Shortly after, a modified version for 3D imaging, namely U-Net3D 6, was presented, in order to utilize the spatial context of volumetric data. Voxels without majority annotation were marked with an ignore label and thus ignored in subsequent analyses.Ī popular network architecture choice for medical image segmentation is the U-Net 5, especially promoted to be good for optimization with very few examples. In addition, a standard of reference (SoR) was derived from all three readers by majority voting. The training data set was annotated by a single reader with right and left lobe segments, whereas the test data set was annotated by three different readers. Please refer to the supplement for detailed information about the scanner parameters. Venous phase imaging was performed 70–80 s after intravenous administration of a contrast agent, with a median tube voltage of 100 kVp ranging from 90 to 120 kVp. All CT scans were performed with multidetector-row CT systems, mainly with 16- or higher detector-row systems. The validation data was resampled to 5 mm slice thickness for a unified voxel spacing. For validation an external dataset consisting of 30 CT scans (12 female, 18 male) with a slice thickness of 1.5 mm was collected from the Medipol University Hospital in Istanbul, Turkey. In this work, a dataset consisting of 100 abdominal/liver CT scans (53 female, 47 male) with a slice thickness of 5 mm was collected at the University Medicine Essen. The aim of our study was to develop a convolutional neural network (CNN) based tool for fully automated preoperative assessment of right and left liver volumes with respect to the central hepatic vein from standard computed tomography scans of the liver, without the need of an experienced examiner, which is reproducible and fast. These tools are still very time-consuming and depend on the experience of the examiner. There are several new software tools for automated and accurate volumetry developed in the last few years. The volumetry of the right and left liver lobes is extremely time-consuming and, depending on the experience of the examiner, afflicted with an estimation error of 5%-35% 2– 4. The generally accepted tool for the estimation of the liver volume and its lobes is the contrast enhanced computed tomography or magnetic resonance imaging. The remnant volume in living donors should be at least 30% of the liver volume since donor safety has absolute priority. For non cirrhotic livers in healthy subjects, resections of up to 80% of the liver volume can be tolerated. In order to avoid liver dysfunction in the recipient, the graft weight to body weight ratio should be at least 1%. The total liver volume has a known relation to the body weight, which is described to be around 2.5% in healthy subjects 1. The postoperative morbidity and mortality rate of living donor liver transplantation correlates significantly with functional liver volume for the recipient and the donor. Future remnant liver volume is a key factor for oncologic liver resections, as well as for optimal donor selection in living donor liver transplantation. Our results show that fully automated 3D volumetry of the liver on routine CT imaging can provide reproducible, quantitative, fast and accurate results without needing any examiner in the preoperative work-up for hepatobiliary surgery and especially for living donor liver transplantation.Īccurate assessment of the liver volume is essential in the preoperative work-up for hepatobiliary surgery. Multi-Resolution U-Net 3D neural networks were employed for segmenting these liver regions. Therefore, an in-house dataset of 100 venous phase CT examinations for training and 30 venous phase ex-house CT examinations with a slice thickness of 5 mm for testing and validating were fully annotated with right and left liver lobe. The aim of this study was to develop a fully automated, reproducible, and quantitative 3D volumetry of the liver from standard CT examinations of the abdomen as part of routine clinical imaging. The precise preoperative calculation of functional liver volumes is essential prior major liver resections, as well as for the evaluation of a suitable donor for living donor liver transplantation.
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