MR-guided fine needle aspiration of breast lesions: initial experience.

OBJECTIVE: Fine needle aspiration (FNA) is a minimally invasive procedure that is used to obtain cytologic specimens of suspicious lesions in the breast. The goal of this study was to evaluate the logistics and limitations of MR-guided FNA using a prototype breast localization coil. MATERIALS AND METHODS: MR-guided FNAs were attempted on 18 lesions (detected on mammography and/or palpation) in 16 patients. Patients were prone with their breast compressed mediolaterally between two plates in a circularly polarized RF coil. Lesion position was determined by reference to fiducial markers that corresponded to a grid of holes placed at 5 mm intervals in the compression plate. FNA was performed with a 22G non-ferromagnetic needle. RESULTS: FNA was successful for 11 of 18 lesions (61%). Of the seven unsuccessful cases, there were four in which the lesions were too posteriorly placed to be accessed through the compression plate by the needle. Three cases were too anteriorly placed to be effectively immobilized and, although successfully localized, were insufficiently sampled by the FNA technique. CONCLUSION: MR-guided FNA is possible using a prototype breast localization device in a select group of patients. Current coil design limits its use in performing MR-guided FNA on the most anteriorly and posteriorly placed breast lesions. Unique requirements of FNA under MR guidance as compared to needle localization and biopsy have been identified. Modifications in localization hardware and cytology aspiration needles should overcome these restrictions.