In-111-labelled bleomycin complex for the differentiation of high- and low-grade gliomas

The aim of this study was to evaluate In-111-labelled bleomycin complex (In -111-BLMC) SPET in the differentiation of high- and low-grade gliomas. Nine teen glioma patients, 14 with high-grade and five with low-grade tumours, w ere studied 1, 4 and 24 h after the injection of In-111-BLMC. In the high-g rade glioma group, there was significant uptake of In-111-BLMC in 12 patien ts and no uptake in two patients based on the visual classification of SPET images at 4 and 24 h. In the low-grade glioma group, one patient had low u ptake at 4 and 24 h, but the other four patients showed no visible uptake. The mean tumour to extra cerebral circulation activity ratio (T/Cr) at 4 h was 0.13 +/- 0.10 (n=5) in low-grade gliomas and 1.7 +/- 1.0 (n=14) in high -grade gliomas. At 24 h the T/Cr ratios were 0.56 +/- 0.21 and 3.4 +/- 1.7, respectively. The mean tumour to contralateral normal brain activity ratio s (T/Br) were 5.0 +/- 3.9 (4 h) and 3.0 +/- 2.8 (24 h) in low-grade gliomas , and 37.2 +/- 37.3 (4 h) and 8.3 +/- 8.2 (24 h) in high-grade gliomas. The se higher T/Br ratios did not, however, result in improved differentiation between the two groups of gliomas; at 4 h the T/Cr and T/Br ratios were of equal value, as two high-grade gliomas would have been misclassified as low -grade, but at 24 h the T/Br ratio resulted in more misclassifications. Our results show that In-111-BLMC can be used in the differentiation of high- and low-grade gliomas and that the selection of the reference area for calc ulating tumour to non-tumour ratios is important. ((C) 1999 Lippincott Will iams & Wilkins).