Clinical Characterization of Reverse Redistribution Pattern in 99mTC-Sestamibi Myocardial Perfusion Scan

BACKGROUND AND OBJECTIVES: Reverse redistribution pattern (RRP), that is defined as the worsening of the perfusion defect at rest image, can be observed in 99mTC-sestamibi (methoxy isobutyl isonitrile) myocardial scan with standard stress-rest protocol. This study was prepared to evaluate the prevalence and clinical characteristics of RRP in stress 99mTc-sestamibi myocardial scan. MATERIALS AND METHODS: We retrospectively reviewed 1304 images of 99mTC-sestamibi myocardial perfusion scan performed between January 1995 and June 1997, and scintigraphic findings were compared with clinical and angiographic data. RESULTS: The prevalence of RRP was 5.2%(68 of 1,304). RRP was noted in 6.0% (41 of 679) of the adenosine study and 4.3% (27 of 625) of the exercise study. The mean coronary artery stenosis at RRP territory was 51.5+/-38.9%. However, normal coronary artery at RRP territory was noted in 45.8% (11 of 24). There was no significant differences in luminal narrowing of coronary arteries, TIMI flow grade and LV wall motion between the patient with RRP positive and RRP negative at the infarct related artery territory. CONCLUSION: Reverse redistribution pattern on 99mTC-sestamibi myocardial SPECT does not seem to indicate the presence of significant coronary artery disease or patency of the infarct related arteries in the patients with acute MI.

Localization of Ischemic Area with Exercise Electrocardiography in Angina Pectoris: Correlation with 99mTc-MIBI Myocardial Perfusion Scanning

BACKGROUND: The purpose of the study was to determine the value of exercise electrocardiography in predicting the area of myocardial ischemia. METHOD: Seventy-six anginal patients with a perfusion defect in one vessel territory on exercise 99mTc-MIBI myocardial perfusion scan were studied. Each patient underwent exercise electrocardiograhy using modified Bruce protocol. Exercise electrocardiography was interpreted as abnormal when the horizontal or downsloping depression in ST segment was 0.1 mV or greater at 80 msec after the J point during exercise. Forty-eight patients had exercise induced ST-segment depression. RESULT: Twenty-five patients had exercise induced ST-segment depression in single lead-group and 23 patients had in multiple lead-groups. In 18 patients (18/23) with exercise induced ST-segment depression in multiple lead-groups, the perfusion defect involved the apical area on myocardial perfusion scanning and in 21 patients (21/25) with ST-segment depression in single lead-group, the perfusion defect did not involve the apical area. In patients without perfusion defect in the apical area, ST-segment depression in anterior lead-group (V1 to V4) was associated with myocadial perfusion defects in left anterior descending artery territories in five of five cases (100%), ST-segment depression in lateral lead-group (I, aVL, V5, V6) was associated with defects in left circumflex artery territories in six of six cases (100%), and ST-segment depression in inferior lead group (II, III, aVF) was associated with defects in right coronary artery territories in nine of ten (90%) (p<0.01). In patients with perfusion defect in the apical area, exercise induced ST-segment depressions were observed in multiple lead-groups (18/22). CONCLUSION: ST-segment depression on 12 lead exercise electrocardiography was a good predictor of the site of myocadial ischemia in anginal patients with single vessel territory ischemia when ST-segment depression developed in single lead group. However, ST-segment depressions in mutiple lead-groups suggested that the perfusion defect involved the apical area and did not predict the site of myocardial ischemia.

Usefulness of SPECT Thallium-201 Exercise Myocardial Perfusion Scan in Coronary Artery Disease

To evaluate the usefullness of SPECT thallium-201 exercise myocardial perfusion scan in coronary artery disease, polar maps processing SPECT images were compared to the exercise treadmill test and the findings of coronary angiographies in 12 normal subjects and 27 patients with the coronary artery disease. The following results were obtained : 1) Sensitivity and specificity of thallium-201 exercise myocardial perfusion scan was 96% and 83%, higher than that of exercise treadmill test(81% abd 61%). 2) In the branches of coronry artery, the sensitivity, specificity and positive predicitive values were 82%, 88%, 90% in left anterior descending artery, 33%, 88%, 57% in left circumflex artery and 69%, 81%, 90% 64% in right coronary artery. 3) The good correlation was observed between the degree of perfusion defect in polar map of thallium-201 myocardial scan in stress and 'myocardial ischemic score' predicted in coronary angiography(p<0.001). Also the degree of reversible perfusion defect had significant correlation with the durtion of exercise. 4) The pulmonary to myocardial ratio of thallium-201 uptake in coronary artery disease group higher than that of angina group. And the perfusion defect with stress and double product at maximal exercise had strongest assocition with the pulmonary to myocardial ratio of thallium-201 uptake by stepwise multiple linear regression. In conclusion, SPECT thallium-201 exercise myocardial perfusion scan is superior to the exercise treadmill test in diagnosing the coronary artery disese and is useful for predicting the sites and degree of coronary arterial stenosis. Also the pulmonary to myocardial ratio of thallium-201 uptake is thought to be good new test index in evaluating the left ventricular function of patients with coronary artery disease.

Myocardial Perfusion Imaging in Myocardial Infarction Using 99mTc-MIBI : A New Myocardial Imaging Agent

Technetium-99m methoxyisobutylisonitrile(99m-Tc MIBI), a new myocardial imaging agent, was used in myocardial perfusion scan in 23 patients who had been diagnosed as myocardial infarction to assess its usefulness in elvaluation of coronary artery disease. All patients undertook left ventriculography (LVG) and coronary arteriography (CAG). Gated blood pool scan, plannar scintigraphy and SPECT were also done using 99m-Tc MIBI. After then SPECT image was reconstructed to short axis view of the heart at the level of the base, mid and apex. The data from these studies were compared with the results of EKG, LVG and CAG. Diagnostic sensitivity of myocardial scan using 99m-Tc MIBI was 91.3%. In localization of infarction site and evaluation of its extent, myocardial scan was superior to EKG. CAG revealed significant stenosis at the arteries supplying the area in which the scan showed perfusion defect. In detecting abnormal wall motion, the sensitivity and the specificity were 81.9% and 93.7% respectively. Perfusion defect were found in 75%, 82.5%, and 100% of hypokinetic, akinetic, and dyskinetic segments, respectively. Myocardial perfusion scan using 99m-Tc MIBI was an useful noninvasive test in localizing the site and the extent of infarct and detecting the abnormal left ventricular wall motion.