Macroscopic and microscopic assessments of disease burden by MRI in multiple sclerosis: Relationship to clinical parameters

Abstract

We have evaluated macroscopic white matter abnormalities (visible lesions) together with microscopic abnormalities in the normal appearing white matter (NAWM) of patients with multiple sclerosis (MS) to determine their relative contributions to the development of disability. The total visible lesion volume (TLV) was computed as a measure macroscopic changes, whereas both texture analysis and T2 were used as possible indicators of diffuse disease in the NAWM. Dual echo T2-weighted SE images were obtained from 41 patients with definite MS: 10 primary progressive (PP), 11 secondary progressive (SP), 10 benign (BE), 10 early relapsing remitting (ERR), as well as from 10 healthy controls. Calculation of T2 and texture parameters were performed in a region of frontal NAWM of patients and controls. The TLV of each patient was measured using a semiautomated lesion detection program. No significant differences were found between the controls and the patients for all texture parameters examined. However, NAWM T2 was longer in the patients than in the controls (P = .02). Mean TLV was highest for SP and lowest for BE and ERR patients. A significant correlation was found between TLV and EDSS (P < .01) but not between NAWM T2 or texture and expanded disability status score (EDSS). Our study suggest that: (a) diffuse changes are present in NAWM, (b) texture analysis is unable to detect any subtle structure in the NAWM abnormalities, possibly because of the limited image resolution; (c) in the development of disability in MS, macroscopic lesions are more important than microscopic abnormalities in the NAWM.

Temporal lobe epilepsy: Differential pattern of damage in temporopolar cortex and white matter

“…Likely pathological processes include gliosis and demyelination. Data from other studies suggest in fact that textural changes may be observed within the sclerotic hippocampus in TLE [Yu et al, 2001[Yu et al, , 2002 and demyelinating processes [Gasperini et al, 1996;Mathias et al, 1999]. Alternatively, in light of the histopathological findings described earlier [Hammers et al, 2001[Hammers et al, , 2002, it is possible that the ''simplified'' TPWM texture as defined by entropy may point to alterations in the course of corticogenesis and is reflective of heterotopia, a developmental malformation leading to abnormal neuronal collection and positioning.…”

Corpus callosum index and long-term disability in multiple sclerosis patients

“…The most established MRI parameters used in evaluating disease outcome and routinely used in clinical trials are hyperintensities on T2 weighted images, hypo-intensities in T1 weighted images and contrast enhancing lesions [22,33,48,50]. However, several studies have revealed only a weak correlation between T2 lesion load and clinical disability [14,16,17,35,37]. New MRI techniques have been developed that offer the prospect of greater specificity including measurements of brain volume [12,28,30].…”

Water content and myelin water fraction in multiple sclerosis

“…While such conventional MRI measures provide some information about the disease process, little correlation has been found between MRI BOD (lesion load) and measures of clinical disability [5,21,45], suggesting there is ongoing disease within the normal appearing white matter (NAWM) that is not seen on conventional MRI, but is contributing to disease progression. This idea is supported by pathological studies showing inflammation, demyelination and astrocyte proliferation in areas of white matter away from lesions and other macroscopically visible abnormalities [3,34].…”