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The evaluation of MRI diffusion values of active demyelinating lesions in multiple sclerosis

 Multiple Sclerosis and Related Disorders, Volume 10, November 2016, Pages 97–102

Abstract

Background

Gadolinium (Gd) enhancement of lesions is the main radiologic marker for detection of activity in Multiple Sclerosis (MS). This study compares Diffusion weighted imaging (DWI) characteristics and enhancement to determine whether DWI can be used as an alternative to Gd administration.

Methods

A retrospective study of 72 patients who had MRI with Gd and DWI. Visual assessment and comparison of the Apparent Diffusion Coefficient (ADC) values on Gd+ lesions, all lesions showing restricted diffusion, 2 Gd− lesions and 1 area of normal-appearing white matter (NAWM) in each MRI were performed.

Results

DWI values were measured on 275 T2 lesions, 68 Gd+ and 207 Gd− lesions, as well as 104 NAWM. 34 Gd+ lesions showed restricted diffusion. The median ADC-minimum of Gd+ lesions was significantly lower than NAWM and even lower than Gd− lesions. Most DWI restricted lesions were also Gd+(specificity≥94%), however many Gd+ lesions did not show visually detectable restriction in DWI (sensitivity≤34%). The median ADC-minimum of symptomatic lesions was lower than asymptomatic lesions.

Conclusion

While Gd+ lesions have lower ADC-minimum, visual DWI assessment cannot replace Gd administration for identifying active lesions. Gd+ lesions showing restricted diffusion are clinically important as they are more likely associated with neurological symptoms.

Highlights

  • Diffusivity is heterogeneous in Gd+ MS lesions compared to Gd− lesions.
  • Visually restrict lesions in ADC map often enhance with Gd on T1-weighted images.
  • Visually restrict lesions in ADC map is a weak surrogate marker for enhancement.
  • Gd− enhanced study cannot be replaced by DWI/ADC.
  • Lower ADC values of lesions did correlate more tightly with the symptomatic lesions.

Keywords: Multiple sclerosis, Diffusion magnetic resonance imaging, Gadolinium, Magnetic resonance imaging, Restricted diffusion, Detection of new MRI activity.

Footnotes

a University of Ottawa, Canada

b Department of Radiology, University of Ottawa, Department of Medical Imaging, The Ottawa Hospital, Canada

c Ottawa Hospital, General Campus, University of Ottawa, Canada

d The Ottawa Hospital Research Institute and the University of Ottawa, Canada

Corresponding author.