Figure 7.
Magnitude (top row) and R2* (bottom row) images of ex vivo frozen tissue, using half RF excitation without & with out-of-slice saturation (TE =100 µs). Arrow shows location and orientation of cryoprobe. Without the saturation bands, there is significant out-of-slice signal contribution adding into the desired slice within the iceball, leading to artificially high R2* measurements. There is high signal intensity and blurring in the unfrozen tissue due to poor slice selectivity. Both magnitude and R2* images are dramatically improved with the saturation bands.