Image quality and activity optimization in oncological ¹⁸ F-FDG PET using the all-digital DigitMI 930 PET/CT

Background Acquisition time is a critical parameter in positron emission tomography (PET) systems. Shorter acquisition times lead to reduced event counts, which can degrade image quality and increase noise levels. This study aimed to evaluate the performance of reduced acquisition times and analyze semi-quantitative metrics across different patient age groups, thereby providing guidance for clinical practice involving shorter acquisition protocols in positron emission tomography/computed tomography (PET/CT) scanning. Methods The impact of reduced acquisition times was assessed. The study involved 43 patients who underwent all-digital DigitMI 930 PET/CT scans with a 180-second scan duration at each bed position. The list-mode PET data were resampled into G10s, G20s, G40s, G60s, and G120s. Then, the data were stratified by age group. Subjective evaluation was conducted using a 5-point Likert scale. The coefficient of variation, signal-to-noise ratio, tumor-to-background ratio, and standardized uptake values (SUV), including SUV max , SUV mean , and SUV peak , were assessed for semi-quantitative evaluation. Results The results demonstrated that two nuclear medicine physicians rated all short acquisition images at or above a score of 3 in image quality, lesion conspicuity, and image noise level. At G10s, significant differences were observed in SUV peak ( P = 0.0015) and SUV mean ( P = 0.0019) compared with G180s. For G20s to G120s, relative to G180s, the differences in lesion SUV max , SUV peak , and SUV mean were 0.09–0.51, 0.04–0.33, 0.03–0.20, respectively. Wilcoxon signed-rank tests ( T -values: 1420-1661) showed no statistically significant differences across these groups (all P >0.05) for SUV peak . In addition, images of G20s–G120s exhibited a lower coefficient of variation (CoV, 0.10–0.21) and a comparable tumor-to-background ratio (TBR, 2.21–2.26). Further analysis indicated that SUV max remained stable from G10s for younger (≤54 years) and middle-aged adults (55–69 years), while the older group (≥70 years) exhibited a highly significant difference ( P <0.001). The G10s group across all age categories showed significant differences in SUV peak and SUV mean . In contrast, within three age groups, the G20s-G120s, G40s–G120s, and G60s-G120s groups, each showed no significant differences in SUV peak and SUV mean compared with the G180s group ( T -values: 142–201, 163–202, 162–231, all P >0.05, determined by Wilcoxon signed-rank tests). Conclusion Reducing the acquisition time to 20 seconds per bed (s/bed) position appeared to maintain subjectively acceptable image quality. In addition, the DigitMI 930 PET/CT system allowed adjustable acquisition times that could be tailored to different age groups: approximately 20 s/bed for patients ≤54 years, 40 s/bed for patients aged 55–69 years, and 60 s/bed for patients ≥70 years. This flexibility may help clinicians optimize scanning protocols to balance efficiency and patient comfort while maintaining diagnostic reliability.