Prognostic value of MRI in assessing extramural venous invasion in rectal cancer: multi-readers’ diagnostic performance
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This study was conducted in order to determine the prognostic value of MRI for extramural venous invasion (EMVI) in rectal cancer compared to pathology and to assess the diagnostic performance of multireaders.
We retrospectively enrolled 222 patients (M:F = 148:74; mean age ± standard deviation, 61.5 ± 12 years) with histopathologically proven rectal cancers who underwent preoperative MRI between 2007 and 2016. Among them, 74 patients had positive EMVI on pathology (pEMVI) and 148 patients had negative pEMVI. Three radiologists with 7 (reviewer 1), 3 (reviewer 2), and 1 (reviewer 3) year of experience in rectal MR imaging determined the presence of EMVI on MRI (mrEMVI) using a 5-point grading system. Using histopathologic results as the reference standard, radiologists’ performances were analyzed and compared with receiver operating characteristic (ROC) analysis. For assessment of interobserver variation, intraclass correlation coefficients (ICC) were used. Lastly, Kaplan–Meier estimation and Cox proportional hazard models were used for survival analysis.
The area under the ROC curve (AUC) was highest in reviewer 1 (0.829), followed by reviewer 2 (0.798) and reviewer 3 (0.658). Differences in AUCs between reviewer 1 or 2 and reviewer 3 were statistically significant (p < 0.001). ICC was substantial between reviewers 1 and 2. Overall survival (OS) was significantly different according to the positive circumferential resection margin, adjuvant treatment, and the presence of mrEMVI, but not by the presence of pEMVI.
For experienced radiologists, the diagnostic performance of mrEMVI was good, resulting in better prediction of OS than with pEMVI, with substantial interobserver agreement.
• When read by experienced radiologists, MR can provide reliable diagnostic performance in assessing EMVI for patients with rectal cancer.
• Positive mrEMVI is an adverse prognostic factor of overall survival and may influence the clinical decision-making.
KeywordsRectal neoplasms Blood vessels Magnetic resonance imaging Chemoradiotherapy Prognosis
Extramural venous invasion
EMVI evaluated on MR
Pathologically detected EMVI
This study has received funding from the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning (NRF-2016R1A2B4007762) and from the Seoul National University Hospital Research Fund No. 03-2016-450.
Compliance with ethical standards
The scientific guarantor of this publication is Joon Koo Han.
Conflict of interest
The authors declare that they have no conflict of interest.
Statistics and biometry
No complex statistical methods were necessary for this paper.
Written informed consent was waived by the Institutional Review Board.
Institutional Review Board approval was obtained.
• case–control study
• performed at one institution