Assessment of heart wall motion: modified spatial modulation of magnetization for MR imaging

This paper reports a new noninvasive method for detecting a regional myocardial infarction. The method consists of superimposing a magnetization grid onto different image planes of the human heart. In this study the spatial modulation of magnetization (SPAMM) in magnetic resonance imaging was modified to accommodate the use of a conventional clinical magnet. The percentages of circumferential shortening (PCS) and the percentages of wall thickening (PWT) during a cardiac cycle were estimated by measuring the amount of deformation of each grid from the end of the diastole to the end of the systole. A small data base was established on 10 subjects (6 normal volunteers and 4 patients). Patients with regional myocardial infarction, when monitored by the modified SPAMM investigation, showed smaller values of PCS and PWT in the areas where myocardial infarction was diagnosed by catheterization. The amount in decrement was directly proportional to the severity of the regional lesions.