Vacuum-assisted breast biopsies (VAB) carried out on an open 1.0T MR imager: Influence of patient and target characteristics on the procedural and clinical results.

PURPOSE: The study was conducted in order to assess the clinical impact of MRI-guided vacuum-assisted breast biopsies carried out using an open 1.0T open MRI-system. MATERIAL AND METHODS: The clinical, imaging, interventional and histological data of all 132 patients with a first MRI-guided vacuum-assisted breast biopsy carried out between 07/2005 and 03/2012at the Radiological Department were extracted from the clinical files. The clinical outcome of patients with benign histological findings was assessed based on the clinical files and queries of the local gynecologists in charge. In the 103 interventional image data sets available target localization and target size were evaluated by two board-certified senior radiologists. Clinical data, lesion characteristics and interventional results were evaluated statistically using subgroup analyses. RESULTS: 131 of 132 MRI-guided breast biopsies (99.2%) were carried out successfully. The median interventional duration was 30min (25%-percentile 25min, 75%-percentile 35min, maximum 75min). Minor complications occurred in 12 interventions of the 131 (9.2%). The histological work-up of the biopsy specimen showed benign results in 98 of 131 interventions (74.8%), lesions with uncertain biological potential in 5 biopsies (3.8%) and malignant findings in 28 biopsies (21.4%). There were 2 false negative histological findings. Neither the patient age nor the medical history nor the anticipated risk of developing breast cancer had an impact on the success rates and the complication rates. In the 103 interventions with available image data sets the maximum target lesion diameters were 1-5mm in 16 lesions (15.5%), 6-10mm in 41 lesions (39.8%) and 11-15mm in 29 lesions (28.2%). There was a positive correlation between the maximum diameters and the rate of malignancy of the target lesions (p=0.020) as well as a trend towards longer interventional procedure durations in smaller target lesions (p=0.183). CONCLUSION: MRI-guided vacuum-assisted breast biopsy for suspicious breast lesions is a clinically safe and feasible method even in small target lesions when using an open high-field MRI-system.

Impact of clinical and lesion characteristics on the results of MR-guided wire localizations of the breast using an open 1.0-T MRI system.

PURPOSE: Preoperative magnetic resonance (MR)-guided wire localizations are warranted in patients with suspicious focal breast lesions on MR mammographic findings without equivalent in x-ray mammography and ultrasonography. The study was performed to assess the impact of clinical parameters, tumor size, and target localization on the procedural characteristics in magnetic resonance imaging (MRI)-guided wire localizations of breast lesions using an open 1.0-T open MR system. MATERIAL AND METHODS: The clinical, radiological, and histological characteristics of all 347 patients and all 394 interventional procedures performed in a 6-year interval were extracted from the clinical files. Two board-certified senior radiologists evaluated the impact of target localization and the size on the interventional results in the available 302 image data sets. Patient characteristics, lesion characteristics, and interventional results were statistically correlated in subgroup analyses. RESULTS: A total of 387 of the 394 MR-guided wire localizations (98.2%) were technically successful. In 7 cases (2.3%), the intervention was aborted because the suspicious finding of the diagnostic MR mammography could not be visualized during the intervention. Minor complications occurred in 13 interventions (3.3%). The histological workup of the operative specimen showed benign results in 226 of the 394 interventions (57.4%) and malignant findings in 154 wire localizations (39.1%). The mean (SD) length of the interventional procedure time defined as the time interval between the start of the first and of the last MRI sequence as documented in the electronic MRI data sets was 24.6 (8.4) minutes. Patient age, medical history, and the anticipated risk for developing breast cancer and a simultaneous known carcinoma did not affect the technical success and complication rates and the interventional procedure time. A total of 60 targets (19.5%) were located in the retromamillary zone, 89 targets (28.9%) in the peripheral zone, and 1 target (0.3%) near the chest wall. The maximum diameter was 1 to 5 mm in 64 lesions (21.2%), 6 to 10 mm in 136 lesions (45.0%), 11 to 15 mm in 56 lesions (18.6%), and 16 mm or greater in 46 lesions (15.2%). A total of 23 of the 100 histologically proven invasive carcinomas had a maximum MRI diameter of 1 to 5 mm (23.0%) and 38 (38.0%) of 6 to 10 mm. CONCLUSIONS: Magnetic resonance-guided wire localizations of suspicious breast lesions using an open high-field MR system are a clinically safe and feasible method even in small target lesions and anatomical regions that are usually considered difficult to access.