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[Proposal for a Guideline of Risk Reduction and Sensitivity Optimization in Imaging Tests for People with Diabetes].
Donato, S, Simões, H, Donato, P
Acta medica portuguesa. 2021;(5):388-394
Abstract
Diabetes is a very common chronic disease in the Portuguese population, with an estimated prevalence of 13.6% in the adults. Doubts often arise regarding the best preparation and the risks associated with doing imaging tests in these patients. In this article we intend to review the main precautions in imaging tests in people with diabetes and to suggest a guideline to reduce the risks and optimize the sensitivity of these tests in this population. The main topics addressed in this article are the need to suspend metformin after the administration of endovascular iodinated contrast due to the risk of lactic acidosis, the precautions in insulin-treated patients or those taking medicines with a higher risk of hypoglycemia when performing imaging tests that require fasting, and the influence of hyperglycemia and of anti-diabetic therapy on the sensitivity of PET-FDG. With this review and the presentation of a guideline, we intend to demystify and simplify the management of individuals with diabetes who are undergoing imaging tests.
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Advanced imaging techniques for neuro-oncologic tumor diagnosis, with an emphasis on PET-MRI imaging of malignant brain tumors.
Overcast, WB, Davis, KM, Ho, CY, Hutchins, GD, Green, MA, Graner, BD, Veronesi, MC
Current oncology reports. 2021;(3):34
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Abstract
PURPOSE OF REVIEW This review will explore the latest in advanced imaging techniques, with a focus on the complementary nature of multiparametric, multimodality imaging using magnetic resonance imaging (MRI) and positron emission tomography (PET). RECENT FINDINGS Advanced MRI techniques including perfusion-weighted imaging (PWI), MR spectroscopy (MRS), diffusion-weighted imaging (DWI), and MR chemical exchange saturation transfer (CEST) offer significant advantages over conventional MR imaging when evaluating tumor extent, predicting grade, and assessing treatment response. PET performed in addition to advanced MRI provides complementary information regarding tumor metabolic properties, particularly when performed simultaneously. 18F-fluoroethyltyrosine (FET) PET improves the specificity of tumor diagnosis and evaluation of post-treatment changes. Incorporation of radiogenomics and machine learning methods further improve advanced imaging. The complementary nature of combining advanced imaging techniques across modalities for brain tumor imaging and incorporating technologies such as radiogenomics has the potential to reshape the landscape in neuro-oncology.
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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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Value of 18F-FDG-PET to predict PD-L1 expression and outcomes of PD-1 inhibition therapy in human cancers.
Kaira, K, Kuji, I, Kagamu, H
Cancer imaging : the official publication of the International Cancer Imaging Society. 2021;(1):11
Abstract
Anti-programmed cell death-1 (PD-1)/programmed death ligand-1 (PD-L1) antibodies are administered in varied human cancer types. The expression of PD-L1 within tumor cells has been identified as a predictive marker, although assessing its expression has benefitted only patients with non-small cell lung cancer (NSCLC) or head and neck cancer. Whereas, more than 75% of the patients with NSCLC showing partial response to PD-1 blockade therapy experienced long-term survival for more than 5-years Thus, identifying the responders to PD-1 blockade at early phase after its initiation is of clinical importance. The 2-deoxy-2-[fluorine-18] fluoro-D-glucose (18F-FDG) on positron emission tomography (PET) can evaluate any tumor shrinkage by assessing the metabolic tumor volume at an earlier phase than conventional modalities such as computed tomography (CT). While several reports describe the correlation of PD-L1 expression with 18F-FDG uptake rate in the tumor cells, it remains to be delineated whether this rate determined by the glucose metabolism and hypoxia is associated with the status of immune microenvironment, including the expression of PD-L1. Moreover, details of the relationship between expression of PD-L1 and 18F-FDG uptake is still unclear. Therefore, we reviewed the clinical significance of 18F-FDG uptake on PET as a predictor of the efficacy of PD-1 blockade therapy, by correlating with the expression of PD-L1, in patients with several neoplasms.
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Neuroinflammation and immunoregulation in glioblastoma and brain metastases: Recent developments in imaging approaches.
