Correcting for Gradient Imperfections in Ultra-Short Echo Time Imaging

Jeremy F. Magland¹, Hamidreza Saligheh-Rad¹, Felix W. Wehrli¹

Imperfections in readout gradients can cause scanner-specific problems in ultra-short echo time (UTE) imaging sequences. In addition to slight gradient delays, the shape of the readout gradient waveform may not be trapezoidal. Here we describe a simple technique for mapping the k-space trajectory of the initial readout ramp in a UTE pulse sequence. The method uses data from a short calibration scan in which two dimensions of spatial encoding is applied prior to readout. After correcting for B0 inhomogeneity, the method provides a very accurate measurement of the k-space trajectory during the ramp, which can be used as input to a gridding-based reconstruction algorithm.