OBJECTIVES: We sought to determine serial changes of enhanced and nonenhanced tissue on late gadolinium-enhanced cardiac magnetic resonance(CMR) imaging in patients with a myocardial infarction(MI) and to assess whether thickness of nonenhanced myocardium can improve the detection of preserved contractile function in the chronic state. BACKGROUND: Previous studies demonstrated that enhancement on late gadolinium-enhanced CMR images indicates myocardial necrosis, and nonenhancement shows the presence of viable myocardium. METHODS: The CMR studies were performed within one week(scan 1) and more than five months(scan 2) after the onset of MI in 18 patients. The area and mean thickness of enhanced tissue and nonenhanced myocardium were measured by using a 30-segment model. Systolic wall thickening on cine CMR at scan 2 was assessed for evaluating regional contractile function. RESULTS: The amount of enhanced tissue significantly decreased from scan 1 to 2(22.1±14.0 ml vs. 15.0±9.3 ml, p< 0.001). The averaged thickness of nonenhanced myocardium in the infarct segments significantly increased from scan 1 to 2(5.2±3.0 mm vs. 6.6±3.2 mm, p< 0.001). Receiver operating characteristic analysis demonstrated that the measurement of thickness of nonenhanced myocardium, compared with measurement of percent transmural enhancement, had better diagnostic accuracy for predicting improved systolic wall thickening form scan 1 to 2 in dysfunctional segments(Az 0.650 vs. 0.594, p< 0.05). CONCLUSIONS: The amounts of enhanced tissue and nonenhanced myocardium significantly altered from the acute to chronic state in MI patients. The diagnostic performance of CMR imaging for detection of preserved contractile function can be significantly improved by measuring thickness of nonenhanced myocardium in MI patients. OBJECTIVES: We sought to determine serial changes of enhanced and nonenhanced tissue on late gadolinium-enhanced cardiac magnetic resonance (CMR) imaging in patients with myocardial infarction (MI) and to assess whether thickness of nonenhanced myocardium can improve the detection of preserved contractile function in the chronic state. Previous studies describe that enhancement on late gadolinium-enhanced CMR images indicates myocardial necrosis, and nonenhancement shows the presence of viable myocardium. METHODS: The CMR studies were performed within one week (scan 1) and more than five months (scan 2) after the onset of MI in 18 patients. The area and mean thickness of enhanced tissue and nonenhanced myocardium were measured by using a 30-segment model. Systolic wall thickening on cine CMR at scan 2 was assessed for regionalregion function. RESULTS: The amount of enhanced tissue significantly decreased from scan 1 to 2 (22.1 ± 14.0 ml vs. 15.0 ± 9.3 ml, p < 0.001). The averaged thickness of nonenhanced myocardium in the infarct segments significantly increased from scan 1 to 2 (5.2 ± 3.0 mm vs. 6.6 ± 3.2 mm, p <0.001). Receiver operating characteristic analysis demonstrated that the measurement of thickness of nonenhanced myocardium , compared with measurement of percent transmural enhancement, had better diagnostic accuracy for predicting improved systolic wall thickening form scan 1 to 2 in dysfunctional segments (Az 0.650 vs. 0.594, p <0.05). CONCLUSIONS: The amounts of enhanced tissue and nonenhanced myocardium altered from the acute to chronic state in MI patients. The diagnostic performance of CMR imaging for detection of preserved contractile function can be significantly improved by measuring thickness of nonenhanced myocardium in MI patients.