Stephan Skawran

We aimed to assess the prognostic value of [¹⁸F]flotufolastat PET in patients with metastatic prostate cancer during taxane-based chemotherapy (CTx). Methods: In total, 69 patients who received CTx as well as baseline and follow-up [¹⁸F]flotufolastat PET/CT scans were included. Imaging response was assessed by visual RECIP 1.0 dichotomized into progressive disease (PD) and non-PD. Biochemical response was defined as a prostate-specific antigen decrease of greater than 50% (castration-resistant) or a decline to less than 0.2 ng/mL (hormone-sensitive). Kaplan-Meier analysis was performed regarding overall survival, and the Harrell concordance index was calculated. Results: Patients with PD showed a significantly shorter median overall survival of 12 mo (95% CI, 8.3 mo to not reached) compared with non-PD (45 mo; 95% CI, 37 mo to not reached). The Harrell concordance index for RECIP (0.84; 95% CI, 0.72-0.97; P < 0.001) was higher than biochemical response (0.66; 95% CI, 0.49-0.84; P = 0.07). Conclusion: [¹⁸F]flotufolastat PET assessed using visual RECIP has high prognostic utility in patients with metastatic prostate cancer undergoing CTx.

Objectives: We aimed to explore the diagnostic efficacy of whole-body dynamic (WBD) acquisition using [ ¹⁸ F]-Fluorodeoxyglucose-positron-emission-tomography/computed-tomography ([ ¹⁸ F]FDG-PET/CT) for the assessment of giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) compared with the standard static PET/CT. Methods: Twenty-five patients with suspected GCA and/or PMR were prospectively enrolled in this single-center study. WBD PET imaging was performed before treatment using a standard PET/CT scanner with a multibed multipass dynamic whole-body acquisition approach (dPET). Reconstructed datasets were used to generate metabolic rate of [ ¹⁸ F]FDG (MR _FDG ) images based on standard Patlak analysis. In case of pathologic FDG uptake, VOIs placed in vessel walls and joints were used for quantitation and definition of the target-to-background ratio (TBR): uptake in VOIs of vessel walls and joints (maximum values), to VOIs in blood pool (GCA), or to VOIs in normal muscles (PMR) (mean values). The final diagnosis based on the available imaging and laboratory results (except dPET), served as the standard of reference. Results: Seventeen of the 25 patients (68%) showed pathologic FDG uptake, of which 5 (20%) were finally diagnosed with GCA alone, 6 (24%) with PMR alone, and another 6 (24%) with both conditions. TBR difference between dPET and static PET was significant in both diseases(GCA P P 18 F]FDG-PET/CT provided a significantly higher TBR in patients with GCA and PMR compared with standard static PET imaging. WBD [ ¹⁸ F]FDG-PET/CT may potentially enhance the diagnostic accuracy in detecting GCA and PMR.

Prostate-specific membrane antigen (PSMA) PET has the potential to monitor the response to taxane-based chemotherapy in patients with prostate cancer and shows promise for predicting outcomes and improving response evaluation. This retrospective study aimed to determine the prognostic value of [⁶⁸Ga]Ga-PSMA-11 PET (PSMA PET)-derived quantitative tumor burden parameters for overall survival (OS). Methods: Databases from 6 institutions were screened for patients with prostate cancer who underwent PSMA PET and whose serum prostate-specific antigen (PSA) measurements were recorded at baseline and after completing taxane-based chemotherapy. Tumor segmentation was performed using artificial intelligence-based software, and PSMA PET whole-body quantitative parameters were obtained, including PSMA-positive tumor volume (PSMA-VOL), SUV_max, and SUV_mean Univariate Cox regression analyses were used to evaluate the association of whole-body quantitative PSMA parameters and PSA levels with OS. The Harrell concordance index (C-index) was used to determine prognostic accuracy. Optimal cutoffs were determined by maximizing the log-rank statistic. Results: In total, 128 patients were included in the study; 62 (48%) had hormone-sensitive prostate cancer, and 66 (52%) had castration-resistant prostate cancer. At baseline, PSMA-VOL had the highest prognostic value for OS compared with serum PSA, SUV_max, and SUV_mean (C-index of 0.88, 0.80, 0.69, and 0.29, respectively), whereas the percentage change in PSA levels had the highest prognostic value during treatment compared with percentage change in PSMA-VOL, SUV_max, and SUV_mean (C-index of 0.94, 0.85, 0.90, and 0.85, respectively). Conclusion: Baseline and posttherapeutic PSMA PET quantitative parameters are prognostic for OS after taxane-based chemotherapy in patients with metastatic prostate cancer. Baseline PSMA-VOL had the highest prognostic value for OS, whereas changes in PSA levels outperformed changes in quantitative PSMA PET parameters during treatment.

