Quantification of myocardial infarct size and transmurality by contrast-enhanced magnetic resonance imaging in men

Contrast-enhanced magnetic resonance (ce-MR) imaging allows precise delineation of infarct transmurality. An issue of debate is whether data analysis should be performed visually or quantitatively. Accordingly, a head-to-head comparison was performed between visual and quantitative analyses of infarct transmurality on ce-MR imaging. In addition, infarct transmurality was related to the severity of wall motion abnormalities at rest. In 27 patients with long-term ischemic left ventricular (LV) dysfunction (LV ejection fraction 33 ± 8%) and previous infarction, cine MR imaging (to assess regional wall motion) and ce-MR imaging were performed. Using a 17-segment model, each segment was assigned a wall motion score (from normokinesia to dyskinesia), and segmental infarct transmurality was visually assessed on a 5-point scale (0 = no infarction, 1 = transmurality ≤25% of LV wall thickness, 2 = transmurality 26% to 50%, 3 = transmurality 51% to 75%, and 4 = transmurality 76% to 100%). Quantification of transmurality was performed with threshold analysis; myocardium showing signal intensity above the threshold was considered scar tissue, and percent transmurality was calculated automatically. Wall motion was abnormal in 56% of the 459 segments, and 55% of segments showed hyperenhancement (indicating scar tissue). The agreement between visual and quantitative analyses was excellent: 90% of segments (κ 0.86) were categorized similarly by visual and quantitative analyses. Infarct transmurality paralleled the severity of contractile dysfunction; 96% of normal or mildly hypokinetic segments had infarct transmurality ≤25%, whereas 93% of akinetic and dyskinetic segments had transmurality >50% on visual analysis. In conclusion, visual analysis of ce-MR imaging studies may be sufficient for assessment of transmurality of infarction.