Roesler, R, Dini, SA, Isolan, GR
Clinical and experimental immunology. 2021;(3):314-324
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Abstract
Brain tumors and brain metastases induce changes in brain tissue remodeling that lead to immunosuppression and trigger an inflammatory response within the tumor microenvironment. These immune and inflammatory changes can influence invasion and metastasis. Other neuroinflammatory and necrotic lesions may occur in patients with brain cancer or brain metastases as sequelae from treatment with radiotherapy. Glioblastoma (GBM) is the most aggressive primary malignant brain cancer in adults. Imaging methods such as positron emission tomography (PET) and different magnetic resonance imaging (MRI) techniques are highly valuable for the diagnosis and therapeutic evaluation of GBM and other malignant brain tumors. However, differentiating between tumor tissue and inflamed brain tissue with imaging protocols remains a challenge. Here, we review recent advances in imaging methods that have helped to improve the specificity of primary tumor diagnosis versus evaluation of inflamed and necrotic brain lesions. We also comment on advances in differentiating metastasis from neuroinflammation processes. Recent advances include the radiosynthesis of 18 F-FIMP, an L-type amino acid transporter 1 (LAT1)-specific PET probe that allows clearer differentiation between tumor tissue and inflammation compared to previous probes, and the combination of different advanced imaging protocols with the inclusion of radiomics and machine learning algorithms.
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Total-body PET Imaging: A New Frontier for the Assessment of Metabolic Disease and Obesity.
Chondronikola, M, Sarkar, S
PET clinics. 2021;(1):75-87
Abstract
Obesity and associated metabolic syndrome are a global public health issue. Understanding the pathophysiology of this systemic disease is of critical importance for the development of future therapeutic interventions to improve clinical outcomes. The multiorgan nature of the pathophysiology of obesity presents a unique challenge. Total-body PET imaging, either static or dynamic, provides a vital set of tools to study organ crosstalk. The visualization and quantification of tissue metabolic kinetics with total-body PET in health and disease provides essential information to better understand disease physiology and potentially develop diagnostic and therapeutic modalities.
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Vulnerable plaque imaging using 18F-sodium fluoride positron emission tomography.
Kwiecinski, J, Slomka, PJ, Dweck, MR, Newby, DE, Berman, DS
The British journal of radiology. 2020;(1113):20190797
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Abstract
Positron emission tomography (PET) with 18F-sodium fluoride (18F-NaF) has emerged as a promising non-invasive imaging modality to identify high-risk and ruptured atherosclerotic plaques. By visualizing microcalcification, 18F-NaF PET holds clinical promise in refining how we evaluate coronary artery disease, shifting our focus from assessing disease burden to atherosclerosis activity. In this review, we provide an overview of studies that have utilized 18F-NaF PET for imaging atherosclerosis. We discuss the associations between traditional coronary artery disease measures (risk factors) and 18F-NaF plaque activity. We also present the data on the histological validation as well as show how 18F-NaF uptake is associated with plaque morphology on intravascular and CT imaging. Finally, we discuss the technical challenges associated with 18F-NaF coronary PET highlighting recent advances in this area.
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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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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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15O-Water PET MPI: Current Status and Future Perspectives.
Maaniitty, T, Knuuti, J, Saraste, A
Seminars in nuclear medicine. 2020;(3):238-247
Abstract
Myocardial perfusion imaging with 15O-water positron emission tomography (PET) is a validated tool for quantitative measurement of myocardial blood flow (MBF) and myocardial flow reserve (MFR). Current scanner and software technology enable quantification of global and regional MBF in clinical PET myocardial perfusion imaging studies. Reduced stress MBF or MFR measured by 15O-water PET accurately detects hemodynamically significant coronary artery stenosis defined by intracoronary fractional flow reserve (FFR) measurement in patients with suspected obstructive coronary artery disease (CAD). Furthermore, MBF and MFR provide prognostic information on mortality and risk of myocardial infarction. Clinical experience in some centers indicates that clinical application of 15O-water PET in evaluation of CAD is feasible and guides management decisions on revascularization. This review discusses basic concepts of measuring MBF with 15O-water PET and reviews clinical studies on its application in evaluation of obstructive CAD.