MR-Relaxometry of Myocardial Tissue

Abstract

This study evaluates if MR-relaxometry of myocardial tissue reveals significant differences in cardiac amyloidosis (CA) compared with patients with systemic amyloidosis but without cardiac involvement (NCA) and a healthy control group. Therefore, we measured T1 and T2 relaxation times (RT) of the left ventricular myocardium with magnetic resonance imaging at 1.5 T. Nineteen consecutive patients (14 males, 5 females; mean age, 59 +/- 6.1 years) with histologically proven CA were evaluated. T1-RT and T2-RT were measured by using a saturation-recovery TurboFLASH sequence and a HASTE sequence, respectively. Additionally, morphologic and functional data were acquired. Results were compared with patients with systemic amyloidosis but without cardiac involvement (NCA; 5 males, 4 females, 48.9 +/- 15.4 years) and 10 healthy, age-matched control subjects (5 males, 5 females, 60.4 +/- 6.4 years). MR-relaxometry revealed a significant elevation of T1-RT of the left ventricular myocardium in CA-patients compared with that in NCA-patients and the age-matched control group [mean +/- SD (95% CI) 1340 +/- 81 (1303-1376) msec, 1213 +/- 79 (1160-1266) msec, 1146 +/- 71 (1096-1196) msec, respectively; CA vs. control, P < 0.0001; CA vs. NCA:, P < 0.0003; NCA vs. control, P = 0.07]. T2-RT showed a marginal but significant increase in CA-patients compared with NCA-patients and the control group [mean +/- SD (95% CI) 81 +/- 12 (76-86) msec, 71 +/- 11 (64-79) msec, 72 +/- 9 (65-79) msec, respectively; CA vs. control, P = 0.04; CA vs. NCA, P = 0.04; NCA vs. control, P = 0.91]. T1-RT was best suited to discriminate between the groups as shown by logistic regression. A cut-off value of >or=1273 milliseconds for T1-RT was defined using receiver-operator characteristics-analysis to establish the diagnosis of CA with a high sensitivity (84%) and specificity (>89%). Measurement of T1 and T2 RT is a novel approach for noninvasive evaluation of CA. MR-relaxometry might improve diagnostic reliability of magnetic resonance imaging for evaluation of cardiac involvement in systemic amyloidosis.