To investigate the correlation and feature changes of in vitro body contours and diaphragmatic displacement in different exhalation modes. We used the dynamic magnetic resonance imaging to sample the right thoracic sagittal image of 28 young volunteers in three modes of thoracic breathing, abdominal breathing, and free breathing. Measurements of the five external contours and diaphragmatic changes in the images were taken and their correlation and displacement characteristics were evaluated using their time-shift curves. We found that guided thoracic breathing has a more stable diaphragmatic shift. In the three breathing modes models, the height of the navel in the abdomen of the body contour displacement and the diaphragmatic shift has a high correlation. While the former three sections in the diaphragm section, the diaphragms near the posterior vertebrae had larger displacement amplitudes and the highest correlation with in vitro displacement. We recommend that the patient be able to have guided thoracic breathing to ensure stability of organ displacements. When the treatment or examination is performed, if the target area is located near the posterior abdominal wall of the thoracoabdominal junction, more displacement may need to be considered to ensure that the treatment target volume completely encompasses the tumor.
