The value of lateral chest X-rays for the diagnosis of lymphadenopathy in children with pulmonary tuberculosis

A research report submitted to the Faculty of Health Sciences, University of Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Medicine in the branch of Diagnostic Radiology Johannesburg 2018.INTRODUCTION: Tuberculosis (TB) is an important public health issue, but diagnosis in children can be challenging. The radiological hallmark of pulmonary TB (PTB) in children is mediastinal lymphadenopathy, however there is inter-observer variability in detecting this. The value of the lateral CXR in addition to the frontal view to detect lymphadenopathy has not been well studied. OBJECTIVES: To investigate the prevalence of lymphadenopathy in children with confirmed PTB detected on frontal compared to frontal-lateral CXRs. METHODS: This was a secondary analysis of a study from Red Cross Children’s Hospital in Cape Town. Children with definite TB and a control group (Lower respiratory tract infection other than TB) who had frontal and lateral CXRs were included in this study. Three radiologists independently read the CXRs in 2 separate sittings (frontal CXR and ‘combination frontallateral’ CXR). A 3 reader consensus reading was used during data analysis. Odds ratios and 95% confidence intervals were calculated to determine the presence of lymphadenopathy. Kappa statistics were calculated to determine inter reader agreement. RESULTS: Of 172 children (88 confirmed TB and 84 control children), with a median age of 29 months, lymphadenopathy was reported in 86 (50%) patients on the frontal CXR alone and in 143 (83%) on the frontal-lateral CXR combination, p= 0.00. Amongst confirmed PTB cases, 52 (60%) had lymphadenopathy on the frontal CXR alone while 72 (82%) had lymphadenopathy on the frontal-lateral CXR combination, p= 0.00. Amongst the control group, 34 (40%) had lymphadenopathy on the frontal CXR alone while 71 (85%) had lymphadenopathy on the frontal-lateral CXR combination, p= 0.00. The consensus reading using a frontal-lateral CXR combination resulted in a 5 fold increase (OR 4,9; 95% CI 2,9-8,4) in diagnosis of lymphadenopathy compared to a frontal CXR only. Overall inter reader agreement for all 3 readers was fair on both the frontal CXR (Kappa= 0,21) and the frontal-lateral CXR (Kappa= 0,23) combination. CONCLUSION: The addition of a lateral view to the frontal CXR increased detection of lymphadenopathy, however, the prevalence of lymphadenopathy was similar in children with PTB and those in the control group, with fair inter reader agreement.LG201

Deep Learning to Quantify Pulmonary Edema in Chest Radiographs

Purpose: To develop a machine learning model to classify the severity grades of pulmonary edema on chest radiographs. Materials and Methods: In this retrospective study, 369,071 chest radiographs and associated radiology reports from 64,581 (mean age, 51.71; 54.51% women) patients from the MIMIC-CXR chest radiograph dataset were included. This dataset was split into patients with and without congestive heart failure (CHF). Pulmonary edema severity labels from the associated radiology reports were extracted from patients with CHF as four different ordinal levels: 0, no edema; 1, vascular congestion; 2, interstitial edema; and 3, alveolar edema. Deep learning models were developed using two approaches: a semi-supervised model using a variational autoencoder and a pre-trained supervised learning model using a dense neural network. Receiver operating characteristic curve analysis was performed on both models. Results: The area under the receiver operating characteristic curve (AUC) for differentiating alveolar edema from no edema was 0.99 for the semi-supervised model and 0.87 for the pre-trained models. Performance of the algorithm was inversely related to the difficulty in categorizing milder states of pulmonary edema (shown as AUCs for semi-supervised model and pre-trained model, respectively): 2 versus 0, 0.88 and 0.81; 1 versus 0, 0.79 and 0.66; 3 versus 1, 0.93 and 0.82; 2 versus 1, 0.69 and 0.73; and, 3 versus 2, 0.88 and 0.63. Conclusion: Deep learning models were trained on a large chest radiograph dataset and could grade the severity of pulmonary edema on chest radiographs with high performance.Comment: The two first authors contributed equall

Diseases of the Chest, Breast, Heart and Vessels 2019-2022

This open access book focuses on diagnostic and interventional imaging of the chest, breast, heart, and vessels. It consists of a remarkable collection of contributions authored by internationally respected experts, featuring the most recent diagnostic developments and technological advances with a highly didactical approach. The chapters are disease-oriented and cover all the relevant imaging modalities, including standard radiography, CT, nuclear medicine with PET, ultrasound and magnetic resonance imaging, as well as imaging-guided interventions. As such, it presents a comprehensive review of current knowledge on imaging of the heart and chest, as well as thoracic interventions and a selection of "hot topics". The book is intended for radiologists, however, it is also of interest to clinicians in oncology, cardiology, and pulmonology

Diseases of the Chest, Breast, Heart and Vessels 2019-2022

This open access book focuses on diagnostic and interventional imaging of the chest, breast, heart, and vessels. It consists of a remarkable collection of contributions authored by internationally respected experts, featuring the most recent diagnostic developments and technological advances with a highly didactical approach. The chapters are disease-oriented and cover all the relevant imaging modalities, including standard radiography, CT, nuclear medicine with PET, ultrasound and magnetic resonance imaging, as well as imaging-guided interventions. As such, it presents a comprehensive review of current knowledge on imaging of the heart and chest, as well as thoracic interventions and a selection of "hot topics". The book is intended for radiologists, however, it is also of interest to clinicians in oncology, cardiology, and pulmonology

