A Formula to Calculate Standard Liver Volume Using Thoracoabdominal Circumference

Area of Science:

• Hepatobiliary surgery
• Transplantation medicine
• Medical imaging and diagnostics

Background:

• Accurate standard liver volume (SLV) estimation is critical for split liver grafts and living donor liver transplantation (LDLT).
• Existing weight-based formulas for SLV are unreliable in cirrhotic patients.
• A novel, weight-independent method for SLV calculation is needed to prevent complications.

Purpose of the Study:

• To develop and validate a new formula for estimating standard liver volume (SLV) independent of patient weight.
• To assess the formula's accuracy in predicting liver graft volume, particularly for small grafts in LDLT.
• To compare the new formula's performance against existing weight-based SLV prediction methods.

Main Methods:

• Computed tomography (CT) scans were used for volumetric evaluation of livers in LDLT donors.
• An optimal formula using thoracoabdominal circumference (TAC) was derived via leave-one-out cross-validation.
• Formula accuracy was validated against existing methods using analysis of variance and exact logistic regression for small graft prediction.

Main Results:

• The developed formula is: SLV = (TAC × 3.5816) - (Age × 3.9844) - (Sex × 109.7386) - 934.5949.
• This new formula showed no significant difference compared to CT-determined liver volumes, unlike historical formulas.
• The formula effectively predicted small-for-size syndrome in LDLT, with an odds ratio of 7.94 (P = 0.025).

Conclusions:

• A novel, weight-independent formula for calculating standard liver volume (SLV) has been developed.
• This formula demonstrates robust predictive accuracy for SLV and identification of potentially small liver grafts.
• The new method offers a valuable tool for optimizing graft selection in living donor liver transplantation.