[Evaluation for degree of malignancy and prognosis of patients with brain glioma using 99Tcm-MIBI brain SPECT].

Background & Objective: It is important and useful to evaluate the degree of malignancy for therapeutic scheme and prognosis evaluation. Traditional imaging methods such as CT and MRI play the important role in distinguishing glioma, but sometimes it was still difficult to diagnose accurately only having the aid of these anatomic information. Stereotaxic needle biopsy is an invasive method and indicates only local pathologic change, sometimes the error of sample collection will result in inaccurate grading. 18F-FDG PET can reflect the glucose metabolic rate of tumor directly and is thought as the most useful method, but the cost is too high so that it cannot be used widely at present. This study measured (99)Tc(m)-MIBI uptake in the patients with different pathological types using (99)Tc(m)-MIBI brain scan and evaluated the malignant degree of astrocytoma and its prognosis.

Methods: Fifty-two patients with glioma and 15 collators were retrospectively analyzed. (99)Tc(m)-MIBI was injected into each patient via elbow vein. SPECT was performed 20 min(early phase) and 2 h (delayed phase) after injection. (1)Diagnostic indices such as sensitivity, specificity, and accuracy were calculated. (2) The tumor to non-tumor ratios (T/N) were calculated according to ROI and compared between groups of different malignancy grading by t-test. (3) The survival time (by means of mean survival time, MST) after (99)Tc(m)-MIBI brain SPECT was follow-up surveyed. According to T/N ratios, the patients were divided into four groups. The MST was compared between four groups by t-test.

Results: (1) Among 52 cases of glioma, 44 showed positive and 2 collators showed false-positive on (99)Tc(m)-MIBI SPECT and the sensitivity, specificity, and accuracy were 84.6%, 86.7%, and 85.1%,respectively. (2) On early phase and delayed phase,when T/N ratio was compared, there was no significant difference between grade-I astrocytoma and grade-II astrocytoma (P >0.05), nor was between patients with ependymocytomas and patients with oligodendrogliomas (P >0.05). There was significantly different between every other two groups (P< 0.001),showing the higher the malignancy of astrocytoma,the more the T/N ratio. (3)Comparison of MST indicated that the more the T/N ratio, the shorter the MST. MST in group with T/NT ratio of 1.2-2.0 was significantly longer than that in group with T/NT ratio of 4.1-(t=5.412,P< 0.001) and that in group with T/N ratio of 3.1-4.0(t=4.418,P< 0.001). MST in group of 2.1-3.0 was significantly longer than that in group of 4.1-(t=3.382, 0.002< P< 0.005) and that in group of 3.1-4.0 (t=2.389,0.02< P< 0.05). MST showed no significant difference between the group of 1.2-2.0 and the group of 2.1-3.0 (t=1.691,P >0.05), nor did between the group of 3.1-4.0 and group of 4.1-(t=1.629,P >0.05).

Conclusion: As a noninvasive technique, (99)Tc(m)-MIBI brain SPECT is effective to diagnose brain glioma and distinguish its malignancy degree. This method, by monitoring the T/N ratio closely, is useful to discriminate tumor viability and determine the prognosis of patients.