Diffusion-weighted magnetic resonance imaging of white matter in bipolar disorder: a pilot study.
OBJECTIVE
Diffusion-weighted magnetic resonance imaging (MRI) has shown increased sensitivity in detecting brain white matter disease compared to traditional T2-weighted MRI. Diffusion-weighted imaging (DWI) can quantitatively assess the microstructural integrity of white matter using the average apparent diffusion coefficient (ADC(av)), a measure of the extent to which water molecules move freely within tissue. On the basis of numerous studies suggesting white matter disease in bipolar patients, particularly patients with more severe illness, this study aimed to test the utility of DWI in assessing the white matter integrity of bipolar patients with severe illness.


METHODS
The existing MRI scans of eight bipolar patients and eight age-matched controls with neurological illness were examined retrospectively. ADC(av) values for pixels within white matter regions of interest (ROIs) were calculated and used to plot ADC(av) frequency histograms for each ROI. Mean ADC(av) values for the two groups were then compared by ANCOVA.


RESULTS
The bipolar mean ADC(av) (0.855 +/- 0.051 x 10(-3) mm2/s) for combined white matter ROIs significantly exceeded that of controls (0.799 +/- 0.046 x 10(-3) mm2/s), while covarying for age (F = 4.47, df = 3, p = 0.025).


CONCLUSIONS
This is the first report of an elevated ADC(av) in the white matter of a group of patients with bipolar disorder. In this group of patients with severe illness, increased white matter ADC(av) suggests microstructural changes consistent with decreased white matter integrity. DWI may be an additional, useful tool to assess white matter abnormalities in bipolar disorder.
Geriatric Division, Department of Psychiatry, University of Maryland School of Medicine, VA Maryland Healthcare System, Baltimore, MD 21201, USA.
William T
WT
Regenold
Christopher A
CA
D'Agostino
Narayanan
N
Ramesh
Mehrul
M
Hasnain
Steven
S
Roys
Rao P
RP
Gullapalli
D000328:Adult; D001714:Bipolar Disorder / Q000175:diagnosis*; D001921:Brain / Q000033:anatomy & histology / Q000473:pathology*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008954:Models, Biological; D009778:Occipital Lobe / Q000473:pathology; D010296:Parietal Lobe / Q000473:pathology; D010865:Pilot Projects; D012189:Retrospective Studies; D013702:Temporal Lobe / Q000473:pathology