Purpose It is unclear whether the use of contrast enhanced (CE) CT for attenuation correction (AC) of 18FFDG PET leads to higher quantification inaccuracies when used in high-sensitivity LAFOV systems. This project aimed to assess the clinical feasibility of CE-CT for AC in LAFOV-PET for lymphoma patients. Methods Lymphoma patients who underwent LAFOV-18FFDG-PET for restaging with low dose AC-CT and diagnostic CE-CT were included in this retrospective analysis. PET images were reconstructed using ultra-high sensitivity (UHS) mode with CE-CT and AC-CT. Lesions and reference regions (liver and mediastinal blood pool (BP)) were evaluated. Results SUVmax of BP and the liver increased when CE-CT was used instead of AC-CT for AC (BP: median 2.41vs.2.21, p < 0.01, 8.78% intra-patient increase; liver: 3.07vs.2.87, p < 0.01, 7.86% medina intra-patient increase). Similarly, SUVmean was higher in CE-CT reconstructions (BP: 1.96vs.1.77, p < 0.01, 10.14% median intra-patient increase; liver: 2.50vs.2.32, p < 0.01, 7.54% median intra-patient increase). SUVmax of lesions showed a similar magnitude of increase (5.97vs.5.68, p < 0.01, 5.80% median intra-lesion increase). The SUV-ratio of the lesions to reference organs decreased when CE-CT instead of AC-CT was used for AC (BP: 2.79vs.2.99, p < 0.01, median per-lesion decrease - 4.90%; liver: 1.85vs.1.97, p < 0.01, median per-lesion decrease - 2.64%). Conclusion The use of CE-CT for AC of LAFOV-PET in UHS mode leads to higher SUV measurements. Also, lymphoma lesions show a consistent increase in uptake. The errors in the lesions seem higher than in conventional standard axial field-of-view PETs that use CE-CT for AC. Therefore, interpretation of borderline cases warrants attention to potential errors.
Penner et al. (Mon,) studied this question.