CT features of acute COVID-19 and long-term follow-up.

Since the first few cases of pneumonia attributed to infection with the highly contagious novel coronavirus 2 (SARs-CoV-2) were detected in Wuhan, China, in December 2019, imaging has proven an invaluable diagnostic tool throughout the resulting global pandemic. This review describes the imaging features of severe pulmonary disease caused by SARs-CoV-2, named COVID-19 by the World Health Organization (WHO), particularly focussing on computed tomography (CT). CT plays an important role in understanding the pathology behind the progression of disease, as well as helping to identify the potential complications of COVID-19 pneumonia and recognising possible alternative or concurrent diagnoses. This review also focusses on follow-up imaging of survivors of COVID-19, which continues to contribute substantially to our understanding of the longer-term pulmonary changes in patients who have survived severe COVID-19 pneumonia.

Development of a multi-task learning V-Net for pulmonary lobar segmentation on CT and application to diseased lungs.

AIM: To develop a multi-task learning (MTL) V-Net for pulmonary lobar segmentation on computed tomography (CT) and application to diseased lungs. MATERIALS AND METHODS: The described methodology utilises tracheobronchial tree information to enhance segmentation accuracy through the algorithm's spatial familiarity to define lobar extent more accurately. The method undertakes parallel segmentation of lobes and auxiliary tissues simultaneously by employing MTL in conjunction with V-Net-attention, a popular convolutional neural network in the imaging realm. Its performance was validated by an external dataset of patients with four distinct lung conditions: severe lung cancer, COVID-19 pneumonitis, collapsed lungs, and chronic obstructive pulmonary disease (COPD), even though the training data included none of these cases. RESULTS: The following Dice scores were achieved on a per-segment basis: normal lungs 0.97, COPD 0.94, lung cancer 0.94, COVID-19 pneumonitis 0.94, and collapsed lung 0.92, all at p<0.05. CONCLUSION: Despite severe abnormalities, the model provided good performance at segmenting lobes, demonstrating the benefit of tissue learning. The proposed model is poised for adoption in the clinical setting as a robust tool for radiologists and researchers to define the lobar distribution of lung diseases and aid in disease treatment planning.

Significance of connective tissue disease features in idiopathic interstitial pneumonia.

In idiopathic interstitial pneumonia (IIP), the significance of connective tissue disease (CTD) features in the absence of a specific CTD diagnosis remains unclear. We studied the clinical and prognostic utility of a diagnosis of undifferentiated CTD (UCTD) in patients with biopsy-proven IIP. IIP patients undergoing surgical lung biopsy (1979-2005) were studied (nonspecific interstitial pneumonia (NSIP), n = 45; idiopathic pulmonary fibrosis, n = 56). UCTD was considered present when serum autoantibodies were present and symptoms or signs suggested CTD. The relationship between UCTD and NSIP histology was evaluated. A clinical algorithm that best predicted NSIP histology was constructed using a priori variables. The prognostic utility of UCTD, and of this algorithm, was evaluated. UCTD was present in 14 (31%) NSIP and seven (13%) IPF patients. UCTD was not associated with a survival benefit. The algorithm predictive of NSIP (OR 10.4, 95% CI 3.21-33.67; p<0.0001) consisted of the absence of typical high-resolution computed tomography (HRCT) features for IPF and 1) a compatible demographic profile (females aged <50 yrs) or 2) Raynaud's phenomenon. In patients with an HRCT scan not typical for IPF, this algorithm predicted improved survival (hazard ratio 0.35, 95% CI 0.14-0.85; p = 0.02) independent of IIP severity. UCTD is associated with NSIP histology. However, the diagnostic and prognostic significance of UCTD in IIP patients remains unclear.

Optimal scoring of serial change on chest radiography in sarcoidosis.

