The New Radiolabeled Peptide ^99mTcEDDA/HYNIC-TOC: Is It a Feasible Choice for Diagnosing Gastroenteropancreatic NETs?

(1) Background: The aim of our study is to reveal the advantages and limitations of the use of 99mTcEDDA/HYNIC-TOC (Tektrotyd®, Polatom) in the diagnosis of gastroenteropancreatic neuroendocrine tumors and to compare our results with the values obtained for 111In-pentetreotide and 68Ga-DOTA-peptides, routinely used in medical practice. (2) Methods: This retrospective monocentric study included 173 patients with gastroenteropancreatic neuroendocrine tumors who underwent 99mTcEDDA/HYNIC-TOC scans as part of their clinical management. The examination protocol included a whole-body scan acquired 2 h after the radiotracer’s administration, with the SPECT/CT performed 4 h post-injection. Physiological and abnormal uptake were established by two experienced physicians and, based on the obtained results, sensitivity, specificity, accuracy, positive predictive value and negative predictive value were calculated. (3) Results: Our method presented a sensitivity of 90.5%, a specificity of 71.9%, and an accuracy of 84.3%, with a positive predictive value of 86.7% and a negative predictive value of 78.8%. (4) Conclusions: 99mTc-EDDA/HYNIC-TOC, a receptor-based radiopharmaceutical, could represent a competitor for 68Ga-labeled peptides in the diagnosis and management of patients with gastroenteropancreatic neuroendocrine tumors. Our results show a lower sensitivity (90.5%) than 68Ga-DOTA-peptides, but with great specificity, accuracy, positive, and negative predictive values

Standardized Uptake Values on SPECT/CT: A Promising Alternative Tool for Treatment Evaluation and Prognosis of Metastatic Neuroendocrine Tumours

(1) Background: The aim of our study was to assess the feasibility of 99mTcEDDA/HYNIC-TOC SPECT/CT quantitative analysis in evaluating treatment response and disease progression in patients with NETs. (2) Methods: This prospective monocentric study evaluated 35 SPECT/CT examinations performed on 14 patients with neuroendocrine tumours who underwent a baseline and at least one follow-up 99mTcEDDA/HYNIC-TOC scan as part of their clinical management. The examination protocol included a whole-body scan acquired 2 h after the radiotracer’s administration, with the SPECT/CT performed 4 h post-injection. Images were analyzed by two experienced physicians and patients were classified into response categories based on their changes in SUV values. (3) Results: We evaluated 14 baseline studies and 21 follow-up scans, accounting for 123 lesions. A statistically positive correlation has been found between the SUVmax and SUVpeak values in tumoral lesions (p 99mTcEDDA/HYNIC-TOC SPECT/CT data in patients with neuroendocrine tumours could represent an alternative to 68Ga-DOTA-peptides PET/CT for the monitoring and prognosis of NETs

Quantitative SPECT/CT Parameters in the Assessment of Transthyretin Cardiac Amyloidosis—A New Dimension of Molecular Imaging

Aims: Cardiac transthyretin amyloidosis (ATTR) represents the accumulation of misfolded transthyretin in the heart interstitium. Planar scintigraphy with bone-seeking tracers has long been established as one of the three main steps in the non-invasive diagnosis of ATTR, but lately, single-photon emission computed tomography (SPECT) has gained wide recognition for its abilities to exclude false positive results and offer a possibility for amyloid burden quantitation. We performed a systematic review of the existing literature to provide an overview of the available SPECT-based parameters and their diagnostic performances in the assessment of cardiac ATTR. Methods and Methods: Among the 43 papers initially identified, 27 articles were screened for eligibility and 10 met the inclusion criteria. We summarised the available literature based on radiotracer, SPECT acquisition protocol, analysed parameters and their correlation to planar semi-quantitative indices. Results: Ten articles provided accurate details about SPECT-derived parameters in cardiac ATTR and their diagnostic potential. Five studies performed phantom studies for accurate calibration of the gamma cameras. All papers described good correlation of quantitative parameters to the Perugini grading system. Conclusions: Despite little published literature on quantitative SPECT in the assessment of cardiac ATTR, this method offers good prospects in the appraisal of cardiac amyloid burden and treatment monitoring