MRI-guided breast biopsy at 3T using a dedicated large core biopsy set: feasibility and initial results.

OBJECTIVE: The increasing importance of breast MRI in the diagnostic processes concerning breast cancer yield often lesions that are visible on MRI only. To assess the nature of these lesions, pathologic analysis is necessary. Therefore, MR-guided biopsy should be available. Breast MRI at 3T has shown advantage over 1.5T. Unfortunately, current equipment for MR-guided biopsy is better suited for intervention at 1.5T due to the danger of heating titanium co-axial sleeves and large susceptibility artifacts. We evaluated a dedicated 3T breast biopsy set that uses plastic coaxial needles to overcome these problems. MATERIALS AND METHODS: We performed MRI-guided breast biopsy in 23 women with 24 MRI-only visible breast lesions at 3T. Biopsy procedures were performed with plastic coaxial needles in a closed bore 3T clinical MR system on a dedicated phased array breast coil with a commercially available add-on stereotactic biopsy device. RESULTS: Width of the needle artifact was 2mm in all 24 cases. Biopsy procedure was completed between 35 and 67 min. The procedure was judged moderately easy in 12 and normal in 10 cases. One procedure was judged difficult and there was one technical failure. CONCLUSION: MRI-guided breast biopsy at 3T is a fast and accurate procedure. The plastic coaxial needles reduce the susceptibility artifact largely and do not increase the difficulty of the procedure. The diagnostic yield is at least equal to the diagnostic yield of the same procedure at 1.5T. Therefore, this technique can be safely used for lesions only visible at 3T MRI.

MR-guided breast biopsy using an active marker: a phantom study.

PURPOSE: To evaluate the advantages of using an active marker (active micro coil) for MR-guided breast biopsy procedures. MATERIALS AND METHODS: An add-on breast biopsy guidance device used with a standard breast coil was equipped with an active marker. The marker's position was determined with a dedicated MRI sequence. In combination with custom software, the biopsy planning process was reduced basically to defining the target in the diagnostic MR images. Automatic control scans verified the settings of the biopsy guidance device. To measure the targeting accuracy, x-ray control of the needle placement was performed in phantoms containing 36 small titanium cylinders. The reliability of the procedure was evaluated in 24 core needle biopsies on phantoms. Workflow enhancements were analyzed. RESULTS: The root mean square deviation of the needle position from the target perpendicular to the needle axis was 1.25 mm, in three-dimensions it was 1.35 mm. All targets were sampled successfully. The duration of a phantom biopsy was nine minutes. CONCLUSION: The use of an active marker can offer advantages for MR-guided breast biopsies in terms of handling and procedure time as well as accuracy.

MR imaging-guided prostate biopsy with a closed MR unit at 1.5 T: initial results.

The authors evaluated a magnetic resonance (MR) imaging-compatible biopsy device comprising a needle guide that can be visualized with MR imaging and manipulated mechanically from outside the MR unit. With approval from the local ethics committee and patient consent, this device was tested in 12 patients by using a closed 1.5-T MR unit and a body phased-array coil. Patients had elevated prostate-specific antigen levels (6-60 ng/mL) and one or more areas in the prostate that were suspicious for carcinoma at prebiopsy MR imaging. Biopsy was performed with transrectal access and with the patient prone. A 16-gauge MR imaging-compatible needle was successfully positioned with the device, and between six and nine tissue cores were obtained in each patient. In one patient, two suspicious basal areas could not be reached with the device. Histologic analysis showed prostate cancer in five patients and prostatitis in six. No complications were observed. The device enabled MR imaging-guided core-needle biopsy of prostate areas suspicious for cancer on MR images.