LESION LOAD QUANTIFICATION IN SERIAL MR OF EARLY RELAPSING MULTIPLE-SCLEROSIS PATIENTS IN AZATHIOPRINE TREATMENT - A RETROSPECTIVE STUDY

Azathioprine (AZA) has a slight but consistent effect on clinical outc ome in multiple sclerosis (MS), but very few data are available on mag netic resonance imaging (MRI) changes. We performed a retrospective st udy aimed to quantify changes of lesion load in two serial proton dens ity weighted MRI sequences (TR 2500, TE 30, 1.5 T) at a mean interval of 2.5 years in 36 relapsing-remitting (RR) MS patients: 19 had been t reated with AZA, beside steroids after relapses (AZA group), and 17 ha d been treated with steroids only (control group). All but 3 patients were in the early phase of the disease. Total lesion area (TLA) was me asured by manual outlining method and the arbitrary score proposed by Ormerod (total score) was also calculated from the number and diameter of lesions. Lesion load was the same at baseline, but median percenta ge difference of TLA between first and second scan was +15.6% in contr ol, -43.7% in the AZA group (p < 0.05, Mann-Whitney test). The distrib ution of patients according to TLA change, assuming that an increase o r decrease was significant if larger than 50%, was found to be signifi cantly different in favor of AZA-treated patients (chi(2) = 35.92, p < 0.001). These results suggest an effect of AZA treatment on MRI lesio n load in early RR MS: a larger prospective study is worthwhile.