Correlating quantitative MR imaging with histopathology in X-linked adrenoleukodystrophy

Area of Science:

• Neuroimaging
• Neuropathology
• Biochemistry

Background:

• Quantitative MRI techniques offer potential for improved diagnostic accuracy of white matter abnormalities.
• X-linked Adrenoleukodystrophy (X-ALD) is a demyelinating disease affecting white matter.

Purpose of the Study:

• To evaluate if apparent diffusion coefficient (ADC), fractional anisotropy (FA), and magnetization transfer ratio (MTR) correlate with white matter damage severity in X-ALD patients.
• To determine if these MRI parameters are consistent between in vivo and postmortem brain tissue.
• To assess the predictive value of these MRI parameters for histopathological findings.

Main Methods:

• In vivo and postmortem MRI (ADC, FA, MTR) and magnetic resonance spectroscopy (MRS) were performed on X-ALD patients and controls.
• MRI parameters were correlated with histopathological assessments of astrogliosis, myelin, axons, and cell density.
• Linear regression analysis was used to develop predictive models.

Main Results:

• MRS revealed distinct metabolite changes in X-ALD patients, varying with demyelination severity.
• While absolute values differed, relative MRI parameter changes indicating white matter damage were consistent between in vivo and postmortem tissue.
• High ADC and low FA/MTR values were associated with abnormal white matter; these parameters strongly correlated with histopathology, with ADC and FA being the best predictors.

Conclusions:

• Quantitative MRI parameters reflect white matter pathology in X-ALD patients and are preserved in postmortem tissue.
• These MRI findings have significant potential for predicting the histopathological severity of white matter damage in X-ALD.