[Evaluation of brain tumor by 99mTc-MIBI: comparison study with 201Tl and predictivity of therapeutic effect]

We compared the detectability of 99mTc-MIBI and 201Tl-chloride for brain tumor in relationship with histopathology. We also evaluated correlation between therapeutic effect using ACNU, Cisplatine and the degree of MIBI tumor uptake. The subjects were 31 brain tumor histologically confirmed by operation or biopsy. Dual-isotope SPECT technique was performed at both 20 min and 180 min after tracer injection. A tumor to normal lung ratio on both early (ER) and delayed image (DR) and retention index (RI) were calculated. The positive rates of 99mTc-MIBI (90.3% and 77.4%) were comparable to that of 201Tl (90.3% and 80.6%). In the relationship with histopathology, both MIBI and Tl accumulated in 100% of glioblastoma (GBM), metastasis (meta), anaplastic astrocytoma and 25% of low grade astrocytoma on both early and delayed images. On semiquantitative analysis, there were no statistical significance among GBM, meta and anaplastic astrocytoma of ER, DR, RI in the both radiopharmaceuticals. However, both ER and DR in GBM tended to be higher than those of anaplastic astrocytoma. In spite of intense MIBI uptake, GBM patients died within six months except one patient. We concluded that MIBI can be helpful in detecting brain tumor as Tl. MIBI also might be useful in estimating the degree of malignancy in glioma. However, intense MIBI uptake did not mean favorable therapeutic effect in patients with GBM treated with ACNU and Cisplatine.