Inversion recovery with embedded self‐calibration (IRES)

With self‐calibrated parallel acquisition, the calibration data used to characterize coil response are acquired within the actual, parallel scan. Although this eliminates the need for a separate calibration scan, it reduces the net acceleration factor of the parallel scan. Furthermore, this reduction gets worse at higher accelerations. A method is described for three‐dimensional inversion recovery gradient‐echo imaging in which calibration is incorporated into the sequence but with no loss of net acceleration. This is done by acquiring the calibration data using very small (≤4°) tip angle acquisitions during the delay interval after acquisition of the accelerated imaging data. The technique is studied at 3 Tesla with simulation, phantom, and in vivo experiments using both image‐space‐based and k ‐space‐based parallel reconstruction methods. At nominal acceleration factors of 3 and 4, the newly described inversion recovery with embedded self‐calibration (IRES) method can retain effective acceleration with comparable SNR and contrast to standard self‐calibration. At a net two‐dimensional acceleration factor of 4, IRES can achieve higher SNR than standard self‐calibration having a nominal acceleration factor of 6 but the same acquisition time. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.