Evaluation of intrathoracic tracheal narrowing in patients with obstructive ventilatory impairment using dynamic chest radiography: A preliminary study

ACR Appropriateness Criteria® Tracheobronchial Disease

A variety of thoracic imaging modalities and techniques have been used to evaluate diseases of the trachea and central bronchi. This document evaluates evidence for the use of thoracic imaging in the evaluation of tracheobronchial disease, including clinically suspected tracheal or bronchial stenosis, tracheomalacia or bronchomalacia, and bronchiectasis. Appropriateness guidelines for initial imaging evaluation of tracheobronchial disease and for pretreatment planning or posttreatment evaluation are included. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Dynamic chest radiographic evaluation of the effects of tiotropium/olodaterol combination therapy in chronic obstructive pulmonary disease: the EMBODY study protocol for an open-label, prospective, single-centre, non-controlled, comparative study

INTRODUCTION

To date, there is limited evidence on the effects of bronchodilators on respiratory dynamics in chronic obstructive pulmonary disease (COPD). Dynamic chest radiography (DCR) is a novel radiographic modality that provides real-time, objective and quantifiable kinetic data, including changes in the lung area (Rs), tracheal diameter, diaphragmatic kinetics and pulmonary ventilation during respiration, at a lower radiation dose than that used by fluoroscopic or CT imaging. However, the therapeutic effect of dual bronchodilators on respiratory kinetics, such as chest wall dynamics and respiratory muscle function, has not yet been prospectively evaluated using DCR.

AIM

This study aims to evaluate the effects of bronchodilator therapy on respiratory kinetics in patients with COPD using DCR.

METHODS AND ANALYSIS

This is an open-label, prospective, single-centre, non-controlled, comparative study. A total of 35 patients with COPD, aged 40-85 years, with a forced expiratory volume in the first second of 30-80%, will be enrolled. After a 2-4 weeks washout period, patients will receive tiotropium/olodaterol therapy for 6 weeks. Treatment effects will be evaluated based on DCR findings, pulmonary function test results and patient-related outcomes obtained before and after treatment. The primary endpoint is the change in Rs after therapy. The secondary endpoints include differences in other DCR parameters (diaphragmatic kinetics, tracheal diameter change and maximum pixel value change rate), pulmonary function test results and patient-related outcomes between pre-therapy and post-therapy values. All adverse events will be reported.

ETHICS AND DISSEMINATION

Ethical approval for this study was obtained from the Ethics Committee of Chiba University Hospital. The results of this trial will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

jRCTs032210543.

A Multi-armed Unfurling Actuator for Airway Lumen Measurement

Objective measurement of the lumen area demands an intraoperative diagnostic tool to aid on-site decision-making. We present a compliant mechanism-based unfurling actuator assembly integrated with a shaft connected to a motorized encoder to translate torque from the user at the proximal end to the actuator at the distal end. The actuator assembly has flexible arms coiled inside a cylindrical casing that moves radially outward upon actuation. Leveraging 3D printing of flexible materials, the unfurling actuator's four-arm design enables patency measurements in circumferential tracheal stenosis of varying grades. The rotary encoder output is correlated with the radially outward movement of the unfurling arms to estimate the lumen diameter. The measurement stability is analyzed using process control charts; data distribution over ten iterations reveals nearly 100% of process data falls between ±3 sigma (Upper and Lower control limits). Comparing measurements from the tool with direct measurement (vernier caliper) and ImageJ analysis, one-way ANOVA for circular morphology yields no significant differences in diameter p = 0.974 and area measurements p = 0.975.Clinical Relevance- Central airway narrowing reduces the effective lumen area in the tracheal and bronchial segments. Grading the degree of narrowing is often based on a suspicion index. A quick but thorough assessment of the airway caliber is essential in emergent or planned intubation, whether congenital, iatrogenic, or idiopathic tracheal stenosis.

