Validation of in vivo myocardial strain measurement by magnetic resonance tagging with sonomicrometry

OBJECTIVES This study was designed to validate Strain measurements obtained using magnetic resonance tagging with spatial modulation of magnetization (SPAMM). We compared circumferential segment shortening measurements (%S) o btained using SPAMM to sonomicrometry %S in a canine model with (n = 28) an d without (n = 3) coronary artery ligation. BACKGROUND Magnetic resonance tagging enables noninvasive measurement of my ocardial strain, but such strain measurements have not yet been validated i n vivo. METHODS Circumferential sonomicrometry crystal pairs were placed in apical myocardium at ischemic risk in ligation studies and in adjacent and remote myocardium. The %S was obtained from closely juxtaposed sonomicrometry and SPAMM sites. RESULTS Paired data were available from 19 of 31 studies. Both methods dist inguished remote From ischemic function effectively (p = 0.014 for SPAMM an d p = 0.002 for sonomicrometry). SPAMM %S was similar to sonomicrometry %S in ischemic myocardium (2 +/- 3 vs. 0 +/- 3, p = 0.067) but was slightly hi gher than sonomicrometry %S in remote myocardium (11 +/- 10 vs. 7 +/- 5, p = 0.033). End-systolic (n = 30) and late systolic (n = 34) SPAMM %S correla ted well with sonomicrometry %S (r = 0.84, p < 0.0001 and r = 0.88, p < 0.0 001). CONCLUSIONS Magnetic resonance tagging using SPAMM can quantitate myocardia l strain in ischemic and remote myocardium. This study validates its applic ation in scientific investigation and clinical assessment of patients with myocardial ischemia. {J Am Coll Cardiol 2001;38:555-61) 2001 by the America n College of Cardiology.