Fig. 5
CS reconstruction of retrospectively under-sampled phantom data. Results of CS reconstruction of retrospectively under-sampled phantom CSI data acquired with one average and 32 × 32 PE steps. Images represent the signal amplitude (magnitude-modulated by the receive profile of the surface coil, the position of which is indicated in the top left panel) following FT reconstruction of fully-sampled data, and CS reconstruction of data with R = 1, 3, and 5 (top to bottom). All images are plotted on the same scale. The white dashed lines in the top left panel illustrate the position of the displayed profiles (second column from left); solid and dashed lines indicate vertical and horizontal profiles, respectively. Note the reduction in noise around the phantom arising from the CS reconstruction for R = 1 relative to the FT reconstruction and smoother profiles across the phantom. Increasing acceleration factor and decreasing SNR resulted in blurring of the boundaries of the phantom in the images. The third column shows the correlation between the normalized signal amplitude of fully-sampled FT reconstructed data (x-axis) and of the CS reconstructed under-sampled data (y-axis); data were normalized to the mean signal arising from the ROI indicated in Fig. 1c. Linear regression yielded slopes of 1.09, 0.98, and 0.88, with R2 values of 0.98, 0.96, and 0.89, respectively. The right-hand column shows Bland-Altman plots for normalized FT- and CS-reconstructed signal amplitudes. The mean difference in signal amplitude is indicated by a solid line, and 95 % confidence interval by dashed lines. The value of the mean difference in amplitude is indicated on the plots. All plot amplitudes are in arbitrary units