Lung Ultrasound Surface Wave Elastography Research Articles

Noninvasive measurement of lung elastic properties

Many lung diseases are associated with dramatic changes in mechanical properties of the lung. Chest radiographs and computed tomography (CT) are the most common clinical methods for evaluating lung disease, but they are expensive, use radiation, and do not measure lung stiffness. Shear wave elastography (SWE) uses ultrasound radiation force (URF) to generate wave propagation in the tissue. However, URF should not be applied to the lung, because there are air and blood in the alveoli. Relatively high-intensity ultrasound can cause alveolar hemorrhage and lung injury. We have developed a noninvasive, and clinically feasible technology, lung ultrasound surface wave elastography (LUSWE), that is capable of measuring lung elastic properties with speed and accuracy. LUSWE uses a handheld shaker to generate a local small harmonic vibration on the chest surface. The resulting wave propagates through the intercostal muscle and propagates on the lung. The surface wave speed is noninvasively measured using an ultrasound technique. LUSWE is safe because diagnostic ultrasound is only used to detect the wave propagation along the lung duo to mechanical wave generation on the chest. LUSWE may be used to assess multiple lung disorders such as lung fibrosis or lung edema.

Application of lung ultrasound surface wave elastography in the evaluation of diffuse lung diseases

The evaluation of diffuse lung disease invariably involves chest computerized tomography (CT). The detailed information obtained is often equivalent to that from lung biopsies. It, however, involves exposure to ionising radiation which limits its repeated application in monitoring and follow up. Ultrasound techniques offer potentially safer/cheaper alternatives and lung ultrasound surface wave elastography (LUSWE) is a novel, noninvasive, and clinically feasible technique to quantify lung stiffness, an important biomechanical property that changes in diffuse fibrotic and infiltrative lung diseases. We have developed a sensitive, accurate and reproducible technique to measure changes in lung surface stiffness by using surface wave transmission speed and demonstrated its value in detecting and staging the degree of fibrosis in diffuse interstitial lung diseases, specifically idiopathic pulmonary fibrosis and progressive systemic sclerosis associated lung disease, as well as changes in heart failure. The technique consists of ultrasound detection of the propagation speed of a wave generated by the vibrations from an indenting shaker in multiple intercostal spaces to provide a representative assessment of both lungs. It offers the prospect of simple, radiation-free, repetitive assessment of changes in acute and chronic diffuse lung diseases with the potential for easy and rapid bedside use, all important considerations in clinical practice.

Lung Ultrasound Surface Wave Elastography for Assessing Patients With Pulmonary Edema.

B-Mode ultrasound insonation of lungs that are dense with extravascular lung water (EVLW) produces characteristic reverberation artifacts termed B-lines. The number of B-lines present demonstrates reasonable correlation to the amount of EVLW. However, analysis of B-line artifacts generated by this modality is semi-quantitative relying on visual interpretation, and as a result, can be subject to inter-observer variability. The purpose of this study was to translate the use of a novel, quantitative lung ultrasound surface wave elastography technique (LUSWE) into the bedside assessment of pulmonary edema in patients admitted with acute congestive heart failure. B-mode lung ultrasound and LUSWE assessment of the lungs were performed using anterior and lateral intercostal spaces in the supine patient. 14 patients were evaluated at admission with reassessment performed 1-2 days after initiation of diuretic therapy. Each exam recorded the total lung B-lines, lung surface wave speeds (at 100, 150, and 200 Hz) and net fluid balance. The patient cohort experienced effective diuresis (average net fluid balance of negative 2.1 liters) with corresponding decrease in pulmonary edema visualized by B-mode ultrasound (average decrease of 13 B-Lines). In addition, LUSWE demonstrated a statistically significant reduction in the magnitude of wave speed from admission to follow-up. The reduction in lung surface wave speed suggests a decrease in lung stiffness (decreased elasticity) mediated by successful reduction of pulmonary edema. In summary, LUSWE is a noninvasive technique for quantifying elastic properties of superficial lung tissue that may prove useful as a diagnostic test, performed at the bedside, for the quantitative assessment of pulmonary edema.

Lung mass density prediction using machine learning based on ultrasound surface wave elastography and pulmonary function testing.

