Purpose: Image-guided biopsy is crucial for diagnosis and surgical planning of women with breast cancer. High-resolution breast functional imaging using positron emission mammography (PEM) demonstrates increased sensitivity for tumour detection compared to conventional modalities. We aim to extend PEM imaging by integrating it with an ultrasound (US)-guided biopsy technique to improve sampling of breast lesions. This study validates the PEM/US guidance device for breast biopsy by quantifying its accuracy.
Methods: An image-guided biopsy device was designed to operate on an advanced PEM system. The device is based on a remote-center-of-motion design and includes a biopsy gun with an integrated US transducer for in-plane imaging of the detected lesion. We validated the device by simulating a detector plate and breast with target lesions in known positions. Twenty-five biopsy procedures were performed on a tissue-mimicking agar breast phantom with embedded cylindrical targets. The needle was guided real-time using US and postfire images were acquired. The biopsy accuracy was quantified as the target being identified in the biopsy sample, distance from the centre of the target and needle, and angle between predicted and actual needle trajectories.
Results: Biopsy success was demonstrated across all trials. The mean targeting error was 0.35Â±0.20mm and the mean trajectory error was 0.48Â±0.35Â°. The targeting and trajectory errors as a function of needle insertion depths demonstrated insignificant linear trends with increasing needle insertion depths. Needle insertion error and mechanical deflection properties will be further examined to evaluate deviations.
Conclusion: We present a new PEM/US guidance device for breast biopsy. Biopsy success across all trials demonstrates reliable in-plane guidance within US elevational resolution. Device accuracy allows sampling of lesions <1mm in diameter. This validation demonstrates feasibility to accurately sample small, detectable lesions when implemented on a high-sensitivity PEM system. Future work will integrate the image-guidance device on the PEM system.
Funding Support, Disclosures, and Conflict of Interest: Funding supported by the Ontario Institute for Cancer Research (OICR) and Natural Sciences and Engineering Research Council (NSERC) of Canada.