²⁰¹Ti single photon emission tomography in the evaluation of residual and recurrent astrocytoma

Twenty-five patients with malignant astrocytoma, either postoperatively (15 cases) or with recurrent tumour versus gliosis (10 cases) were included in this study.201TI single photon emission computed tomography (SPECT) was performed with the calculation of early and delayed uptake values and retention index. A high mean value of early and delayed uptake correlated with a low retention index in patients with high-grade astrocytoma in both postoperative residual and recurrent groups, versus a lower mean value of early and delayed uptake with a high retention index in patients with low-grade tumours. All postoperative cases with high-grade astrocytoma had high201TI uptake >1.5, whereas 66.6% of cases with low-grade astrocytoma had low201TI uptake <1.5. There was a correlation between retention index of201TI and tumour grade with r = 0.47. Also, recurrent cases showed remarkable differences in early and delayed201TI uptake (P < 0.05) and retention index (P < 0.001) compared with postradiation gliosis. There was a higher sensitivity in detection of tumour viability by201TI SPECT of 100% versus 80% using computed tomographic scanning and in the differentiation between recurrent tumour and postradiation gliosis. © 1994 Chapman and Hall Ltd.