The objective of this study is to predict in vivo lung mass density for patients with interstitial lung disease using different gradient boosting decision tree (GBDT) algorithms based on measurements from lung ultrasound surface wave elastography (LUSWE) and pulmonary function testing (PFT). Age and weight of study subjects (57 patients with interstitial lung disease and 20 healthy subjects), surface wave speeds at three vibration frequencies (100, 150, and 200 Hz) from LUSWE, and predicted forced expiratory volume (FEV1% pre) and ratio of forced expiratory volume to forced vital capacity (FEV1%/FVC%) from PFT were used as inputs while lung mass densities based on the Hounsfield Unit from high resolution computed tomography (HRCT) were used as labels to train the regressor in three GBDT algorithms, XGBoost, CatBoost, and LightGBM. 80% (20%) of the dataset was used for training (testing). The results showed that predictions using XGBoost regressor obtained an accuracy of 0.98 in the test dataset. The obtained results suggest that XGBoost regressor based on the measurements from LUSWE and PFT may be able to noninvasively assess lung mass density in vivo for patients with pulmonary disease.

Introduction of lung ultrasound surface wave elastography

Ultrasonography is not widely used for lung assessment because ultrasound cannot image deep lung tissue. Many lung diseases including interstitial lung disease (ILD) are associated with changes in lung's elastic properties. ILD includes multiple serious lung disorders associated with lung fibrosis and can lead to respiratory failure and pulmonary hypertension. High-resolution CT (HRCT) is the clinical standard for diagnosing lung fibrosis, but it results in increased radiation exposure for patients. Lung fibrosis is associated with stiffened lung parenchyma. Current clinical techniques including HRCT cannot measure lung elastic properties. Most ILDs are typically distributed in the lung's peripheral and subpleural regions. We developed noninvasive lung ultrasound surface wave elastography (LUSWE) to measure lung surface wave speed safely and quickly. In this abstract, we will present some basics for LUSWE. We will also present its clinic application for assessing ILD. We studied 30 healthy controls, 16 mild ILD patients, 45 moderate ILD patients, and 27 severe ILD patients. Lung surface wave speed has good sensitivity and specificity for separating ILD patients from healthy subjects as well as for separating mild ILD patients from healthy subjects. LUSWE is useful for other lung disorders such as pulmonary edema.

Predicting lung mass density of patients with interstitial lung disease and healthy subjects using deep neural network and lung ultrasound surface wave elastography

The Hounsfield unit (HU) obtained from high resolution computed tomography (HRCT) has been used to assess lung pathology. However, lung mass density has not been quantified in vivo noninvasively. The objective of this study was to develop a method for analyzing lung mass density of superficial lung tissue of patients with interstitial lung disease (ILD) and healthy subjects using a deep neural network (DNN) and lung ultrasound surface wave elastography (LUSWE). Surface wave speeds at three vibration frequencies (100, 150 and 200 Hz) from LUSWE and a pulmonary function test (PFT) including predicted forced expiratory volume (FEV1% pre) and ratio of forced expiratory volume to forced vital capacity (FEV1%/FVC%) were used. Predefined lung mass densities based on the HU for ILD patients and healthy subjects (77 in total) were also used to train the DNN model. The DNN was composed of four hidden layers of 1024 neurons for each layer and trained for 80 epochs with a batch size of 20. The learning rate was 0.001. Performances of two types of activation functions in the DNN, rectified linear activation unit (ReLU) and exponential linear unit (ELU), as well as, machine learning models (support vector regression, random forest, Adaboost) were evaluated. The test dataset of wave speeds, FEV1% pre and FEV%/FVC%, was used to predict lung mass density. The results showed that predictions using a DNN with ELU obtained a comparatively better performance in the testing dataset (accuracy = 0.89) than those of DNN with ReLU or machine learning models. This method may be useful to noninvasively analyze lung mass density by using the DNN model together with the measurements from LUSWE and PFT.

An ex vivo technique for quantifying mouse lung injury using ultrasound surface wave elastography

Idiopathic pulmonary fibrosis is a progressively fatal disease with limited treatments. The bleomycin mouse model is often used to simulate the disease process in laboratory studies. The aim of this study was to develop an ex vivo technique for assessing mice lung injury using lung ultrasound surface wave elastography (LUSWE) in the bleomycin mouse model. The surface wave speeds were measured at three frequencies of 100, 200, and 300 Hz for mice lungs from control, mild, and severe groups. The results showed significant differences in the lung surface wave speeds, pulse oximetry, and compliance between control mice and mice with severe pulmonary fibrosis. LUSWE is an evolving technique for evaluating lung stiffness and may be useful for assessing pulmonary fibrosis in the bleomycin mouse model.

