[Impact of Matrix Size and Magnification Ratio on PET Imaging Using a Semiconductor PET/CT System]

We investigated the effects of matrix size and magnification ratio on positron emission tomography (PET) image quantitative characteristics using a semiconductor detector PET/CT.

Three types of phantom were filled with ¹⁸F-fluorodeoxyglucose solution and scanned. Images were reconstructed using the ordered-subsets expectation-maximization method, with matrix sizes of 128, 220, 256, 440, 512, and 880, and magnification ratios of 1.0, 1.5, 2.0, 2.5, and 3.0. We evaluated the maximum standardized uptake value (SUVmax), percentage coefficient of variation (%CV), and full width at half maximum (FWHM).

Minimal differences in the SUVmax, %CV, and FWHM were observed between the matrix sizes of 128 and 220, and between 440, 512 and 880. However, significant differences were observed between the matrix sizes of 220 and 256, as the largest difference, and between 256 and 440. The influence of the magnification ratio on the image quality was small.

The magnification ratio has a minor effect on quantitative values and image quality, whereas the impact of matrix size is significant. A noticeable difference in evaluation was observed between matrix sizes of 220 and 256. This was considered an important factor in determining the matrix size for this device.