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Detection of Cerebral Degeneration in Amyotrophic Lateral Sclerosis Using High-Field Magnetic Resonance Spectroscopy
Sanjay Kalra, MD;
Christopher C. Hanstock, PhD;
W. R. Wayne Martin, MD;
Peter S. Allen, PhD;
Wendy S. Johnston, MD
Arch Neurol. 2006;63:1144-1148.
Background Clinical assessment is insensitive to the degree of cerebral involvement in amyotrophic lateral sclerosis (ALS). Regional brain concentrations N-acetylaspartylglutamate (NAA) plus myo-inositol (Ins), as measured by magnetic resonance spectroscopy, are respectively decreased and increased, suggesting that these compounds may provide a biomarker of the degree of cerebral involvement in ALS.
Objective To test the hypothesis that the NAA/Ins ratio may provide an index of cerebral involvement in patients with ALS.
Design High-field (3.0-T) magnetic resonance spectroscopy was performed to determine the NAA/creatine plus phosphocreatine (NAA/Cr), NAA/choline (NAA/Cho), Ins/Cr, and NAA/Ins ratios in the motor cortex.
Participants Seventeen patients with ALS and 15 healthy control subjects were studied.
Results In patients with ALS, the greatest abnormality was a 22% decrease in NAA/Ins (71% sensitivity and 93% specificity, P = .001); Ins/Cr was increased 18% (88% sensitivity and 53% specificity, P = .04), NAA/Cr was decreased 10% (88% sensitivity and 47% specificity, P = .04), and NAA/Cho was decreased 14% (53% sensitivity and 87% specificity, P = .047). Correlation of the ALS Functional Rating Scale with NAA/Ins approached statistical significance (R = 0.43, P = .07).
Conclusion The NAA/Ins ratio may provide a meaningful biomarker in ALS given its optimal sensitivity and specificity profile.
Author Affiliations: Division of Neurology, Department of Medicine (Drs Kalra, Martin, and Johnston), and Department of Biomedical Engineering (Drs Hanstock and Allen), University of Alberta, Edmonton.
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