Person:

Hackney, David

MRI at 3 T has increased sensitivity in detecting overt multiple sclerosis (MS) brain lesions; a growing body of data suggests clinically relevant damage occurs in the normal-appearing white matter (NAWM). We tested a novel pulse sequence to determine whether 3 T MRI spin–spin relaxometry detected damage in NAWM of MS patients (n = 13) vs. age-matched normal controls [(NL) (n = 11)]. Baseline characteristics of the MS group were: age (mean ± SD) 42.5 ± 5.4 (range 33–51 years), disease duration 9.0 ± 6.4 (range 1–22 years), Expanded Disability Status Scale score 2.5 ± 1.7 (range 1–6.5). Brain MRI measures, obtained at 3 T, included global and regional NAWM transverse relaxation rate [R2 (= 1/T2)], derived from 3D fast spin-echo T2 prepared images, and global white matter volume fraction derived from SPGR images. The regional NAWM areas investigated were the frontal lobe, parietal lobe, and the genu and splenium of the corpus callosum. Mean NAWM R2 was lower (indicating T2 prolongation) in MS than NL in the whole brain (p = 0.00047), frontal NAWM (p = 0.00015), parietal NAWM (p = 0.0069) and callosal genu (p = 0.0019). Similarly, R2 histogram peak position was lower in NAWM in MS than NL in the whole brain (p = 0.019). However, the normalized WM volume fractions were similar in both MS and NL (p > 0.1). This pilot study suggests that a novel 3D fast spin-echo pulse sequence at 3 T, used to derive R2 relaxation maps, can detect tissue damage in the global and regional cerebral NAWM of MS patients that is missed by conventional lesion and atrophy measures. Such findings may represent demyelination, inflammation, glial proliferation and axonal loss.

Objective Assess the relationship between spinal cord T2 hyperintense lesions and clinical status in multiple sclerosis (MS) with 1.5 and 3T MRI.

Methods Whole cord T2-weighted fast spin-echo MRI was performed in 32 MS patients [Expanded Disability Status Scale (EDSS) score (mean±SD: 2±1.9), range 0–6.5]. Protocols at 1.5T and 3T were optimized and matched on voxel size.

Results Moderate correlations were found between whole cord lesion volume and EDSS score at 1.5T (rs =.36, p=0.04), but not at 3T (rs =0.13, p=0.46). Pyramidal Functional System Score (FSS) correlated with thoracic T2 lesion number (rs=.46, p=0.01) and total spinal cord lesion number (rs=0.37, p=0.04) and volume (rs=0.37, p=0.04) at 1.5T. Bowel/bladder FSS correlated with T2 lesion volume and number in the cervical, thoracic, and total spine at 1.5T (rs 0.400.57, all p<0.05). These MRI-FSS correlations were non-significant at 3T. However, these correlation coefficients did not differ significantly between platforms (Choi’s test p>0.05). Correlations between whole cord lesion volume and timed 25-foot walk were non-significant at 1.5T and 3T (p>0.05). Lesion number and volume did not differ between MRI platforms in the MS group (p>0.05).

Conclusions Despite the use of higher field MRI strength, the link between spinal lesions and MS disability remains weak. The 1.5T and 3T protocols yielded similar results for many comparisons.