Clinical Significance of Reverse Redistribution Phenomenon on Delayed Tc-99m Tetrofosmin Myocardial Perfusion Imaging in Patients with Acute Myocardial Infarction / 핵의학분자영상

PURPOSE: This study was performed to investigate the clinical significance of reverse redistribution (RR) phenomenon detected on delayed Tc-99m tetrofosmin myocardial single photon emission computed tomography (SPECT) in patients with acute myocardial infarction after revascularization. MATERIALS AND METHODS: A Tc-99m tetrofrosmin myocardial SPECT was performed in 67 consecutive patients after revascularization for acute myocardial infarction. Myocardial SPECT imaging was performed for early imaging at 40 min and for delayed imaging at 180 min after reinjection at myocardial stress. Regional myocardial uptakes were scored by 4-point scoring in the left ventricular wall divided into 17 segments. Reverse redistribution was defined as an increase of more than 2 point in the activity score on the delayed image. Follow-up myocardial SPECT and coronary angiography (CAG) were performed 9 months later. RESULTS: On myocardial SPECT performed following revascularization, RR was observed in 100 of all 319 segments (31%) and in 43 patients (64%). The abnormalities of perfusion and regional wall motion were more severe in the patients with RR compared to those without RR (p<0.05). On follow-up myocardial SPECT, the myocardial perfusion, regional wall motion, and myocardial thickness were significantly improved in the patients with RR (p<0.05) however, these changes were not significant in those without RR. There was no significant difference between the patients with RR and those without RR in the occurrence of restenosis on CAG. CONCLUSIONS: In patients with acute myocardial infarction, the regions showing the RR phenomenon on delayed Tc-99m tetrofosmin SPECT may reflect viable myocardium and indicate recovery of salvaged myocardium.

Defect of 18F-FDG Uptake Observed in Infarcted Myocardium Showing Reverse Redistribution on Rest / 24-Hour Delayed 201Tl Myocardial SPECT after Acute Myocardial Infarction / 핵의학분자영상

Reverse redistribution is frequently observed after revascularization in acute myocardial infarction, and usually regarded as a predictor of viable myocardium on stress/rest and 2- to 4-hour redistribution 201Tl SPECT. However, there is not enough report of reverse redistribution in case of 24-hour delayed SPECT, which is commonly used for viability assessment. In this report, a case of reverse redistribution on rest and 24-hour delayed 201Tl SPECT is reported with use of automatic segmental quantitative analysis. The myocardium of reverse redistribution was dysfunctional on gated SPECT, and diagnosed as non-viable on 18F-FDG PET.

Correlation between Reverse Redistribution and Subendocardial Myocardial Infarction Observed in Myocardial Contrast Echocardiography / 대한핵의학회잡지

PURPOSE: The aim of this study is to better understand the pattern and nature of reverse redistribution (RR) in myocardial perfusion imaging. MATERIALS AND METHODS: In consecutive 20 acute myocardial infarction (MI) patients, frequency of RR was correlated with that of subendocardial MI that was detected by myocardial contrast echocardiography (MCE). RR was judged to be present when there was more than one grade of worsening in perfusion at 24 hr delayed images compared with the initial rest images. MCE evaluated the significant lack of opacification in the subendocardial myocardium relative to the subepi-cardial myocardium to suggest the subendocardial MI. Kendall's nonparametric correlation coefficiency was calculated. RESULTS: Concordant cases were 15 of 20 (75%) and correlation was statistically significant (p=0.0285). CONCLUSION: Our results suggested that RR was correlated with MCE-detected nontransmural MI.

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.

Assessment of Viability in Regional Myocardium with Reversed Redistribution by Thallium Reinjection in Patients with Acute Myocardial Infarction / 대한핵의학회잡지

PURPOSE: The aim of this study was to evaluate whether T1-201 reinjection distinguishes viable from non-viable myocardium in patients with reverse redistribution after acute myocardial infarction. MATERIALS AND METHODS: We studied 42 patients with acute myocardial infarction (age, 55+/-12 years). Eighteen (43%) out of 42 showed reverse redistribution on dipyridamole stress-4 hour redistribution T1-201 single photon emission computed tomography (SPECT). T1-201 reinjection was performed at 24 hours. Reverse redistribution was defined as worsening of perfusion defect at 4 hour delayed scan. All patients underwent follow-up echocardiography in 4 months to assess regional wall motion improvement. T1-201 uptake on reinjection images were analyzed for the prediction of myocardial wall motion improvement. RESULTS: Of 36 segments with reverse redistribution, 17 segments showed normal wall motion on echocardiography, while 19 segments showed all motion abnormalities. Of 19 the segments with reverse redistribution, 11 (58%) showed enhanced uptake after 24 hour reinjection. Myocardial wall motion was improved in 10 of 11 segments (90%) with enhanced uptake on reinjection. Wall motion improvement was not seen in 5 of 8 segments (63%) without enhanced thallium uptake. When myocardial viability was assessed by the uptake on reinjection image, nine of 10 segments (90%) with normal or mildly decreased uptake showed improved wall motion. Wall motion was not improved in 5 of 9 segments (56%) with severely decreased uptake. CONCLUSION: In patients with acute myocardial ifarction, T1-201 reinjection imaging on myocardial segments with reverse redistribution has a high positive predictive value in the assessment of myocardial viability.