Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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We sought to advance methodology for studying microglial activation and putative therapeutic downregulation in response to minocycline by means of noninvasive in vivo imaging. A reproducible focal white matter lesion was used to reliably compare treatment conditions. ⋯ Zymosan-induced microglial activation and its response to minocycline can be quantitatively imaged in the rat brain using (11)C-(R)-PK11195 PET. The ability to detect a treatment effect in a focal white-matter lesion may be of use in studying therapies for multiple sclerosis (MS).
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Translocator protein (TSPO), also referred to as peripheral benzodiazepine receptor (PBR), is a crucial 18-kDa outer mitochondrial membrane protein involved in numerous cellular functions, including the regulation of cholesterol metabolism, steroidogenesis, and apoptosis. Elevated expression of TSPO in oncology correlates with disease progression and poor survival, suggesting that molecular probes capable of assaying TSPO levels may have potential as cancer imaging biomarkers. In preclinical PET studies, we characterized a high-affinity aryloxyanilide-based TSPO imaging ligand, 18F-N-fluoroacetyl-N-(2,5-dimethoxybenzyl)-2-phenoxyaniline (18F-PBR06), as a candidate probe for the quantitative assessment of TSPO expression in glioma. ⋯ These preclinical studies illustrate that 18F-PBR06 is a promising tracer for visualization of TSPO-expressing tumors. Importantly, the close correlation between 18F-PBR06 uptake and TSPO expression in tumors and normal tissues, coupled with the high degree of displaceable binding from both tumors and the normal brain, represents a significant improvement over other TSPO imaging ligands previously evaluated in glioma. These data suggest the potential of 18F-PBR06 to elucidate the role of TSPO in oncology, as well as its potential development as a cancer imaging biomarker.
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Interstitial lung diseases include different clinical entities with variable prognoses. Idiopathic pulmonary fibrosis (IPF), the most common, presents the most severe outcome (death within 3-5 y), whereas nonspecific interstitial pneumonia (NSIP) shows a more indolent progression. Preclinical evidence of somatostatin receptor (SSTR) expression on fibroblasts in vitro and in lung fibrosis murine models, coupled with the longer survival of mice with fibrotic lungs treated with agents blocking SSTR, supports the hypothesis of imaging fibroblast activity in vivo by visualization of SSTR with (68)Ga-DOTANOC PET/CT. The aim of this study was to evaluate (68)Ga-DOTANOC PET/CT in patients with IPF and NSIP. ⋯ Our preliminary data show that (68)Ga-DOTANOC PET/CT demonstrates SSTR overexpression in IPF patients; this may prove interesting for the evaluation of novel treatments with somatostatin analogs.
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The utility of (18)F-FDG PET/CT for response assessment in malignant lung tumors treated with radiofrequency ablation (RFA) and for the detection and prediction of local recurrence was investigated. ⋯ (18)F-FDG PET/CT parameters on both preablation and postablation scans may predict local recurrence in patients treated with RFA for lung metastases and primary lung cancers.