FIG 3. Percentage section aliasing, calculated as widening of the full-width-at-half-maximum of the steady-state signal intensity profile relative to the desired slab thickness, plotted as a function of the designated flip angle (dotted line). Experimental measurements (circles) from our subjects agreed fairly well with the theoretical deductions. Note that, at a 70° flip angle, the percentage section aliasing is nearly 30%, meaning that about one-third of the sections would be subject to interference from CSF outside the image slab. By lowering the flip angle to 30° or 40°, the percentage section aliasing decreases to <20%.