Procedure-related uptake on CXCR4 PET/CT: a frequent pitfall independent of time and anatomical site

Abstract

Abstract Introduction As a pan-tumor tracer, chemokine receptor 4 (CXCR4)-directed [ 68 Ga]Ga-PentixaFor is frequently utilized in patients with hematological malignancies. We aimed to evaluate the impact of recent surgical and interventional procedures on uptake. Methods Patients undergoing [ 68 Ga]Ga-PentixaFor PET/CT after prior surgical or interventional procedures were analyzed. Uptake at the procedural site was assessed visually and quantitatively (by applying maximum standardized uptake values [SUV max ], target-to-background ratios [TBR]). Quantitative parameters were compared across anatomical region groups (bone, organ, (sub-)cutaneous, muscle). We stratified patients demonstrating uptake in procedural sites into an early (0–30 days) and late group (≥ 31 days between intervention and [ 68 Ga]Ga-PentixaFor PET). In patients with available [ 18 F]FDG PET/CT, quantitative correlation analyses between both radiotracers were also performed. Results Among 425 [ 68 Ga]Ga-PentixaFor PET/CT examinations, 87 prior invasive procedures (20.5%) were identified. In 53 patients allocated to the early group, 29 subjects demonstrated uptake (54.7%), while in the late group, 22 out of 34 subjects revealed tracer accumulation at procedural sites (64.7%). Across the predefined temporal intervals, uptake rates varied numerically but did not differ significantly overall ( p = 0.071). [ 68 Ga]Ga-PentixaFor SUV max (ρ = -0.03, p = 0.807) and TBR (ρ = 0.02, p = 0.876) showed no significant association between time since procedure. On a compartment level, SUV max ( p = 0.482) and TBR ( p = 0.696) revealed no significant differences across investigated anatomical regions. In cases with available [ 18 F]FDG PET (21/51 [41.2%]), quantitative uptake in procedural sites correlated significantly between both radiotracers (SUV max : ρ = 0.55, p = 0.016; TBR: ρ = 0.68, p = 0.001), indicating that different inflammatory signatures at procedural sites may be captured by both radiotracers. Conclusions Post-procedural CXCR4 uptake occurs frequently, with no statistically significant overall association with time since intervention or involved anatomical compartment.