TECHNETIUM-99M(V)-DMSA AND TL-201 IN BRAIN-TUMOR IMAGING - CORRELATION WITH HISTOLOGY AND MALIGNANT GRADE

This study was performed to compare imaging ability between pentavalen t Tc-99m-DMSA and (TlCl)-Tl-201 in primary and metastatic brain tumors and to evaluate the relationship between retention and histologic mal ignancy. Methods: Patients with a brain tumor were selected by MRI and /or CT. Dynamic, early and delayed static SPECT images of the brain we re obtained immediately, 30 min and 3 hr after intravenous administrat ion of approximately 555 MBq Tc-99m(V)-DMSA and 111 MBq Tl-201-Cl, res pectively. Both studies were performed on separate days within a week. Uptake ratios, retention ratio and retention index were calculated an d compared with tumor histology and malignancy grade. Results: One-hun dred six studies were performed on 100 patients and 118 lesions were d emonstrated: 16 glioblastomas, 13 anaplastic astrocytomas (Grade III), 19 astrocytomas (Grade II), 29 meningiomas, 11 schwannomas and 14 met astases. Approximately 93% and 88%, respectively, of primary and metas tatic brain tumors were demonstrated by Tc-99m(V)-DMSA and (TlCl)-Tl-2 01. The early uptake ratios were closely related to the tumor vascular ity, but had no statistically significant difference in the tumor hist ology or histologic malignancy on either radiopharmaceuticals. The del ayed uptake ratio, retention ratio and retention index were higher in malignant tumors than benign ones on Tc-99m(V)-DMSA, however, there wa s no statistically significant difference between benign and malignant tumors on (TlCl)-Tl-201. Conclusion: Technetium-99m(V)-DMSA washout f rom the tumor was highly dependent upon its histology and histologic m alignancy. The delayed uptake ratio, retention ratio and retention ind ex significantly reflected tumor histology and clearly distinguished b etween benign and malignant tumors with a statistically significant di fference. There was no statistically significant difference in (TlCl)- Tl-201 uptake or washout among the brain tumors. Technetium-99m-DMSA i s superior to (TlCl)-Tl-201 in imaging quality, sensitivity to brain t umors and specificity for differentiating benign tumors from malignant ones. These results could suggest the clinical utility of Tc-99m(V)-D MSA in imaging primary and metastatic brain tumors and differentiating their histological malignancy grade noninvasively.