Abstract
There is a wide range of values reported in volumetric studies of the amygdala. The use of single plane thick magnetic resonance imaging (MRI) may prevent the correct visualization of anatomic landmarks and yield imprecise results. To assess whether there is a difference between volumetric analysis of the amygdala performed with single plane MRI 3-mm slices and with multiplanar analysis of MRI 1-mm slices, we studied healthy subjects and patients with temporal lobe epilepsy. We performed manual delineation of the amygdala on T1-weighted inversion recovery, 3-mm coronal slices and manual delineation of the amygdala on three-dimensional volumetric T1-weighted images with 1-mm slice thickness. The data were compared using a dependent t-test. There was a significant difference between the volumes obtained by the coronal plane-based measurements and the volumes obtained by three-dimensional analysis (P < 0.001). An incorrect estimate of the amygdala volume may preclude a correct analysis of the biological effects of alterations in amygdala volume. Three-dimensional analysis is preferred because it is based on more extensive anatomical assessment and the results are similar to those obtained in post-mortem studies.
Highlights
The amygdala is responsible for defining the intensity of emotional responses, for determining targets to which responses are directed and for promoting behavioral and visceral alterations in response to emotionally burdening stimuli
All patients with temporal lobe epilepsy (TLE) presented unilateral hippocampal atrophy and lateralization of seizures based on ictal recording that was concordant with the side of the hippocampal atrophy
analysis of variance (ANOVA) did not show a significant difference in amygdala volume between controls and patients with TLE (Figure 2A), with >95% power
Summary
The amygdala is responsible for defining the intensity of emotional responses, for determining targets to which responses are directed and for promoting behavioral and visceral alterations in response to emotionally burdening stimuli. Neuroimaging studies have demonstrated the role of the amygdala in emotional recognition concerning memory [2,3], fear conditioning [4], facial expression [5,6], and auditory stimuli [2,7]. This is believed to be a consequence of its function of formation of long-term memory associated with emotionally arousing events [2,3]. Reduction of the volume of the amygdala has been shown to be able to lateralize patients with temporal lobe epilepsy [8,9], and has been shown to occur in recurrent depression [10], obses-
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