The Possibilities of Magnetic Resonance Imaging in the Differential Diagnosis of Recurrent Rectal Cancer and Postoperative Scars

The purpose: to develop differential diagnostic criteria  of recurrence and scarring by using various MRI techniques. Materials and methods. MRI of the pelvis was performed in 139 patients at different times after removal of colorectal cancer. Recurrence was diagnosed in 48 (34.5%) patients. The shape, size, structure, signal characteristics and the intensity of the accumulation of contrast agent in zones of recurrence and scarring were analyzed. The patients were divided into three groups with different types of postoperative MRI pattern of pelvic: patients without scarring in the pelvis, patients with a homogeneous scarring, patients with inhomogeneous scarring. The present  study was compared with MRI data performed in the early  stages after surgery. Results. The recurrences with typical MR characteristics were so easy to identify and did not require differential  diagnosis. The patients with recurrence occurred in severe  scar process in the pelvis needed for differential diagnosis.  The detection of recurrence and monitoring of patients  without scarring in the pelvis was not difficult. The greatest  difficulties arose during the initial examination of patients  with inhomogeneous scarring. The difficulties in the differential diagnosis occurred at small sizes of recurrence up to 15 mm, making it impossible to assess their structure and  signal characteristics; in the event of relapse in presacral  areas of scarring, the presence of areas of hemorrhage  in the tumor structure. Conclusions. The presence of severe scar process in the pelvis was the main reason for difficulties in detection and differential diagnosis of recurrence of rectal cancer.