Differentiation of poorly differentiated colorectal adenocarcinomas from well- or moderately differentiated colorectal adenocarcinomas at contrast-enhanced multidetector CT.

PURPOSE

The purpose of the study is to describe the CT findings of poorly differentiated (PD) colorectal adenocarcinoma (CRAC) compared with those of well- (WD) or moderately differentiated (MD) CRAC.

MATERIALS AND METHODS

One hundred and thirteen patients with pathologically proven PD (n = 26), WD (n = 35), or MD (n = 52) CRACs and who had undergone preoperative, contrast-enhanced multidetector CT (MDCT) imaging were included. Analysis of the CT findings included the morphologic and enhancement features of primary tumors and regional lymph nodes (LNs), and the presence of direct invasion, colonic obstruction, and distant metastasis. The significance of these findings was determined using the χ (2) test.

RESULTS

Significant features favoring the diagnosis of PD CRACs over WD or MD CRACs included their bulky shape, heterogeneous enhancement, iso- or hypoattenuation compared with that of muscle, nodular pericolic fat infiltration, regional LNs > 10 mm, and/or with iso- or hypoattenuation compared with that of muscle, and the presence of distant metastasis (P < 0.05). When at least two of these seven imaging features were used in combination, the sensitivity and specificity in the diagnosis of PD CRACs were 88% and 70%, respectively.

CONCLUSION

Using characteristic CT features, one can differentiate PD CRAC from WD or MD CRAC with a high degree of accuracy on contrast-enhanced MDCT.