Somatostatin Receptor Targeted PET-CT and Its Role in the Management and Theranostics of Gastroenteropancreatic Neuroendocrine Neoplasms.

Somatostatin receptor (SSTR) agonist-based Positron Emission Tomography-Computed Tomography (PET-CT) imaging is nowadays the mainstay for the assessment and diagnostic imaging of neuroendocrine neoplasms (NEN), especially in well-differentiated neuroendocrine tumors (NET) (World Health Organization (WHO) grade I and II). Major clinical indications for SSTR imaging are primary staging and metastatic workup, especially (a) before surgery, (b) detection of unknown primary in metastatic NET, (c) patient selection for theranostics and appropriate therapy, especially peptide receptor radionuclide therapy (PRRT), while less major indications include treatment response evaluation on and disease prognostication. Dual tracer PET-CT imaging using SSTR targeted PET tracers, viz.

PSMA Receptor-Based PET-CT: The Basics and Current Status in Clinical and Research Applications.

Prostate-specific membrane antigen (PSMA) is a 100 kD, 750 amino acid (AA) long type II transmembrane glycoprotein that has a short N-terminal intracellular domain with 19 AA, 24 AA transmembrane proteins and a large C-terminal extracellular domain with 707 AA. PSMA has been mapped to chromosome 11p 11-12 in the region of the folate hydrolase gene (FOLH1) and has no known natural ligand. The protein possesses enzymatic activity-glutamate carboxypeptidase II (GCP-II)-and is thought to have role in folate uptake (FOLH1 gene).

Dual-Tracer PET-Computed Tomography Imaging for Precision Radio-Molecular Theranostics of Prostate Cancer: A Futuristic Perspective.

Dual/multi-tracer PET-computed tomography (CT) scan has been an interesting and intriguing concept and is promising in noninvasive and overall characterization of tumor biology and heterogeneity and has scientifically augmented the practice of precision oncology. In prostate carcinoma, particularly in metastatic castration-resistant prostate carcinoma setting, dual-tracer PET-CT can be potentially useful in selecting patients for chemotherapy, androgen deprivation therapy or prostate-specific membrane antigen (PSMA)-based peptide receptor radioligand therapy either as mono-therapy or as combination therapy, ascertaining differentiation status, staging/restaging, prognostication, and predicting progression/response. PSMA PET/CT has great potential as a "rule out" test in baseline staging, while being very useful in restaging and metastatic workup.

An Appraisal and Update of Fluorodeoxyglucose and Non-Fluorodeoxyglucose-PET Tracers in Thyroid and Non-Thyroid Endocrine Neoplasms.

Endocrine neoplasms and malignancies are a diverse group of tumors with varied clinical, histopathologic, and functional features. These tumors vary from sporadic to hereditary, isolated entities to multiple neoplastic syndromes, functioning and non functioning tumors, unifocal locally invasive, and advanced to multifocal tumors with disseminated distant metastases. The presence of various specific biomarkers and specific receptor targets serves as valuable tools for diagnosis, prognosis, and management.

Discordance Between Histopathologic Grading and Dual-Tracer PET/CT Findings in Metastatic NETs and Outcome of Lu-DOTATATE PRRT: Does In Vivo Molecular PET Perform Better from the Viewpoint of Prediction of Tumor Biology?

Discordance between histopathologic grading and dual-tracer PET/CT (Ga-DOTATATE and F-FDG) findings in neuroendocrine tumors (NETs), though not typical, can be encountered in real-world scenarios. The aim of this study was to assess patients with discordance between World Health Organization (WHO) 2017 grade-predicted molecular PET/CT imaging and the actual dual-tracer PET/CT findings (by exploring their histopathologic, immunohistochemical, and molecular imaging characteristics), with a view toward identifying the prognostic determinants affecting outcome in a peptide receptor radionuclide therapy setup. Thirty-six patients with histopathologically proven inoperable, locally advanced or metastatic NETs, referred for peptide receptor radionuclide therapy, were included in this study.

Concept proposal for a six-tier integrated dual tracer PET-CT (68Ga-PSMA and FDG) image scoring system ('Pro-PET' score) and examining its potential implications in metastatic castration-resistant prostate carcinoma theranostics and prognosis.

Objectives: To develop and examine a scoring system in metastatic castration-resistant prostate carcinoma (mCRPC) that integrates findings of both 68Ga-prostate-specific membrane antigen (PSMA) and flurodeoxyglucose (FDG) PET-CT imaging in a single combined parameter and referred to as the 'Pro-PET' score.

Methods: A six-tier integrated dual tracer PET-CT (68Ga-PSMA and FDG) Image Scoring System ('Pro-PET' score) was conceptualized, based on the findings of both 68Ga-PSMA-11 and FDG PET-CT in patients of mCRPC. This proposed integrated scoring was examined in a retrospective analytical study assessing mCRPC patients (n = 47) referred for 177Lu-PSMA-617 peptide receptor radioligand therapy (PRLT) and had both FDG and 68Ga-PSMA PET-CT undertaken within 15 days of each other without any interim treatment intervention.

Examining Absorbed Doses of Indigenously Developed Lu-PSMA-617 in Metastatic Castration-Resistant Prostate Cancer Patients at Baseline and During Course of Peptide Receptor Radioligand Therapy.

The objective of this study was to estimate the absorbed doses to the normal organs and tumor lesions in metastatic castration-resistant prostate cancer (mCRPC) patients treated with indigenously developed Lu-PSMA-617 that could establish optimal treatment protocol with minimum risk to the dose-limiting organs. Furthermore, attempt was also made to compare radiation absorbed doses for normal organs and tumor lesions in subsequent cycles of Lu-PSMA-617 peptide receptor radioligand therapy (PRLT) in the same group of patients during the course of treatment. A total of 30 patients of proven mCRPC were enrolled for this prospective study.

