BACKGROUND: Radiation-induced changes in post-irradiated brain tumors may produce morphological alterations similar to those of tumor recurrence on computed tomography (CT). However, 201Tl single-photon-emission computed tomography (SPECT), with its ability to image metabolic changes, may differentiate post-irradiated gliotic changes from metabolically active congregations of viable tumor cells. This study was carried out to compare these two imaging modalities for the follow-up evaluation of post-irradiated brain tumors. METHODS: Thirty-five patients with previously irradiated primary brain tumors were evaluated for this study. 201Tl SPECT and CT were carried out during follow-up, which ranged from 3 to 125 months (median, 18 months). These findings were compared with the clinical outcome, as observed during the subsequent follow-up. RESULTS: Sensitivity, specificity, and the overall accuracy of 201Tl SPECT were 82.7%, 83.3%, and 82.8%, compared to 58.6%, 66.6%, and 58.3%, respectively, for CT. Post-scan progression-free survival (PFS) was significantly different for those patients having positive and those having negative evidence of tumor recurrence based on the imaging studies during follow-up. However, PFS was better correlated with 201Tl SPECT results than with the CT results. With 201Tl SPECT, median PFS was 4 months for those with positive reports, versus 33 months for those with negative reports (P = 0.003), compared to a corresponding median PFS of 3 months versus 14 months (P = 0.025), respectively, with CT. On multivariate analysis, age and 201Tl SPECT were the only significant variables for predicting post-scan PFS. CONCLUSION: 201Tl SPECT, with its ability to be taken up by viable tumor tissues, is superior to CT for the follow-up evaluation of post-irradiated brain tumors.
BACKGROUND: Radiation-induced changes in post-irradiated brain tumors may produce morphological alterations similar to those of tumor recurrence on computed tomography (CT). However, 201Tl single-photon-emission computed tomography (SPECT), with its ability to image metabolic changes, may differentiate post-irradiated gliotic changes from metabolically active congregations of viable tumor cells. This study was carried out to compare these two imaging modalities for the follow-up evaluation of post-irradiated brain tumors. METHODS: Thirty-five patients with previously irradiated primary brain tumors were evaluated for this study. 201Tl SPECT and CT were carried out during follow-up, which ranged from 3 to 125 months (median, 18 months). These findings were compared with the clinical outcome, as observed during the subsequent follow-up. RESULTS: Sensitivity, specificity, and the overall accuracy of 201Tl SPECT were 82.7%, 83.3%, and 82.8%, compared to 58.6%, 66.6%, and 58.3%, respectively, for CT. Post-scan progression-free survival (PFS) was significantly different for those patients having positive and those having negative evidence of tumor recurrence based on the imaging studies during follow-up. However, PFS was better correlated with 201Tl SPECT results than with the CT results. With 201Tl SPECT, median PFS was 4 months for those with positive reports, versus 33 months for those with negative reports (P = 0.003), compared to a corresponding median PFS of 3 months versus 14 months (P = 0.025), respectively, with CT. On multivariate analysis, age and 201Tl SPECT were the only significant variables for predicting post-scan PFS. CONCLUSION: 201Tl SPECT, with its ability to be taken up by viable tumor tissues, is superior to CT for the follow-up evaluation of post-irradiated brain tumors.
Authors: C Walker; B Haylock; D Husband; K A Joyce; D Fildes; M D Jenkinson; T Smith; J Broome; K Kopitzki; D G du Plessis; J Prosser; S Vinjamuri; P C Warnke Journal: Br J Cancer Date: 2006-10-10 Impact factor: 7.640