Serial motion assessment by reference tracking (SMART): application to detection of local functional impact of chronic myocardial ischemia.

Purpose: To compare measurements of wall motion and thickening with and without correcting for cardiac twisting and shortening. Method: Inversion recovery Gd-DPTA perfusion and cine motion MRI were performed on 12 pigs with chronic ischemia induced by ameroid occluder. Analyses were based on conventional fixed plane imaging and serial motion assessment by reference tracking (SMART). Results: Normal motion was 31.3 ± 1.9%, and normal wall thickening was 41.4 ± 2.2%. At the maximum perfusion defect, SMART wall motion was 10.5 ± 2.4% and fixed wall motion was 20.6 ± 1.7% (p < 0.004), SMART wall thickening was 20.1 ± 4.4%, and fixed wall thickening was 32 ± 1.9% (p < 0.03). Conclusion: SMART measurements of wall thickening and motion detect much smaller thickening and motion in ischemic myocardium than fixed radial metrics. SMART data, covering the entire heart, should prove twice as sensitive to abnormalities in motion and thickening, such as any produced by ischemic heart disease or improved by treatment.