Quantification of lung surface wave speed in a water-filled lung: An ex vivo swine lung study

Lung edema is a common symptom of congestive heart failure and inflammatory conditions, such as acute respiratory distress syndrome. Currently, computed tomography (CT) is considered the standard to assess lung edema, but it requires ionizing radiation and poses a significant logistic burden. Lung ultrasound (LUS) has previously been used to assess lung edema using ultrasound B-line artifacts, but analysis of the B-line artifacts relies on visual interpretation. We developed lung ultrasound surface wave elastography (LUSWE) to measure lung surface wave speed safely. This project aims to evaluate LUSWE to quantify lung surface wave speed in an ex vivo water-filled swine lung. The lung surface wave speeds were measured at baseline and at frequencies of 100 Hz, 200 Hz, 300 Hz, and 400 Hz. Then, an amount of water was filled into the lung through its trachea. Ultrasound imaging was used to guide the water filling until significant changes were visible on the imaging. The lung surface wave speeds were measured. An additional 120 ml of water was then filled into the lung. The lung surface wave speeds were measured again. The results demonstrated that the lung surface wave speed decreased with respect to water content.Lung edema is a common symptom of congestive heart failure and inflammatory conditions, such as acute respiratory distress syndrome. Currently, computed tomography (CT) is considered the standard to assess lung edema, but it requires ionizing radiation and poses a significant logistic burden. Lung ultrasound (LUS) has previously been used to assess lung edema using ultrasound B-line artifacts, but analysis of the B-line artifacts relies on visual interpretation. We developed lung ultrasound surface wave elastography (LUSWE) to measure lung surface wave speed safely. This project aims to evaluate LUSWE to quantify lung surface wave speed in an ex vivo water-filled swine lung. The lung surface wave speeds were measured at baseline and at frequencies of 100 Hz, 200 Hz, 300 Hz, and 400 Hz. Then, an amount of water was filled into the lung through its trachea. Ultrasound imaging was used to guide the water filling until significant changes were visible on the imaging. The lung surface wave speeds were measured...

A Pilot Study of Wet Lung Using Lung Ultrasound Surface Wave Elastography in an Ex Vivo Swine Lung Model.

Extravascular lung water (EVLW) is a basic symptom of congestive heart failure and other conditions. Computed tomography (CT) is standard to assess EVLW, but it requires ionizing radiation and radiology facilities. Lung ultrasound reverberation artifacts called B-lines have been used to assess EVLW. However, B-line artifact analysis relies on visual interpretation and subjects to inter-observer variability. We developed lung ultrasound surface wave elastography (LUSWE) to measure lung surface wave speed. This research aims to develop LUSWE to measure the change of lung surface wave speed due to lung water in an ex vivo swine lung model. The surface wave speeds of a fresh ex vivo swine lung were measured at four frequencies of 100 Hz, 200 Hz, 300 Hz, and 400 Hz. An amount of water was then filled into the lung through its trachea. Ultrasound imaging was used to guide the water filling until significant changes were visible on the imaging. The lung surface wave speeds were measured. An additional 120 ml of water was then filled into the lung. The lung surface wave speeds were then measured again. The results demonstrated that the lung surface wave speed decreased with respect to water content.

Assessment of Interstitial Lung Disease Using Lung Ultrasound Surface Wave Elastography: A Novel Technique With Clinicoradiologic Correlates.

Optimal strategies to detect early interstitial lung disease (ILD) are unknown. ILD is frequently subpleural in distribution and affects lung elasticity. Lung ultrasound surface wave elastography (LUSWE) is a noninvasive method of quantifying superficial lung tissue elastic properties. In LUWSE a handheld device applied at the intercostal space vibrates the chest at a set frequency, and the lung surface wave velocity is measured by an ultrasound probe 5 mm away in the same intercostal space. We explored LUWSE's ability to detect ILD and correlated LUSWE velocity with physiological, quantitative, and visual radiologic features of subjects with known ILD and of healthy controls. Seventy-seven subjects with ILD, mostly caused by connective tissue disease, and 19 healthy controls were recruited. LUSWE was performed on all subjects in 3 intercostal lung regions bilaterally. Comparison of LUSWE velocities pulmonary function testing, visual assessment, and quantitative analysis of recent computed tomographic imaging with Computer-Aided Lung Informatics for Pathology Evaluation and Rating (CALIPER) software. Sonographic velocities were higher in all lung regions for cases, with the greatest difference in the lateral lower lung. Median velocity in m/s was 5.84 versus 4.11 and 5.96 versus 4.27 (P<0.00001) for cases versus controls, left and right lateral lower lung zones, respectively. LUSWE velocity correlated negatively with vital capacity and positively with radiologist and CALIPER-detected interstitial abnormalities. LUSWE is a safe and noninvasive technique that shows high sensitivity to detect ILD and correlated with clinical, physiological, radiologic, and quantitative assessments of ILD. Prospective study in detecting ILD is indicated.

