Application of Ultrasound Image Tracking Algorithm for Real-Time Diaphragmatic Excursion Measurement
Many studies use ultrasound for diaphragmatic excursion (DE) evaluation. The calculation of DE value requires recording the diaphragm movement, freezing the ultrasound image, recalling video and measuring target distance which is time consuming. We aimed at using an ultrasound image tracking algorithm (UITA) to trace diaphragm movement and reveal DE values in real time. We tested UITA with 40 young volunteers under four respiration conditions: standing with quiet breathing (SQB), supine with quiet breathing (SuQB), standing with deep breathing (SDB), and supine with deep breathing (SuDB). The value of DE during SQB, SuQB, SDB, and SuDB was 24.5 ± 10.2, 31.9 ± 10.5, 68.9 ± 15.9, and 98.1 ± 27.4 mm, respectively. We found displacement of diaphragm can be translated to waveforms like spirometry graphs with real-time DE value. DE decreased about 30% in the standing position than in the supine position. Quiet breathing or deep breathing had similar effect on the percent decrease of DE. Further studies are needed to validate this tracking algorithm as a clinical tool in patients with the diaphragm dysfunction.