Purpose: A surgical navigation system supports the comprehension of anatomical information during surgery. Patient-to-image registration is the alignment process between CT volume and patient coordinate systems. Achieving accurate registration in the surgical navigation of laparoscopic surgery is very challenging due to soft tissue deformation. This paper presents a new patient-to-image registration method based on internal anatomical landmarks for improving registration accuracy in the surgical navigation of laparoscopic gastrectomy for gastric cancer.
Methods: Our proposed registration method progressively utilizes internal anatomical landmarks. In laparoscopic gastrectomy for gastric cancer, the surgeon cuts the blood vessels around the stomach. The positions of the cut vessels are sequentially used as fiducials for registration during surgery. The proposed method uses a weighted point-based registration method for computing the transformation matrix using the fiducials both on the body surface and on the blood vessels. When a blood vessel is cut during surgery, the proposed progressive registration method measures the cut vessel's position and computes a transformation matrix by adding the cut vessel as a fiducial.
Results: We applied our proposed progressive registration method using the positional information of the blood vessels acquired during laparoscopic gastrectomy in 20 cases. We evaluated it using target registration error in four blood vessels. The average target registration error in the four blood vessels was 12.6 mm and ranged from 2.1 to 32.9 mm.
Conclusion: Since the proposed progressive registration can reduce registration error, our proposed method is very useful for the surgical navigation of laparoscopic gastrectomy. Our proposed progressive registration method might increase the accuracy of surgical navigation in laparoscopic gastrectomy.
Keywords: Gastric cancer; Laparoscopic gastrectomy; Laparoscopic surgery; Registration; Surgical navigation.