BACKGROUND: The optimal means of quantifying change on chest radiography in sarcoidosis is uncertain. In current guidelines, the role of serial measurement of carbon-monoxide diffusing capacity (DLco) remains undefined and the prevalence of discordance between serial chest radiographic change and pulmonary function tends is unknown. OBJECTIVE: To identify and explore key uncertainties in the monitoring of sarcoidosis by serial pulmonary function tests and chest radiography. DESIGN: 354 patients with sarcoidosis and concurrent tests (chest radiography and PFTs within three months at baseline, two years and/or four years) were studied. Chest radiographs were assessed by two radiologists for changes in stage and disease extent. Radiographic change and pulmonary function trends were quantified and compared. RESULTS: Change in radiographic extent of lung disease was always more frequent than change in stage (p < 0.0001) and there was poor agreement between change in stage and change in radiographic extent (Kw = 0.21 at two years; Kw = 0.23 at four years). Change in disease extent on chest radiography was linked to PFT trends on analysis of variance (p < 0.0005 for FEV1, FVC, DLco), whereas change in radiographic stage was not. Changes in gas transfer were often isolated or discordant with other serial data. Discordance between pulmonary function data and chest radiographic data was observed in 50% of cases. CONCLUSIONS: Change in radiographic extent is more applicable to routine monitoring in sarcoidosis than change in radiographic stage. In future guidelines, the role of serial gas transfer estimation and reconciliation of divergent chest radiographic and functional trends might usefully be addressed.

Chest radiography patterns in 75 adolescents with vertically-acquired human immunodeficiency virus (HIV) infection.

AIM: To evaluate lung disease on chest radiography (CR), the relative frequency of CR abnormalities, and their clinical correlates in adolescents with vertically-acquired human immunodeficiency virus (HIV) infection. MATERIALS AND METHODS: CRs of 75 patients [59 inpatients (33 males; mean age 13.7±2.3 years) and 16 outpatients (eight males; mean age 14.1±2.1 years)] were retrospectively reviewed by three independent observers. The overall extent of disease (to the nearest 5%), its distribution, and the proportional extents (totalling 100%) of different radiographic patterns (including ring/tramline opacities and consolidation) were quantified. CR features and clinical data were compared. RESULTS: CRs were abnormal in 51/75 (68%) with "extensive" disease in 38/51 (74%). Ring/tramline opacities and consolidation predominated (i.e., proportional extent >50%) in 26 and 21 patients, respectively. Consolidation was significantly more common in patients hospitalized primarily for a respiratory illness than patients hospitalized for a non-respiratory illness or in outpatients (p<0.005, χ(2) for trend); by contrast, ring/tramline opacities did not differ in prevalence across the groups. On stepwise logistic regression, predominant consolidation was associated with progressive dyspnoea [odds ratio (OR) 5.60; 95% confidence intervals (CI): 1.60, 20.1; p<0.01] and was associated with a primary respiratory cause for hospital admission (OR: 22.0; CI: 2.7, 181.1; p<0.005). Ring/tramline opacities were equally prevalent in patients with and without chronic symptoms and in those admitted to hospital with respiratory and non-respiratory illness. CONCLUSION: In HIV-infected adolescents, evaluated in secondary practice, CR abnormalities are prevalent. The presence of ring/tramline opacities, believed to reflect chronic airway disease, is not linked chronic respiratory symptoms.

CARD15/NOD2 polymorphisms are associated with severe pulmonary sarcoidosis.

Sarcoidosis and Crohn's disease are heterogeneous systemic diseases characterised by granulomatous inflammation. Caspase recruitment domain (CARD)15 is a major susceptibility gene for Crohn's disease, and specifically for ileal and fibrostenotic subtypes. The C-C chemokine receptor (CCR)5 gene has been associated with both parenchymal pulmonary sarcoidosis and perianal Crohn's disease. This study explored associations between CARD15 polymorphisms, CCR5 haplotype and distinct pulmonary sarcoidosis subtypes. 185 Caucasian sarcoidosis patients were genotyped for CARD15 and CCR5 polymorphisms. The genetic data were compared with 347 healthy controls and were examined for associations with serial pulmonary function tests and chest radiographs. CARD15 genotypes did not differ between the unselected sarcoidosis cohort and controls. However, patients carrying the functional 2104T (702W) polymorphism were more likely to have radiographic stage IV disease at 4-yr follow-up. All patients possessing both CARD15 2104T and CCR5 HHC haplotype had stage IV disease at presentation. Carriage of 2104T was associated with worse forced expiratory volume in 1 s, whereas carriage of the CARD15 1761G (587R) polymorphism was associated with better lung function. For the first time, an association between two CARD15 polymorphisms and specific sarcoidosis phenotypes has been demonstrated, as well as an additive effect of possessing CARD15 2104T and CCR5 HHC haplotype.

