Colorectal mucinous carcinoma: findings on MRI

The purpose of this work was to define the characteristic MR features of colorectal mucinous carcinomas and to correlate the mucin pool with the signal intensity of this tumor.

MRI of 12 cases of pathologically proven colorectal carcinoma containing mucin was evaluated. We analyzed the signal intensity of tumor on T1- and T2-weighted MR images and correlated the area of intratumoral high signal intensity on T2-weighted images with the mucinous pool on the pathologic specimens. Two radiologists independently estimated the area of high signal intensity in the tumor on T2-weighted images and one pathologist estimated the amount of mucinous pool in the pathologic specimen.

In 9 (75%) of 12 cases, focal or diffuse high signal intensity areas were detected on T2-weighted fast spin echo images. In seven cases in which mucin pools were seen macroscopically, partial (n = 3) or diffuse high signal intensity areas were noted on the T2-weighted images. Among the five cases in which microscopic mucinous pools were detected on the pathologic slides, three cases showed no high signal foci on MR images, and in the remaining two cases, high signal intensity areas were noted as small foci.

Intratumoral high signal intensity on T2-weighted fast spin echo MR images occurs in mucinous carcinomas and correlates with the mucin pools on pathologic specimens.