Direct comparison of [18F]FDG brain images acquired from a phantom and patients using SiPM- and PMT-PET/CT

Background Silicon photomultiplier-positron emission tomography (SiPM-PET) has better sensitivity, spatial resolution, and timing resolution than photomultiplier tubes (PMT)-PET. The present study aimed to clarify the advantages of SiPM-PET in 18F-fluoro-2-deoxy-D-glucose ([18F]FDG) brain imaging in a head-to-head comparison with PMT-PET in phantom and clinical studies. Methods Image contrast was calculated from images acquired from a Hoffman 3D brain phantom and image noise and uniformity were calculated from pooled images acquired from a pool phantom using SiPM- and PMT-PET. Sequential PMT-PET and SiPM-PET [18F]FDG images were acquired over a period of 10 min from 22 individuals. All images were separately normalized to a standard [18F]FDG PET template, then mean standardized uptake values (SUVmean) and Z-score were calculated by MIMneuro and Cortex ID Suite, respectively. Results Image contrast, image noise, and uniformity in SiPM-PET changed 27.5%, -2.1%, and − 138.2% from PMT-PET, respectively. These physical indices of SiPM-PET satisfied the criteria for acceptable image quality published by the Japanese Society of Nuclear Medicine of > 55%, ≤ 15% and ≤ 0.0249, respectively. The residual background count was reduced with time-of-flight algorithm especially in SiPM-PET. The SUVmean using SiPM-PET was significantly higher than PMT-PET and did not correlate with a time delay. Z-scores were also significantly higher in images acquired from SiPM-PET (except for the bilateral posterior cingulate) than PMT-PET because the peak signal that was extracted by the calculation of Z-score in Cortex ID Suite was raised. Conclusions The better spatial and timing resolution, and sensitivity in SiPM-PET were contributed to better image contrast, image noise, and uniformity on brain [18F]FDG images. SiPM-PET offers better quality and more accurate quantitation of brain PET images. The SUVmean and Z-score in SiPM-PET was higher than PMT-PET. [18F]FDG images acquired using SiPM-PET will help to improve diagnostic outcomes based on the statistical image analysis because the SiPM-PET was more localized the distribution of glucose metabolism on Z-score maps.