Abstract | UNLABELLED: METHODS: Focal cortical ischemia was induced in 25 CDF rats using the photothrombosis (PT) model. At different time points up to 6 weeks after the induction of PT, [( 18)F]FET and [(3)H]MET were injected intravenously. Additionally, contrast-enhanced magnetic resonance imaging (MRI) was performed in 10 animals. One hour after tracer injection, brains were cut in coronal sections and evaluated by dual-tracer autoradiography. Lesion-to-brain (L/B) ratios were calculated by dividing the maximal uptake in the lesion by the mean uptake in the brain. An L/B ratio of >2.0 was considered indicative of pathological uptake. Histological slices were stained by cresyl violet and supplemented by immunostainings for glial fibrillary acidic protein (GFAP) and CD68 in selected cases. RESULTS: A variably increased uptake of both tracers was observed in the PT lesion and its demarcation zone up to 7 days after PT for [( 18)F]FET and up to 6 weeks for [(3)H]MET. The cutoff level of 2.0 was exceeded in 12/25 animals for [( 18)F]FET and in 18/25 animals for [(3)H]MET. Focally increased tracer uptake matched contrast enhancement in MRI in 3/10 cases for [( 18)F]FET and in 5/10 cases for [(3)H]MET. Immunohistochemical staining in lesions with differential uptake of [( 18)F]FET and [(3)H]MET revealed that selective uptake of [( 18)F]FET was associated with GFAP-positive astrogliosis while selective [(3)H]MET uptake correlated with CD68-positive macrophage infiltration. CONCLUSIONS: [( 18)F]FET, like [(3)H]MET, may exhibit significant uptake in the periphery of cortical infarctions, which has to be considered in the differential diagnosis of unknown brain lesions. There are discrepancies between [( 18)F]FET and [(3)H]MET uptake in the area of infarctions that appear to be caused by the preferential uptake of [( 18)F]FET in reactive astrocytes versus the preferential uptake of [(3)H]MET in macrophages.
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Authors | Dagmar Salber, Gabriele Stoffels, Dirk Pauleit, Guido Reifenberger, Michael Sabel, Nadim Jon Shah, Kurt Hamacher, Heinz H Coenen, Karl-Josef Langen |
Journal | Nuclear medicine and biology
(Nucl Med Biol)
Vol. 33
Issue 8
Pg. 1029-35
(Nov 2006)
ISSN: 0969-8051 [Print] United States |
PMID | 17127177
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Fluorine Radioisotopes
- O-(2-fluoroethyl)tyrosine
- Radiopharmaceuticals
- Tritium
- Tyrosine
- Methionine
|
Topics |
- Animals
- Brain Ischemia
(metabolism)
- Cerebral Cortex
(blood supply)
- Fluorine Radioisotopes
- Male
- Methionine
(pharmacokinetics)
- Radiopharmaceuticals
(pharmacokinetics)
- Rats
- Rats, Inbred F344
- Tritium
- Tyrosine
(analogs & derivatives, pharmacokinetics)
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