Thoracoabdominal organ volumes for small women

Abstract

Objective: Thoracoabdominal injuries commonly occur as a result of motor vehicle crashes. In order to design occupant protection systems that reduce risk of injury, researchers are using a variety of tools, including computational human body models. Though research has been conducted to provide morphological and volumetric data for the thoracoabdominal cavity of the average male, there is currently an interest in developing models for a wider range of occupants. One particular cohort of interest is the small female by stature and weight because of their use in restraint system development. Geometric data on thoracoabdominal organs are needed to construct accurate representations of female occupants. This study aimed to gather information on organ volumes from clinical medical imaging studies of small females.

Methods: Anonymized clinical computed tomography (CT) and magnetic resonance images were used to segment organs relevant to crash-induced injuries: namely, the liver, spleen, left kidney, right kidney, pancreas, gallbladder, lungs, and heart. Segmentations were conducted using semi-automatic techniques. Additionally, diametric measurements of the vena cava, aorta, trachea, and colon were obtained from the medical images at discrete locations using linear measurement tools.

Results: A total of 14 adult scans were selected with stature and weight ranges of 145.0 to 162.6 cm and 43.7 to 65.5 kg, respectively. The following are the average thoracoabdominal organ volumes: liver (1,224.5 ± 220.7 mL), spleen (151.6 ± 42.1 mL), left kidney (123.7 ± 20.1 mL), right kidney (115.4 ± 20.9 mL), heart (417.8 ± 36.6 mL), pancreas (54.1 ± 11.8 mL), and gallbladder (20.6 ± 13.4 mL). The average diameters were 19.7 ± 3.2 mm and 17.7 ± 5.1 mm for the vena cava and aorta, respectively. The colon had an average diameter of 37.9 ± 7.1 mm.

Conclusion: Data characterizing the small female are important to validate the geometries used in computational models, including models derived from scaling techniques and those developed using subject-specific medical imaging. The goal of this study was to use a sample of subjects anthropometrically representative of small females to evaluate the average volume for organs commonly injured in motor vehicle crashes. Based on these data, the right and left lungs were strongly correlated with stature and the heart was strongly correlated with weight. Ultimately, these measurements will be useful for the validation of computational models of the small female.

Keywords: 5th percentile female; abdominal organ volume; modeling; segmentation; small female.