Dominic Ufton

The Lugano Imaging Committee recently refined the Deauville Score (DS), subdividing DS5 into DS5a (>2x liver uptake without new lesions) and DS5b (new lesions). We investigated whether this improves prognostic discrimination at interim positron emission tomography after two cycles (PET-2) in patients with advanced-stage classical Hodgkin lymphoma (AS-cHL) treated in recent GHSG randomized phase III trials. The primary analysis cohort was HD18 post-amendment standard arms (uniform treatment with six cycles of eBEACOPP); sensitivity cohorts were HD18 intention-to-treat, and HD21 eBEACOPP and BrECADD arms. Progression-free survival (PFS) was analyzed by landmark Cox models starting at PET2. DS5a was infrequent (4-6% across cohorts: 39/639; 67/1745; 33/568; 29/560). In the primary cohort, DS5 vs DS1-3 was associated with inferior PFS (hazard ratio [HR] 3.00, 95% confidence interval [CI] 1.25-7.23) and vs DS1-4 (HR 2.35, 95% CI 1.01-5.50). Across sensitivity cohorts, DS5a remained adverse compared with DS1-4 (HR range 2.57-5.47), while DS4 according to the new definition did not consistently separate from DS1-3, which is likely a result of PET-adapted treatment. Overall survival trends were concordant, but interpretation is limited by few events. To our knowledge, this is the first prognostic validation of the refined DS in prospectively randomized trial populations. The newly introduced DS5a isolates a small high-risk AS-cHL, which further supports risk assessment and adaptation using quantitative biomarkers from PET. HD18 NCT00515554; HD21 NCT02661503

Purpose To overcome difficulties with regard to anatomic discrimination of intrapelvic tumors and non-specific intrapelvic uptake (i.e. excreted activity in the urinary bladder) by early acquisition of FAPI-PET in prone position. Methods 15 patients with rectosigmoid (RSC) and squamous cell carcinoma of the anus (SCCA) underwent early-imaging ⁶⁸Ga-FAPI-46-PET/CT-scans in prone position 5.9 ± 1.3 min after radiotracer injection. SUV and metric values for primary tumors, metastases, bladder and background tissues were measured. Tumor-to-background ratios (TBR) were calculated. Results Despite early acquisition, SUV was already high in tumors and metastases, leading to high TBR. A sufficient, on average at least 2.56 ± 0.66 cm, spatial distance between tumor and bladder uptake was observed in all cases. Conclusion An early-imaging protocol in prone position with ⁶⁸Ga-FAPI-46-PET/CT presents a viable option for non-invasive staging of SCCA and RSC with high TBR and good spatial separation from the urinary bladder.

Objectives: Tumor volume in prostate-specific membrane antigen (PSMA-TV)–PET/computed tomography (CT) has shown an emerging impact for prognosis and response evaluation in patients with prostate cancer. We evaluated the robustness of different PSMA-TV delineation methods. Materials and methods: A total of 40 ¹⁸F-JK-7-PSMA-PET/CT performed on the same scanner were analyzed. PSMA-TV measurements were performed using a standardized uptake value of 4.0 as a fixed threshold (T1), 41% of the single hottest voxel as an adaptive threshold (T2), and a liver-specific threshold (T3) for delineation in two reconstruction methods [four iterations and 12 subsets (R1) and three iterations and 21 subsets while applying a point spread function and a time-of-flight algorithm (R2)]. Differences between the segmentation thresholds in R1 and R2 were gathered and tested for statistical significance. Results: PSMA-TV differed significantly between R1Tx and R2Tx for individual segmentation thresholds, with PSMA-TV in R2 being significantly smaller than in R1 using the same segmentation method. Comparing the differences in PSMA-TV between R1 and R2 reconstruction between the three separate segmentation thresholds showed significantly larger absolute volume differences for T2 compared with T3 and significantly larger relative volume differences for T2 compared with T1 and T3. Conclusion: Reconstruction settings greatly influence the measurement of PSMA-TV, regardless of the segmentation threshold chosen; however, our results indicate that the fixed thresholds (T1 and T3) are less susceptible to reconstruction-induced volumetry effects than a relative threshold.

Osseous metastases are a common finding in prostate cancer, usually affecting the central skeleton. Metastases in the peripheral skeleton are less frequent but can occur as isolated findings as well. Therefore, imaging protocols limited to the trunk may miss such lesions and extended range (total-body) PSMA-PET/CT may be helpful for comprehensive evaluation, especially when peripheral metastases are suspected, for example, due to clinical symptoms.