Liver volumetry: Is imaging reliable? Personal experience and review of the literature

Abstract

The amount of the future liver remnant volume is fundamental for hepato-biliary surgery, representing an important potential risk-factor for the development of post-hepatectomy liver failure. Despite this, there is no uniform consensus about the amount of hepatic parenchyma that can be safely resected, nor about the modality that should be chosen for this evaluation. The pre-operative evaluation of hepatic volume, along with a precise identification of vascular and biliar anatomy and variants, are therefore necessary to reduce surgical complications, especially for extensive resections. Some studies have tried to validate imaging methods [ultrasound, computed tomography (CT), magnetic resonance imaging] for the assessment of liver volume, but there is no clear evidence about the most accurate method for this evaluation. Furthermore, this volumetric evaluation seems to have a certain degree of error, tending to overestimate the actual hepatic volume, therefore some conversion factors, which should give a more reliable evaluation of liver volume, have been proposed. It is widespread among non-radiologists the use of independent software for an off-site volumetric analysis, performed on digital imaging and communications in medicine images with their own personal computer, but very few studies have provided a validation of these methods. Moreover, while the pre-transplantation volumetric assessment is fundamental, it remains unclear whether it should be routinely performed in all patients undergoing liver resection. In this editorial the role of imaging in the estimation of liver volume is discussed, providing a review of the most recent literature and a brief personal series of correlations between liver volumes and resection specimens' weight, in order to assess the precision of the volumetric CT evaluation.

Validating New Software for Semiautomated Liver Volumetry – Better than Manual Measurement?

“…D'Onofrio et al used the same semiautomated software as we did but compared it to software running on a personal computer. They found a total liver volume of 1787.31 ml, which is comparable to the results found in the present study [14]. Certainly every method has its own limitations and it is difficult to compare absolute volumes across different studies.…”

“…However, D'Onofiro et al also measured resected liver parts with different sizes with the same semiautomated software as used in the present study. They found a mean volume of resected liver parts of 1021.23 ml, which is comparable to our results, although they only used the weight of the surgical specimen as the gold standard [14]. Additionally, they did not give any information about the time needed for volumetry and reproducibility.…”

“…In the abovementioned studies [8,11,14] [20]. The present study systematically assessed different levels of experience, which makes this study unique.…”

Fast and accurate liver volumetry prior to hepatectomy

“…15,16 Therefore, OsiriX ® liver volumetry was selected as reference measurement to compare with auto-segmentation using iNtuition ® . Volumetric analysis using OsiriX ® version 5.0.2 32-bit was performed by two observers (observer 1 and 2).…”

Computed tomography volume measurements of the liver using a liver segmentation and analysis package: an intra- and inter-rater reliability study

“…Multiple automated and semi-automated liver segmentation tools have been developed and are collectively referred to as software assisted image post-processing (SAIP) tools. [13] SAIP tools are increasing in popularity and have been proven to be very accurate in predicting liver volumes. [14,15] Studies have shown that measurement of liver volume using SAIP tools correlate well with manual volumetry, [16] and with the added advantage of being a substantially faster method of volume calculation, [17] they are being touted as the new gold standard for liver volumetry.…”