Objective: A pseudoatrophy effect, mostly affecting white matter, can be observed in patients with multiple sclerosis (MS) early on natalizumab therapy. We aimed to investigate whether a similar pattern could be found after interferon-beta treatment onset.
Methods: From a prospective, ongoing cohort, 123 patients treated with interferon-beta were included. A brain MRI was performed at baseline (3 months prior) and 12 months after therapy onset in all patients. SPM8 software was used for volumetric analysis. Brain parenchymal, gray and white matter volumes at baseline and follow-up were obtained, allowing calculation of percentage of volume changes (BVc, GMVc, and WMVc, respectively). Descriptive statistics and linear regression models were performed.
Results: Eighty-four patients were analyzed (39 patients were excluded mostly due to incomplete MRI protocol or segmentation errors); baseline mean age was 33.6 years (SD 8.7), median disease duration was 2.8 years (.3-14), and median EDSS was 1.5 (0-6). Forty-nine patients (58.3%) had baseline gadolinium-enhancing (Gd+) lesions with a median number of 1 (0-18). The regression analysis (adjusted by the number of Gd+ at follow-up MRI, age, disease duration, and baseline EDSS) showed that a higher baseline number of Gd+ lesions was predictive of larger decreases in BVc and WMVc (P = .013 and P = .003, respectively) but not GMVc (P = .777).
Conclusion: Concurrent inflammation has an impact on brain volume measurements (especially white matter) during the first year of interferon-beta therapy, and should be taken into account when interpreting early brain volume changes on therapy.
Keywords: Multiple sclerosis; brain atrophy; interferon treatment; pseudoatrophy.
Copyright © 2016 by the American Society of Neuroimaging.