Correlation of preoperative thallium SPECT with histological grading and overall survival in adult gliomas.

BACKGROUND: The management and prognosis of a glioma depend on the tumour's histological grade. Thus, preoperative prediction of the grade is routinely needed to indicate whether surgery or biopsies are required. It has been proposed that thallium single photon emission computed tomography (SPECT), in a relative short series, will aid this prediction. AIM: To confirm the correlation between the results of preoperative thallium SPECT and grade of tumour as well as patient survival, and to define the cut-off value of the optimal thallium index for the detection of high grade gliomas in a large series of patients. METHODS: One hundred and eighteen patients treated for glioma were retrospectively included in this study. All patients underwent preoperative 201Tl SPECT upon initial presentation and were referred for neurosurgery. Initial scintigraphic findings were correlated with the histological grade of the tumour and overall patient survival. RESULTS: Thallium uptake was highly correlated with histological grade; the mean thallium indices for low grade and high grade gliomas were 1.8 and 4.9, respectively. On the basis of receiver operating characteristic analysis, the optimal cut-off value of the thallium index for the detection of high grade glioma was determined. By using 2.2 as the value for the threshold thallium index, the sensitivity and specificity were 93% and 72%, respectively. Kaplan-Meier estimates of the overall survival curves, as a function of the thallium index, indicated that it was correlated with the overall survival (P<0.001). CONCLUSION: Thallium SPECT provides useful information about the histological grade of the tumour and overall patient survival. Additionally, in spite of its relatively weak resolution, it appears to be a powerful routine clinical tool for the management of gliomas.

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.