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Preoperative staging of rectal cancer using magnetic resonance imaging with external phase-arrayed coils
Giuseppe Gagliardi1, Sancar Bayar, Robert Smith
1Department of Surgical Oncology, School of Medicine, Yale University, 333 Cedar St, New Haven, CT 06520, USA.
Hypothesis:
Rectal cancer can be accurately staged preoperatively by magnetic resonance imaging (MRI) with external phase-arrayed coils.
Design:
Comparison of MRIs with pathologic staging.
Setting:
University hospital.
Patients:
Twenty-eight consecutive patients with biopsy-proven rectal cancer who did not undergo irradiation.
Intervention:
Patients underwent imaging using a 1.5-T MRI scanner with external phase-arrayed surface coils. Streaking of the perirectal fat and disruption of the bowel wall margin were interpreted as transmural invasion. Lymph nodes were defined as metastatic when they had a diameter of at least 0.5 cm. Tumors were staged according to the TNM staging system (American Joint Committee on Cancer guidelines) as confined to the bowel wall (T1-T2) and invading through the bowel wall (T3-T4). Patients underwent anterior resection (n = 15), abdominoperineal resection (n = 11), or local excision (n = 2).
Main Outcome Measures:
Calculation of sensitivity, specificity, and accuracy for invasion through the bowel wall and lymph node status.
Results:
Sensitivity of MRI in detecting invasion through the bowel wall was 89% (16/18), specificity was 80% (8/10), and accuracy was 86% (24/28). Sensitivity for malignant lymphadenopathy was 67% (8/12), specificity was 71% (10/14), and accuracy 69% (18/26).
Conclusion:
Although more costly and not as accurate as endoscopic ultrasound, MRI with phase-arrayed coils had excellent sensitivity at detecting transmural penetration of rectal cancer.