title: Factors affecting the restaging accuracy of magnetic resonance imaging after preoperative chemoradiation in patients with rectal cancer.
abstract: OBJECTIVE
  We evaluated patient or tumor factors associated with the preoperative restaging accuracy of magnetic resonance imaging (MRI) for determining T and N stages as well as circumferential resection margin (CRM) involvement after chemoradiation (CRT) in patients with locally advanced rectal cancer.
  
  
  METHODS
  Seventy-seven patients with rectal cancer that were treated with preoperative CRT (50.4 Gy) followed by radical resection were included. Post-CRT MRI was performed approximately 4 weeks after preoperative CRT.
  
  
  RESULTS
  The median tumor distance from the anal verge was 6 cm, 48 (62%) of which were anterior and 29 (38%) posterior. The median tumor diameter was 3 cm. A stage-by-stage comparison showed that correct staging occurred in 62%, 43%, and 86% of patients for T staging, N staging, and CRM prediction, respectively. Shorter distance to the anal verge (<5 cm), smaller tumor diameter (<1 cm), and anterior tumor location were associated with incorrect T staging. There were no significant variables in terms of N staging accuracy. Shorter tumor distance and anterior tumor location were associated with incorrect CRM prediction.
  
  
  CONCLUSIONS
  Our findings suggest that specific tumor factors such as small, distal, or anterior rectal tumors are closely associated with the accuracy of MRI after preoperative CRT.
authors: Department of Surgery, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.
authors: I Y
authors: IY
authors: Kim
authors: Department of Radiology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.
authors: S W
authors: SW
authors: Cha
authors: Department of Radiology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.
authors: J H
authors: JH
authors: Ahn
authors: Department of Surgery, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea. Electronic address: youngwkim@yonsei.ac.kr.
authors: Y W
authors: YW
authors: Kim
mesh_terms: D000230:Adenocarcinoma / Q000556:secondary* / Q000628:therapy*; D000368:Aged; D059186:Chemoradiotherapy, Adjuvant; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D018365:Neoplasm, Residual; D011300:Preoperative Care; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*; D047368:Tumor Burden
keywords: Magnetic resonance imaging; Preoperative chemoradiation; Rectal cancer; Restaging