Medical image data used for the development of computational human body models are often retrospectively acquired, and researchers are unlikely to encounter scans of healthy individuals in specific postures. We prospectively acquired scans in both prone and supine postures from 22 healthy young adults; M:F 1:1, with age, height, and weight of 28.8±7.0 years, 173.0±7.8 cm, and 70.6±10.9 kg. While prone, subjects arms were superior to the head and supported by a foam insert at axilla. Breath held, T1-weighted MRI scans were acquired using a Siemens Skyra 3T with an in-plane resolution of 1.56 mm (TR: 4.10 ms, TE: 1.23 ms, thickness: 2 mm, matrix: 256x256, FOV: 400 mm). Gross thoraco-abdominal compression was considered as the change in perpendicular distance in the transverse plane measured from the anterior margin of L4/L5 to the table (for prone) or exterior body surface (for supine). Gross thoraco-abdominal, liver and spleen compression were found to be 8.5% (71.6±12.9 mm prone vs. 78.7±12.4 mm supine; p=0.0013), 17.7% (110.4±4.1 mm prone vs. 134.8±2.6 mm supine; p<0.0001), and 3.5% (53.8±1.9 mm prone vs. 57.3±2.9 mm supine) respectively. Gender and spleen compression differences were not noted. The liver and spleen migrated on average 8.3 mm posteriorly, 11.4 mm rightward, 15.1 mm superiorly and 4.1 mm anteriorly, 6.1 mm rightward, 1.7 mm superiorly respectively. The data obtained from this set may be of use in computational biomechanics, surgical simulation, and medical device design.