The purpose of this study was to evaluate the relationship of body habitus, blood glucose level and injected dose, respectively, with BGO (Bi₄Ge₃O₁₂) positron emission tomography (PET) image quality using commercially available 2-deoxy-2-[¹⁸F] fluoro-D-glucose (FDG). We also evaluated the relationship between PET image quality and acquisition time for each weight group.
Method: One hundred twenty-five patients (66 male, 59 female) were enrolled in the study. We adopted liver signal-to-noise ratio (liver SNR) as an image quality index, derived from the region of interest (ROI) placed on the axial image of the liver.
Results: The correlation coefficient between liver SNR and dose per weight was 0.502. The liver SNR indicated a negative relationship with body weight, body mass index (BMI) and cross sectional area of the patient's body, with the correlation coefficients of -0.594, -0.479 and -0.522, respectively. For all weight groups, an extended acquisition time of at least 60 s/bed was necessary to improve liver SNR.
Conclusion: The findings of this study are potentially of use for designing imaging protocols for the BGO-PET/CT system when using commercially available FDG. It is easy to obtain good image quality for patients of low to average body size with the standard injection dose. However, large patients should be injected, wherever possible, with an FDG dose of up to 5 MBq/kg. The acquisition time in overweight and obese patients should be as longer as possible than in standard weight patients.