Measurement of Myocardial T(1ρ) with a Motion Corrected, Parametric Mapping Sequence in Humans

PURPOSE: To develop a robust T(1ρ) magnetic resonance imaging (MRI) sequence for assessment of myocardial disease in humans. MATERIALS AND METHODS: We developed a breath-held T(1ρ) mapping method using a single-shot, T(1ρ)-prepared balanced steady-state free-precession (bSSFP) sequence. The magnetization trajectory was simulated to identify sources of T(1ρ) error. To limit motion artifacts, an optical flow-based image registration method was used to align T(1ρ) images. The reproducibility and accuracy of these methods was assessed in phantoms and 10 healthy subjects. Results are shown in 1 patient with pre-ventricular contractions (PVCs), 1 patient with chronic myocardial infarction (MI) and 2 patients with hypertrophic cardiomyopathy (HCM). RESULTS: In phantoms, the mean bias was 1.0 ± 2.7 msec (100 msec phantom) and 0.9 ± 0.9 msec (60 msec phantom) at 60 bpm and 2.2 ± 3.2 msec (100 msec) and 1.4 ± 0.9 msec (60 msec) at 80 bpm. The coefficient of variation (COV) was 2.2 (100 msec) and 1.3 (60 msec) at 60 bpm and 2.6 (100 msec) and 1.4 (60 msec) at 80 bpm. Motion correction improved the alignment of T(1ρ) images in subjects, as determined by the increase in Dice Score Coefficient (DSC) from 0.76 to 0.88. T(1ρ) reproducibility was high (COV < 0.05, intra-class correlation coefficient (ICC) = 0.85–0.97). Mean myocardial T(1ρ) value in healthy subjects was 63.5 ± 4.6 msec. There was good correspondence between late-gadolinium enhanced (LGE) MRI and increased T(1ρ) relaxation times in patients. CONCLUSION: Single-shot, motion corrected, spin echo, spin lock MRI permits 2D T(1ρ) mapping in a breath-hold with good accuracy and precision.