Background: In [ ¹⁸ F]F-PSMA-1007 PET imaging, focal bone uptake without morphological correlate (MC) on CT, is often classified as benign. In [ ⁶⁸ Ga]Ga-PSMA-11, intense focal uptake without MC in a classical location is considered suspicious. The prevalence of focal bone uptake with or without MC on [ ⁶⁸ Ga]Ga-PSMA-11 PET/CT remains unclear. Methods: This single-center, retrospective study included patients who underwent a [ ⁶⁸ Ga]Ga-PSMA-11 PET/CT scan for initial staging or biochemical recurrence (BCR) of prostate cancer between 04/16 − 11/21, with written informed consent for use of clinical data and adequate follow-up. For each patient with focal PSMA accumulation in the bones, up to three of these lesions were scored based on PSMA-RADS 2.0 and a clinical interpretation of suspicion for malignancy including clinical information was provided. In addition, MC on CT were assessed. A composite reference standard including imaging and clinical follow-up data was used. Results: Out of 824 patients, 323 met eligibility criteria, with 101 showing PSMA-positive bone lesions. 176 lesions were included, 25% of 61 in the staging cohort had no MC, of which 73% were malignant. In the BCR group, 52% of 115 lesions were without MC, of which 48% were malignant. The sensitivity/specificity reached with PSMA-RADS 2.0, and MC on CT was 100%/100%and 78%/36% for staging, and 83%/100% and 60%/72% for BCR, respectively. Conclusion: Focal [ ⁶⁸ Ga]Ga-PSMA-11 positive lesions without MC on CT are frequent, especially on scans for BCR, with the majority being malignant. Considering PSMA-RADS 4 lesions on [ ⁶⁸ Ga]Ga-PSMA-11 on staging exams, significantly improves the accuracy. Incorporating clinical information and considering PSMA-RADS 3B can further improve the sensitivity for BCR scans.

Over the past decade, prostate-specific membrane antigen positron emission tomography (PSMA-PET) has revolutionized prostate cancer (PCa) imaging, offering greater sensitivity and specificity compared to conventional imaging modalities such as CT, MRI, and bone scintigraphy. PSMA-PET is particularly valuable in staging newly diagnosed patients with intermediate- and high-risk disease, detecting biochemical recurrence, and evaluating metastatic cases. By utilizing radiotracers that accumulate specifically in PSMA-expressing cells, even small metastases can be detected, offering a detailed assessment of cancer extent and enabling more targeted diagnostic evaluations. Among the most utilized radiotracers, [⁶⁸Ga]- and [¹⁸F]-labeled PSMA tracers enable precise imaging even with low disease burden. This diagnostic precision also supports advanced therapeutic approaches, including metastasis-directed therapy for oligometastatic cases and systemic treatment options, such as radioligand therapy, which presents new treatment perspectives for metastatic, castration-resistant PCa. This review examines the evolution of PSMA-PET in the diagnostics and therapy of PCa while comparing the current recommendations from leading clinical guidelines. The integration of PSMA-PET into clinical practice has redefined the management of PCa, improving diagnostic accuracy and enabling personalized treatment strategies, while lacking prospective long-term outcome data. As PSMA-PET continues to expand in clinical application, this review highlights its significant advancements while critically addressing limitations to ensure balanced and evidence-based implementation in prostate cancer care.

Purpose: Hypophysitis occurs in up to 10% of patients treated with immune-checkpoint inhibitors (ICIs). MRI shows no abnormalities of the pituitary gland in one third of patients. A delayed diagnosis increases the risk for life-threatening adrenal crisis, underscoring the need for early detection. This study evaluates the diagnostic accuracy FDG PET/CT in detecting ICI-induced hypophysitis in a cohort of melanoma patients. Materials and Methods: Patients with metastatic melanoma and ICI-induced hypophysitis, who underwent FDG PET/CT 90 days before to 10 days after diagnosis, were compared with an age- and sex-matched control group of patients undergoing ICI treatment without signs of hypophysitis. The ratio of SUV_max of the pituitary gland to the SUV_mean of the blood pool (target-to-background ratio [TBR]) was calculated. Diagnostic accuracy of the TBR was assessed using area under the receiver operating characteristics curve analysis. Results: A total of 28 patients was included. The majority of patients with hypophysitis received ipilimumab/nivolumab (64.3%, 9/14). Visual assessment of the TBR distribution demonstrated a positive correlation with decreasing time to diagnosis. To evaluate diagnostic performance, only patients with FDG PET/CT 50 days before to 8 days after diagnosis (11/14) were included. TBR was significantly higher in these compared with the control group (median [interquartile range], 2.78 [2.41] vs 1.59 [0.70], respectively; P = 0.034). A sensitivity of 72.7% and a specificity of 90.9% were achieved at a TBR threshold of 2.41 (area under the receiver operating characteristics curve = 0.769). Conclusions: Our findings suggest that, in patients undergoing ICI treatment for metastatic melanoma, a pituitary TBR of approximately 2.4 may indicate impending ICI-induced hypophysitis.

