Korean Journal of Radiology

The Korean Society of Radiology (대한영상의학회)
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MRI Assessment of Complete Response to Preoperative Chemoradiation Therapy for Rectal Cancer: 2020 Guide for Practice from the Korean Society of Abdominal Radiology

  • Seong Ho Park (Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center) ;
  • Seung Hyun Cho (Department of Radiology, Kyungpook National University Medical Center, School of Medicine, Kyungpook National University) ;
  • Sang Hyun Choi (Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center) ;
  • Jong Keon Jang (Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center) ;
  • Min Ju Kim (Department of Radiology, Ewha Womans University Seoul Hospital) ;
  • Seung Ho Kim (Department of Radiology, Inje University College of Medicine, Haeundae Paik Hospital) ;
  • Joon Seok Lim (Department of Radiology, Severance Hospital, Yonsei University College of Medicine) ;
  • Sung Kyoung Moon (Department of Radiology, Kyung Hee University Hospital) ;
  • Ji Hoon Park (Department of Radiology, Seoul National University College of Medicine, Seoul National University Bundang Hospital) ;
  • Nieun Seo (Department of Radiology, Severance Hospital, Yonsei University College of Medicine) ;
  • Korean Society of Abdominal Radiology Study Group for Rectal Cancer (Korean Society of Abdominal Radiology)
  • Received : 2020.04.18
  • Accepted : 2020.04.19
  • Published : 2020.07.01
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Abstract

Objective: To provide an evidence-based guide for the MRI interpretation of complete tumor response after neoadjuvant chemoradiation therapy (CRT) for rectal cancer using visual assessment on T2-weighted imaging (T2) and diffusion-weighted imaging (DWI). Materials and Methods: PubMed MEDLINE, EMBASE, and Cochrane Library were searched on November 28, 2019 to identify articles on the following issues: 1) sensitivity and specificity of T2 or DWI for diagnosing pathologic complete response (pCR) and the criteria for MRI diagnosis; 2) MRI alone vs. MRI combined with other test(s) in sensitivity and specificity for pCR; and 3) tests to select patients for the watch-and-wait management. Eligible articles were selected according to meticulous criteria and were synthesized. Results: Of 1615 article candidates, 55 eligible articles (for all three issues combined) were identified. Combined T2 and DWI performed better than T2 alone, with a meta-analytic summary sensitivity of 0.62 (95% confidence interval [CI], 0.43-0.77; I2 = 80.60) and summary specificity of 0.89 (95% CI, 0.80-0.94; I2 = 92.61) for diagnosing pCR. The criteria for the complete response on T2 in most studies had the commonality of remarkable tumor decrease to the absence of mass-like or nodular intermediate signal, although somewhat varied, as follows: (near) normalization of the wall; regular, thin, hypointense scar in the luminal side with (near) normal-appearance or homogeneous intermediate signal in the underlying wall; and hypointense thickening of the wall. The criteria on DWI were the absence of a hyperintense signal at high b-value (≥ 800 sec/mm2) in most studies. The specific algorithm to combine T2 and DWI was obscure in half of the studies. MRI combined with endoscopy was the most utilized means to select patients for the watch-and-wait management despite a lack of strong evidence to guide and support a multi-test approach. Conclusion: This systematic review and meta-analysis provide an evidence-based practical guide for MRI assessment of complete tumor response after CRT for rectal cancer.

Keywords

References

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