QUANTITATIVE ASSESSMENT OF MAGNETIC-RESONANCE-IMAGING LESION LOAD IN MULTIPLE-SCLEROSIS

Changes of lesion load on yearly conventional spin echo (CSE) T2-weigh ted scans of the brain from patients with multiple sclerosis, measured using computer assisted techniques, are used to monitor long term dis ease evolution, either natural or modified by treatment. Although lesi on load measurements have several advantages over clinical measures of outcome (they provide a more objective and sensitive measure of disea se evolution, which has a linear distribution and a more strict relati on with the underlying pathology), the poor correlation between change s of lesion load and changes of disability is of concern when using su ch an approach for monitoring multiple sclerosis trials. In this revie w, the main sources of variation in T2 lesion load from brain MRT of p atients with multiple sclerosis will be considered, along with possibl e strategies to, at least partially, overcome them. Also, some of the newer fully automated techniques to segment multiple sclerosis lesions , which have been validated against manual outlining, and a recently d eveloped coregistration technique are presented. It is hoped that a mo re reliable and standardised approach to lesion load measurements in m ultiple sclerosis will lead to better correlation with clinical diseas e course, to a higher confidence in the results of trials, and to redu ced numbers of scans needed to conduct the trials, thus improving cost efficiency and reducing discomfort of the patients.