Development of IKOMAP Formulas for Determining Appropriate Liver Transection Line in Ultrasound-Guided Minimally Invasive Partial Hepatectomy Considering Liver Inclination.

Abstract

Background: Ultrasound-guided minimally invasive liver resection on inclined surfaces presents challenges in accurately setting transection lines.

Methods: This study aimed to propose IKOMAP formulas to calculate the distance (Y) from the point directly above the tumor (Point C) to the optimal marking point (Point A) on inclined surfaces. The goal was to reliably reach Point D, which represents the shortest distance from the tumor while maintaining assigned surgical margins on the transection line. The formula was derived using five parameters: the probe incidence angle (a), hepatic resection angle (b), tumor radius (U), tumor depth (V), and resection margin distance (Z). The deepest point on the assumed straight transection line was defined as point B.

Results: From triangle ABC, Y = BC × tan(90° - b + a), and from triangle BDE, BC = (U + Z)/sin(90° - b + a) + U + V. Substituting these values yields the final formula: Y = {(U + Z)/sin(b - a) + (U + V)/tan(b - a)}.

Conclusions: IKOMAP formulas enable the precise calculation of the optimal marking point on inclined surfaces, ensuring surgical margin accuracy based on the preset and assigned parameters.