Combined Lu-DOTATATE Peptide Receptor Radionuclide Therapy and Platinum-Based Chemotherapy in Recurrent, Metastatic Sinonasal Neuroendocrine Carcinoma: A Promising Therapeutic Option.

Sinonasal neuroendocrine carcinomas (SNCs), in contrast to neuroendocrine carcinomas at other sites, are notorious for their recurrent and locally aggressive nature. The clinical concern is primarily due to their complex anatomy and close proximity to vital structures, compounded by lack of proper understanding of pathogenesis, no definitive classification or staging system, and no established treatment guidelines. We present the promise of combined treatment with Lu-DOTATATE-based peptide receptor radionuclide therapy (PRRT) and platinum-based chemotherapy in a patient with high-grade, recurrent, and metastatic SNC (that demonstrated high uptake on both Ga-DOTATATE and F-FDG PET/CT), which showed a significant partial response.

Comparison of Dual-Tracer PET and CT Features to Conventional Risk Categories in Assessing Response to Lu-PSMA-617 Therapy for Metastatic Prostate Adenocarcinoma with Urinary Bladder Involvement.

The present communication details the imaging characteristics, peculiarities, and response to Lu-labeled prostate-specific membrane antigen (PSMA)-617-targeted radioligand therapy (PRLT) in accordance with Gleason score and use of dual-tracer PET (Ga-PSMA-11 and F-FDG) in patients with urinary bladder invasion or metastasis by prostate cancer, including the prognostic value of F-FDG PET in predicting response to treatment. The CT attenuation units (Hounsfield units) correlated with the prostate primary in the case of direct tumor extension from the prostate, whereas in hematogenous metastatic seeding the Hounsfield units were lower than in the primary prostatic tumor. A favorable outcome to Lu-PSMA-617 PRLT was observed in patients with low or no baseline F-FDG uptake despite a high Gleason score and a high-risk National Comprehensive Cancer Network prognostic category and did not correlate with the latter alone, whereas a high SUV on F-FDG PET/CT was associated with an adverse outcome.

Implications of fluorodeoxyglucose uptake in low-intermediate grade metastatic neuroendocrine tumors from peptide receptor radionuclide therapy outcome viewpoint: A semi-quantitative standardized uptake value-based analysis.

Dual tracer positron emission tomography (PET) imaging approach (with Ga-DOTATATE PET-computed tomography (CT) for somatostatin receptor and 18-fluorodeoxyglucose (FDG) PET-CT for glucose transporter receptor) plays a vital role in baseline differentiation, treatment decision-making, and prognostic assessment of neuroendocrine tumors (NETs). The aims of this study were to observe and compare the clinical behavior of low-/intermediate-grade NETs depending on their baseline FDG metabolism (calculated through pre-peptide receptor radionuclide therapy [PRRT] FDG standardized uptake value [SUV]) and to determine its prognostic importance in predicting extent of therapeutic response (post-PRRT) in terms of symptomatic, biochemical, and scan parameters along with the long-term impact on progression-free survival (PFS) and overall survival (OS). Fifty-nine patients with low (≤2%) and intermediate (3-20% Mib-1/Ki-67 index) grade metastatic NET were selected for this retrospective analysis and divided into three groups: Group 1 consisted of patients having low-grade FDG uptake at baseline, predefined as SUV< 5 ( = 13); Group 2 consisted of those having intermediate-grade FDG uptake at baseline, SUV5-10 ( = 34), and Group 3 consisted of patients having high-grade FDG uptake at baseline, defined as SUV>10 ( = 12).

Rare-Site Primary Soft-Tissue Neuroendocrine Tumor with Metastases and Near-Complete Resolution with Lu-DOTATATE: Documenting a Promising Clinical Application of Peptide Receptor Radionuclide Therapy.

Neuroendocrine tumors (NETs) of the skin or soft tissue are rare (mostly described as sites of metastasis), whereas primary soft-tissue NETs are extremely rare; they are usually diagnosed at advanced stages with distant metastases because of their indolent nature. We herein describe our experience with 2 such cases. In the first case, the NET originated in the retroperitoneal soft tissue, and in the second case, the patient was a middle-aged lady with NET arising from soft tissue in the pelvis.

Metastatic or locally advanced mediastinal neuroendocrine tumours: outcome with 177Lu-DOTATATE-based peptide receptor radionuclide therapy and assessment of prognostic factors.

Background: Primary neuroendocrine tumours (NETs) of mediastinum are unusual tumours with aggressive biological behaviour with limited treatment options and guarded prognosis.

Methods: Twenty-seven patients with histopathologically and radiologically proven metastatic or advanced mediastinal NET, who had undergone 177Lu-DOTATATE PRRT, were included in this retrospective analysis. Descriptive statistics was employed to calculate the cumulative overall survival (OS) and progression-free survival (PFS), determining correlation and strength of correlation between different variables with OS and PFS and finally, predictors of outcome (OS and PFS).

Biodistribution and Dosimetry of Indigenously Produced I-Rituximab in B-Cell Lymphoma: Pilot Study Estimating Patient-Specific Dose Comparing 2 Different Dosimetric Methods.

Cost containment through indigenous production of radioimmunotherapy agents for non-Hodgkin lymphoma (NHL) would be a pivotal step toward wider clinical availability, especially in developing countries. We examined the biodistribution and dosimetry of indigenously developed and radiolabeled I-rituximab, using the monoclonal antibody of chimeric origin, in patients with B-cell lymphoma for potential use in radioimmunotherapy. This prospective study included 13 patients with B-cell NHL who underwent low-dose diagnostic scanning for dosimetric and biodistribution studies.