Impact of breast biopsy markers on magnetic resonance-guided focused ultrasound

The placement of a biopsy marker at the time of breast biopsy is standard of care to mark the biopsy site and facilitate surgical excision. However, their impact on incisionless treatments like magnetic resonance-guided focused ultrasound remains underexplored. These factors are important considerations for the design and execution of translational research in this field.

Five commercially available markers were evaluated. Magnetic resonance imaging studies characterized artifact size across various treatment planning and monitoring sequences, as well as MR thermometry performance during focused ultrasound heating. Hydrophone scans collected acoustic field measurements in the presence of biopsy markers. Ablated volume in ex vivo tissue with and without markers present was estimated using measurements from thermal dose and gross tissue processing.

Substantial variability in artifact size and shape was observed across the markers. Thermometry showed both imaging and measurement artifacts, with off-target sites showing erroneous temperature change measurements of -30 to 100 °C in some cases. Acoustic field measurements revealed shape- and material-dependent distortions when markers were positioned near the ultrasound focus. Ablation experiments showed mixed effects on treatment volumes.

The presence of biopsy markers introduces marker-dependent complexities into magnetic resonance-guided focused ultrasound treatment planning and monitoring. Reliable monitoring and energy delivery are achievable when the target is sufficiently far from the marker but become unreliable when the target is close to the marker. Accordingly, the potential impacts of biopsy markers on the safety and efficacy of MR-guided focused ultrasound treatments should be considered carefully.