Restaging of Rectal Cancer with MR Imaging after Concurrent Chemotherapy and Radiation Therapy.
In patients with rectal cancer who have received concurrent chemotherapy and radiation therapy (CCRT) before surgery, magnetic resonance (MR) imaging has low accuracy in prediction of the pathologic stage owing to overstaging or understaging. The factors related to this problem include fibrosis, desmoplastic reaction, edema, inflammation, and viable tumor nets at a fibrotic scar from a previous tumor. Preoperative diagnosis with MR imaging of histologic variants of rectal adenocarcinoma, especially mucinous adenocarcinoma, is important because these variants tend to have a poor response to CCRT. In addition, these variants manifest with high signal intensity on T2-weighted images after CCRT; this finding makes it difficult to differentiate residual tumors from remaining mucin pools. MR volumetry and functional MR imaging may be helpful in prediction and assessment of tumor response to CCRT. Awareness of post-CCRT changes helps radiologists achieve appropriate restaging of irradiated rectal cancer with MR imaging and can lead to a reduction in understaging or overstaging. It is important to obtain and compare both pre- and post-CCRT images before interpreting the post-CCRT images.
Department of Radiology, Gangnam Severance Hospital, and Department of Radiology, Severance Hospital, Yonsei University College of Medicine, 612 Eonjuro, Gangnam-gu, Seoul 135-720, Korea.
Dae Jung
DJ
Kim
Joo Hee
JH
Kim
Joon Seok
JS
Lim
Jeong-Sik
JS
Yu
Jae-Joon
JJ
Chung
Myeong-Jin
MJ
Kim
Ki Whang
KW
Kim
D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000517:prevention & control*; D009367:Neoplasm Staging; D018714:Radiotherapy, Adjuvant; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000628:therapy*; D016896:Treatment Outcome