Classic and New Diagnostic Approaches to Childhood Tuberculosis

Tuberculosis in childhood differs from the adult clinical form and even has been suggested that it is a different disease due to its differential signs. However, prevention, diagnostics, and therapeutic efforts have been biased toward adult clinical care. Sensibility and specificity of new diagnostic approaches as GeneXpert, electronic nose (E-nose), infrared spectroscopy, accelerated mycobacterial growth induced by magnetism, and flow lateral devices in children populations are needed. Adequate and timely assessment of tuberculosis infection in childhood could diminish epidemiological burden because underdiagnosed pediatric patients can evolve to an active state and have the potential to disseminate the etiological agent Mycobacterium tuberculosis, notably increasing this worldwide public health problem

Assessment of airway compression on chest radiographs in children with pulmonary tuberculosis

Study rationale: Diagnosis of pulmonary tuberculosis (PTB) in children relies heavily on chest radiography as sputum samples are difficult to obtain and only yield positive results in 30-74% of children treated for PTB. However, radiological signs between lower respiratory tract infections (LRTI) and PTB overlap considerably and there is a wide inter-observer agreement in the detection of lymphadenopathy, considered the hallmark of PTB. Small pliable paediatric airways are easily compressed by enlarged lymph nodes. Unlike lymph nodes, however, the lucent airways contrast against the surrounding mediastinal structures on radiographs, thus airway compression may serve as a more objective criterion for diagnosing PTB. Many studies have reviewed the radiographic features of PTB in children but few included airway compression or used a control group and none have evaluated inter-observer agreement. Objective: To investigate frequency and inter-observer agreement of airway compression on chest radiographs in children with PTB compared to those with another LRTI. Methods: Chest radiographs of children admitted to Red Cross War Memorial Children’s Hospital with suspected PTB were read by two readers according to a standardised format and a 3rd when there was disagreement. Radiographs of children with definite PTB were compared to those with another LRTI. Frequency and location of airway compression were evaluated. Findings were correlated with human immunodeficiency virus (HIV) infection and age. Inter-observer agreement was assessed using kappa statistic. Results: Radiographs of 505 children (median age 25.9 months [IQR 14.3-62.2]) were reviewed; 97/505 (19%) children were HIV-infected. Airway compression occurred in 54/188 (28.7%) definite PTB cases versus 24/317 (7.6 %) of other LRTI cases (OR 4.9; 95%CI 2.9–8.3). The left main bronchus was most affected in 51/493 (10.3%). A higher frequency of airway compression occurred in infants at 22/101 (21.8%) compared to 56/404 (13.9%) in older children (OR 1.7; 95%CI 1.00–3.00). No association between airway compression and HIV infection was found. Inter-observer agreement ranged from none to fair (kappa of 0.0-0.4). Discussion: The overall frequency of airway compression in definite PTB is compatible with reports in the literature. Although airway compression used alone is not a specific sign, if seen on radiographs, there is a strong correlation with PTB compared to other LRTI with infants at higher risk due to their smaller airways. Contradictory to other studies, our study showed the left main bronchus to be affected twice more commonly than the bronchus intermedius in both age groups. This is thought to be due to different patient selection. Confirming reports in the literature, no significant association between airway compression and HIV status was found. A disappointing finding was the poor inter-observer agreement. Contributing aspects include the lack of standardised criteria in the definition of airway compression and suboptimal visualisation of the airways on standard chest radiographs due to patient, technical and post processing factors. Conclusion: There is a strong association between airway compression on chest radiographs and definite PTB, particularly in infants, irrespective of HIV status. However, its clinical use as an objective criterion in the diagnosis of PTB is limited by poor inter-observer agreement

Learning to detect chest radiographs containing lung nodules using visual attention networks

Machine learning approaches hold great potential for the automated detection of lung nodules in chest radiographs, but training the algorithms requires vary large amounts of manually annotated images, which are difficult to obtain. Weak labels indicating whether a radiograph is likely to contain pulmonary nodules are typically easier to obtain at scale by parsing historical free-text radiological reports associated to the radiographs. Using a repositotory of over 700,000 chest radiographs, in this study we demonstrate that promising nodule detection performance can be achieved using weak labels through convolutional neural networks for radiograph classification. We propose two network architectures for the classification of images likely to contain pulmonary nodules using both weak labels and manually-delineated bounding boxes, when these are available. Annotated nodules are used at training time to deliver a visual attention mechanism informing the model about its localisation performance. The first architecture extracts saliency maps from high-level convolutional layers and compares the estimated position of a nodule against the ground truth, when this is available. A corresponding localisation error is then back-propagated along with the softmax classification error. The second approach consists of a recurrent attention model that learns to observe a short sequence of smaller image portions through reinforcement learning. When a nodule annotation is available at training time, the reward function is modified accordingly so that exploring portions of the radiographs away from a nodule incurs a larger penalty. Our empirical results demonstrate the potential advantages of these architectures in comparison to competing methodologies