99mTc-EDDA/HYNIC-TOC in management of patients with head and neck somatostatin receptor positive tumors

Single Photon Emission Computed Tomography Tracer

Single photon emission computed tomography (SPECT) is the state-of-the-art imaging modality in nuclear medicine despite the fact that only a few new SPECT tracers have become available in the past 20 years. Critical for the future success of SPECT is the design of new and specific tracers for the detection, localization, and staging of a disease and for monitoring therapy. The utility of SPECT imaging to address oncologic questions is dependent on radiotracers that ideally exhibit excellent tissue penetration, high affinity to the tumor-associated target structure, specific uptake and retention in the malignant lesions, and rapid clearance from non-targeted tissues and organs. In general, a target-specific SPECT radiopharmaceutical can be divided into two main parts: a targeting biomolecule (e.g., peptide, antibody fragment) and a γ-radiation-emitting radionuclide (e.g., ^99mTc, ¹²³I). If radiometals are used as the radiation source, a bifunctional chelator is needed to link the radioisotope to the targeting entity. In a rational SPECT tracer design, these single components have to be critically evaluated in order to achieve a balance among the demands for adequate target binding, and a rapid clearance of the radiotracer. The focus of this chapter is to depict recent developments of tumor-targeted SPECT radiotracers for imaging of cancer diseases. Possibilities for optimization of tracer design and potential causes for design failure are discussed and highlighted with selected examples.

Role of Combined [68Ga]Ga-DOTA-SST Analogues and [18F]FDG PET/CT in the Management of GEP-NENs: A Systematic Review

Gastro-entero-pancreatic neuroendocrine neoplasia (GEP-NENs) are rare tumors, but their frequency is increasing. Neuroendocrine tumors normally express somatostatin (SST) receptors (SSTR) on cell surface, especially G1 and G2 stage tumors, but they can show a dedifferentiation in their clinical history as they become more aggressive. Somatostatin receptor imaging has previously been performed with a gamma camera using [¹¹¹In]In or [^99mTc]Tc-labelled compounds, while [⁶⁸Ga]Ga-labelled compounds and PET/CT imaging has recently become the gold standard for the diagnosis and management of these tumors. Moreover, in the last few years ¹⁸F-fluorodeoxyglucose ([¹⁸F]FDG) PET/CT has emerged as an important tool to define tumor aggressiveness and give relevant prognostic information, particularly when coupled with [⁶⁸Ga]Ga-labelled SST analogues PET/CT. This review focuses on the importance of combined imaging with [⁶⁸Ga]Ga-labelled SST analogues and [¹⁸F]FDG for the management of GEP-NENs.

Clinical application of 99mTc-HYNIC-TOC SPECT/CT in diagnosing and monitoring of pancreatic neuroendocrine neoplasms

OBJECTIVE

Our aim of this research was to determine the value of SPECT/CT with ^99mTc-HYNIC-TOC for evaluation of the pancreatic masses which were suspected as neuroendocrine neoplasms and follow-up of patients with pancreatic neuroendocrine neoplasms.

METHODS

We retrospectively analyzed 184 patients who performed ^99mTc-HYNIC-TOC SPECT/CT. All the patients were divided into two groups: one for assessment of diagnostic efficiency for pancreatic suspected masses (n = 140) and another for monitoring recurrence after surgery (n = 44). The image findings acquired at 2 h postinjection were compared to final diagnoses from pathological results and clinical follow-up. Then, the correlation between ratios of tumor-to-background (TBR) and tumor grade was analyzed.

RESULTS

In group 1, 95/140 (67.9%) patients were confirmed as neuroendocrine neoplasms including 85 neuroendocrine tumors and 10 neuroendocrine carcinomas. Patient-based analysis showed that the sensitivity, specificity and accuracy of diagnosing neuroendocrine neoplasms with SPECT/CT were 81.1, 84.4 and 82.1%. There was significant difference of TBRs among G1, G2 and G3 (F = 3.175, P = 0.048). In group 2, 22/44 (50.0%) patients occurred metastasis mainly in liver. The sensitivity, specificity and accuracy of monitoring recurrence were 87.0, 100 and 93.2%.

CONCLUSIONS

^99mTc-HYNIC-TOC SPECT/CT is a reliable method of diagnosing and monitoring of pancreatic neuroendocrine neoplasms, especially neuroendocrine tumors.

The role of radionuclide probes for monitoring anti-tumor drugs efficacy: A brief review

Despite recent advances in the development of new therapeutic agents and diagnostic imaging modalities, cancer is still one of the main causes of death worldwide. A better understanding of the molecular signature of cancer has promoted the development of a new generation of anti-cancer drugs and diagnostic agents that specifically target molecular components such as genes, ligands, receptors and signaling pathways. However, intrinsic heterogeneity of tumors has hampered the overall success of target therapies even among patients with similar tumor types but unpredictable different responses to therapy. In this sense, post-treatment response monitoring becomes indispensable and nuclear medicine imaging modalities could provide the tools for an early indication of therapeutic efficacy. Herein, we briefly discuss the current role of PET and SPECT imaging in monitoring cancer therapy together with an update on the current radiolabeled probes that are currently investigated for tumor therapy response assessment.