Efficacy of High Resolution Magnetic Resonance Imaging in Preoperative Local Staging of Rectal Cancer

Aysun Uçar,Özgül Sağol,Mehmet Füzün,Cem Terzi,Selman Sökmen,Funda Obuz,Sülen Sarıoğlu

doi:10.4274/mirt.43153

Abstract

Objective: To assess the efficacy of high-resolution magnetic resonance imaging (HRMRI) for preoperative local staging in patients with rectal cancer who did not receive preoperative radiochemotherapy. Methods: In this retrospective study, 30 patients with biopsy proved primary rectal cancer were evaluated by HRMRI. Two observers independently scored the tumour and lymph node stages, and circumferential resection margin (CRM) involvement. The sensitivity, specificity, the negative predictive value and the positive predictive value of HRMRI findings were calculated within the 95% confidence interval. The area under the curve was measured for each result. Agreement between two observers was assessed by means of the Kappa test. Results: In T staging the accuracy rate of HRMRI was 47-67%, overstaging was 10-21%, and understaging was 13-43%. In the prediction of extramural invasion with HRMRI, the sensitivity was 79-89%, the specificity was 72-100%, the PPV was 85-100%, the NPV was 73-86%, and the area under the curve was 0.81-0.89. In the prediction of lymph node metastasis, the sensitivity was 58-58%, the specificity was 50-55%, the PPV was 43-46%, and the NPV was 64-66%. The area under the curve was 0.54-0.57. When the cut off value was selected as 1 mm, the sensitivity of HRMRI was 38-42%, the specificity was 73-82%, the PPV was 33-42%, and NPV was 79-81% in the prediction of the CRM involvement. The correlation between the two observers was moderate for tumour staging, substantial for lymph node staging and predicting of CRM involvement.Conclusion: Preoperative HRMRI provides good predictive data for extramural invasion but poor prediction of lymph node status and CRM involvement.Conflict of interest:None declared.

Highlights

Rectal cancer, defined as a tumour with its lower edge within 15 cm from the anal verge, accounts for about a third of all colorectal malignancies
Rectal carcinoma was in the distal rectum in patients, in the middle rectum in patients, in the superior rectum in 5 patients
Our study showed that MRI is able to predict those patients in whom the circumferential resection margin (CRM) is not involved, allowing them to proceed to surgery without the need for preoperative a b c

Summary

Introduction

Rectal cancer, defined as a tumour with its lower edge within 15 cm from the anal verge, accounts for about a third of all colorectal malignancies. The clinical challenge is to identify preoperatively the cohort of rectal cancer patients who are at high risk of local tumour recurrence. Recent publications have suggested that detailed rectal anatomy can be demonstrated using thin section magnetic resonance (MR) imaging with a pelvic phased-array coil [5,6,7]. This technique permits accurate T-stage determination and determination of the tumour involving surgical resection margins. The ability of thin section MR imaging in identifying the mesorectal fascia has been demonstrated, but there is conflicting evidence regarding the overall accuracy of MR imaging in staging rectal cancer [7,8,9,10,11,12,13]. The purpose of our study was to assess the overall diagnostic accuracy of HRMRI for preoperative T and N staging and prediction of the CRM involvement in patients with rectal cancer who had not received preoperative radiochemotherapy

Methods

Results

Conclusion