COMPARATIVE-ASSESSMENT OF POUR DIFFERENT TL-201 TUMOR UPTAKE INDEXES IN THE EVALUATION OF BRAIN-TUMORS

The objective of this study was to determine which semiquantitative th allium-201 brain tumor index correlated best with clinical outcome. Fi fty-two patients had Tl-201 brain single-photon emission computer tomo graphy (SPECT) performed for the evaluation of recurrent brain tumor, A semi-quantitative tumor index was calculated utilizing four currentl y available techniques: 1) the ratio of average counts of the region o f interest (ROI) in the lesion area and its mirror image in normal bra in tissue, 2) the ratio of maximum counts of the region of interest in the lesion area and its average counts in the mirror image, 3) the ra tio of maximum counts of the region of interest in the lesion area and its mirror image and 4) the ratio of the average counts of the region of interest in the lesion area and the region of interest of the scal p, A two-tailed Student's t test was performed, The mean value plus on e standard deviation was used to assess the sensitivity and specificit y correlated with clinical follow-up evaluation, defined as inactive o r active at the time of brain SPECT by the referring neurosurgeons, Re sults of correlation coefficient, P value, mean, standard deviation, s ensitivity, and specificity of each index using cutoff values were obt ained. For those patients with recurrence or residual malignant tumor after therapy, the maximum count ratio index correlated best with clin ical outcome. It provided a sensitivity of 92% and specificity of 88% in differentiating active from inactive brain tumors.