Purpose: To retrospectively compare diagnostic performance and interobserver variability for computed tomography (CT) and magnetic resonance (MR) imaging in the pretreatment evaluation of early invasive cervical cancer, with surgical pathologic findings as the reference standard.
Materials and methods: This HIPAA-compliant study had institutional review board approval and informed consent for evaluation of preoperative CT (n = 146) and/or MR imaging (n = 152) studies in 156 women (median age, 43 years; range, 22-81 years) from a previous prospective multicenter American College of Radiology Imaging Network and Gynecologic Oncology Group study of 172 women with biopsy-proved cervical cancer (clinical stage > or = IB). Four radiologists (experience, 7-15 years) interpreted the CT scans, and four radiologists (experience, 12-20 years) interpreted the MR studies retrospectively. Tumor visualization and detection of parametrial invasion were assessed with receiver operating characteristic curves (with P < or = .05 considered to indicate a significant difference). Descriptive statistics for staging and kappa statistics for reader agreement were calculated. Surgical pathologic findings were the reference standard.
Results: For CT and MR imaging, respectively, multirater kappa values were 0.26 and 0.44 for staging, 0.16 and 0.32 for tumor visualization, and -0.04 and 0.11 for detection of parametrial invasion; for advanced stage cancer (> or =IIB), sensitivities were 0.14-0.38 and 0.40-0.57, positive predictive values (PPVs) were 0.38-1.00 and 0.32-0.39, specificities were 0.84-1.00 and 0.77-0.80, and negative predictive values (NPVs) were 0.81-0.84 and 0.83-0.87. MR imaging was significantly better than CT for tumor visualization (P < .001) and detection of parametrial invasion (P = .047).
Conclusion: Reader agreement was higher for MR imaging than for CT but was low for both. MR imaging was significantly better than CT for tumor visualization and detection of parametrial invasion. The modalities were similar for staging, sharing low sensitivity and PPV but relatively high NPV and specificity.