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Series of myocardial FDG uptake requiring considerations of myocardial abnormalities in FDG-PET/CT.
Minamimoto, R
Japanese journal of radiology. 2021;(6):540-557
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Abstract
Distinct from cardiac PET performed with preparation to control physiological FDG uptake in the myocardium, standard FDG-PET/CT performed with 4-6 h of fasting will show variation in myocardial FDG uptake. For this reason, important signs of myocardial and pericardial abnormality revealed by myocardial FDG uptake tend to be overlooked. However, recognition of possible underlying disease will support further patient management to avoid complications due to the disease. This review demonstrates the mechanism of FDG uptake in the myocardium, discusses the factors affecting uptake, and provides notable image findings that may suggest underlying disease.
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Radiotracers for Bone Marrow Infection Imaging.
Jødal, L, Afzelius, P, Alstrup, AKO, Jensen, SB
Molecules (Basel, Switzerland). 2021;(11)
Abstract
INTRODUCTION Radiotracers are widely used in medical imaging, using techniques of gamma-camera imaging (scintigraphy and SPECT) or positron emission tomography (PET). In bone marrow infection, there is no single routine test available that can detect infection with sufficiently high diagnostic accuracy. Here, we review radiotracers used for imaging of bone marrow infection, also known as osteomyelitis, with a focus on why these molecules are relevant for the task, based on their physiological uptake mechanisms. The review comprises [67Ga]Ga-citrate, radiolabelled leukocytes, radiolabelled nanocolloids (bone marrow) and radiolabelled phosphonates (bone structure), and [18F]FDG as established radiotracers for bone marrow infection imaging. Tracers that are under development or testing for this purpose include [68Ga]Ga-citrate, [18F]FDG, [18F]FDS and other non-glucose sugar analogues, [15O]water, [11C]methionine, [11C]donepezil, [99mTc]Tc-IL-8, [68Ga]Ga-Siglec-9, phage-display selected peptides, and the antimicrobial peptide [99mTc]Tc-UBI29-41 or [68Ga]Ga-NOTA-UBI29-41. CONCLUSION Molecular radiotracers allow studies of physiological processes such as infection. None of the reviewed molecules are ideal for the imaging of infections, whether bone marrow or otherwise, but each can give information about a separate aspect such as physiology or biochemistry. Knowledge of uptake mechanisms, pitfalls, and challenges is useful in both the use and development of medically relevant radioactive tracers.
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131I-metaiodobenzylguanidine and peptide receptor radionuclide therapy in pheochromocytoma and paraganglioma.
Jungels, C, Karfis, I
Current opinion in oncology. 2021;(1):33-39
Abstract
PURPOSE OF REVIEW Pheochromocytomas and paragangliomas are rare tumors arising, respectively, from the adrenal medulla and extra-adrenal sympathetic or parasympathetic paraganglia. The main therapeutic objectives in case of metastatic disease are the reduction of tumor burden and the control of symptoms resulting from excessive catecholamine secretion. Treatment choices constitute not only a wait and see attitude, locoregional approaches, chemotherapy regiments but also radiopharmaceutical agents, and they should be discussed in a specialized multidisciplinary board. This review will briefly discuss the radiopharmaceutical modalities in patients with pheochromocytomas and paragangliomas (I-MIBG and PRRT). RECENT FINDINGS I-MIBG (Azedra) has received FDA approval for patients with iobenguane-scan-positive, unresectable, locally advanced or metastatic pheochromocytomas and paragangliomas who require systemic anticancer therapy, whereas peptide receptor radionuclide therapy using radiolabelled somatostatin analogues is currently performed in compassionate use, with very promising results. No prospective head-to-head comparison between the modalities has been conducted to date. SUMMARY Promising results have been reported for both radiopharmaceutical agents, mostly in the setting of retrospective series. No prospective head-to-head comparison between the modalities is yet available.
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High-Specific-Activity-131I-MIBG versus 177Lu-DOTATATE Targeted Radionuclide Therapy for Metastatic Pheochromocytoma and Paraganglioma.
