3-DIMENSIONAL OPTICAL ANALYSIS OF CHEST-WALL MOTION

A method for kinematic analysis of chest wall motion is presented, bas ed on a television-image processor that allows a three-dimensional ass essment of volume change of the trunk by automatically computing the c oordinates of several passive markers placed on relevant landmarks of the thorax and abdomen. The parallel computation used for the image pr ocessing allows for a real time recognition of the passive markers wit h the necessary accuracy. A geometric model also allows the online com putation of the contribution to the chest volume by the different part s. For this purpose, the model presented here is based on 54 tetrahedr ons that can be grouped into 9 compartments and 3 sections representin g 1) upper thorax (mainly reflecting the action of neck and parasterna l muscles and the effect of pleural pressure), 2) lower thorax (mainly reflecting the action of diaphragm and the effect of pleural and abdo minal pressure), and 3) abdomen (mainly reflecting the actions of diap hragm and abdominal muscles). By this model, the volume can also be sp lit into three vertical sections pointing out asymmetries between the right and left sides. The method is noninvasive, nonionizing, and leav es the subject maximum freedom of movement during the test, thus being suitable for routine clinical analysis. The monitoring of the subject can be prolonged in time and can be performed in different postures: standing, sitting, and supine. The method was tested on 12 healthy sub jects showing its good accuracy, reliability, and reproducibility.