of vessels and segments.