Evaluation of hippocampal volume based on MR imaging in patients with bipolar affective disorder applying manual and automatic segmentation techniques.

PURPOSE: To compare the hippocampal volumes in patients with bipolar disorder (BD) and healthy controls, obtained by applying different segmentation methods (manual, Freesurfer [FS], and FSL). MATERIALS AND METHODS: The study included 27 patients with BD and 40 healthy controls. T1-weighted images in the sagittal plane were acquired on a 3 Tesla (T) MR scanner. Hippocampal volumetry was performed using one manual and two automated methods (FS and FSL). One-way repeated analysis of variance was applied to test the differences in hippocampal volumes using the three segmentation methods. To evaluate the agreement among the three tested volumetric segmentation methods the intraclass correlation coefficients (ICCs) were calculated. RESULTS: Hippocampal volumes obtained from all methods were significantly different (P < 0.05) in BD patients after intracranial volume correction, indicating a reduction in volume, unless from the manual method of the left hippocampal volume. The ICCs of the hippocampal volume between the manual method and FS were 0.846 (right) and 0.859 (left), and between the manual method and FSL were 0.746 (right) and 0.654 (left). CONCLUSION: Both manual and automatic segmentation methods detected reductions in the hippocampal volumes in BD patients. Automated segmentation methods are a robust and reproducible option for assessing hippocampal volume.

In vivo evaluation of cortical thickness with magnetic resonance imaging in patients with bipolar disorder

Changes in cortical thickness can be related to neuropsychiatric disorders and neurodegenerative processes. Previous studies have been conducted to characterize the pattern of changes in cortical thickness in several psychiatric diseases. The aim of the present study was to evaluate changes in cortical thickness with magnetic resonance imaging (MRI) in patients with bipolar disorder. Twenty-seven patients with bipolar disorder (14 male, 36.0 ± 16.2 years old; 13 female, 41.6 ± 10.7 years old) and 40 healthy controls (16 male, 36.0 ± 10.5 years old; 24 female, 37.0 ± 4.7 years old) underwent 3T MRI. Sagittal T1-weighted magnetization prepared rapid acquisition gradient echo images were acquired (voxel size, 1.33 mm³; 128 slices; in-plane matrix resolution, 256 × 256; flip angle, 7º; repetition time, 2530 ms; echo time, 3.39 ms; inversion time, 1100 ms). Cortical segmentation was performed using FreeSurfer 4.0.5. The results indicated both thinning and thickening of the cerebral cortex in patients with bipolar disorder compared with controls, depending on gender. Significant (p < .01) thickening was observed in the right hemisphere superior-parietal cortex in female patients with bipolar disorder, and significant (p < .05) thinning was observed in the left hemisphere caudal-anterior cingulate in male patients with bipolar disorder. The other regions did not show significant differences. The results suggest that an analysis of cortical thickness with MRI in patients with bipolar disorder may allow identification of areas that may be morphologically changed compared with controls. Demonstration of these alterations will elucidate the pathophysiology of bipolar disorder and may contribute to better therapies for this disorder.