The Lancet Oncology Commission on imaging and nuclear medicine makes a persuasive argument to include imaging as part of comprehensive approaches to reduce global morbidity and mortality from cancer ...and recommends actions to increase implementation in LMICs.1 This Commission builds upon two reports published in 2015 regarding gaps in access to cancer surgery and radiotherapy in LMICs.2,3 A key point in this report is that the scale-up of imaging capacity should be comprehensive and strategically aligned with treatment capacity. Compared with HICs, patients in LMICs might have more advanced disease, and the distributions of cancer types might differ because of environmental factors, barriers to cancer screening and primary care, and genetics.5,6 Although there is a gap between HICs and LMICs in all types of medical imaging, more advanced medical imaging techniques that are highly relevant to cancer, such as PET combined with CT (PET/CT), show even more pronounced inequalities. Another report, which focused on the use of nuclear medicine in a regional hospital in Nigeria, highlighted that, in addition to infrastructure and training, strategic plans on how to implement imaging into the clinical workflow and geographical access issues should also be considered.7 Even in wealthier nations, substantial variation exists in the implementation of PET/CT scans.8 In some cases, there might be an opportunity to implement more advanced imaging techniques at an earlier stage rather than a gradual progression of medical imaging technologies—eg, 68Ga generators that last for months can provide on-site and on-demand labelling of radiopharmaceuticals, such as 68Ga-DOTATATE and 68Ga-prostate-specific membrane antigen, which can be prepared at local sites using kits.
The two primary molecular pathologies in Alzheimer's disease are amyloid-β plaques and tau-immunoreactive neurofibrillary tangles. Investigations into these pathologies have been restricted to ...cerebrospinal fluid assays, and positron emission tomography tracers that can image amyloid-β plaques. Tau tracers have recently been introduced into the field, although the utility of the tracer and its relationship to other Alzheimer biomarkers are still unknown. Here we examined tau deposition in 41 cognitively normal and 11 cognitively impaired older adults using the radioactive tau ligand (18)F-AV-1451 (previously known as T807) who also underwent a lumbar puncture to assess cerebrospinal fluid levels of total tau (t-tau), phosphorylated tau181 (p-tau181) and amyloid-β42 Voxel-wise statistical analyses examined spatial patterns of tau deposition associated with cognitive impairment. We then related the amount of tau tracer uptake to levels of cerebrospinal fluid biomarkers. All analyses controlled for age and gender and, when appropriate, the time between imaging and lumbar puncture assessments. Symptomatic individuals (Clinical Dementia Rating > 0) demonstrated markedly increased levels of tau tracer uptake. This elevation was most prominent in the temporal lobe and temporoparietal junction, but extended more broadly into parietal and frontal cortices. In the entire cohort, there were significant relationships among all cerebrospinal fluid biomarkers and tracer uptake, notably for tau-related cerebrospinal fluid markers. After controlling for levels of amyloid-β42, the correlations with tau uptake were r = 0.490 (P < 0.001) for t-tau and r = 0.492 (P < 0.001) for p-tau181 Within the cognitively normal cohort, levels of amyloid-β42, but not t-tau or p-tau181, were associated with elevated tracer binding that was confined primarily to the medial temporal lobe and adjacent neocortical regions. AV-1451 tau binding in the medial temporal, parietal, and frontal cortices is correlated with tau-related cerebrospinal fluid measures. In preclinical Alzheimer's disease, there is focal tauopathy in the medial temporal lobes and adjacent cortices.
This observational study aimed to determine whether individuals with fibromyalgia (FM) exhibit higher levels of neuroinflammation than healthy controls (HCs), as measured with positron emission ...tomography using 18FDPA-714, a second-generation radioligand for the translocator protein (TSPO). Fifteen women with FM and 10 HCs underwent neuroimaging. Distribution volume (VT) was calculated for in 28 regions of interest (ROIs) using Logan graphical analysis and compared between groups using multiple linear regressions. Group (FM vs HC) was the main predictor of interest and TSPO binding status (high- vs mixed-affinity) was added as a covariate. The FM group had higher VT in the right postcentral gyrus (b = 0.477, P = 0.033), right occipital gray matter (GM; b = 0.438, P = 0.039), and the right temporal GM (b = 0.466, P = 0.042). The FM group also had lower VT than HCs in the left isthmus of the cingulate gyrus (b = -0.553, P = 0.014). In the subgroup of high-affinity binders, the FM group had higher VT in the bilateral precuneus, postcentral gyrus, parietal GM, occipital GM, and supramarginal gyrus. Group differences in the right parietal GM were associated with decreased quality of life, higher pain severity and interference, and cognitive problems. In support of our hypothesis, we found increased radioligand binding (VT) in the FM group compared with HCs in several brain regions regardless of participants' TSPO binding status. The ROIs overlapped with prior reports of increased TSPO binding in FM. Overall, increasing evidence supports the hypothesis that FM involves microglia-mediated neuroinflammation in the brain.
