Objective: The purpose of our study was to assess the added value of MR mammography, mammography, and sonography compared with mammography and sonography in diagnostic evaluation of the breast.
Materials and methods: We evaluated reports of MR mammography, conventional mammography, and sonography of the breast in 89 patients who had been referred for surgical biopsy. The dynamic MR mammography examinations were obtained on a 1.0-T MR imager using a double-breast coil and a three-dimensional axial fast low-angle shot sequence. Each type of study was interpreted by a different observer. All mammograms and sonograms were available to all observers. Without knowledge of biopsy results, observers classified mammograms and sonograms (which we call the standard method) as well as mammograms, sonograms, and MR mammograms (which we call the combined method). Classifications were on a per-breast basis: no disease; probably a benign or malignant lesion; and most likely a benign or malignant lesion. A classification of no disease or most likely a benign or malignant lesion was considered to represent a high confidence of the observer in the diagnosis.
Results: Of 98 breasts evaluated with the standard method, observer confidence was high for 44% of all malignant lesions versus 86% with the combined method. The highest specificity (92%) was achieved by interpretation of the standard method (combined method, 64%). The highest sensitivity (95%) was achieved by interpretation of the combined method (standard method, 83%). Overall accuracy was 87% for the standard method and 83% for the combined method. In separate analyses of nonpalpable and palpable lesions, the combined method achieved an accuracy of 74% for nonpalpable lesions and 88% for palpable lesions. The standard method achieved an accuracy of 85% for nonpalpable lesions and 88% for palpable lesions.
Conclusion: MR mammography as an adjunct to mammography and sonography reveals breast cancer with a higher confidence and sensitivity than do mammography and sonography only. The combined method can be recommended if the greatest possible sensitivity or negative predictive value is wanted. However, the combined method is not useful for screening or workup of suspicious lesions because of its lower specificity and accuracy.