Cranial and spinal MRI before and after treatment with Natalizumab. A. Axial FLAIR (fluid attenuation inversion recovery) scan performed on October 2008 before Natalizumab treatment showing multiple hyperintense MS lesions in the periventricular areas of both hemisheres. B. Sagittal STIR (Short TI Inversion Recovery) sequence of spinal cord performed on October 2008, showing a high number of hyperintense demyelinating lesions in the cervical and dorsal spinal tracts (two representative are indicated by arrows). C. Axial FLAIR scan performed on October 2008 showing hyperintense subcortical MS lesions of both hemisheres. D. After intravenous injection of Gadolinium, an intense contrast enhancement is shown in one subcortical lesion of the right parietal area (arrow). E. Representative axial T1-wheighted scan (periventricular section) after intravenous injection of Gadolinium, performed on October 2009 during natalizumab treatment. Multiple hypointense MS lesions are evident in the periventricular areas of both hemispheres (the largest is indicated by the arrow) with no Gadolinium-enhancement. The MRI evaluation also included T2 and FLAIR scans of the whole brain. Besides the absence of contrast-enhancement, no new or enlarging T2-FLAIR lesions were evident after natalizumab treatment (not shown).