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Pathologic damage in MS assessed by diffusion-weighted and magnetization transfer MRI
M Cercignani1, G Iannucci, M A Rocca
1Department of Neuroscience, Scientific Institute Ospedale San Raffaele, University of Milan, Italy.
Objective:
To compare diffusion characteristics of MS lesions, normal-appearing white matter (NAWM) from patients, and normal white matter from control subjects, and to investigate the correlations between the magnetization transfer ratio (MTR) and a directionally averaged tissue water diffusion coefficient (D) in patients.
Background:
MS and other pathologic processes that modify tissue integrity can result in abnormal diffusion of water molecules detectable by diffusion-weighted imaging (DWI).
Methods:
Conventional dual-echo and DWI scans were obtained from 35 patients with relapsing-remitting MS and 24 healthy control subjects. MT scans were also obtained from the patients. After coregistration of all scans, MTR and D values from MS lesions and NAWM in different regions were marked using the dual-echo scans as a reference. D values from the same brain regions in control subjects were acquired. Histograms of MTR and D were also produced.
Results:
Patients with MS had significantly higher D values in all the areas studied. Moreover, histogram metrics (peak height, peak site, and average D) from patients were substantially different from those of control subjects. In patients, average lesion D and MTR were markedly different from those in the NAWM. There was an inverse correlation between average lesion MTR and D inside lesions, whereas no correlation was found for average MTR and D taken from the histograms.
Conclusions:
DWI detects severe tissue disruption inside lesions and subtle widespread abnormalities in NAWM in patients with relapsing-remitting MS. MT and DWI may provide information about different aspects of brain pathology in MS.
Insights
Diffusion-weighted imaging (DWI) reveals significant tissue damage in multiple sclerosis (MS) lesions and subtle abnormalities in normal-appearing white matter (NAWM). Magnetization transfer (MT) and DWI offer complementary insights into MS brain pathology.
Area of Science:
- Neuroimaging
- Biomedical Engineering
- Radiology
Background:
- Multiple sclerosis (MS) alters white matter integrity, affecting water molecule diffusion.
- Diffusion-weighted imaging (DWI) is sensitive to these microstructural changes.
Purpose of the Study:
- Compare diffusion characteristics in MS lesions, normal-appearing white matter (NAWM), and control white matter.
- Investigate correlations between magnetization transfer ratio (MTR) and diffusion coefficient (D) in MS patients.
Main Methods:
- Acquired conventional dual-echo, DWI, and MT scans from 35 relapsing-remitting MS patients and 24 controls.
- Coregistered scans to quantify MTR and D values in lesions and NAWM.
- Generated histograms of MTR and D for comparative analysis.
Main Results:
- MS patients exhibited significantly higher D values in all brain regions studied.
- Histogram metrics for D differed substantially between MS patients and controls.
- Lesional D and MTR were markedly different from NAWM in MS patients, with an inverse correlation between lesion MTR and D.
Conclusions:
- DWI effectively detects severe tissue disruption in MS lesions and subtle abnormalities in NAWM.
- MT and DWI provide distinct yet complementary information regarding MS neuropathology.