Therapeutic response of immunoglobulin 4-related aortitis and pancreatitis demonstrated by diffusion-weighted MRI

Immunoglobulin (IgG) 4-related disease is a systemic inflammatory disease, and it affects vascular system as aortitis, periaortitis, or aneurysm. However, due to a lack of serum biomarker on aortic damage and the multiorgan involvement, it is difficult to assess aortic inflammatory activity of IgG4-related disease. We described a case of IgG4-related pancreatitis and aortitis, which was visualized with magnetic resonance merged image of diffusion weighted and T(1) weighted images. The aortic signal intensity or apparent diffusion coefficient value reduced or increased after oral prednisone administration, respectively. Magnetic resonance diffusion weighted image and apparent diffusion coefficient may be a useful imaging tool for assessment of vascular inflammation in IgG4-related aortitis.