RESUMO
PURPOSE: To assess the prevalence and characteristics of malignant breast lesions not identified with magnetic resonance (MR) imaging. MATERIALS AND METHODS: Breast tissue specimens were obtained in 464 of 967 patients who had undergone dynamic gadolinium-enhanced T1-weighted fast low-angle shot three-dimensional MR imaging of both breasts. A comparison of sensitivity, specificity, and predictive values of the prospectively recorded findings of mammography, ultrasonography (US), and MR imaging with the histopathologic results was performed with receiver operating characteristic (ROC) curve analysis. MR imaging examination findings that caused a false-negative diagnosis were reviewed to identify possible sources of error. RESULTS: Histopathologic analysis revealed 244 benign and 354 malignant lesions. The sensitivity values for mammography, mammography combined with US, MR imaging alone, and the combination of all three modalities were 73.7%, 88.1%, 88.4%, and 95.5%, and the areas under the ROC curves were 0.744, 0.829, 0.850, and 0.876, respectively. Twenty-eight (8.4%) of 334 invasive and 13 (65%) of 20 intraductal carcinomas were missed with MR imaging. In eight cases, motion artifacts (n = 1), tumor location near or beyond the outer boundary of the field of view (n = 3), inadequate infusion of the contrast material (n = 1), and masking of the tumors by intensively enhanced surrounding glandular tissue (n = 3) were identified as adequate explanations for the false-negative results. The remaining missed breast cancers (n = 33) exhibited very diffuse growth patterns or were 5 mm or smaller. CONCLUSION: MR imaging did not depict 41 of 354 malignant tumors for several reasons.