Jha, A, Taïeb, D, Carrasquillo, JA, Pryma, DA, Patel, M, Millo, C, de Herder, WW, Del Rivero, J, Crona, J, Shulkin, BL, et al
Clinical cancer research : an official journal of the American Association for Cancer Research. 2021;(11):2989-2995
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Abstract
Targeted radionuclide therapies (TRT) using 131I-metaiodobenzylguanidine (131I-MIBG) and peptide receptor radionuclide therapy (177Lu or 90Y) represent several of the therapeutic options in the management of metastatic/inoperable pheochromocytoma/paraganglioma. Recently, high-specific-activity-131I-MIBG therapy was approved by the FDA and both 177Lu-DOTATATE and 131I-MIBG therapy were recommended by the National Comprehensive Cancer Network guidelines for the treatment of metastatic pheochromocytoma/paraganglioma. However, a clinical dilemma often arises in the selection of TRT, especially when a patient can be treated with either type of therapy based on eligibility by MIBG and somatostatin receptor imaging. To address this problem, we assembled a group of international experts, including oncologists, endocrinologists, and nuclear medicine physicians, with substantial experience in treating neuroendocrine tumors with TRTs to develop consensus and provide expert recommendations and perspectives on how to select between these two therapeutic options for metastatic/inoperable pheochromocytoma/paraganglioma. This article aims to summarize the survival outcomes of the available TRTs; discuss personalized treatment strategies based on functional imaging scans; address practical issues, including regulatory approvals; and compare toxicities and risk factors across treatments. Furthermore, it discusses the emerging TRTs.
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Ramatroban-Based Analogues Containing Fluorine Group as Potential 18F-Labeled Positron Emission Tomography (PET) G-Protein Coupled Receptor 44 (GPR44) Tracers.
Huang, LA, Huang, KX, Tu, J, Kandeel, F, Li, J
Molecules (Basel, Switzerland). 2021;(5)
Abstract
Diabetes remains one of the fastest growing chronic diseases and is a leading source of morbidity and accelerated mortality in the world. Loss of beta cell mass (BCM) and decreased sensitivity to insulin underlie diabetes pathogenesis. Yet, the ability to safely and directly assess BCM in individuals with diabetes does not exist. Measures such as blood glucose provide only a crude indirect picture of beta cell health. PET imaging could, in theory, allow for safe, direct, and precise characterization of BCM. However, identification of beta cell-specific radiolabeled tracers remains elusive. G-protein coupled receptor 44 (GPR44) is a transmembrane protein that was characterized in 2012 as highly beta cell-specific within the insulin-positive islets of Langerhans. Accordingly, radiolabeling of existing GPR44 antagonists could be a viable method to accelerate PET tracer development. The present study aims to evaluate and summarize published analogues of the GPR44 antagonist ramatroban to develop 18F-labeled PET tracers for BCM analysis. The 77 corresponding ramatroban analogues containing a fluorine nuclide were characterized for properties including binding affinity, selectivity, and pharmacokinetic and metabolic profile, and 32 compounds with favorable properties were identified. This review illustrates the potential of GPR44 analogues for the development of PET tracers.
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Recent Advances in Photo-mediated Radiofluorination.
Bui, TT, Kim, HK
Chemistry, an Asian journal. 2021;(16):2155-2167
Abstract
Carbon-fluorine bond formations have received a lot of attention because organofluorine compounds are widely used in pharmaceutical, agricultural, and materials science applications. In particular, the incorporation of fluorine-18, which is a commonly used radioisotope for radiopharmaceuticals for positron emission tomography (PET), a molecular imaging tool for the visualization of biochemical events, human metabolism processes, and the measurement and diagnosis of diseases in humans, plays a crucial role in clinical and preclinical studies. Several synthetic methodologies for carbon-fluorine-18 bond formation have been developed. However, conventional fluorination methods have some remaining drawbacks such as the high temperature and basic environment. Photo-induced catalysis is an emerging technique that allow chemists to achieve the synthesis of target molecular architectures under mild conditions. Moreover, several radiofluorination strategies have been developed via photocatalysis. In this review, we focused on describing recent advances in the field of light-mediated radiofluorination.
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18F-Sodium Fluoride PET: History, Technical Feasibility, Mechanism of Action, Normal Biodistribution, and Diagnostic Performance in Bone Metastasis Detection Compared with Other Imaging Modalities.
Ahuja, K, Sotoudeh, H, Galgano, SJ, Singh, R, Gupta, N, Gaddamanugu, S, Choudhary, G
Journal of nuclear medicine technology. 2020;(1):9-16
Abstract
The skeleton is the third most common site for metastasis overall, after the lungs and liver. Accurate diagnosis of osseous metastasis is critical for initial staging, treatment planning, restaging, treatment monitoring, and survival prediction. Currently, 99mTc-methylene diphosphonate whole-body scanning is the cornerstone of imaging to detect osseous metastasis. Although 18F-sodium fluoride (18F-NaF) was one of the oldest medical tracers for this purpose, it was replaced by other tracers because of their better physical properties, until recently. Continued development of PET scanners has opened a new era for 18F-NaF, and given its higher sensitivity, there have been increasing applications in imaging. In this review, we will discuss the history, technical aspects, radiobiology, and biodistribution of this tracer. Finally, we compare the accuracy of 18F-NaF PET with other conventional imaging methods for detection of osseous metastasis.