Dynamic chest radiography: a state-of-the-art review

Dynamic chest radiography (DCR) is a real-time sequential high-resolution digital X-ray imaging system of the thorax in motion over the respiratory cycle, utilising pulsed image exposure and a larger field of view than fluoroscopy coupled with a low radiation dose, where post-acquisition image processing by computer algorithm automatically characterises the motion of thoracic structures. We conducted a systematic review of the literature and found 29 relevant publications describing its use in humans including the assessment of diaphragm and chest wall motion, measurement of pulmonary ventilation and perfusion, and the assessment of airway narrowing. Work is ongoing in several other areas including assessment of diaphragmatic paralysis. We assess the findings, methodology and limitations of DCR, and we discuss the current and future roles of this promising medical imaging technology.Critical relevance statement Dynamic chest radiography provides a wealth of clinical information, but further research is required to identify its clinical niche.

[Paradigm Shift in Respiratory Diagnosis: Current Status and Future Prospects of Dynamic Chest Radiography]

Dynamic chest radiography (DCR) is a flat-panel detector (FPD) -based functional X-ray imaging, which is performed as an additional examination in chest radiography. The large field of view of FPDs permits real-time observation of motion/kinetic findings on the entire lungs, right and left diaphragm, ribs, and chest wall; heart wall motions; respiratory changes in lung density; and diameter of the intrathoracic trachea. Since the dynamic FPDs had been developed in the early 2000s, we focused on the potential of dynamic FPDs for functional X-ray imaging and have launched a research project for the development of an imaging protocol and digital image-processing techniques for the DCR. The quantitative analysis of motion/kinetic findings is helpful for a better understanding of pulmonary function, because the interpretation of dynamic chest radiographs is challenging and time-consuming for radiologists, pulmonologists, and surgeons. Recent clinical studies have demonstrated the usefulness of DCR combined with the digital image processing techniques for the evaluation of pulmonary function and circulation. Especially, there is a major concern in color-mapping images based on dynamic changes in radiographic lung density, where pulmonary impairments can be detected as color defects, even without the use of contrast media or radioactive medicine. Dynamic chest radiography is now commercially available for the use in general X-ray room and therefore can be deployed as a simple and rapid means of functional imaging in both routine and emergency medicine. This review article describes the current status and future prospects of DCR, which might bring a paradigm shift in respiratory diagnosis.

Two cases of chronic obstructive pulmonary disease evaluated by dynamic-ventilatory digital radiography for pulmonary function and assessment of treatment efficacy

Spirometry is a crucial test used in the diagnosis and monitoring of patients with chronic obstructive pulmonary disease (COPD). Severe acute respiratory syndrome coronavirus 2 pandemic has posed numerous challenges in performing spirometry. Dynamic-ventilatory digital radiography (DR) provides sequential chest radiography images during respiration with lower doses of radiation than conventional X-ray fluoroscopy and computed tomography. Recent studies revealed that parameters obtained from dynamic DR are promising for evaluating pulmonary function of COPD patients. We report two cases of COPD evaluated by dynamic-ventilatory DR for pulmonary function and treatment efficacy and discuss the potential of dynamic DR for evaluating COPD therapy.

Prediction of forced vital capacity with dynamic chest radiography in interstitial lung disease

PURPOSE

The pulmonary function test (PFT) has played an essential role in diagnosing and managing interstitial lung disease (ILD) but has its contraindications and difficult conditions to perform. Therefore, the present study aimed to evaluate dynamic chest radiography (DCR) ability to predict forced vital capacity (FVC) and other PFT parameters of ILD patients.

METHOD

The prospective observational study included 97 patients who underwent DCR at Tenri Hospital (Tenri, Japan) between June 2019 and April 2020. Twenty-five patients with stable disease status underwent DCR twice to evaluate test-retest reliability using the intraclass correlation coefficient. From the lung field areas measured by DCR, lung volumes at maximum inspiration (V.ins) and expiration (V.exp) were estimated. Correlation coefficients between the measured values of DCR and PFT parameters were calculated. Multilinear models for predicting FVC and other PFT parameters were developed.

RESULTS

Intraclass correlation coefficients between first and second measurements of V.ins and V.exp were 0.94 (95% CI: 0.89-0.97, p < 0.001) and 0.88 (95% CI: 0.78-0.94, p < 0.001), respectively. The correlation coefficient between V.ins and FVC was 0.86 (95% CI: 0.79-0.90, p < 0.001). A multilinear model for predicting FVC was developed using V.ins, V.exp, age, sex, and body mass index as predictor variables, wherein the adjusted coefficient of determination was 0.814.

