小川 浩¹, 竹原 康雄^{1, 2}, 長縄 慎二¹

Hiroshi OGAWA¹, Yasuo TAKEHARA^{1, 2}, Shinji NAGANAWA¹

¹名古屋大学大学院医学系研究科放射線医学教室, ²名古屋大学大学院医学系研究科新規低侵襲画像診断法基盤開発研究寄附講座

¹Department of Radiology, Nagoya University Graduate School of Medicine, ²Department of Fundamental Development for Advanced Low Invasive Diagnostic Imaging, Nagoya University Graduate School of Medicine

キーワード : IgG4, autoimmune pancreatitis, computed tomography, diffusion-weighted image, MR elastography

自己免疫性膵炎（autoimmune pancreatitis：AIP）は，IgG4関連全身性疾患の膵臓表現型である．AIPが初めて文献に記載されて四半世紀になるが，その間にさまざまな専門分野の臨床医にその特徴的な画像所見が徐々に知られるようになった．AIPの画像診断にとってCTとMRIはとても役立つ画像診断法である．典型的な特徴としては，膵臓の局所あるいは全体のソーセージ様腫大（sausage-like swelling），主膵管貫通像（duct-penetrating sign），患部の被膜様構造（capsule-like rim），造影剤投与後の均一な遅延性濃染（homogeneous delayed enhancement）あるいは造影された膵管像，さらに全身性疾患として他臓器の併存病態を反映した特徴的複合所見が挙げられる．本総説では，MRを用いて測定される拡散，灌流，弾性率の特徴など，AIPの診断に役立つCTやMRIの最近の動向と今後について解説する．

Autoimmune pancreatitis (AIP) is a pancreatic phenotype of IgG4-related systemic disease. Since its first description in the literature, characteristic imaging features have gradually become known to many clinicians encompassing various specialties in the past quarter century. CT and MRI have been the workhorses for imaging diagnosis of AIP. Typical features include sausage-like swelling of the focal or entire pancreas, duct-penetrating sign, a capsule-like rim of the affected lesions, and homogeneous delayed enhancement or enhanced duct sign after contrast administration, as well as characteristic combined findings reflecting coexisting pathologies in the other organs as a systemic disease. In this review, recent and future developments in CT and MRI that may help diagnose AIP are discussed, including restricted diffusion and perfusion and increased elasticity measured using MR.