Flexible cardiac T₁ mapping using a modified look-locker acquisition with saturation recovery

A modified Look-Locker acquisition using saturation recovery (MLLSR) for breath-held myocardial T₁ mapping is presented. Despite its reduced dynamic range, saturation recovery enables substantially higher imaging efficiency than conventional inversion recovery T₁ mapping because it does not require time for magnetization to relax to equilibrium. Therefore, MLLSR enables segmented readouts, shorter data acquisition windows, and shorter breath holds compared with inversion recovery. T₁ measurements in phantoms using MLLSR showed a high correlation with conventional single-point inversion recovery spin echo. In vivo T₁ measurements from normal and infarcted myocardium in 41 volunteers and patients were consistent with previously reported values. Twenty subjects were also scanned with MLLSR using an accelerated sampling scheme that required half the scan time (eight vs. 16 heartbeats) but yielded equivalent results. The flexibility afforded by the improved imaging efficiency of MLLSR allows the acquisition to be tailored to particular clinical needs and to individual patient's breath-holding abilities.