Prospective correction of patient-specific respiratory motion in myocardial T1and T2mapping

Purpose Respiratory motion in cardiovascular MRI presents a challenging problem with many potential solutions. Current approaches require breath-holds, apply retrospective image registration, or significantly increase scan time by respiratory gating. Myocardial T(1)and T(2)mapping techniques are particularly sensitive to motion as they require multiple source images to be accurately aligned prior to the estimation of tissue relaxation. We propose a patient-specific prospective motion correction (PROCO) strategy that corrects respiratory motion on the fly with the goal of reducing the spatial variation of myocardial parametric mapping techniques. Methods A rapid, patient-specific training scan was performed to characterize respiration-induced motion of the heart relative to a diaphragmatic navigator, and a parametric mapping pulse sequence utilized the resulting motion model to prospectively update the scan plane in real-time. Midventricular short-axis T(1)and T(2)maps were acquired under breath-hold or free-breathing conditions with and without PROCO in 7 healthy volunteers and 3 patients. T(1)and T(2)were measured in 6 segments and compared to reference standard breath-hold measurements using Bland-Altman analysis. Results PROCO significantly reduced the spatial variation of parametric maps acquired during free-breathing, producing limits of agreement of -47.16 to 30.98 ms (T-1) and -1.35 to 4.02 ms (T-2), compared to -67.77 to 74.34 ms (T-1) and -2.21 to 5.62 ms (T-2) for free-breathing acquisition without PROCO. Conclusion Patient-specific respiratory PROCO method significantly reduced the spatial variation of myocardial T(1)and T(2)mapping, while allowing for 100% efficient free-breathing acquisitions.