Background Detection of the site of recurrence using PSMA-PET/CT is important to guide treatment in patients with biochemical recurrence of prostate cancer (PCa). The aim of this study was to evaluate the positivity rate of [18F]PSMA-1007-PET/CT in patients with biochemically recurrent PCa and identify parameters that predict scan positivity as well as the type and number of detected lesions. This monocentric retrospective study included 137 PCa patients with biochemical recurrence who underwent one or more [18F]PSMA-1007-PET/CT scans between August 2018 and June 2019. PET-positive malignant lesions were classified as local recurrence, lymph node (LN), bone or soft tissue lesions. The association between biochemical/paraclinical parameters, as PSA value, PSA doubling time, PSA velocity, Gleason score (GS) and androgen deprivation therapy (ADT), and scan positivity as well as type and number of detected lesions was evaluated using logistic regression analysis (binary outcomes) and Poisson models (count-type outcomes). Results We included 175 [18F]PSMA-1007-PET/CT scans after radical prostatectomy (78%), external beam radiation therapy (8.8%), ADT (7.3%), brachytherapy (5.1%) and high intensity focused ultrasound (0.7%) as primary treatment (median PSA value 1.6 ng/ml). Positivity rate was 80%. PSA value and PSA velocity were significant predictors of scan positivity as well as of the presence of bone and soft tissue lesions and number of bone, LN and soft tissue lesions, both in uni- and/or multivariable analysis. Multivariable analysis also showed prior ADT as predictor of bone and soft tissue lesions, GS as predictor of the number of bone lesions and ongoing ADT as predictor of the number of LN lesions. Conclusion [18F]PSMA-1007-PET/CT showed a high positivity rate in patients with biochemically recurrent PCa. PSA value and PSA velocity were significant predictors of scan positivity as well as of the presence and number of bone and soft tissue lesions and the number of LN lesions. Our findings can guide clinicians in optimal patient selection for [18F]PSMA-1007-PET/CT and support further research leading to the development of a prediction nomogram.

Peptide receptor radionuclide therapy (PRRT) consists of the administration of a tumor-targeting radiopharmaceutical into the circulation of a patient. The radiopharmaceutical will bind to a specific peptide receptor leading to tumor-specific binding and retention. The only target that is currently used in clinical practice is the somatostatin receptor (SSTR), which is overexpressed on a range of tumor cells, including neuroendocrine tumors and neural-crest derived tumors. Academia played an important role in the development of PRRT, which has led to heterogeneous literature over the last two decades, as no standard radiopharmaceutical or regimen has been available for a long time. This review provides a summary of the treatment efficacy (e.g., response rates and symptom-relief), impact on patient outcome and toxicity profile of PRRT performed with different generations of SSTR-targeting radiopharmaceuticals, including the landmark randomized-controlled trial NETTER-1. In addition, multiple optimization strategies for PRRT are discussed, i.e., the dose–effect concept, dosimetry, combination therapies (i.e., tandem/duo PRRT, chemoPRRT, targeted molecular therapy, somatostatin analogues and radiosensitizers), new radiopharmaceuticals (i.e., SSTR-antagonists, Evans-blue containing vector molecules and alpha-emitters), administration route (intra-arterial versus intravenous) and response prediction via molecular testing or imaging. The evolution and continuous refinement of PRRT resulted in many lessons for the future development of radionuclide therapy aimed at other targets and tumor types.

Objectives PSMA-PET has become the PET technique of choice to localise the site of biochemically recurrent prostate cancer (PCa). With hybrid PET/MRI, the advantages of MRI are added to molecular characteristic of PET. The aim of this study was to investigate the incremental value of PET/MR versus PET/CT in patients with biochemically recurrent PCa by head-to-head comparison. Methods Thirty-four patients with biochemically recurrent PCa were prospectively included. They underwent [ 68 Ga]Ga-PSMA-11 PET/CT, followed by simultaneous PET/MR. All PET (PET CT , PET MR ), CT and MR images were evaluated for number of lesions and location. The number of lesions at specific sites was compared using Wilcoxon-sign-rank test. For PET, the maximum and mean standardised uptake values (SUVs) were calculated for each lesion compared using a two-sided paired t test.Results PET CT and PET MR scans were positive in 19 and 20 patients, detecting 73 and 79 lesions respectively. All lesions detected on PET CT were also detected on PET MR . CT and MRI only were positive in 14 and 17 patients, detecting 38 and 50 lesions, respectively, which was significantly lower than PET CT and PET MR respectively. Combined interpretation showed more lesions on PET/MR than on PET/CT (88 vs 81). No significant difference in detection of presence of local recurrence nor distant metastases was found. SUV mean and SUV max values were significantly higher on PET MR than on PET CT in local recurrence and lymph node metastases. Conclusions [ 68 Ga]Ga-PSMA-11 PET/MR was able to detect biochemically recurrent PCa at least as accurately as PET/CT for local recurrence, lymph node metastasis and distant metastasis. Key Points• PSMA PET/MRI detects the location of biochemical recurrence at least as accurately as PET/CT. • Substitution of PET/CT by PET/MRI adds sensitivity in PSMA lesion detection also in the setting of distant recurrence due to both the MR and TOF PET components.

An 87-year-old man, without significant history, presented at the emergency department with recurrent episodes of fever and weight loss for several weeks without diagnosis, despite extensive routine investigations including conventional imaging. 18F-FDG PET/CT revealed strongly increased uptake in the peripheral vessels of the upper and lower limbs with relative sparing of the larger vessels. Temporal artery biopsy was positive for arteritis. The diagnosis of giant cell arteritis with mainly involvement of upper and lower limbs was made, and treatment with high-dose oral methylprednisolone was started, resulting in a rapid clinical and biochemical improvement.

A 56-year-old woman presented with right iliac fossa pain. Abdominal CT showed a mesenteric mass in the right iliac fossa, adjacent to the vena cava inferior and right ureter. Biopsy of the mass revealed a well-differentiated neuroendocrine tumor. 68Ga-DOTATATE PET/CT showed strong somatostatin receptor expression only within in a small, central area of this mesenteric mass, with faint 68Ga-DOTATATE uptake in the majority of this mesenteric mass. Pathology revealed an IgG4-positive storiform fibrosis surrounding a mesenteric adenopathy. 68Ga-DOTATATE PET/CT discriminates between neuroendocrine tumor lymph node metastases and fibrosis, hereby avoiding potential sampling error of tumor biopsies and guiding surgical approach.