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Diagnostic Performance of PET or PET/CT with Different Radiotracers in Patients with Suspicious Lung Cancer or Pleural Tumours according to Published Meta-Analyses.
Lococo, F, Muoio, B, Chiappetta, M, Nachira, D, Petracca Ciavarella, L, Margaritora, S, Treglia, G
Contrast media & molecular imaging. 2020;:5282698
Abstract
PURPOSE Several meta-analyses have reported data about the diagnostic performance of positron emission tomography or positron emission tomography/computed tomography (PET or PET/CT) with different radiotracers in patients with suspicious lung cancer (LC) or pleural tumours (PT). This review article aims at providing an overview on the recent evidence-based data in this setting. METHODS A comprehensive literature search of meta-analyses published in PubMed/MEDLINE and Cochrane Library database from January 2010 through March 2020 about the diagnostic performance of PET or PET/CT with different radiotracers in patients with suspicious LC or PT was performed. This combination of keywords was used: (A) "PET" OR "positron emission tomography" AND (B) "lung" OR "pulmonary" OR "pleur∗" AND (C) meta-analysis. Only meta-analyses on PET or PET/CT in patients with suspicious LC or PT were selected. RESULTS We have summarized the diagnostic performance of PET or PET/CT with fluorine-18 fluorodeoxyglucose (18F-FDG) and other radiotracers taking into account 17 meta-analyses. Evidence-based data demonstrated a good diagnostic performance of 18F-FDG PET or PET/CT for the characterization of solitary pulmonary nodules (SPNs) or pleural lesions with overall higher sensitivity than specificity. Evidence-based data do not support the routine use of dual time point (DTP) 18F-FDG PET/CT or fluorine-18 fluorothymidine (18F-FLT) PET/CT in the differential diagnosis of SPNs. Even if 18F-FDG PET/CT has high sensitivity and specificity as a selective screening modality for LC, its role in this setting remains unknown. CONCLUSIONS Evidence-based data about the diagnostic performance of PET/CT with different radiotracers for suspicious LC or PT are increasing, with good diagnostic performance of 18F-FDG PET/CT. More prospective multicenter studies and cost-effectiveness analyses are warranted.
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Molecular Imaging in the Head and Neck: Diagnosis and Therapy.
Howard, BA
Radiologic clinics of North America. 2020;(6):1135-1146
Abstract
This article is a summary of the most up-to-date applications of radiopharmaceuticals to the diagnosis and therapy of benign and malignant diseases involving endocrine or neuroendocrine organs of the head and neck, focusing on radiotracers approved by the US Food and Drug Administration, such as I-123- and I-131-sodium iodide, F-18-fluorodeoxyglucose, Tc99m-sestamibi, as well as the more recently approved tracers Ga-68 DOTATATE and Lu-177 DOTATATE.
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Pigmented villous nodular synovitis mimicking metastases on 18F-FDG PET/CT in a patient with rectal mucosal melanoma: a case report.
Yen, YA, Wu, LC, Lu, NM, Lee, CH
BMC musculoskeletal disorders. 2020;(1):13
Abstract
BACKGROUND Mucosal melanomas are rare and have a high potential for metastasizing. Surgical resection is the treatment of choice for single distant metastases. Malignant melanoma usually shows the highest uptake of fluorine-18 fluorodeoxyglucose (18F-FDG). 18F- FDG positron emission tomography /computed tomography (PET/CT) is usually used for melanoma staging. An extensive literature review revealed only 4 published case reports and an original paper involving 8 cases (12 cases in total) of patients with skin melanomas in whom pigmented villous nodular synovitis (PVNS) mimicked metastatic melanoma, however, none of the melanomas reported were of rectal mucosal origin. CASE PRESENTATION A 60-year-old woman presented with recent diagnosis of rectal mucosal melanoma, two additional 18F-FDG-avid lesions in the left ankle and left foot were detected on 18F-FDG PET/CT. Metastases were initially suspected; however, the final diagnosis was PVNS. CONCLUSIONS This is the first report of PVNS mimicking metastases on 18F-FDG PET/CT in a patient with rectal mucosal melanoma. Although high 18F-FDG-avid lesions in patients with rectal mucosal melanoma are highly suspected to be metastasis and warrant an meticulous examination, the present case is a reminder that in such patients, not all lesions with high 18F-FDG uptake, especially those near a joint, are metastases and that more extensive resection is unnecessary.