A Novel Normalized Cross-Correlation Speckle-Tracking Ultrasound Algorithm for the Evaluation of Diaphragm Deformation.

Xiong Ye,Zhi Liu,Ying Ma,Hui Xiao,Ye Song,Lihua Hu,Jianwen Luo

doi:10.3389/fmed.2021.612933

Abstract

Objectives: To develop a two-dimensional normalized cross-correlation (NCC)-based ultrasonic speckle-tracking algorithm for right diaphragm deformation analysis.Methods: Six healthy and eight mechanical ventilation patients were enrolled in this study. Images were acquired by a portable ultrasound system in three sections. DICOM data were processed with NCC to obtain the interframe/cumulative vertical and horizontal displacements, as well as the global strain of the right diaphragm, with continuous tracking and drift correction.Results: The NCC algorithm can track the contraction and relaxation of the right diaphragm by following the respiratory movement continuously. For all three sections, the interframe and accumulated horizontal displacements were both significantly larger than the corresponding vertical displacements (interframe p values: 0.031, 0.004, and 0.000; cumulative p values: 0.039, 0.001, and <0.0001). For the global strain of the right diaphragm, there was no significant difference between each pair of sections (all p > 0.05), regardless of whether the horizontal interval of the initial diaphragm point was 1, 3, 5, or 10 times in the sampling interval.Conclusions: This study developed a novel diaphragm deformation ultrasound imaging method. This method can be used to estimate the diaphragm interframe/accumulated displacement in the horizontal and vertical directions and the global strain on three different imaging planes, and it was found that the strain was not sensitive to the imaging plane.

Highlights

The diaphragm is a thin (2–4 mm), movable, dome-shaped, muscular-fibrous structure with a central tendon that separates the thorax from the abdomen and maintains the pressure gradient between those two cavities [1]
In 2013, we proposed the concept of diaphragm deformation analysis and used commercial myocardial speckle-tracking software to evaluate diaphragm strain in healthy volunteers [22]
In this study, according to respiratory physiology, we developed a novel speckle-tracking algorithm [i.e., normalized cross-correlation (NCC) algorithm [25]] to evaluate the kinetic characteristics of the right diaphragm first and carried out a preliminary clinical study in 14 volunteers

Summary

Introduction

The diaphragm is a thin (2–4 mm), movable, dome-shaped, muscular-fibrous structure with a central tendon that separates the thorax from the abdomen and maintains the pressure gradient between those two cavities [1]. It is a vital organ that plays a major role in maintaining ventilation for mammals, as it provides ∼80% of the volume capacity for respiration [2]. There are various causes of PhN injury, such as cardiac or neck surgery, trauma, pneumonectomy, lung tumors, lung or liver transplantation, metabolic disorders, chronic lung diseases, as well as many systemic diseases, such as multiple sclerosis, that can lead to diaphragm paralysis and respiratory failure. Among intensive care unit (ICU) patients, 70% of those with sepsis and multiple organ failure will develop diaphragm dysfunction, which can lead to difficulty in weaning from mechanical ventilation and a prolonged ICU stay [11, 12].

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