Two-dimensional MR spectroscopy of minimal hepatic encephalopathy and neuropsychological correlates in vivo.
OBJECTIVE
To evaluate regional cerebral metabolic and structural changes in patients with minimal hepatic encephalopathy (MHE) using two-dimensional (2D) MR spectroscopy (MRS) and T( (1) )-weighted MRI, to correlate the observed MR changes with neuropsychological (NP) test scores, and to compare the diagnostic accuracy of MRI, 2D MRS, and NP tests in discriminating between patients and healthy subjects.


METHODS
Thirty-three MHE patients and 30 healthy controls were investigated. The 2D localized correlated spectroscopy (L-COSY) was performed in the frontal and occipital brain on a 1.5 Tesla (T) MR scanner. The NP test battery included 15 tests, grouped into 6 cognitive domains. Globus pallidus signal intensities were calculated from T(1)-weighted images.


RESULTS
The 2D MRS showed significant differences in ratios of the following metabolite(s) peaks with respect to creatine (Cr): decreased myo-inositol (mI), choline (Ch), mICh, and increased (glutamate plus glutamine) (Glx) in patients compared with healthy subjects in both occipital and frontal lobes. Frontal lobe taurine also showed a decline in patients. The NP test results revealed declines in cognitive speed, motor function, executive function, and global cognitive status. Significant correlations were found between the altered metabolites and NP tests. Alteration in the mICh/Cr ratio was noted as a powerful discriminant between healthy subjects and the patients.


CONCLUSIONS
The study demonstrates that relative metabolite levels determined by 2D MRS, in particular mICh/Cr, provide the best diagnostic prediction for MHE. The results suggest that depletions of myo-inositol, choline and taurine with respect to creatine correlate with measures of neuropsychological impairment.
Singhal
Aparna
A
Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, California 90095-1721, USA.
Nagarajan
Rajakumar
R
Hinkin
Charles H
CH
Kumar
Rajesh
R
Sayre
James
J
Elderkin-Thompson
Virginia
V
Huda
Amir
A
Gupta
Rakesh K
RK
Han
Steven-Huy
SH
Thomas
M Albert
MA
D005260:Female; D006501:Hepatic Encephalopathy / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008099:Liver / Q000378:metabolism / Q000473:pathology; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity