Dynamic 99Tcm-ECD SPET correlates well with 201Tl indices in brain tumours

The dynamic Tc-99(m)-ethyl cysteinate dimer (Tc-99(m)-ECD) single photon emission tomographic (SPET) characteristics of brain tumours were investigated and compared with Tl-201-chloride SPET indices. Thirty-five patients with histologically confirmed benign and malignant tumours were evaluated using dynamic and standard Tc-99(m)-ECD. Twenty-eight patients were also examined using standard Tl-201 SPET. The following Tl-201 indices were calculated: early uptake ratio, delayed uptake ratio, washout rate and retention index. The relationship between uptake of Tc-99(m)-ECD on dynamic SPET and Tl-201 indices was analysed. Nine patients showed positive uptake on dynamic Tc-99(m)-ECD SPET, all of whom had benign tumours, including five meningothelial meningiomas, three pituitary adenomas of the chromophobe type and one chemodectoma without malignancy. The mean early uptake ratio of the tumours with positive uptake was significantly higher than that of the tumours with negative uptake (17.1 +/- 5.5 vs 9.0 +/- 5.7, P = 0.004). The mean washout rate of the tumours with positive uptake was significantly higher than that of the tumours with negative uptake (61.0 +/- 27.7 vs 0.35 +/- 30.9, P = 0.0004). The mean retention index of the tumours with positive uptake was significantly lower than that of the tumours with negative uptake (0.27 +/- 0.12 vs 0.88 +/- 0.48, P = 0.000006). Only benign tumours showed positive uptake on dynamic Tc-99(m)- ECD SPET. The Tl-201 indices correlated well with the uptake of Tc-99(m)-ECD on dynamic SPET. The results suggest that dynamic Tc-99(m)-ECD SPET can identify the benign character of tumours of the brain. ((C) 1999 Lippincott Williams & Wilkins).