CONCLUSIONS

Lung volumes measured by DCR correlated with the lung function of ILD patients. Prediction models with high predictive power and internal validity were developed, suggesting that DCR can predict FVC and other PFT parameters of ILD patients.

Chest Dynamic-Ventilatory Digital Radiography in Chronic Obstructive or Restrictive Lung Disease

Objective

The aim of this study was to identify the relationships between parameters obtained from dynamic-ventilatory digital radiography (DR) and ventilatory disorders.

Methods

This study comprised 273 participants with respiratory diseases who underwent spirometry and functional residual capacity measurements (104 with normal findings on spirometry as controls, 139 with an obstructive lung disorder, 30 with a restrictive lung disorder) were assessed by dynamic-ventilatory DR. Sequential chest radiography images of the patient’s slow and maximum breathing were captured at 15 frames per second by a dynamic flat-panel imaging system. The system measured the following parameters: lung area at maximum inspiration divided by height (lung area_in/height), changes in tracheal diameter due to respiratory motions, rate of tracheal narrowing, diaphragmatic motion, and rate of change in lung area due to respiratory motion. Relationships between these parameters and ventilatory disorders were analyzed.

Results

Lung area_in/height in patients with restrictive disorders showed significant decreases. Tracheal diameter change and tracheal narrowing rate in patients with obstructive disorders were significantly increased compared to both the control participants and patients with restrictive disorders. Patients with obstructive disorders and patients with restrictive disorders showed decreased diaphragmatic motion and lung area change rate. With the restrictive disorders as references, the area under the curve (AUC), sensitivity and specificity of lung area_in/height were 0.88, 0.77, and 0.88, respectively. With the obstructive disorders as references, the AUC, sensitivity and specificity of tracheal narrowing rate were 0.67, 0.53 and 0.81, respectively.

Conclusion

Dynamic-ventilatory DR shows potential as a method for the detection and evaluation of ventilatory disorders in patients with respiratory diseases.

Dynamic perfusion digital radiography for predicting pulmonary function after lung cancer resection

Background

Accurate prediction of postoperative pulmonary function is important for ensuring the safety of patients undergoing radical resection for lung cancer. Dynamic perfusion digital radiography is an excellent and easy imaging method for detecting blood flow in the lung compared with the less-convenient conventional lung perfusion scintigraphy. As such, the present study aimed to confirm whether dynamic perfusion digital radiography can be evaluated in comparison with pulmonary perfusion scintigraphy in predicting early postoperative pulmonary function and complications.

Methods

Dynamic perfusion digital radiography and spirometry were performed before and 1 and 3 months after radical resection for lung cancer. Correlation coefficients between blood flow ratios calculated using dynamic perfusion digital radiography and pulmonary perfusion scintigraphy were then confirmed in the same cases. In all patients who underwent dynamic perfusion digital radiography, the correlation predicted values calculated from the blood flow ratio, and measured values were examined. Furthermore, ppo%FEV1 or ppo%DLco values, which indicated the risk for perioperative complications, were examined.

Results

A total of 52 participants who satisfied the inclusion criteria were analyzed. Blood flow ratios measured using pulmonary perfusion scintigraphy and dynamic perfusion digital radiography showed excellent correlation and acceptable predictive accuracy. Correlation coefficients between predicted FEV1 values obtained from dynamic perfusion digital radiography or pulmonary perfusion scintigraphy and actual measured values were similar. All patients who underwent dynamic perfusion digital radiography showed excellent correlation between predicted values and those measured using spirometry. A significant difference in ppo%DLco was observed for respiratory complications but not cardiovascular complications.

Conclusions

Our study demonstrated that dynamic perfusion digital radiography can be a suitable alternative to pulmonary perfusion scintigraphy given its ability for predicting postoperative values and the risk for postoperative respiratory complications. Furthermore, it seemed to be an excellent modality because of its advantages, such as simplicity, low cost, and ease in obtaining in-depth respiratory functional information.

Trial registration

Registered at UMIN on October 25, 2017. https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_his_list.cgi?recptno=R000033957

Registration number: UMIN000029716

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-021-02158-w.