(18)F-labeled amino acids are an important class of imaging agents for positron emission tomography (PET) that target the increased rates of amino acid transport by many tumor cells. This class of ...tracers is structurally diverse, and the biological and imaging properties of a given (18)F-labeled amino acid depends largely upon its mechanism of transport. The system L amino acid transport system has been a major focus of tracer development in this field, but more recently (18)F-labeled amino acids have been developed for other transporters including system A, glutamine, glutamate and cationic amino acid transport systems. Radiolabeled amino acids are best established for brain tumor imaging, but there are emerging applications in other types of cancer such as neuroendocrine tumors and prostate cancer. This review provides an overview of (18)F-labeled amino acids for oncologic imaging in terms of design considerations, radiosynthetic methods, and key clinical applications.
Clinical application of PET/MRI in oncology Sotoudeh, Houman; Sharma, Akash; Fowler, Kathryn J. ...
Journal of magnetic resonance imaging,
August 2016, Letnik:
44, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Hybrid imaging with integrated positron emission tomography (PET) and magnetic resonance imaging (MRI) combines the advantages of the high‐resolution anatomic data from MRI and functional imaging ...data from PET, and has the potential to improve the diagnostic evaluation of various types of cancers. The clinical oncologic applications of this newest hybrid imaging technology are evolving and substantial efforts are underway to define the role of PET/MRI in routine clinical use. The current published literature suggests that PET/MRI may play an important role in the evaluation of patients with certain types of malignancies, involving anatomic locations such as the pelvis and the liver. The purpose of this article is to review the current published PET/MRI literature in specific body oncologic applications. In addition, PET/MRI protocols and some of the technical issues of this hybrid imaging will be briefly discussed. J. Magn. Reson. Imaging 2016;44:265–276.
Amino acids are required nutrients for proliferating tumor cells, and amino acid transport is upregulated in many tumor types. Studies of radiolabeled amino acids in animals and humans demonstrate ...that amino acid based tracers have advantageous characteristics relative to 2-
18
Ffluoro-2-deoxyglucose in certain tumors, particularly brain gliomas. Non-natural amino acids for tumor imaging generally have greater metabolic stability and can be labeled with longer-lived radionuclides for positron emission tomography and single photon emission computed tomography such as fluorine-18 and iodine-123. Amino acids enter cells via amino acid transport with varying selectivity based on their chemical structure. This review focuses on the rationale, biological basis, current status and future prospects of radiolabeled non-natural amino acids for tumor imaging and discusses various classes of these compounds including aromatic, alicyclic and α,α-dialkyl amino acids.
PET/MRI scanners cannot be qualified in the manner adopted for hybrid PET/CT devices. The main hurdle with qualification in PET/MRI is that attenuation correction (AC) cannot be adequately measured ...in conventional PET phantoms because of the difficulty in converting the MR images of the physical structures (e.g., plastic) into electron density maps. Over the last decade, a plethora of novel MRI-based algorithms has been developed to more accurately derive the attenuation properties of the human head, including the skull. Although promising, none of these techniques has yet emerged as an optimal and universally adopted strategy for AC in PET/MRI. In this work, we propose a path for PET/MRI qualification for multicenter brain imaging studies. Specifically, our solution is to separate the head AC from the other factors that affect PET data quantification and use a patient as a phantom to assess the former. The emission data collected on the integrated PET/MRI scanner to be qualified should be reconstructed using both MRI- and CT-based AC methods, and whole-brain qualitative and quantitative (both voxelwise and regional) analyses should be performed. The MRI-based approach will be considered satisfactory if the PET quantification bias is within the acceptance criteria specified here. We have implemented this approach successfully across 2 PET/MRI scanner manufacturers at 2 sites.
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