The feasibility of quantitative assessment of dynamic F-fluorodeoxyglucose PET in Takayasu's arteritis: a pilot study.

Purpose: PET has been demonstrated to be sensitive for detecting active inflammation in Takayasu's arteritis (TAK) patients, but semi-quantitative-based assessment may be susceptible to various biological and technical factors. Absolute quantification via dynamic PET (dPET) may provide a more reliable and quantitative assessment of TAK-active arteries. The purpose of this study was to investigate the feasibility and efficacy of dPET in quantifying TAK-active arteries compared to static PET.

Materials And Methods: This prospective study enrolled 10 TAK-active patients (fulfilled the NIH criteria) and 5 control participants from March to October 2022. One-hour dPET scan (all TAK and control participants) and delayed static PET scan at 2-h (all TAK patients) were acquired. For 1-h static PET, summed images from 50 to 60 min of the dPET were extracted. PET parameters derived from 1- and 2-h static PET including SUV (SUV and SUV), target-to-background ratio (TBR) (TBR and TBR), net influx rate (K), and TBR extracted from dPET were obtained. The detectability of TAK-active arteries was compared among different scanning methods using the generalized estimating equation (GEE) with a logistic regression with repeated measures, and the GEE with gamma distribution and log link function was used to evaluate the different study groups or scanning methods.

Results: Based on the disease states, 5 cases of TAK were classified as untreated and relapsed, respectively. The SUV on 2-h PET was higher than that on 1-h PET in the untreated patients (P < 0.05). However, no significant differences were observed in the median SUV between 1-h PET and 2-h PET in the relapsed patients (P > 0.05). The TBR was significantly higher than both TBR and TBR (all P < 0.001). Moreover, the detectability of TAK-active arteries by dPET-derived K was significantly higher than 1-h and 2-h PET (all P < 0.001). Significant differences were observed in K, SUV, TBR, and TBR among untreated, relapsed, and control groups (all P < 0.05).

Conclusions: Absolute quantitative assessment by dPET provides an improved sensitivity and detectability in both visualization and quantification of TAK-active arteries. This elucidates the clinical significance of dPET in the early detection of active inflammation and monitoring recurrence.