Background: The levator ani muscle (LAM) is crucial for pelvic floor stability, yet its quantitative MRI assessment is only a recent focus. Our study aims to standardize the quantitative analysis of the LAM morphology within the 3D Pelvic Inclination Correction System (3D-PICS). Methods: We analyzed 35 static MR datasets from nulliparous women examining the pubovisceral (PVM), iliococcygeal (ICM), coccygeal (COC), and puborectal muscle (PRM). The PVM consists of three origin-insertion pairs, namely the puboanal (PAM), puboperineal (PPM) and pubovaginal muscle (PVaM). The analysis included a quantitative examination of the morphology of LAM, focusing on the median location (x/y/z) (x: anterior–posterior, y: superior–inferior, z: left–right) of the origin and insertion points (a), angles (b) and lengths (c) of LAM. Inter-rater reliability was calculated. Results: Interindividual variations in 3D coordinates among muscle subdivisions were shown. In all, 93% of all origin and insertion points were found within an SD of <8 mm. Angles to the xz-plane range between −15.4° (right PRM) and 40.7° (left PAM). The PRM is the largest pelvic muscle in static MRI. The ICC indicated moderate-to-good agreement between raters. Conclusions: The accurate morphometry of the LAM and its subdivisions, along with reliable inter-rater agreement, was demonstrated, enhancing the understanding of normal pelvic anatomy in young nulliparous women.

Background: Liver uptake in [⁶⁸Ga]Ga-PSMA-11 PET is used as an internal reference in addition to clinical parameters to select patients for [¹⁷⁷Lu]Lu-PSMA-617 radioligand therapy (RLT). Due to increased demand, [⁶⁸Ga]Ga-PSMA-11 was replaced by [¹⁸F]F-PSMA-1007, a more lipophilic tracer with different biodistribution and splenic uptake was suggested as a new internal reference. We compared the intra-patient tracer distribution between [⁶⁸Ga]Ga-PSMA-11 and [¹⁸F]F-PSMA-1007. Methods: Fifty patients who underwent PET examinations in two centers with both [¹⁸F]F-PSMA-1007 and [⁶⁸Ga]Ga-PSMA-11 within one year were included. Mean standardized uptake values (SUV_mean) were obtained for liver, spleen, salivary glands, blood pool, and bone. Primary tumor, local recurrence, lymph node, bone or visceral metastasis were also assessed for intra- and inter-individual comparison. Results: Liver SUV_mean was significantly higher with [¹⁸F]F-PSMA-1007 (11.7 ± 3.9) compared to [⁶⁸Ga]Ga-PSMA-11 (5.4 ± 1.7, p < .05) as well as splenic SUV_mean (11.2 ± 3.5 vs.8.1 ± 3.5, p < .05). The blood pool was comparable between the two scans. Malignant lesions did not show higher SUV_mean on [¹⁸F]F-PSMA-1007. Intra-individual comparison of liver uptake between the two scans showed a linear association for liver uptake with SUV_mean [⁶⁸Ga]Ga-PSMA-11 = 0.33 x SUV_mean [¹⁸F]F-PSMA-1007 + 1.52 (r = .78, p < .001). Conclusion: Comparing biodistribution of [⁶⁸Ga]Ga and [¹⁸F]F tracers, liver uptake on [⁶⁸Ga]Ga-PSMA-11 PET is the most robust internal reference value. Liver uptake of [¹⁸F]F-PSMA-1007 was significantly higher, but so was the splenic uptake. The strong intra-individual association of hepatic accumulation between the two scans may allow using of a conversion factor for [¹⁸F]F-PSMA-1007 as a basis for RLT selection.

Purpose: To define the normal range and threshold values for pathologic prolapse on MRI using the PICS line and assess its correlation with the pubococcygeal line (PCL). Methods: This prospective, IRB-approved study included 20 nulliparous volunteers and 18 prolapse patients (POP-Q Stage ≥ 2). Organ positions (bladder, cervix, anorectal junction) relative to PICS and PCL were measured on dynamic MRI. Differences in organ position were compared. Receiver-operating characteristic (ROC) analysis was performed to identify cutoff values for prolapse using the PICS line. The correlation between PICS and PCL measurements was tested with Spearman’s rank correlation. Results: In volunteers, median bladder and cervix positions measured to the PICS at rest were − 2.7 cm and − 5.3 cm compared to − 1.9 cm and − 2.7 cm in patients (p < 0.001). During straining, bladder and cervix were at − 0.9 cm and − 3.2 cm in volunteers versus + 2.5 cm and + 2.5 cm in patients (p < 0.001). Correlation was strong for PICS and PCL measurements for all three compartments (δ = 0.883–0.970, p ≤ 0.001). AUCs of PICS for the anterior and middle compartment were 0.98 (95% confidence interval [CI] 0.96–1.00, p < 0.001) and 0.96 (95% CI 0.89–1.00, p < 0.001) for differentiating patients from healthy volunteers. AUC for the posterior compartment was 0.76 (95% CI 0.57–0.96, p = 0.034). Conclusion: PICS measurements reliably differentiate patients from volunteers in the anterior and middle compartment. Future studies need to identify a reliable threshold for the posterior compartment. PICS and PCL measurements are strongly correlated. Graphical