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Abstract

Objectives: Before liver transplant, it is necessary to know the size of the organ in advance of the procedure. We studied the correlation between liver volumetric computed tomography results and liver weight. Materials and Methods: Postmortem volumetric computed tomography was conducted on cadavers before autopsy, and 3-dimensional liver volume was estimated with semiautomated software. Liver weight was then determined at autopsy. Linear regression and univariate analysis of variance results were used to determine the accuracy of volumetric 3-dimensional computed tomography in estimating liver weight. We also used 2-dimensional liver sizes to design a 2-dimensional formula to estimate liver volume. Results: We found that 3-dimensional volumetric computed tomography was able to accurately estimate liver weight (standard error = 157 g) with a liver density of 0.99 g/mL. Intraobserver and interobserver variabilities were small. The 2-dimensional formula estimated liver weight slightly less accurately (standard error = 212 g). Conclusions: We conclude that liver weight can be estimated accurately with 3-dimensional volumetric computed tomography; estimates were more precise than with the 2-dimensional formula-based liver volume estimation. Volumetric computed tomography can be an important tool during preoperative workup before transplant surgery. Key words: Density, Formula, VolumeIntroduction Liver transplant requires a precise workup of both the donor's and recipient's liver, including evaluation of liver anatomy, parenchyma, vascular supply, and volume. The preoperative assessment of liver volume can be crucial for transplant success. The recipient needs a future liver remnant volume of at least about 30% of the standard liver size. 1,2 In addition, a liver size of about 30% must be preserved in a healthy living donor for survival. Several studies have investigated the estimation of liver size using mathematical formulas to estimate liver volume. [3][4][5][6] However, these formulas were based on the patient's body surface area, body weight, body length, sex, age, and/or race. Standard errors (SE) in the range of 275 to 328 mL were found. Because liver size and shape vary widely between individuals, it may be difficult, if not impossible, to apply estimation formulas with parameters that are based on the body versus the liver.State-of-the-art transplant surgery necessitates imaging of the liver and its vascular supply, which is usually performed with contrast-enhanced computed tomography (CT) or magnetic resonance imaging. Therefore, most donors and recipients of liver transplant have a preoperative CT or magnetic resonance imaging scan. During the past decade, hepatic volumetry and 3-dimensional imaging techniques with CT have been introduced to increase the precision and safety of liver surgery. 7

CT Volumetry of Convoluted Objects—A Simple Method Using Volume Averaging

“…Since the introduction of computed tomography (CT) in the 1970s, there have been numerous methods proposed to estimate the volume of organs or tissues from CT images. The manual planimetric method of tracing the tissue's boundary is perhaps the simplest approach but has its weaknesses [1][2][3][4]: it is tedious, prone to inter-user variation, has difficulty in identifying unsharp interfaces and is often inaccurate [5][6][7]. Other, more sophisticated approaches include:…”

“…A semiautomatic method in which software interpolates an organ contour from a manually outlined contour in one slice [4].…”