Prediction of Histologic Grade and Multidrug Resistance of Brain Tumors Using Brain SPECT

OBJECTIVE: Computerized tomography(CT) and magnetic resonance imaging(MRI) are very useful in detection of structural change in the brain including tumors. However, they can not inform functional and biological behavior of such lesions. 99m Tc-Methoxyisobutyl isonitrile(MIBI) is considered as a substrate for MDR1 gene-encoded permeability glycoprotein(P-gp) and it has been used in the evaluation of multidrug resistance(MDR) in various tumors. The purpose of the study is to demonstrate the presence of MDR in brain tumor and brain tumor grading by an external imaging with 201Thallium and 99m Tc-MIBI SPECT. METHODS: 201Thallium and 99m Tc-MIBI SPECT were performed in 18 patients with malignant tumors and in six patients with benign tumors. Immunohistochemical staining(IHC) of the tumor specimen for P-gp was also performed. The histologic grading of the tumors and immunohistochemical staining for P-gp were compared to the dual brain SPECT findings of 201Thallium and 99m Tc-MIBI SPECT studies. Brain tumor with positive 201Thallium SPECT and negative 99m Tc-MIBI SPECT is considered to be multidrug resistance. An uptake index obtained from brain SPECT was used for tumor grading. MDR1 gene-encoded P-gp was assessed by immunohistochemical staining using a monoclonal antibody for P-gp. RESULTS: The malignant group showed significantly higher uptake indices in the 201Thallium and 99m Tc-MIBI SPECT than benign group. The uptake index of 99m Tc-MIBI SPECT was inversely correlated with P-gp immunohistochemical staining without statistical significance. CONCLUSION: 201Thallium and 99m Tc-MIBI SPECT are useful for predicting histologic grade of brain tumors, and 99m Tc-MIBI SPECT might be useful for predicting the presence of MDR protein.

Comparison of Dobutamine Echocardiography and Thallium Scan in Assessment of Viable Myocardium After Acute Myocardial Infarction

BACKGROUND: It is clinically important to evaluate myocardial viability after acute myocardial infarction. There are several methods like dobutamine stress echocardiography (DSE) and thallium scan to identify viable myocardium. Thallium SPECT assesses cellular integrity and dobutamine stress echocardiography assesses contractile reserve of myocardium. METHODS: Between March and August 1995, 30 consecutive patients (27 men and 3 women; mean age 52+/-12years) within 3 weeks after acute myocardial infarction were admitted to Asan Medical Center. Each underwent two-dimensional echocardiography before and during dobutamine infusion 8.6+/-6.5 days after acute myocardial infarction and thallium scan with rest-redistribution or stress-redistribution-reinjection protocol 8.1+/-6.4 days after acute myocardial infarction. Viability myocardium was considered if there were improvement in regional wall motion during dobutamine infusion (5, 10mg/kg/min for 5min and 20, 30mg/kg/min for 3min), With thallium SPECT, myocardial viability was considered if regional wall motion was normal, if perfusion defect, were either completely or partial mildly reversible, or if myocardial perfusion decreasedly or moderately and if irreversible perfusion was defect. Follow-up echocardiography was performed 3+/-1 months after acute myocardial infarction. Recovery of regional function was identified when follow-up echocardiography showed improvement of wall motion. We evaluated the accuracy of dobutamine stress echocardiography and thallium scan by concordant interpretation in acute and follow-up studies. RESULTS: Among the enrolled 30 patients, 27 patients had Q-wave MI. Thrombolysis was performed in 17 patients (57%) and PTCA was done in 18 patients (60%). The location of myocardial infarction wall in 20 patients and the inferior and lateral wall in 10 patients. Dobutamine stress echocardiography was performed safely in 30 patients 8.6+/-6.5 days after acute myocardial infarction. Improved wall motion was apparent in 15 patients (50%) after follow-up echocardiography 3+/-1 months after acute myocardial infarction. The positive and negative predictive values of dobutamine stress echocardiography were 14/17 (82%) and 12/13 (92%), respectively. Thallium SPECT was done in 26 patients 8.1+/-6.4 days after acute myocardial infarction. Among these 26 patients, follow-up echocardiography showed improved wall motion in 12 patients. The positive and negative predictive values of thallium SPECT were 9/10 (90%) and 13/16 (80%), respectively. Positive dobutamine stress echocardiography (r=0.46, p=0.001), positive thallium SPECT (r=0.44, p=0.003), hypokinetic segments (p=0.01) and non-anterior MI (p=0.02) were associated with reversible postischemic dysfunction. CONCLUSION: Dobutamine stress echocardiography (DSE) can be safely performed early after acute myocardial infarction. Both dobutamine stress echocardiography and thallium SPECT are reliable and complementary methods to diagnose viable myocardium.