Background: Numerous PSMA-based tracers are used for diagnostic prostate cancer imaging, but comprehensive comparisons between multiple ligands are lacking. This study aimed to compare physiological skeletal uptake and tracer uptake in commonly recommended PSMA reference regions across three different PSMA ligands in prostate cancer patients. Methods: A total of 281 prostate cancer patients were included. Using PET and SPECT imaging, target volumes of interest were defined via a semiautomatic method, and standardized uptake values (SUV) were calculated for the skeletal system and reference regions (liver, spleen, parotid gland, and blood pool). Results: Significant differences in SUV uptake were observed, with [¹⁸F]F-PSMA-1007 showing higher SUV values in the skeletal system. The parotid gland displayed the highest variability in uptake, while the blood pool and liver exhibited more homogeneous uptake across patients. Conclusions: While radioligands behave similarly in bone regions, there are notable differences in SUV patterns, particularly for PSMA-1007, which showed higher bone uptake. Parotid gland uptake variability suggests a reconsideration of its suitability as a reference region, while the liver, spleen, and blood pool showed more consistent uptake. During comparison, the technetium-labeled SPECT ligand proved as similarly effective as the two PET ligands for diagnostic imaging.

Background: Pancreatic neuroendocrine tumors (PanNETs) are relatively rare neoplasms with heterogeneous behavior, ranging from indolent to aggressive disease. The evolution of nuclear medicine has allowed the development of an efficient and advanced toolkit for the diagnosis and treatment of PanNETs. Case: A 45-year-old woman was diagnosed with a grade 1 PanNET and multiple liver metastases. She underwent distal pancreatectomy with splenectomy, extended liver resection, and radiofrequency ablation (RFA). Surgical planning was guided by [^99mTc]Tc-EDDA/HYNIC-TOC SPECT/CT (single-photon emission computed tomography/computed tomography) and preoperative [^99mTc]Tc-mebrofenin-based functional liver volumetry. Functional liver volumetry based on dynamic [^99mTc]Tc-mebrofenin SPECT/CT facilitated precise surgical planning and reliable assessment of the efficacy of parenchymal modulation, thereby aiding in the prevention of post-hepatectomy liver failure. Liver fibrosis was non-invasively evaluated using two-dimensional shear wave elastography (2D-SWE). Tumor progression was monitored using somatostatin receptor scintigraphy, chromogranin A, and contrast-enhanced CT. Recurrent disease was treated with somatostatin analogues (SSAs) and [¹⁷⁷Lu]Lu-DOTA-TATE peptide receptor radionuclide therapy (PRRT). Despite progression to grade 3 disease (Ki-67 from 1% to 30%), the patient remains alive 53 months post-diagnosis, in complete remission, with an ECOG (Eastern Cooperative Oncology Group) status of 0. Conclusions: Functional imaging played a pivotal role in guiding therapeutic decisions throughout the disease course. This case not only underscores the clinical utility of advanced nuclear imaging but also illustrates the dynamic nature of pancreatic neuroendocrine tumors. The transition from low-grade to high-grade disease highlights the need for further studies on tumor progression mechanisms and the potential role of adjuvant therapies in managing PanNETs.

Background: Neuroendocrine neoplasms (NENs) are a diverse group of malignancies in which somatostatin receptor expression can be crucial in guiding therapy. We aimed to evaluate the effectiveness of [^99mTc]Tc-EDDA/HYNIC-TOC SPECT/CT in differentiating neuroendocrine tumor histology, selecting candidates for radioligand therapy, and identifying correlations between somatostatin receptor expression and non-imaging parameters in metastatic NENs. Methods: This retrospective study included 65 patients (29 women, 36 men, mean age 61) with metastatic neuroendocrine neoplasms confirmed by histology, follow-up, or imaging, comprising 14 poorly differentiated carcinomas and 51 well-differentiated tumors. Somatostatin receptor SPECT/CT results were assessed visually and semiquantitatively, with mathematical models incorporating histological, oncological, immunohistochemical, and laboratory parameters, followed by biostatistical analysis. Results: Of 392 lesions evaluated, the majority were metastases in the liver, lymph nodes, and bones. Mathematical models estimated somatostatin receptor expression accurately (70–83%) based on clinical parameters alone. Key factors included tumor origin, oncological treatments, and the immunohistochemical marker CK7. Associations were found between age, grade, disease extent, and markers (CEA, CA19-9, AFP). Conclusions: Our findings suggest that [^99mTc]Tc-EDDA/HYNIC-TOC SPECT/CT effectively evaluates somatostatin receptor expression in NENs. Certain immunohistochemical and laboratory parameters, beyond recognized factors, show potential prognostic value, supporting individualized treatment strategies.

Meningiomas are the most common primary intracranial tumors, showing highly heterogeneous behavior and clinical outcomes. While the majority are benign, about one in five meningiomas are classified as higher grade (WHO Grade II–III), characterized by a more aggressive, treatment-resistant pathology. Although surgical resection remains the first-line therapy, peptide receptor radionuclide therapy is emerging as a novel and promising option for advanced, multifocal, or recurrent disease. The theranostic paradigm allows simultaneous detection and treatment of somatostatin receptor-expressing lesions using a single radiopharmaceutical. In this review, we explore the evolving role of PRRT in the management of meningiomas. We provide an integrated overview of preclinical findings—including radiosensitization mechanisms—and summarize the rapidly expanding clinical literature, which in recent years has grown both in patient numbers and in methodological sophistication. Particular emphasis is placed on advances in dosimetry, quantitative imaging, and radiomics, which are beginning to refine patient selection and improve response prediction. Together, current evidence highlights the therapeutic potential of radionuclide therapy in aggressive or refractory meningiomas and underscores the need for further prospective trials to define its optimal clinical application.

Background an purpose Amino acid–based PET/CT imaging is gaining prominence in the management of central nervous system tumors. This prospective study aimed to assess the added value of 18F-DOPA PET/CT, combined with conventional MRI, for defining the gross tumor volume (GTV) in patients with glial tumors. Materials and methods Fifty-five patients with glial tumors were enrolled. Standard radiotherapy planning included multiple MRI scans obtained preoperatively and postoperatively. A mid- treatment MRI (reMRI) was acquired at two-thirds of the radiotherapy course. All patients underwent 18F-DOPA PET/CT before radiotherapy to define a biological target volume (BTV). Spatial congruence between GTVs was assessed using the Dice similarity coefficient. Results In 54% of reirradiation cases and 48% of primary postoperative irradiations, 18F-DOPA PET/CT identified metabolically active tumor regions that became radiologically apparent on MRI only 4–6 weeks later. The discrepancy between BTV and MRI-based GTV suggests that conventional MRI may overestimate or underestimate biologically active tumor tissue. The highest spatial overlap was observed between GTVs based on postoperative MRI and reMRI (Dice index = 0.602). Venn analysis indicated modality-dependent target volume heterogeneity, with partial spatial concordance between anatomical (MRI-based) and biological (DOPA PET–based) GTVs. Patients with residual tumor on postoperative MRI or 18F-DOPA PET/CT had significantly worse overall survival (OS) (p < 0.05). Conclusions 18F-DOPA PET/CT provides value in radiotherapy planning for glial tumors by enabling earlier detection of biologically active tissue and improving target volume definition. Its ability to identify metabolically active regions before morphological MRI changes supports its use in primary and reirradiation settings.