Application of lung ultrasound surface wave elastography for assessment of extravascular lung water in patients hospitalized with congestive heart failure

Lung ultrasound (LUS) detects the presence of extravascular lung water (EVLW) through the visualization of B-Line artifacts. However, the qualitative nature of LUS limits its effectiveness in serial or longitudinal studies such as evaluating changes in EVLW at different time points in patients undergoing diuretic therapy for congestive heart failure. Lung ultrasound surface wave elastography (LUSWE) is a novel technique using a small handheld device that can measure superficial lung tissue elastic properties. We aimed to evaluate the use of LUSWE to measure quantitative changes in lung elasticity caused by acute changes in EVLW. We performed LUSWE on consecutive days in 14 patients hospitalized for acute congestive heart failure with evidence of pulmonary edema (clinical EVLW). From day#1 to day#2, the patients had an average diuresis of net negative 2.1 l associated with an average decrease in 13 B-Lines by lung ultrasound, signifying a reduction in EVLW. LUSWE analysis demonstrated a significant reduction (p < 0.05) in surface wave velocity in all interrogated intercostal spaces from day#1 to day#2. In summary, LUSWE performed at the bedside was able to demonstrate improvement in lung compliance (decreased elasticity) correlating with a reduction in EVLW in hospitalized patients being treated for congestive heart failure.

A quantitative method for measuring the changes of lung surface wave speed for assessing disease progression of interstitial lung disease

Lung ultrasound surface wave elastography (LUSWE) is a novel non-invasive technique for measuring superficial lung tissue stiffness. The purpose of the study described here was to develop LUSWE for assessment of progression in patients with interstitial lung disease (ILD). In this study, LUSWE was used to measure changes in lung surface wave speeds at 100, 150 and 200 Hz through six intercostal lung spaces for 52 patients with ILD. The mean age was 63.1 ± 12.0 y (range: 20–85, 23 male and 29 female). The follow-up interval was 9.2 ± 3.5 mo depending on each patient's return appointment and availability. For each patient, disease progression between the baseline and follow-up tests was evaluated clinically using a 7-point Likert scale comprising three grades of improvement (mild, moderate, marked), unchanged status and three grades of worsening (mild, moderate, marked). Clinical assessments were based on changes in pulmonary function tests together with high-resolution computed tomography, echocardiography and clinical evaluations. This study illustrates the correlations between changes in lung surface wave speed and clinical assessments. Correlations of changes in lung surface wave speed at lower lateral and posterior portions of the lung portions with clinical assessments were good. LUSWE provides quantitative global and regional changes in lung surface wave speed that may be useful for quantitative assessment of progression of ILD.

Lung Ultrasound Surface Wave Elastography for Assessing Interstitial Lung Disease.

Our goal is to translate lung ultrasound surface wave elastography (LUSWE) for assessing patients with interstitial lung disease (ILD) and various connective tissue diseases including systemic sclerosis (SSc). LUSWE was used to measure the surface wave speed of lung at 100, 150, and 200 Hz through six intercostal lung spaces for 91 patients with ILD and 30 healthy control subjects. In addition, skin viscoelasticity was measured on both forearms and upper arms for patients and controls. The surface wave speeds of patients' lungs were significantly higher than those of control subjects. Patient skin elasticity and viscosity were significantly higher than those of control subjects. In dividing ILD patients into two groups, ILD with SSc patients and ILD without SSc patients, significant differences between each patient group with the control group were found for both the lung and skin. No significant differences were found between the two patient groups, although there were some differences at a few locations and at 100 Hz for skin viscoelasticity. Significant differences of surface wave speed were found between ILD patients and healthy control subjects for both the lung and skin. LUSWE may be useful for assessing ILD and SSc and screening early stage patients.

Effect of a Thin Fluid Layer on Surface Wave Speed Measurements: A Lung Phantom Study.

