An interictal technetium-99m ECD brain SPECT scan (top) as compared with an ictal technetium-99m ECD brain SPECT scan (second row). On the ictal brain SPECT scan one can see increased hyperemia involving the left temporal lobe (third and fourth rows). Using subtraction comparison, one can see statistically significant differences between the ictal and interictal scan involving the left temporal lobe. The test for statistical significance has z values between three and four (red color = z value of 4).