Acoustic reflector-enabled forward-viewing ultrasound image-guided access.

Purpose: Existing ultrasound (US) image-guided needle access methods applied in various surgical procedures (such as percutaneous nephrolithotomy) face the challenge of keeping the needle tip visible during the insertion process due to the unguaranteed alignment between the US image and needle. We propose a needle insertion mechanism with reflector-integrated US imaging, where the US image plane and the needle are mechanically aligned, and the needle is inserted in a forward-viewing style to provide more intuitive access.

Approach: An acoustic reflector is used to redirect the US image plane while the needle goes through the slit in the middle of the acoustic reflector so that the needle path aligns with the US image plane. Both the bracket holding the needle and the acoustic reflector are rotatable to provide clinicians with the flexibility to search for the optimal needle insertion orientation. Effects of the slit in the reflector on the quality of post-reflection ultrasound images were evaluated. Needle tip visibility was evaluated in water and ex vivo beef tissue. Needle access accuracy was evaluated using point targets embedded in gelatin, and errors between the needle tip and point targets are estimated from X-ray images.

Results: The slit in the reflector has limited effects on post-reflection image quality. The needle tip was visible in water and in ex vivo tissue, and its visibility was quantified using a signal-to-noise ratio. Needle access results showed an average insertion error of less than 3 mm.

Conclusions: Our results demonstrate the clinical potential of the reflector-enabled forward-viewing US image-guided access mechanism.