Lung ultrasound (US) surface wave elastography (SWE) is a novel technique that measures superficial lung tissue elastic properties. A thin pleural fluid layer covers a lung, but its effect on lung measurements in SWE is unknown. We modeled a lung and pleural fluid with sponges and a thin layer of US transmission gel. Sponge surface wave speeds measured from SWE were compared for sponges without and with the thin US gel layer at 3 wave excitation frequencies. The comparison showed that the sponge surface wave speed measurements were not affected by the thin gel layer.

The effect of pleural fluid layers on lung surface wave speed measurement: Experimental and numerical studies on a sponge lung phantom

Pleural effusion manifests as compression of pleural fluid on the lung parenchyma contributing to hypoxemia. Medical procedures such as drainage of plural fluid releases this compression and increases oxygenation. However, the effect of pleural effusion on the elasticity of lung parenchyma is unknown. By using lung ultrasound surface wave elastography (LUSWE) and finite element method (FEM), the effect of pleural effusion on the elasticity of superficial lung parenchyma in terms of surface wave speed measurement was evaluated in a sponge phantom study. Different thicknesses of ultrasound transmission gel used to simulated pleural fluid were inserted into a condom, which was placed between the sponge and standoff pad. A mechanical shaker was used to generate vibration on the sponge phantom at different frequencies ranging from 100 to 300 Hz while the ultrasound transducer was used to capture the motion for measurement of surface wave speed of the sponge. FEM was conducted based on the experimental setup and numerically assessed the influence of pleural effusion on the surface wave speed of the sponge. We found from FEM experiments that the influence of thickness of ultrasound transmission gel was statistically insignificant on the surface wave speed of the sponge at 100 and 150 Hz.

Lung ultrasound surface wave elastography

Lung ultrasound surface wave elastography (LUSWE) was developed for noninvasively measuring superficial lung tissue stiffness. In LUSWE, a 0.1 second harmonic vibration is generated on the chest wall of a subject using a handheld vibrator. An ultrasound probe is aligned with the vibration excitation in the same intercostal space to measure the generated surface wave propagation on the lung. A human subject is examined in a sitting position. The lung is tested at the total lung volume and through three intercostal spaces on each lung. In a prospective clinical study, we measure the lung surface wave speeds at 100 Hz, 150 Hz, and 200 Hz on 91 patients with interstitial lung disease (ILD) and 30 healthy control subjects. Significant differences of wave speed between patients and controls were found in all 6 lung regions and for 3 frequencies. We also found positive correlation between LUSWE and clinical assessments including CT and pulmonary function tests. LUSWE is used to track the changes of surface wave speed for patients. LUSWE is a safe and noninvasive technique for generating and measuring surface wave propagation on the lung. LUSWE may complement the clinical standard high-resolution computed tomography for assessing ILD.Lung ultrasound surface wave elastography (LUSWE) was developed for noninvasively measuring superficial lung tissue stiffness. In LUSWE, a 0.1 second harmonic vibration is generated on the chest wall of a subject using a handheld vibrator. An ultrasound probe is aligned with the vibration excitation in the same intercostal space to measure the generated surface wave propagation on the lung. A human subject is examined in a sitting position. The lung is tested at the total lung volume and through three intercostal spaces on each lung. In a prospective clinical study, we measure the lung surface wave speeds at 100 Hz, 150 Hz, and 200 Hz on 91 patients with interstitial lung disease (ILD) and 30 healthy control subjects. Significant differences of wave speed between patients and controls were found in all 6 lung regions and for 3 frequencies. We also found positive correlation between LUSWE and clinical assessments including CT and pulmonary function tests. LUSWE is used to track the changes of surface wave ...

A Lung Phantom Model to Study Pulmonary Edema Using Lung Ultrasound Surface Wave Elastography

Lung ultrasound surface wave elastography (LUSWE) is a novel technique used to measure superficial lung tissue stiffness. A phantom study was carried out in the study described here to evaluate the application of LUSWE to assess lung water for pulmonary edema. A lung phantom model with cellulose sponge was used; various volumes of water were injected into the sponge to model lung water. Shaker-generated surface wave propagation on the sponge surface was recorded by a 10-MHz ultrasound probe at three shaker frequencies: 100, 150 and 200Hz. Surface wave speeds were calculated but did not exhibit dependence on the volume of injected water. However, the shear viscosity of the sponge increased with water content, and shear elasticity also exhibited a subtle increase. This study suggests that sponge viscoelasticity might change with the water content, which can be detected by LUSWE.

