1. Restriction Spectrum Imaging in Multiple Sclerosis
Piotr Sowa, MD
Dep. of Radiology and Nuclear Medicine / Oslo University Hospital
Institute of Clinical Medicine / University of Oslo, Norway

2. Background RSI = Restriction Spectrum Imaging
Newly introduced MRI diffusion-based sequence
DWI & DTI extension
RSI separates signal
from cylindrical and
spherical structures
Promising results
in neurooncology
Not used in multiple
sclerosis (MS) before

3. Background

4. Background
RSI enables calculation of several diffusion parameters describing the tissue microstructure:
fast apparent diffusion coefficient (fADC)
slow apparent diffusion coefficient (sADC)
fractional anisotropy (FA)
restricted fractional anisotropy (rFA)
cellularity
neurite density (ND)
extracellular water fraction (EWF)
free water fraction (FWF)
The aim of the study was to evaluate the association between diffusion parameters derived from RSI and neurological disability in MS patients.

5. Materials & methods 80 MS-patients in different stages of the disease
diagnosed according to the 2010 McDonald criteria,
mean age 40.2±10.4 (range 20–67) years, 63 (79%) females
77 relapsing remitting (RR) MS, 1 clinical isolated syndrome (CIS), 2 primary progressive (PP) MS
Neurological disability as measured with expanded disability status scale (EDSS)
collected retrospectively from electronic hospital record
Patients were grouped according to their disability:
minimal (EDSS<2.5), n=28
low (EDSS of 2.5-3), n=41
substantial (EDSS >3), n=11

6. Materials & methods Binary masks were created of:
white matter (WM), with Freesurfer software
white matter lesions (WML), with MIPAV software
Parameters were extracted from the whole volume of WML and whole volume of normal appearing white matter (NAWM)
Group analysis and correlation with EDSS were performed

7. Results fADC sADC FA rFA ND Cellularity EWF FWF in WML (grey)
NAWM (white)

8. Results / conclusions
Parameter that differentiated best between disability subgroups was sADC in WML (ANOVA: F=5.5, η2=0.13, p=0.006)
Parameter that correlated best with disability was ND in NAWM (ϱ=-0.38, p=0.011).
in NAWM (not in lesions)
Processes in NAWM are important for disability in MS
RSI can help in solving the clinico-radiological paradox
Diffusion parameters derived from RSI are promising imaging biomarkers in MS

9. Thank you!
P. Sowa, H. F. Harbo, N. S. White, E. G. Celius, H. Bartsch, P. Berg-Hansen, S. M. Moen, L. T. Westlye, O. A. Andreassen, Anders S. Dale, Mona K. Beyer
Oslo University Hospital, University of Oslo, University of California San Diego, Oslo and Akershus University College of Applied Sciences