Fig. 4

Signal amplitude and contamination for virtual phantom reconstructions. Mean signal amplitude from within an ROI normalized to the mean signal of ROI1 is plotted against number of phase encoding steps (Res; PE = 16, 24, 32, 48, 64), ROI number (ROI; 2–5), acceleration factor (R; 1–5), and SNR (∞, 256, 128, 64, 32, and 16) for (a) CS and (b) FT reconstructions; plots share the same scale. The CS plot (a) is divided into 5×4 element rectangles, each corresponding to CS reconstructions at a given SNR/spatial resolution. Columns correspond to acceleration factor (R = 1-5; left to right) and rows to ROI2-5 (top to bottom). SNR decreases towards the right and resolution increases towards the bottom. The FT plot (b) is divided into 6×4 element rectangles, each rectangle corresponding to FT reconstructions carried out at a given spatial resolution; columns correspond to SNR (∞, 256, 128, 64, 32, and 16; left to right) and rows to ROI2-5 (top to bottom). The number of phase encoding steps increases towards the bottom of the plot. Triangles below/left of the plots indicate parameter magnitude with the thin end corresponding to the lowest value. If a CS reconstruction performs identically to the equivalent FT reconstruction, then the column of the CS plot (a) should appear identical to the corresponding column of the FT plot (b). Mean signal contamination arising from outside an ROI detected within that ROI normalized to the mean signal from ROI1 is plotted against number of phase encoding steps, ROI number, CS acceleration factor, and SNR for both (c) CS and (d) FT reconstructions; plots share the same scale. Interpretation of the plots is analogous to that of the amplitude plots above. Increasing SNR and decreasing acceleration factor improves agreement between CS and FT reconstructions. Note the separate scale bars for amplitude and contamination plots