Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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Iodine-123-beta-carbomethoxy-3 beta-(4-iodophenyltropane) (CIT) has been used as a probe of dopamine transporters in Parkinson's disease patients using SPECT. This tracer has a protracted period of striatal uptake enabling imaging 14-24 hr postinjection for stable quantitative measures of dopamine transporters, and it binds with nanomolar affinity to the serotonin transporter. Iodine-123 fluoropropyl (FP)CIT is an analog of [123I]-beta-CIT and has been shown to achieve peak tracer uptake in the brain within hours postinjection and to provide greater selectivity for the dopamine transporter. The purpose of the present study was to compare [123I]-beta-CIT with [123I]-FPCIT in a within-subject design. ⋯ These data suggest that SPECT imaging with [123I]-FPCIT visually demonstrates reductions in striatal uptake similar to [123I]-beta-CIT. iodine-123-FPCIT washed out from striatal tissue 15-20 times faster than [123I]-beta-CIT, and estimates of dopamine transporter loss in Parkinson's disease patients were higher for [123I]-FPCIT than for [123I]-beta-CIT. This was most likely due to the faster rate of striatal washout and establishment of transient equilibrium binding conditions at the dopamine transporter, which the modeling theory suggests produces an overestimation of dopamine transporter density with relatively greater overestimates in healthy control subjects by [123I]-FPCIT.
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The purpose of this study was to determine whether 201Tl retention in focal intracranial lesions can help distinguish central nervous system (CNS) lymphoma from toxoplasmosis and other nonmalignant CNS lesions in patients with acquired immunodeficiency syndrome. ⋯ The retention index increases the specificity of 201Tl brain SPECT in human immunodeficiency virus patients. In the presence of abnormal early 201Tl uptake, it is essential to perform delayed imaging and calculate the retention index to distinguish nonmalignant lesions from lymphoma. The absence of 201Tl uptake on early images at the site of a CT/MRI abnormality excludes the diagnosis of lymphoma with a high degree of confidence and delayed imaging is unnecessary.
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Uptake of 18F-fluorodeoxyglucose (FDG) and 11C-methionine (Met) in mediastinum and hilar lymph nodes was studied using PET in 31 patients with sarcoidosis. The aim of our study was to examine whether these different tracers play a differential role in clinical assessment of pulmonary involvement. ⋯ The results suggest that the FDG/Met uptake ratio using PET may reflect the differential granulomatous status in sarcoidosis and be a useful tool for pretreatment evaluation.
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The aims of this study were to investigate whether the loss of striatal dopamine transporters in early and drug-naive patients with Parkinson's disease could be demonstrated by means of 123I-N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iodoph enyl)tropane (123I-FP-CIT) SPECT in a 1-day protocol and whether the SPECT measures were correlated with disease severity. ⋯ Our findings indicate that 123I-FP-CIT SPECT is a reliable method to discriminate between early, drug-naive Parkinson's disease patients and healthy controls and to identify patients in the preclinical phase of Parkinson's disease. Possibly due to the relatively homogeneous group of Parkinson's disease patients and the use of a suboptimal outcome measure, no significant correlations were found between striatal 123I-FP-CIT binding ratios and disease severity, such as were established earlier with 123I-beta-CIT. Further research is necessary to interpret these findings.