18F-FDG-PET/CT assessment of Takayasu arteritis and effect of time-of-flight reconstruction: an observational study

Abstract

Background: To assess the impact of time-offlight (TOF) positron emission tomography (PET)/ computed tomography (CT) image reconstruction on assessment of Takayasu arteritis (TKA). We reviewed 14 patients (15 cases) who underwent TOF-PET/CT. PET images were reconstructed using ordered-subsets expectation maximisation ± TOF. Uptake in 10 vascular regions was assessed in each case using the four-point visual grading system (3, higher than liver uptake; 0, no uptake). Grades in the TOF-PET/CT and non-TOF-PET/CT groups were compared using the sign test. Relationships between visual grade and arterial FDG uptake pattern in the 10 regions and clinical findings were assessed. Additionally, qualitative summary score (PETVAS) and maximum standard uptake value (SUVmax) were compared between 2 groups using Wilcoxon signed rank test. Results: Except for the highest visual grade, the grades in all 150 regions were significantly higher in the TOF-PET/CT group (p=0.003). FDG uptake pattern and region were not significant determinants of the effect of TOF reconstruction. PETVAS and SUVmax were significantly higher in the TOFPET/ CT group (p=0.02, p<0.001 respectively). Conclusions: Visual grades, PETVAS, and SUVmax were significantly higher when assessed by TOF-PET/CT. The use of the same reconstruction algorithm before and after treatment is recommended when evaluating the response to treatment.