Breast cancer: in vivo proton MR spectroscopy in the characterization of histopathologic subtypes and preliminary observations in axillary node metastases.

PURPOSE: To assess the relationship between breast cancer subtypes and choline detection by using in vivo proton magnetic resonance (MR) spectroscopy and to assess the feasibility of proton MR spectroscopy in the study of axillary lymph node metastases.
MATERIALS AND METHODS: Breast and lymph node MR spectroscopy of lesions identified at contrast material-enhanced MR imaging was performed in 39 patients with breast cancer. Spectroscopic and histopathologic findings were determined and compared. The sensitivity, specificity, and accuracy of the MR spectroscopic technique in the detection of axillary lymph node metastases were determined.
RESULTS: There were four cases of ductal carcinoma in situ (DCIS) and 34 invasive carcinomas, including three with an extensive in situ component. Twenty-six breast lesions were positive for choline at MR spectroscopy; nine, negative; and three, failed cases (ie, determination of positive or negative for choline could not be made). No data were available for one lesion. Four of the nine negative findings were DCIS; three, infiltrating ductal carcinoma (IDC) with an extensive in situ component; and two, IDC. Fourteen axillary lymph nodes were positive for choline; 17, negative; and four, failed cases. No data were available for four nodes. Comparison of the preliminary diagnostic indexes of the MR spectroscopic technique with the ultrasonographically guided fine-needle aspiration biopsy findings in lymph nodes revealed a sensitivity of 82%, specificity of 100%, and accuracy of 90%.
CONCLUSION: Choline is consistently detected in IDC. DCIS and IDC with an extensive in situ component are likely to be negative for choline at MR spectroscopy. In vivo proton MR spectroscopy of axillary lymph nodes in patients with breast cancer is feasible and has encouraging preliminary results.