Detection and Quantification of Dysfunctional Myocardium by Magnetic Resonance Imaging

Abstract

Background Regional left ventricular dysfunction is a major consequence of myocardial ischemia, and its extent determines long-term prognosis. Accurate and reproducible analysis of left ventricular dysfunction is therefore useful for risk stratification and patient management. Methods and Results Short-axis cardiac cine magnetic resonance (MR) imaging was performed in 25 patients after anterior myocardial infarction at 21±2.1 days after the acute onset. The MR images were analyzed with the use of a dedicated analytical software package (MASS version 1.0), which includes a modified centerline method and a new three-dimensional analysis approach. A database of 48 healthy volunteers was constructed to objectively depict myocardial dysfunction in the patients; this database was compared with enzymatically determined infarct size. The mean (±SEM) quantity of dysfunctional myocardium and enzymatically calculated infarct size equaled 24.0±3.0 and 22.3±2.9 g, respectively ( P =.69). Enzymatically determined infarct size correlated strongly with left ventricular dysfunction determined by cine MR imaging ( y =0.90 x +3.7; r =.92, P <.0001). Segments related to the distribution of the left anterior descending coronary artery showed a significantly lower percentage wall thickening in patients than did corresponding segments of 48 normal subjects (46.0±8.22% versus 87.1±3.45%, mean±SEM, respectively; P <.001). The mean (±SEM) end-diastolic wall thickness of the infarcted segment did not differ from that of corresponding normal segments (7.4±0.33 versus 7.5±0.15 mm; P =.75). Conclusions We conclude that the use of three-dimensional quantitative analysis of cine MR images accurately quantifies the extent of regional left ventricular dysfunction in the infarcted heart. This method of analysis may be useful in assessing the effect of interventional therapies.