Preoperative evaluation of pelvic lateral lymph node of patients with lower rectal cancer: comparison study of MR imaging and CT in 53 patients.

Background: Preoperative assessment of the lateral pelvic lymph nodes is important for treatment strategy to patients with lower rectal cancer.

Materials And Methods: Fifty-three patients with primary lower rectal cancer were preoperatively assessed by spiral computed tomography (CT) and magnetic resonance imaging (MRI) at 1.5 T with a phased-array coil. Preoperative tumor and lymph node stages were compared with the final histological findings.

Results: The MRI tumor stage coincided with the histological stage in 36 of 53 patients (68%). The MRI and CT lymph node stage coincided with the histological stage in 33 (62%) and 26 (49%) of 53 patients, respectively. However the accuracy of MRI in detecting the lateral pelvic lymph node involvement was 83%, compared to 77% of CT (p<0.05).

Conclusions: With the use of MRI, the lateral pelvic lymph node involvement can be predicted with high accuracy, allowing preoperative identification of patients who need radiotherapy or extensive surgery to escape recurrence.