Autoimmune pancreatitis associated to renal and aortic involvement: 3.0-TESLA magnetic resonance imaging in diagnosis and follow-up

Abstract

Contest: The criteria for Pancreatic Autoimune Pancreatitis (AIP) diagnosis include pancreatic imaging, serological and histopathological findings, other organs involvement and response to steroid treatment.

Case report: Two cases, the first of focal AIP (FAIP), the second of diffuse AIP (DAIP) associated to renal and abdominal aorta involvement respectively, underwent 3.0-Tesla Magnetic Resonance Imaging (3.0-T MRI) with Diffusion Weighted Imaging (DWI) before and after 1 month of corticosteroid treatment. In both cases Computed Tomography, performed for sudden onset of jaundice and pancreatic-like abdominal pain, had previously shown enlargement of pancreatic head and of all pancreatic gland respectively. Endoscopic ultrasound-guided fine-needle aspiration biopsy of both pancreatic lesions had revealed no malignancy. 3.0-T MRI demonstrated a solid mass in enlarged pancreatic head in the first case, an enlargement of all pancreatic gland in the second case, both hypoenhancing in pancreatic phase of contrast enhanced MRI, with moderate delayed enhancement at venous and late phases. Two wedge shaped regions of decreased enhancement of left kidney and a soft-tissue cuffing around the abdominal aorta were observed in first and second case respectively. At DWI, all pancreatic, renal and aortic lesions showed a high signal intensity from restricted diffusion at high b value (b = 1,000 sec/mm²) images and low apparent diffusion coefficient (ADC) values, compared to the normal ADC value. 3.0-T MRI after treatment, compared to pre-treatment examination, showed marked reduction in size of pancreatic, renal lesions and soft-tissue cuffing aortic lumen. 3.0-T MR DWI revealed an increase of ADC values in all pancreatic, renal and aortic lesions.

Conclusion: We emphasize the role of 3.0-T MRI DWI findings and ADC map values on diagnosis of AIP tanks to evaluating the response to short period of steroid treatment of pancreatic and extra pancreatic lesions.