Comparison of strain-encoded cardiac MRI images with different k-space acquisition strategies
© Ibrahim et al; licensee BioMed Central Ltd. 2010
Published: 21 January 2010
Strain encoding(SENC) is a newly-developed MRI technique for measuring myocardial strain in the through-plane direction . With conventional k-space acquisition, SENC requires two separate acquisitions to obtain two sets of images (low-tune(LT) and high-tune(HT)), which are combined to obtain the strain image. Non-Cartesian k-space trajectories are becoming more popular because they allow for data undersampling with acceptable image quality . In this work, SENC was combined with undersampled radial k-space acquisition and interleaved SENC tunings to reduce scan time to one breath-hold. The results were compared to conventional SENC images.
The LT and HT images were combined in an interleaved fashion (view-sharing) to result in strain images (about 26 phases). Signal-to-noise ratio(SNR) was measured in each image by dividing mean myocardial signal intensity by standard-deviation of background noise. Longitudinal strain values were calculated at the same position and cardiac-phase from corresponding Cartesian and radial images. Bland-Altman analysis was conducted.
Discussion and conclusions
Radial k-space acquisition allows for SENC imaging in one breath-hold with satisfactory image quality. Image misregistration artifacts are minimized using the proposed method. The high-field 3Tesla system compensates for SNR loss associated with reduced data acquisition. Employing the same undersampling ratio with Cartesian acquisition results in deteriorated image quality and introduces artifacts. Future studies will address implementing 3D radial acquisition to improve SNR.