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Session: Poster session I
Session starts: Thursday 24 January, 15:00

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Anton Nikolaev (Radboud UMC)
Hendrik H. G. Hansen (Radboud UMC)
Eleonora Tagliabue (University of Verona)
Bogdan Mihai Maris (University of Verona)
Vincent Groenhuis (University of Twente)
Chris L. de Korte (Radboud UMC)

Abstract:
Fusion-based ultrasound(US)-guided biopsy in a breast is challenging due to the high flexibility of the tissue combined with the fact that the breast is usually differently deformed for CT, MR, and US acquisition which makes registration difficult. This phantom study demonstrates the feasibility of a fusion-based (MRI to 3D US) ultrasound-guided method for breast biopsy. We built a dedicated setup that facilitated 3D ultrasound scanning of the prone-positioned breast while minimally deforming it. In our setup, the phantom was hanging freely inside a cone-shaped water tank. A 152-mm-width ABVS transducer (Siemens Healthcare, Issaquah, WA, USA) was mounted in the cone wall. The cone was able to revolve around the phantom (360° with 1.14° increment) allowing the acquisition of 2D ultrasound data for multiple image planes. Using functional based reconstruction (Rohling, Gee, & Berman, 1999), a volumetric ultrasound image with a resolution of 0.5x0.5x0.5mm resembling the whole breast phantom could be reconstructed within 2 minutes. An aperture array (20 x 14G diameter) was created on the opposite side of the transducer to enable biopsy needle insertion. For lesion localization, the reconstructed US volume was registered to an MRI volume of the phantom acquired using a Siemens Skyra MRI scanner. Based on the lesion location in 3D space, custom-made software rotated the US transducer such that the lesion was in real-time visible in a 2D imaging plane suitable for biopsy and indicated the number of the aperture, and the lateral and axial coordinates on the US image to aid the radiologist in navigating the biopsy needle to the target region for biopsy. The principle was validated by performing a biopsy of a rigid PVA phantom with 4 lesions (1 cm diameter, 14G needle). Lesions were similar to the phantom in echogenicity but different in color. All 4 biopsied specimen contained the color of the lesion. This demonstrates the applicability of the method towards US occult lesions. The tissue deformation due to needle insertion was not taken into account yet. The next step is an incorporation of real-time lesion displacement estimation for needle trajectory correction to further improve the accuracy of the biopsies.