Stereotactic coregistration of 201Tl SPECT and MRI applied to brain tumor biopsies.

UNLABELLED The aim of the present study was to determine the clinical feasibility of integration of stereotactic SPECT (sSPECT) with 201Tl in the stereotactic MRI (sMRI)-based planning of brain tumor biopsy. Furthermore, the predictive value of the integrated techniques was analyzed by comparison with the corresponding histologically determined metabolic activity. METHODS Ten patients underwent combined 201Tl SPECT- and MRI-guided stereotactic biopsy of intracranial lesions according to a previously described technique. An area of abnormal 201Tl uptake was used to guide the stereotactic biopsy trajectory. Several samples were taken along the trajectory above and beneath the target. An extensive histologic diagnosis (tumor grade, mitotic index [MI], and Ki67 index) and the 201Tl index were obtained for all samples and compared statistically. RESULTS Combined 201Tl sSPECT- and sMRI-guided biopsy could be performed on all patients. Ki67 index, MI, and tumor grade correlated significantly. The correlations between MI or Ki67 index and 201Tl index were not significant (0.18 and 0.09, respectively). A trend to significance existed between tumor grade and 201Tl index (R = 0.31; P = 0.06). Mean 201Tl index for grade III tumors (3.27 +/- 1.89 [SD]) was significantly different from that for grade IV tumors (4.34 +/- 1.29). The sample position on the trajectory correlated with the MI (R = 0.39; P = 0.01). In 4 of the 10 patients, a variation in tumor grade could be observed along the trajectory. In all patients, the highest proliferative activity was within 5-10 mm of the target. CONCLUSION These results support the view that 201Tl SPECT may contribute to the successful management of brain tumor patients requiring stereotactic biopsy, without causing a significant increase in discomfort or morbidity. The development of similar techniques integrating sSPECT data in the planning of stereotactic biopsy should be considered by centers performing stereotactic surgery and having access to SPECT technology. In the long term, this technique could become a support for focused gene therapy and cell transfer.