Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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The induction of neuroinflammatory processes, characterized by upregulation of the peripheral benzodiazepine receptor (PBR) expressed by microglial cells, is well correlated with neurodegenerative diseases and with acute neuronal loss. The continually increasing incidence of neurodegenerative diseases in developed countries has become a major health problem, for which the development of diagnostic and follow-up tools is required. Here we investigated a new PBR ligand suitable for PET to monitor neuroinflammatory processes as an indirect hallmark of neurodegeneration. ⋯ (11)C-DPA-713 displays a higher signal-to-noise ratio than (11)C-PK11195 because of a lower level of unspecific binding that is likely related to the lower lipophilicity of (11)C-DPA-713. Although further studies in humans are required, (11)C-DPA-713 represents a suitable alternative to (11)C-PK11195 for PET of PBR as a tracer of neuroinflammatory processes induced by neuronal stress.
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Medullary thyroid carcinoma (MTC) is a rare endocrine tumor arising from the C-cells of the thyroid gland. Calcitonin is the principal serum tumor marker. A rising calcitonin level after total thyroidectomy for localized disease generally indicates residual, recurrent, or metastatic disease. The role of (18)F-FDG PET in MTC remains somewhat unclear. We reviewed our own experience with (18)F-FDG PET in postthyroidectomy MTC patients with elevated calcitonin. ⋯ (18)F-FDG PET can detect residual, recurrent, or metastatic MTC with a reasonable sensitivity of 78% when the calcitonin level is above 1,000 pg/mL but appears of limited use if the calcitonin level is below 500 pg/mL.
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The aim of this study was to evaluate the diagnostic value of a new somatostatin analog, (68)Ga-labeled 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-d-Phe(1)-Tyr(3)-octreotide ((68)Ga-DOTA-TOC), for PET in patients with known or suspected neuroendocrine tumors. PET was compared with conventional scintigraphy and dedicated CT. ⋯ (68)Ga-DOTA-TOC PET shows a significantly higher detection rate compared with conventional somatostatin receptor scintigraphy and diagnostic CT with clinical impact in a considerable number of patients.