Pulmonary sarcoidosis: the 'Great Pretender'.

Sarcoidosis has a wide spectrum of appearances within the thorax. This review will discuss and illustrate the range of pulmonary manifestations on high-resolution computed tomography and chest radiography, concentrating on atypical features and examples of sarcoidosis mimicking other lung diseases. All included cases have been histologically confirmed. Such variable imaging appearances should alert the radiologist to consider sarcoidosis as a differential diagnosis in the context of interstitial lung disease.

Observer accuracy in the detection of pulmonary nodules on CT: effect of cine frame rate.

AIM: To assess the effect of cine frame rate on the accuracy of the detection of pulmonary nodules at computed tomography (CT). MATERIALS AND METHODS: CT images of 15 consecutive patients with (n = 13) or without (n = 2) pulmonary metastases were identified. Initial assessment by two thoracic radiologists provided the "actual" or reference reading. Subsequently, 10 radiologists [board certified radiologists (n = 4) or radiology residents (n = 6)] used different fixed cine frame rates for nodule detection. Within-subjects analysis of variance (ANOVA) was used to evaluate the data. RESULTS: Eighty-nine nodules were identified by the thoracic radiologists (median 8, range 0-29 per patient; median diameter 9 mm, range 4-40 mm). There was a non-statistically significant trend to reduced accuracy at higher frame rates (p=0.113) with no statistically significant difference between experienced observers and residents (p = 0.79). CONCLUSION: The accuracy of pulmonary nodule detection at higher cine frame rates is reduced, unrelated to observer experience.

Application of computed tomography in childhood respiratory infections.

The role of computed tomography (CT), including high-resolution computed tomography (HRCT), is still evolving in children. Radiation dose is an important consideration, but CT has advantages over chest radiography as it is more sensitive and specific for a variety of conditions affecting the pulmonary parenchyma. Careful attention to CT technique is vital for good quality diagnostic images in the paediatric population. The CT appearances of bacterial, viral, fungal, tuberculous and mycoplasma respiratory tract infections are discussed. The role of CT in specific circumstances such as the investigation of complicated bacterial pneumonia, the immunocompromised child and the sequelae of respiratory infections is addressed.

HRCT of paediatric lung disease.

Thin-section or high-resolution computed tomography (HRCT) is used in children for the investigation of disorders such as airway disease and diffuse interstitial lung disease. Advances in CT technology have resulted in faster scan acquisition times, enabling images of sufficient diagnostic quality to be obtained in children during gentle respiration. Whilst radiation dose is an important consideration, the dose of a thin- section CT is approximately one-seventh that of a conventional CT examination. As in adults, thin-section CT is more sensitive than chest radiography and may demonstrate abnormalities despite a normal chest radiograph. HRCT is also more specific than chest radiography for categorizing airway, airspace or interstitial processes in children. The current review will concentrate on the value of CT in airway diseases and diffuse interstitial lung disease.

High-resolution CT of paediatric lung disease.

High-resolution computed tomography (HRCT) has improved our understanding of many lung diseases in adults. The technique is used less often in children due to concerns regarding radiation dose. However, HRCT may provide important diagnostic information in a variety of lung diseases in children including airways diseases and diffuse interstitial lung disease. This review illustrates the HRCT appearances of a variety of conditions and describes the emerging role of the technique in children.

Asbestos-related benign pleural disease.

