Does Tc-99m-Sestamibi in high-grade malignant brain tumors reflect blood-brain barrier damage only?

Tc-99m-Sestamibi (MIBI) has been successfully applied in recurrent glioblas toma. The aim of this study was to evaluate the incremental diagnostic info rmation of MIBI as a tumor-avid radiopharmaceutical compared with Tc-99m-pe rtechnetate (Tc-99m) as sole indicator of the integrity of the blood-brain barrier. Twenty-five patients with confirmed recurrent brain tumors were in cluded. MIBI SPET was performed 10 min after injection of 555 MBq MIBI intr avenously with a triple-headed gamma camera equipped with LE-UHR-PAR collim ators over 360 degrees (3 degrees/step) and stored in a 128(2) matrix. Iden tical acquisition parameters were used for Tc-99m SPET, which was acquired 3 h after injection of 740 MBq Tc-99m. Normalized tumor uptake (NU) was cal culated from attenuation-corrected transaxial slices. In addition, tumor/pl exus, tumor/nasopharynx, and tumor/parotid gland ratios were assessed in bo th studies. No statistically significant differences were detected for the mean NU of tumor tissue with MIBI (0.26 +/- 0.10) and (TC)-T-99m (0.39 +/- 0.33) and for the tumor/ nasopharynx and tumor/parotid gland ratios; only t he tumor/plexus ratio was significantly higher for Tc-99m than for MIBI (p < 0.05). In conclusion, our data indicate that MIDI scintigraphy in brain t umors at 10 min postinjection reveals no additional visual information over that provided by the conventional Tc-99m-pertechnetate brain scan, and in addition, tracer retention reflects primarily blood-brain barrier damage. ( C) 2000 Academic Press.