Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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In this study, we reported age-associated ranges of the regional cerebral (18)F-FDG uptake ratio in pediatric patients as a surrogate to normative data from healthy children. ⋯ Anatomic regions of the brain in children and adolescents exhibited uniquely different (18)F-FDG uptake trends with age. Our results may be useful for studying childhood development and possibly regional metabolic defects in children with traumatic brain injury or central nervous system disorders or children receiving cancer treatment.
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(86)Y (half-life = 14.74 h, 33% β(+)) is within an emerging class of positron-emitting isotopes with relatively long physical half-lives that enables extended imaging of biologic processes. We report the synthesis and evaluation of 3 low-molecular-weight compounds labeled with (86)Y for imaging the prostate-specific membrane antigen (PSMA) using PET. Impetus for the study derives from the need to perform dosimetry estimates for the corresponding (90)Y-labeled radiotherapeutics. ⋯ Compound (86)Y- 6: is a promising candidate for quantitative PET imaging of PSMA-expressing tumors. Dosimetry calculations indicate promise for future (90)Y or other radiometals that could use a similar chelator/scaffold combination for radiopharmaceutical therapy based on the structure of 6.
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MR-based attenuation correction is instrumental for integrated PET/MR imaging. It is generally achieved by segmenting MR images into a set of tissue classes with known attenuation properties (e.g., air, lung, bone, fat, soft tissue). Bone identification with MR imaging is, however, quite challenging, because of the low proton density and fast decay time of bone tissue. The clinical evaluation of a novel, recently published method for zero-echo-time (ZTE)-based MR bone depiction and segmentation in the head is presented here. ⋯ This is the first, to our knowledge, clinical evaluation of skull bone identification based on a ZTE sequence. The results suggest that proton density-weighted ZTE imaging is an efficient means of obtaining high-resolution maps of bone tissue with sufficient anatomic accuracy for, for example, PET attenuation correction.
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In PET studies of patients with Alzheimer disease (AD), prominent hypometabolism can occur in brain regions without major amyloid load. These hypometabolism-only (HO) areas may not be explained easily as a consequence of local amyloid toxicity. The aim of this longitudinal multimodal imaging study was the investigation of locoregional and remote relationships between metabolism in HO areas and longitudinal amyloid increase in functionally connected brain areas, with a particular focus on intrinsic functional connectivity as a relevant linking mechanism between pathology and dysfunction. ⋯ Our results indicate that in AD amyloid accumulation in remote but functionally connected brain regions may significantly contribute to longitudinally evolving hypometabolism in brain regions not strongly affected by local amyloid pathology, supporting the amyloid- and network-degeneration hypothesis.
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(18)F-FDG PET/CT has shown increased accuracy, compared with morphologic imaging, in differentiating malignant peripheral nerve sheath tumors (MPNSTs) from benign neurofibromas (BNFs) in patients with neurofibromatosis type 1 (NF1). Delayed (18)F-FDG PET imaging typically enhances malignant tumor to background. Our goal was to compare the effectiveness of early (1-h) and delayed (4-h) (18)F-FDG PET/CT imaging in differentiating MPNSTs from BNFs in patients with NF1, with and without liver activity normalization. ⋯ Qualitative interpretation of (18)F-FDG PET/CT discriminates MPNSTs from BNFs in NF1 patients with similar accuracy on both early and delayed imaging. Quantitative data showed better sensitivity on delayed acquisition and best test specificity with lesion SULmax normalization to liver activity, more so than with delayed imaging at 4 h.