title: CT features and common causes of arc of Riolan expansion: an analysis with 64-detector-row computed tomographic angiography.
abstract: OBJECTIVE
  To study the manifestations of arc of Riolan expansion (ARE) using multi-detector computed tomography angiography (MDCTA).
  
  
  METHODS
  The manifestations and clinical data of 626 consecutive mesentery CTA images were retrospectively analyzed. The 47 cases with ARE and 47 patients without expansion were involved. The average diameter of arc of Riolan was measured. Two radiologists after reaching consensus analyzed the shapes of mesenteric artery, CT findings and the occurrence and causes of ARE.
  
  
  RESULTS
  The mean diameter of arc of Riolan was 1.2 mm, 4.6 mm, 2.5 mm, 2.3 mm, 1.9 mm, 2.5 mm, and 2.0 mm at baseline and following obstruction of superior mesenteric artery (SMA), stenosis of SMA, obstruction of inferior mesenteric artery (IMA), stenosis of IMA, colon cancer, and active ulcerative colitis, respectively. The expansion of arc of Riolan was the most significant following obstruction of SMA. The diameters of arc of Riolan were significantly different between the upward flow group and the downward or the two-way flow groups, and between the colon tumor group and the active ulcerative colitis group. CT findings such as bowel wall thickening, contrast enhancement, intestinal obstruction, marginal artery expansion, lymph node enlargement varied and were help to identify the cause of ARE.
  
  
  CONCLUSIONS
  ARE often suggests the occurrence of obstructed intestinal feeding artery or intestinal lesions. MDCTA can clearly display the situation of arc of Riolan and collateral circulation, and together with CT symptoms, can guide the selection of diagnosis and treatment schemes in clinic.
authors.affiliation: Department of Radiology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology Wuhan 430014, China.
authors.forename: Yuanliang
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Department of Radiology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology Wuhan 430014, China.
authors.forename: Chaolin
authors.initials: C
authors.lastname: Jin
authors.affiliation: Department of Radiology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology Wuhan 430014, China.
authors.forename: Shutong
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Department of Radiology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology Wuhan 430014, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Radiology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology Wuhan 430014, China.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Jiang
keywords: MDCT angiography; Mesenteric artery; abdominalarteries anomalies