Adaptive sensitivity encoding incorporating temporal filtering (TSENSE)

A number of different methods have been demonstrated which increase the spe ed of MR acquisition by decreasing the number of sequential phase encodes. The UNFOLD technique is based on time interleaving of k-space lines in sequ ential images and exploits the property that the outer portion of the field -of-view is relatively static. The differences in spatial sensitivity of mu ltiple receiver coils may be exploited using SENSE or SMASH techniques to e liminate the aliased component that results from undersampling k-space, In this article, an adaptive method of sensitivity encoding is presented which incorporates both spatial and temporal filtering. Temporal filtering and s patial encoding may be combined by acquiring phase encodes in an interleave d manner. In this way the aliased components are alternating phase. The SEN SE formulation is not altered by the phase of the alias artifact; however, for imperfect estimates of coil sensitivities the residual artifact will ha ve alternating phase using this approach. This is the essence of combining temporal filtering (UNFOLD) with spatial sensitivity encoding (SENSE), Any residual artifact will be temporally frequency-shifted to the band edge and thus may be further suppressed by temporal low-pass filtering. By combinin g both temporal and spatial filtering a high degree of alias artifact rejec tion may be achieved with less stringent requirements on accuracy of coil s ensitivity estimates and temporal low-pass filter selectivity than would be required using each method individually. Experimental results that demonst rate the adaptive spatiotemporal filtering method (adaptive TSENSE) with ac celeration factor R = 2, for real-time nonbreath-held cardiac MR imaging du ring exercise induced stress are presented. Published 2001 Wiley-Liss, Inc.