Initial experience with a SiPM-based PET/CT scanner: influence of acquisition time on image quality

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Abstract

A newly introduced PET/CT scanner (Discovery Meaningful Insights-DMI, GE Healthcare) includes the silicon photomultiplier (SiPM) with time-of-flight (TOF) technology first used in the GE SIGNA PET/MRI. In this study, we investigated the impact of various acquisition times on image quality using this SiPM-based PET/CT.We reviewed data from 58 participants with cancer who were scanned using the DMI PET/CT scanner. The administered dosages ranged 295.3-429.9 MBq (mean?±?SD 356.3?±?37.4) and imaging started at 71-142 min (mean?±?SD 101.41?±?17.52) after administration of the radiopharmaceutical. The patients' BMI ranged 19.79-46.16 (mean?±?SD 26.55?±?5.53). We retrospectively reconstructed the raw TOF data at 30, 60, 90, and 120 s/bed and at the standard image acquisition time per clinical protocol (180 or 210 s/bed depending on BMI). Each reconstruction was reviewed blindly by two nuclear medicine physicians and scored 1-5 (1-poor, 5-excellent quality). The liver signal-to-noise ratio (SNR) was used as a quantitative measure of image quality.The average scores?±?SD of the readers were 2.61?±?0.83, 3.70 Â±?0.92, 4.36?±?0.82, 4.82?±?0.39, and 4.91?±?0.91 for the 30, 60, 90, and 120 s/bed and at standard acquisition time, respectively. Inter-reader agreement on image quality assessment was good, with a weighted kappa of 0.80 (95% CI 0.72-0.81). In the evaluation of the effects of time per bed acquisition on semi-quantitative measurements, we found that the only time point significantly different from the standard time were 30 and 60 s (both with P??25, images can be acquired as fast as 90 s/bed using the SiPM PET/CT and still result in very good image quality (average score >?4).

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