We present a case of carotid glomus paraganglioma incidentally detected using 18 F-choline PET/CT in a 63-year-old man with prostate cancer. 18 F-choline PET/CT scan demonstrated a small area of 18 F-choline uptake (SUV max , 2.3) in the right parapharyngeal space of the neck, later diagnosed as paraganglioma with low proliferation index. 18 F-choline PET/CT may represent a valid alternative for studying paraganglioma when either 18 F-DOPA or 68 Ga-SSA are not available.

Radical prostatectomy (RP) with or without pelvic lymph node dissection (PLND) is the most frequent approach to treat men affected by prostate cancer (PCa), together with primary radiotherapy. Generally, patients performed computed tomography (CT) and bone scintigraphy to stage the disease prior to surgery. However, specific inhibitors directed to the prostate-specific membrane antigen (PSMA) have been recently proposed as radiopharmaceutical for positron emission tomography (PET) imaging. PSMA-PET proved higher diagnostic accuracy to stage high-risk PCa compared to conventional imaging, even if its impact on overall survival is yet to be confirmed. One of the main limitations for PSMA-PET in staging PCa is represented by the low sensitivity in identifying metastatic lymph node, namely in case of nodes smaller than 4–5 mm. Radioguided surgery (RGS) is based on the intraoperative detection of radiation emitted by the specific radiopharmaceutical. Recently, the possibility of performing RGS using cancer-specific radiotracer with high diagnostic accuracy (e.g. PSMA inhibitors) gained attention. In this review, we aimed to explore the value of PSMA-RGS in PCa, aimed at improving the surgery accuracy to remove nodal metastasis. Furthermore, we evaluated different radiation detectors (gamma rays probes vs. beta positron probes) and the diagnostic accuracy of these probes compared to PSMA-PET. A comprehensive literature review was performed in December 2022 with a non-systematic approach. After the first literature screening, a total of 16 studies have been selected and a comprehensive qualitative narrative synthesis of the articles has been performed. First studies showed promising results for PSMA-RGS, and prospective trials demonstrated good concordance of in vivo PSMA-positive detected nodes with histopathology analysis of the specimens. High sensitivity and specificity of the RGS approach were found. Whilst gamma probes have been more broadly explored, the clinical use of beta probes has been tested in feasibility studies only. Finally, Cerenkov luminescence imaging, micro-image guidance and augmented reality/virtual reality approaches in surgery are currently rising attention and are generating future perspectives for PSMA-guided surgery in PCa.

Renal Cell Carcinoma (RCC) is generally characterized by low-FDG avidity, and [18F]FDG-PET/CT is not recommended to stage the primary tumor. However, its role to assess metastases is still unclear. The aim of this study was to evaluate the diagnostic accuracy of [18F]FDG-PET/CT in correctly identifying RCC lung metastases using histology as the standard of truth. The records of 350 patients affected by RCC were retrospectively analyzed. The inclusion criteria were: (a) biopsy- or histologically proven RCC; (b) Computed Tomography (CT) evidence of at least one lung nodule; (c) [18F]FDG-PET/CT performed prior to lung surgery; (d) lung surgery with histological analysis of surgical specimens; (e) complete follow-up available. A per-lesion analysis was performed, and diagnostic accuracy was reported as sensitivity and specificity, using histology as the standard of truth. [18F]FDG-PET/CT semiquantitative parameters (Standardized Uptake Value [SUVmax], Metabolic Tumor Volume [MTV] and Total Lesion Glycolysis [TLG]) were collected for each lesion. Sixty-seven patients with a total of 107 lesions were included: lung metastases from RCC were detected in 57 cases (53.3%), while 50 lesions (46.7%) were related to other lung malignancies. Applying a cut-off of SUVmax ≥ 2, the sensitivity and the specificity of [18F]FDG-PET/CT in detecting RCC lung metastases were 33.3% (95% CI: 21.4–47.1%) and 26% (95%CI: 14.6–40.3%), respectively. Although the analysis demonstrated a suboptimal diagnostic accuracy of [18F]FDG-PET/CT in discriminating between lung metastases from RCC and other malignancies, a semiquantitative analysis that also includes volumetric parameters (MTV and TLG) could support the correct interpretation of [18F]FDG-PET/CT images.