Neuroimaging in patient 1 and patient 2 under ibrutinib treatment. (A) Patient 1. CT without contrast and FDG-PET of the orbits at baseline, and at 3 and 9 months. Assessment at 3 months showed a CR. A clinical response was observed after 2 weeks of initiation of ibrutinib. (B-C) Patient 2. Contrast-enhanced T1-weighted (top) and T2-weighted (bottom) MRI of the spine (B), and contrast-enhanced T1-weighted (top) and FLAIR images (bottom) of the brain (C), at baseline, day 8, and at 1, 3, and 6 months. At day 8, CR was observed in the spine and the brain without remaining contrast enhancement. Anomalies on T2-weighted images took up to 6 months to clear in the brain.