PT - JOURNAL ARTICLE AU - Salber, Dagmar AU - Stoffels, Gabriele AU - Oros-Peusquens, Anna-Maria AU - Shah, Nadim J. AU - Reifenberger, Guido AU - Hamacher, Kurt AU - Coenen, Heinz H. AU - Langen, Karl-Josef TI - Comparison of <em>O</em>-(2-<sup>18</sup>F-Fluoroethyl)-<span class="sc">l</span>-Tyrosine and <span class="sc">l</span>-<sup>3</sup>H-Methionine Uptake in Cerebral Hematomas AID - 10.2967/jnumed.109.071423 DP - 2010 May 01 TA - Journal of Nuclear Medicine PG - 790--797 VI - 51 IP - 5 4099 - http://jnm.snmjournals.org/content/51/5/790.short 4100 - http://jnm.snmjournals.org/content/51/5/790.full SO - J Nucl Med2010 May 01; 51 AB - Radiolabeled amino acids are useful for brain tumor diagnosis, but unspecific uptake near the cerebral hematoma may complicate the differentiation of a neoplastic from a nonneoplastic origin of the hematoma. The aim of this study was to investigate the pattern and time course of O-(2-18F-fluorethyl)-l-tyrosine (18F-FET) and l-3H-methionine (3H-MET) uptake in rats with cerebral hematomas. Methods: Intracerebral hematomas were induced in the striatum of 25 Fischer 344 CDF rats by inoculation of bacterial collagenase. 18F-FET and 3H-MET were injected intravenously at different times up to 4 wk after bleeding. 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 maximal uptake near the hematomas and mean uptake in normal brain tissue. An L/B ratio greater than 1.5 was considered as indicative of pathologic uptake. The autoradiograms were compared with histology and immunostainings for astrogliosis (glial fibrillary acidic protein) and macrophage infiltration (CD68). Results: 18F-FET exhibited significantly increased uptake near the hematomas between 3 and 14 d after bleeding. The time course of pathologic 3H-MET uptake was similar, but after 3–4 wk there was still borderline uptake in single animals. The L/B ratios exceeded the cutoff level of 1.5 in 10 of 23 animals for 18F-FET and in 12 of 22 animals for 3H-MET but did not exceed a value of 3. Immunostainings indicated that increased uptake of both tracers correlated with reactive astrogliosis, whereas 3H-MET uptake was additionally increased in areas with macrophage infiltration. Conclusion: 18F-FET, like 3H-MET, may exhibit significantly increased uptake near cerebral hematomas, especially during the first 2 wk after bleeding, complicating the differentiation between a neoplastic and a nonneoplastic origin of cerebral hematomas.