Assessment of the prognostic factors for a local recurrence of rectal cancer: the utility of preoperative MR imaging

Abstract

Objective: To determine the utility of MR imaging in evaluating the prognostic factors for a local recurrence of rectal cancer following a curative resection.

Materials and methods: The preoperative MR images obtained from 17 patients with a local recurrence and 54 patients without a local recurrence, who had undergone a curative resection, were independently evaluated by three radiologists. The following findings were analyzed: the direct invasion of the perirectal fat by the primary rectal carcinoma, involvement of the perirectal lymph nodes, perirectal spiculate nodules, perivascular encasement, and an enlargement of the pelvic wall lymph nodes. The clinical and surgical profiles were obtained from the patients' medical records. The association of a local recurrence with the MR findings and the clinicosurgical variables was statistically evaluated.

Results: Of the MR findings, the presence of perivascular encasement (p = 0.001) and perirectal spiculate nodules (p = 0.001) were found to be significant prognostic factors for a local recurrence. Of the clinicosurgical profiles, the presence of a microscopic vascular invasion (p = 0.005) and the involvement of the regional lymph nodes (p = 0.006) were associated with a local recurrence. Logistic regression analysis showed that the presence of perirectal spiculate nodules was an independent predictor of a local recurrence (odds ratio, 7.382; 95% confidence interval, 1.438, 37.889; p = 0.017).

Conclusion: The presence of perirectal spiculate nodules and perivascular encasement on the preoperative MR images are significant predictors of a local recurrence after curative surgery for a rectal carcinoma. This suggests that preoperative MR imaging can provide useful information to help in the planning of preoperative adjuvant therapy.

Fig. 1

Spiculate nodule with a perivascular encasement depicted on the preoperative MR images obtained from a 70-year-old man with recurrent rectal cancer. A-D. (A) T1-weighted spin-echo, and (B) T2-weighted fast spin-echo images, obtained in a transverse plane show a spiculate nodule (arrowheads) partially surrounding the mesorectal vessel (thin arrows). The mesorectal vessel appears as a tiny dot with dark signal intensity. The T2-weighted fast spin-echo (C) sagittal, and (D) coronal, MR images show the primary tumor (arrows) in the rectum. The spiculate nodule (arrowheads) surrounding the mesorectal vessel (thin arrows) can also be seen.

Fig. 2

Perirectal spiculate nodule depicted on the preoperative MR images (A) in a 62-year-old man and (B) in a 58-year-old woman with rectal cancer. A transverse T2-weighted fast spin-echo axial MR image shows a nodule with irregular margin (arrowheads) in the perirectal fat adjacent the primary rectal tumor (arrows).

Fig. 3

Enlargement of the pelvic wall lymph node demonstrated on the preoperative MR images obtained in a 60-year-old woman with recurrent rectal cancer. A. A transverse T2-weighted fast spin-echo image shows a nodular tumor deposit (arrow) at the right pelvic wall out of the endopelvic fascia (arrowheads). The patient underwent a pelvic wall, lymph node dissection at the right side, and right internal iliac lymph node involvement was demonstrated. B. Contrast-enhanced transverse CT scan obtained six months after surgery. A pelvic wall recurrence was demonstrated in the follow-up CT at the same site of the enlarged pelvic wall lymph node (arrow).