Dahan Kim1, Dinghui Wang1, and James G Pipe1
1Department of Radiology, Mayo Clinic, Rochester, MN, United States
1Department of Radiology, Mayo Clinic, Rochester, MN, United States
SPGR and MP-RAGE spiral scans with varying ADC time, TR, and FOV can produce constant SNR and T1 contrast by adjusting the flip angle and number of spiral arms. This framework can be potentially automated to reduce image variability and increase patient safety without technologist intervention.
Figure 1. SPGR and MP-RAGE images acquired at three different spiral trajectory lengths (measured by ADC time) show equivalent T1 contrast and SNR, when the number of spiral arms adjusted to match SNR and the flip angle was adjusted to keep TA constant. The T1 contrast was measured as the ratio of WM and GM signals (WM/GM), shown within the figure. The gray and white matter SNR was quantitatively measured and shown in Figure 2.
Figure 2. SPGR and MP-RAGE scans show equivalent gray matter and white matter SNR across scans having different ADC time when the number of spiral arms was adjusted to match the SNR. In comparison, the SNR drops in the SNR-unmatched reference scans, which were acquired without such adjustment. (Shown for the two subjects for SPGR and one subject for MP-RAGE)
