Practical Reviews

Radiology - April 30, 2017 - Vol. 45 - No. 4

Rectal Distention Does Not Significantly Alter Distance Between Tumor, Mesorectal Fascia

Author(s): Ye F, Zhang H, et al

Author Email: zhanghongmei1973@163.com

This article counts as 0.25 credits in MRI.

Rectal distention with gel can improve rectal tumor detection without significantly changing the distance of the tumor to the mesorectal fascia.

Background: MRI can be used to evaluate rectal cancer, which in part can help determine the distance between the tumor and the circumferential resection margin. Distention of the rectum has advantages because it can improve tumor conspicuity, but it has a downside as rectal distention may artificially narrow the distance between the mesorectal fascia.

Objective: To determine if distention of the rectum affects the accuracy of tumor staging on MRI.

Design: Prospective study.

Participants: 44 patients with rectal cancer who underwent MRI with and without rectal distention and had subsequent surgery.

Methods: Patients were evaluated on a 3-Tesla MR scanner without rectal distention and then had a repeat examination with rectal gel administration. Images were interpreted by 2 blinded imagers who described how well the tumor was identified, provided T and N categories, and described the distance of the normal rectal wall and tumor to the mesorectal fascia.

Results: Tumor visualization improved with rectal gel as did characterization of the tumor borders. Interobserver agreement improved from moderate without rectal distention to excellent following rectal gel administration. The distance between the normal rectal wall and mesorectal fascia decreases after rectal gel is administered but the distance between the fascia and the rectal tumor itself does not significantly change.

Conclusions: Rectal distention with gel can improve rectal tumor detection without significantly changing the distance of the tumor to the mesorectal fascia.

Reviewer's Comments: This study makes important findings regarding the imaging of rectal cancer. It has been long held by many radiologists that the use of rectal gel to distend the rectum, while advantageous in terms of the ability to identify tumors, is not useful as it can overstage tumors by overestimating the proximity to the mesorectal fascia. These authors show that while rectal distention does diminish the distance between the mesorectal fascia and the normal rectal wall, the distance of the tumor does not significantly change. Therefore, the presumed drawbacks of rectal gel may have been exaggerated in the past. In addition, the authors showed that tumor identification was improved due to the presence of rectal gel, which provides high signal on T2-weighted images and distends the rectum, allowing improved detection of the tumor along the rectal wall. Because of these findings, radiologists who do not currently use rectal gel in their scanning should consider adding this to their protocols.(Reviewer–Nicholas L. Fulton, MD).

Article Reviewed: JOURNAL CLUB: Preoperative MRI Evaluation of Primary Rectal Cancer: Intrasubject Comparison With and Without Rectal Distention. Ye F, Zhang H, et al: AJR Am J Roentgenol; 2016;207 (July): 32-39.


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David Bushnell, MD
Coordinating Editor

Professor Radiology, University of Iowa
Chief, Diagnostic Imaging Service, Iowa City VAMC
Iowa City, IA
Reports no commercial interest

Murthy R. Chamarthy, MD
Assistant Professor, Radiology
UT Southwestern Medical Center
Parkland Memorial Hospital
Dallas, TX
Reports no commercial interest

Nicholas L. Fulton, MD
Abdominal Imaging Fellow
University Hospitals Cleveland Medical Center
Cleveland, OH
Reports no commercial interest

Armando S. Herradura, III, MD
Clinical Instructor
University of Pittsburgh Medical Center
Pittsburgh, PA
Reports no commercial interest


Mark T. Madsen, PhD, FAAPM, FACR
Professor of Radiology
University of Iowa
Department of Radiology
Iowa City, IA
Reports no commercial interest

Guest
Stephen R. Baker, MD

Program Director, Professor, and Chairman of Radiology
Associate Dean for Graduate Medical Education
New Jersey Medical School
Scotch Plains, NJ
Rutgers University – New Jersey Medical School
Department of Radiology
Newark, NJ
Reports no commercial interest

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