Benign pleural disease is the commonest manifestation of asbestos exposure encountered by radiologists. Benign pleural thickening can appear as circumscribed parietal pleural plaques or as more diffuse thickening of the visceral pleura. Benign-asbestos induced pleural effusions are a significant and under-recognized manifestation of asbestos exposure with important sequelae, such as diffuse pleural thickening which may be associated with functional impairment and for which compensation may be sought. This review concentrates on the strengths and weaknesses of chest radiography and computed tomography for the detection and characterization of benign asbestos-related pleural disease and the relevance of imaging abnormalities to compensation and functional impairment.Peacock, C. (2000). Clinical Radiology55, 422-432.

Diagnostic accuracy of thin-section CT and chest radiography of pediatric interstitial lung disease.

OBJECTIVE: We assessed the accuracy of thin-section CT and chest radiography to diagnose pediatric interstitial lung disease. MATERIALS AND METHODS: We identified 20 infants, boys, and girls (age range, 1 month to 14 years) with histopathologic confirmation of interstitial lung disease. Six boys and girls without interstitial lung disease were also included. Two observers independently assessed chest radiograph and CT images. The observers stated the most likely diagnosis and a differential diagnosis. We evaluated individual CT features and their distribution. RESULTS: Observers' diagnoses on CT images were correct (first choice or differential) in 66% of observations versus 45% on chest radiographs (p < 0.025). Correct diagnoses were made on first choice in 61% of CT observations versus 34% on chest radiographs (p < 0.005). Observers were confident (versus uncertain) in 42% of the CT observations versus 18% on chest radiographs; of the confident diagnoses made on CT, 91% were correct. CT interpretations were most accurate in the diagnosis of pulmonary alveolar proteinosis, congenital lymphangiectasia, and idiopathic pulmonary hemosiderosis. All healthy patients examined with CT were correctly identified as such. We noted a distinctive CT pattern in three patients with nonspecific interstitial pneumonitis and one patient with desquamative interstitial pneumonitis; the CT pattern consisted of upper zone predominant honeycombing on a background of ground-glass attenuation. CONCLUSION: A higher proportion of pediatric interstitial lung diseases can be diagnosed on thin-section CT than on chest radiographs. In our study, confident and correct diagnoses were made more frequently with CT than with chest radiographs.

A comparison of serial computed tomography and functional change in bronchiectasis.

In bronchiectasis the morphological determinants of (marginal) fluctuations in pulmonary function tests are uncertain. The aim of the present study was to evaluate serial computed tomography (CT) changes in relation to pulmonary function trends in patients with bronchiectasis. The relationships between pulmonary function indices and CT scans in 48 adult patients with bronchiectasis were evaluated at baseline and at follow-up, at a median interval of 28 months (range 6-74 months). Two independent observers semiquantitatively scored CT features of bronchial and small airways disease. At initial assessment, the severity of airflow obstruction was linked primarily to the extent of mosaic attenuation. However, serial changes in pulmonary function indices were only associated with serial changes in mucous plugging scores. Alterations in mucous plugging on serial CT were associated with changes in the severity of bronchiectasis and bronchial wall thickness. Greater severity of all three morphological abnormalities at baseline CT were predictive of significant declines in forced expiratory volume in one second, with severe bronchial wall thickness being the most adverse prognostic determinant. Variations in mucous plugging on computed tomography correlate with minor fluctuations in pulmonary function tests in bronchiectasis. However, the severity of bronchial wall thickness is the primary determinant of subsequent major functional decline.

Functional consequences of pleural disease evaluated with chest radiography and CT.

PURPOSE: To identify a system for the quantification of pleural thickening with an acceptable level of interobserver variation and good functional correlation in individuals with pleural disease. MATERIALS AND METHODS: The extent of pleural thickening and plaques was assessed in 50 patients by using the following: (a) a radiographic score based on the International Labour Office system, (b) a subjective simple computed tomographic (CT) score, (c) a subjective comprehensive CT score, (d) an objective nonautomated method, and (e) an objective computer-aided semiautomated method. RESULTS: Similar correlations between the extent of diffuse pleural thickening and forced vital capacity were seen for each system (objective CT, r = -0.72, P <.001; simple CT, r = -0.69, P <.001; radiographic, r = -0.67, P <.001; comprehensive CT, r = -0.66, P <.001). Comparable correlations were observed for total lung capacity. After controlling for extent of diffuse pleural thickening, pleural plaque scores were functionally irrelevant. CONCLUSION: Comparable functional-morphologic correlations were achieved by using different CT and radiographic scoring systems for pleural disease. A subjective simple CT system had the advantages of ease of application and potential to aid in the accurate assessment of the lung parenchyma, which may be important in individuals exposed to asbestos.

