fig 5.

Coronal view, 5-mm section thickness, soft-tissue window CT scan. The scan duration was 1 second. The inactive probe (left) was hyperdense, except at the tip (active tip without vacuum insulation) and caused no relevant artifacts. Stripe-shaped artifacts due to the cryotherapy probe and the fixation device can be seen. The ice (right) appears as a spherically shaped, sharply delineated hypodense formation around the probe tip. Although the density of the frozen brain (mean, −23.7 ± 15.6 Hounsfield units) is clearly differentiable from that of the unfrozen brain (mean, 32.5 ± 3.2 Hounsfield units), the ice:tissue contrast is statistically significantly inferior to that of all MR images (58%, P < .001)