Correlation between enhancing lesion number and volume on standard and triple dose gadolinium-enhanced brain MRI scans from patients with multiple sclerosis.

We investigated the correlations between numbers and volumes of multiple sclerosis (MS) lesions enhancing on standard dose (SD) and triple dose (TD) gadolinium (Gd)-enhanced brain magnetic resonance imaging (MRI) scans, to clarify whether the measurement of enhancing lesion volumes or the use of TD MRI give additional information which can not be obtained by counting enhancing lesions on SD scans. SD and TD Gd-enhanced brain MRI scans were obtained every month for three months from 40 MS patients. The numbers of total and new enhancing lesions were counted, and the total volumes of enhancing lesions were measured from each of the four scans obtained with the two techniques. Univariate correlations between enhancing lesion numbers and volumes were assessed. The numbers of total and new enhancing lesions seen either on SD or TD scans were significantly correlated (r = 0.91 and 0.93, respectively). The numbers and volumes of total enhancing lesions were significantly correlated on both SD (r = 0.90), and TD (r = 0.89) scans. Moderate correlations were found between the total number of enhancing lesions on SD scans and the average difference between TD and SD scans for total enhancing lesion number (r = 0.66), and between the number of new enhancing lesions on SD scans and the average difference between TD and SD scans for new enhancing lesion number (r = 0.50). Our findings indicate that, both on SD and TD MRI, the counts and the volumes of total and new enhancing lesions are highly correlated, and that lesion counting may suffice to monitor MS activity. On the contrary, this study confirms the usefulness of TD MRI for a more complete assessment of the acute changes occurring in MS patients.