Nonspecific interstitial pneumonia and usual interstitial pneumonia: comparative appearances at and diagnostic accuracy of thin-section CT.

PURPOSE: To compare the morphologic abnormalities on thin-section computed tomographic (CT) images in a group of patients with histopathologically confirmed nonspecific interstitial pneumonia (NSIP) or usual interstitial pneumonia (UIP) and a clinical presentation of idiopathic pulmonary fibrosis. MATERIALS AND METHODS: Thin-section CT imaging patterns and distribution of disease in 53 patients with histologic diagnoses of NSIP (n = 21) or UIP (n = 32) were quantified retrospectively and independently by four observers. The appearances of NSIP and UIP at CT were compared with univariate and multivariate techniques. RESULTS: The use of thin-section CT proved to have moderate sensitivity (70%), specificity (63%), and accuracy (66%) in the diagnosis of NSIP. An increased proportion of ground-glass attenuation was the cardinal feature of NSIP at CT (odds ratio: 1.04 for each 1% increase in the proportion of ground-glass attenuation). A histologic diagnosis of NSIP was most frequent (in 24 of 35 observations [69%]) when ground-glass attenuation predominated, and was more frequent with mixed (35 of 79 observations [44%]) than with predominantly reticular disease (25 of 98 [26%] observations, P < .005). Logistic regression analysis of the data indicated that misdiagnosis of UIP in patients with NSIP was associated with less ground-glass attenuation (P < .005) at CT and a subpleural disease distribution (P = .02), with the converse being true for UIP cases misdiagnosed as NSIP. CONCLUSION: In patients with a clinical presentation of idiopathic pulmonary fibrosis, the accuracy of thin-section CT in identifying NSIP is considerably higher than previously reported. At CT, NSIP is characterized by more ground-glass attenuation and a finer reticular pattern than is UIP. Nevertheless, considerable overlap in thin-section CT patterns exists between NSIP and UIP.

HRCT diagnosis of diffuse parenchymal lung disease: inter-observer variation.

BACKGROUND: This study was designed to measure inter-observer variation between thoracic radiologists in the diagnosis of diffuse parenchymal lung disease (DPLD) using high resolution computed tomography (HRCT) and to identify areas of difficulty where expertise, in the form of national panels, would be of particular value. METHODS: HRCT images of 131 patients with DPLD (from a tertiary referral hospital (n = 66) and regional teaching centres (n = 65)) were reviewed by 11 thoracic radiologists. Inter-observer variation for the first choice diagnosis was quantified using the unadjusted kappa coefficient of agreement. Observers stated differential diagnoses and assigned a percentage likelihood to each. A weighted kappa was calculated for the likelihood of each of the six most frequently diagnosed disease entities. RESULTS: Observer agreement on the first choice diagnosis was moderate for the entire cohort (kappa = 0.48) and was higher for cases from regional centres (kappa = 0.60) than for cases from the tertiary referral centre (kappa = 0.34). 62% of cases from regional teaching centres were diagnosed with high confidence and good observer agreement (kappa = 0.77). Non-specific interstitial pneumonia (NSIP) was in the differential diagnosis in most disagreements (55%). Weighted kappa values quantifying the likelihood of specific diseases were moderate to good (mean 0.57, range 0.49-0.70). CONCLUSION: There is good agreement between thoracic radiologists for the HRCT diagnosis of DPLD encountered in regional teaching centres. However, cases diagnosed with low confidence, particularly where NSIP is considered as a differential diagnosis, may benefit from the expertise of a reference panel.