Lung ultrasound surface wave elastography for assessing interstitial lung disease

Many lung diseases including interstitial lung disease (ILD) are associated with changes in the lung’s biomechanical properties. ILD comprises a number of serious diseases in which fibrosis stiffens and damages lung tissue. Most ILDs are typically distributed in the lung’s peripheral and subpleural regions. Pulmonary function test (PFT) and high-resolution computed tomography (HRCT) are used to assess ILD. Ultrasonography is not widely used for lung assessment because ultrasound cannot image deep lung tissue. We have developed lung ultrasound surface wave elastography (LUSWE) for measuring superficial lung wave speed. In LUSWE, a 0.1-s harmonic vibration is generated on the chest wall of a subject using a handheld vibrator. An ultrasound probe is aligned with the vibration excitation in the same intercostal space to measure the generated surface wave propagation on the lung. A human subject is examined in a sitting position. The lung is tested at the total lung volume and through six intercostal spaces. Significant differences of surface wave speed between patients and controls were found in 6 lung regions and for 3 excitation frequencies. A positive correlation between LUSWE and clinical tests including HRCT and PTF was found. LUSWE may complement the clinical standard HRCT for assessing ILD.

Lung mass density analysis using deep neural network and lung ultrasound surface wave elastography

Lung mass density is directly associated with lung pathology. Computed Tomography (CT) evaluates lung pathology using the Hounsfield unit (HU) but not lung density directly. We have developed a lung ultrasound surface wave elastography (LUSWE) technique to measure the surface wave speed of superficial lung tissue. The objective of this study was to develop a method for analyzing lung mass density of superficial lung tissue using a deep neural network (DNN) and synthetic data of wave speed measurements with LUSWE. The synthetic training dataset of surface wave speed, excitation frequency, lung mass density, and viscoelasticity from LUSWE (788,000 in total) was used to train the DNN model. The DNN was composed of 3 hidden layers of 1024 neurons for each layer and trained for 10 epochs with a batch size of 4096 and a learning rate of 0.001 with three types of optimizers. The test dataset (4000) of wave speeds at three excitation frequencies (100, 150, and 200 Hz) and shear elasticity of superficial lung tissue was used to predict the lung density and evaluate its accuracy compared with predefined lung mass densities. This technique was then validated on a sponge phantom experiment. The obtained results showed that predictions matched well with test dataset (validation accuracy is 0.992) and experimental data in the sponge phantom experiment. This method may be useful to analyze lung mass density by using the DNN model together with the surface wave speed and lung stiffness measurements.

Lung ultrasound surface wave elastography for assessing interstitial lung disease

A lung ultrasound surface wave elastography (LUSWE) technique is developed for assessing interstitial lung disease (ILD). In LUSWE, a 0.1 second harmonic vibration is generated on the chest wall of a subject using a handheld vibrator. An ultrasound probe is aligned with the vibration indenter in the same intercostal region to measure the generated surface wave speed of the lung. A human subject is examined in a sitting position. The lung is tested at the total lung volume. The upper anterior lungs are tested through the second intercostal space in the mid-clavicular line. The lower lateral lungs are tested in the mid-axillary line and the lower posterior lungs are tested in the mid-scapular line. In a prospective clinical study, we measure both lungs through the six intercostal regions for patients and healthy controls. The surface wave speed is measured at 100 Hz, 150 Hz, and 200 Hz. Significant differences of wave speed between patients and controls were found in all lung regions at all frequencies. We also found positive correlation between LUSWE and CT analyses. LUSWE is a safe and noninvasive technique for generating and measuring surface wave propagation on the lung. LUSWE may be useful for assessing ILD.A lung ultrasound surface wave elastography (LUSWE) technique is developed for assessing interstitial lung disease (ILD). In LUSWE, a 0.1 second harmonic vibration is generated on the chest wall of a subject using a handheld vibrator. An ultrasound probe is aligned with the vibration indenter in the same intercostal region to measure the generated surface wave speed of the lung. A human subject is examined in a sitting position. The lung is tested at the total lung volume. The upper anterior lungs are tested through the second intercostal space in the mid-clavicular line. The lower lateral lungs are tested in the mid-axillary line and the lower posterior lungs are tested in the mid-scapular line. In a prospective clinical study, we measure both lungs through the six intercostal regions for patients and healthy controls. The surface wave speed is measured at 100 Hz, 150 Hz, and 200 Hz. Significant differences of wave speed between patients and controls were found in all lung regions at all frequencies. We ...