Apparent Diffusion Coefficient Histograms in the Follow-up of Relapsing-Remitting Multiple Sclerosis.

Area of Science:

• Neuroimaging
• Radiology
• Neurology

Background:

• Diffusion-weighted imaging (DWI) provides insights into brain tissue changes in multiple sclerosis (MS).
• Previous studies noted increased diffusivity in normal-appearing brain tissue in MS patients.
• Longitudinal whole-brain histogram analysis of apparent diffusion coefficient (ADC) in active relapsing-remitting MS has not been evaluated.

Purpose of the Study:

• To investigate alterations in apparent diffusion coefficient (ADC) histograms during the follow-up of active relapsing-remitting MS patients.
• To correlate histogram changes with disease activity and other MRI metrics.

Main Methods:

• Nine patients with active, newly diagnosed relapsing-remitting MS underwent MRI twice, three months apart.
• Apparent diffusion coefficient (ADC) histograms were generated after removing extracranial tissues and cerebrospinal fluid.
• Brain volume index (BVI) and lesion volume on FLAIR images were measured; new T2-lesions were counted.

Main Results:

• Five patients showed disease activity on follow-up MRI.
• In patients with disease activity, ADC histogram parameters showed both increases and decreases.
• Changes in BVI or lesion volume did not significantly correlate with histogram changes.
• New T2-lesions positively correlated with changes in mean and upper quartile ADC histogram values.

Conclusions:

• Apparent diffusion coefficient (ADC) histogram alterations reflect disease activity in relapsing-remitting MS.
• Histogram shifts, both to lower and higher ADC values, can occur during inflammatory activity and resolution.
• These changes are primarily linked to subtle inflammatory processes in normal-appearing brain tissue.