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Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Dirty-appearing white matter in multiple sclerosis: volumetric MR imaging and magnetization transfer ratio histogram
Yulin Ge1, Robert I Grossman, James S Babb
1Department of Radiology, New York University School of Medicine, New York, NY, USA.
Background And Purpose:
In contrast to "normal-appearing" white matter (NAWM) in patients with multiple sclerosis (MS), there are subtle, abnormal and diffuse signal intensity changes often seen on T2-weighted MR images, which we have referred to as "dirty-appearing" white matter (DAWM). These areas of DAWM have slightly higher signal intensity than that of NAWM, but lower than that of lesion plaques. Our study was designed to determine the volumetric and magnetization transfer ratio (MTR) features of DAWM in patients with MS.
Methods:
Dual-echo fast spin-echo MR imaging and magnetization transfer imaging were performed in 22 patients with relapsing-remitting MS. Slightly hyperintense DAWM areas were manually outlined on the basis of T2-weighted imaging findings. The volume and MTR of DAWM were calculated and compared with the volume and MTR of NAWM and T2 lesion plaques.
Results:
The average volume of DAWM (18.3 mL) was greater than the average volume of T2 lesion plaques (11.0 mL, P =.04), and the mean MTR in DAWM (38.7%) differed significantly (P <.0001) from that in NAWM (40.7%) and plaques (33.3%). There was a modest negative correlation between either mean MTR (r = -0.60; P =.003) of DAWM or peak height (r = -0.50; P =.02) of DAWM with T2 lesion load. Neither DAWM volume nor total T2 abnormality (DAWM + plaques) volume correlates with the Expanded Disability Status Scale.
Conclusion:
The results of this study indicate that MTR is able to differentiate DAWM from lesion plaques and NAWM and that DAWM might be a different pathologic process of the disease. The notion and quantification of these subtle imaging findings of DAWM areas may improve our understanding of certain stages of disease progression and disease burden in patients with relapsing-remitting MS.
Insights
Dirty-appearing white matter (DAWM) in multiple sclerosis (MS) is distinct from normal white matter and lesions. Magnetization transfer ratio (MTR) imaging can differentiate DAWM, offering insights into disease progression.
Area of Science:
- Neuroimaging
- Radiology
- Neurology
Background:
- Multiple sclerosis (MS) exhibits subtle white matter changes beyond visible lesions.
- Dirty-appearing white matter (DAWM) presents as diffuse T2 signal abnormalities.
- DAWM has distinct signal intensity compared to normal-appearing white matter (NAWM) and T2 lesions.
Purpose of the Study:
- To determine the volumetric and magnetization transfer ratio (MTR) characteristics of DAWM.
- To differentiate DAWM from NAWM and T2 lesion plaques in MS patients.
Main Methods:
- Dual-echo fast spin-echo MRI and MTR imaging were used in 22 relapsing-remitting MS patients.
- DAWM areas were manually delineated on T2-weighted images.
- Volume and MTR of DAWM were compared with NAWM and T2 lesions.
Main Results:
- DAWM volume (18.3 mL) was significantly larger than T2 lesion volume (11.0 mL).
- Mean MTR in DAWM (38.7%) differed significantly from NAWM (40.7%) and plaques (33.3%).
- DAWM MTR showed a negative correlation with T2 lesion load.
Conclusions:
- MTR effectively distinguishes DAWM from NAWM and MS lesions.
- DAWM may represent a distinct pathological process in MS.
- Quantifying DAWM can enhance understanding of MS progression and disease burden.
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