Colorectal carcinoma: a preliminary study on magnetic resonance imaging / 中华放射学杂志

ABSTRACT

Objective To explore the feasibility and value of MRI examination in colorectal carcinoma. Methods Thirty-eight patients with clinically suspected colorectal carcinoma were included in this study and all of them underwent MRI examination. About 300- 1 000 ml water was administered transrectally before scanning. Axial plain scan, three-planar enhanced scan and hydrography were performed, respectively. Results In 38 patients, 31 cases were pathologically proved as colorectal carcinoma. The main MRI findings were intraluminal soft tissue mass (n=5), irregular thickening of colorectal wall and partial or circumferential stenosis of colorectal lumen (n=26). The tumors were all demonstrated as medium signal intensity on T 1-weighted images. Thirty of 31 cases showed slightly hyperintensity and one was conspicuous high signal intensity on T 2-weighted images. Marked enhancement was demonstrated in all foci. Focal low signal structures were presented in the pericolorectal fat on precontrast T 1-weighted SE sequence in 5 cases. Smooth margins were revealed in 12 cases and irregular and/or nodular margins of peripheral wall in 19 cases. Colorectal hydrography showed that there were intraluminal irregular filling defects (n=14), and that "cuff sign" or "sawn-off sign" was demonstrated in the distal end of tumor and its proximal part couldn't be seen (n=10). Thirty of 31 patients with pathologically proved colorectal carcinoma and 4 of 7 patients with non-colorectal carcinoma were correctly identified by MRI. The sensitivity, specificity, and accuracy were 96.8%, 57.1%, and 89.5%, respectively. The accuracy of MRI in T staging was 83.9% (26/31). The accuracy in T1-2, T3, and T4 staging was 75.0% (9/12), 88.2% (15/17), and 100% (2/2), respectively. Conclusion MRI could clearly show the longitudinal and horizontal invasion of colorectal carcinoma as a whole. It could accurately determine the invasive depth of local lesions. Barium enema examination may be partially replaced by colorectal hydrography with MIP reconstruction. It is of directorial value in clinical treatment.