Radiographic Graft Surveillance in Lung Transplantation: Prognostic Role of Parametric Response Mapping.

Rationale: Chronic lung allograft dysfunction (CLAD) results in significant morbidity after lung transplantation. Potential CLAD occurs when lung function declines to 80-90% of baseline. Better noninvasive tools to prognosticate at potential CLAD are needed. Objectives: To determine whether parametric response mapping (PRM), a computed tomography (CT) voxel-wise methodology applied to high-resolution CT scans, can identify patients at risk of progression to CLAD or death. Methods: Radiographic features and PRM-based CT metrics quantifying functional small airway disease (PRMfSAD) and parenchymal disease (PRMPD) were studied at potential CLAD (n = 61). High PRMfSAD and high PRMPD were defined as ⩾30%. Restricted mean modeling was performed to compare CLAD-free survival among groups. Measurements and Main Results: PRM metrics identified the following three unique signatures: high PRMfSAD (11.5%), high PRMPD (41%), and neither (PRMNormal; 47.5%). Patients with high PRMfSAD or PRMPD had shorter CLAD-free median survival times (0.46 yr and 0.50 yr) compared with patients with predominantly PRMNormal (2.03 yr; P = 0.004 and P = 0.007 compared with PRMfSAD and PRMPD groups, respectively). In multivariate modeling adjusting for single- versus double-lung transplant, age at transplant, body mass index at potential CLAD, and time from transplant to CT scan, PRMfSAD ⩾30% or PRMPD ⩾30% continue to be statistically significant predictors of shorter CLAD-free survival. Air trapping by radiologist interpretation was common (66%), was similar across PRM groups, and was not predictive of CLAD-free survival. Ground-glass opacities by radiologist read occurred in 16% of cases and were associated with decreased CLAD-free survival (P < 0.001). Conclusions: PRM analysis offers valuable prognostic information at potential CLAD, identifying patients most at risk of developing CLAD or death.

Multicenter evaluation of parametric response mapping as an indicator of bronchiolitis obliterans syndrome after hematopoietic stem cell transplantation.

Parametric response mapping (PRM) is a novel computed tomography (CT) technology that has shown potential for assessment of bronchiolitis obliterans syndrome (BOS) after hematopoietic stem cell transplantation (HCT). The primary aim of this study was to evaluate whether variations in image acquisition under real-world conditions affect the PRM measurements of clinically diagnosed BOS. CT scans were obtained retrospectively from 72 HCT recipients with BOS and graft-versus-host disease from Fred Hutchinson Cancer Research Center, Karolinska Institute, and the University of Michigan. Whole lung volumetric scans were performed at inspiration and expiration using site-specific acquisition and reconstruction protocols. PRM and pulmonary function measurements were assessed. Patients with moderately severe BOS at diagnosis (median forced expiratory volume at 1 second [FEV1] 53.5% predicted) had similar characteristics between sites. Variations in site-specific CT acquisition protocols had a negligible effect on the PRM-derived small airways disease (SAD), that is, BOS measurements. PRM-derived SAD was found to correlate with FEV1% predicted and FEV1/ forced vital capacity (R = -0.236, P = .046; and R = -0.689, P < .0001, respectively), which suggests that elevated levels in the PRM measurements are primarily affected by BOS airflow obstruction and not CT scan acquisition parameters. Based on these results, PRM may be applied broadly for post-HCT diagnosis and monitoring of BOS.

Crowdsourcing pneumothorax annotations using machine learning annotations on the NIH chest X-ray dataset.

Pneumothorax is a potentially life-threatening condition that requires prompt recognition and often urgent intervention. In the ICU setting, large numbers of chest radiographs are performed and must be interpreted on a daily basis which may delay diagnosis of this entity. Development of artificial intelligence (AI) techniques to detect pneumothorax could help expedite detection as well as localize and potentially quantify pneumothorax. Open image analysis competitions are useful in advancing state-of-the art AI algorithms but generally require large expert annotated datasets. We have annotated and adjudicated a large dataset of chest radiographs to be made public with the goal of sparking innovation in this space. Because of the cumbersome and time-consuming nature of image labeling, we explored the value of using AI models to generate annotations for review. Utilization of this machine learning annotation (MLA) technique appeared to expedite our annotation process with relatively high sensitivity at the expense of specificity. Further research is required to confirm and better characterize the value of MLAs. Our adjudicated dataset is now available for public consumption in the form of a challenge.

Management of systemic sclerosis-associated interstitial lung disease.

PURPOSE OF REVIEW: To review the recently published data and provide a practical overview for management of systemic sclerosis-interstitial lung disease (SSc-ILD). RECENT FINDINGS: Published evidence shows considerable practitioner variability in screening patients for ILD. Recent published data support use of cyclophosphamide or mycophenolate mofetil as first-line treatment of SSc-ILD. For patients not responding to first-line therapies, consideration is given to rituximab as rescue therapy. Recent trials of hematopoietic autologous stem cell transplantation have demonstrated benefit in patients with progressive SSc-ILD. Antifibrotic agents are approved in idiopathic pulmonary fibrosis; studies with antifibrotics are underway for SSc-ILD. SUMMARY: The specter of rapidly progressive lung disease requires clinicians to risk stratify patients according to known predictors for progression and rigorously monitor for symptoms and advancing disease. The abovementioned therapies promise improved efficacy and favorable side-effect profiles compared to cyclophosphamide.

Impact of the revised haemodynamic definition on the diagnosis of pulmonary hypertension in patients with systemic sclerosis.

INTRODUCTION: Pulmonary arterial hypertension (PAH) is one of the leading causes of mortality in systemic sclerosis (SSc). We explored the impact of the updated haemodynamic definition of pulmonary hypertension (PH), as proposed by the 6th World Symposium on Pulmonary Hypertension. METHODS: In this single-centre retrospective analysis, patients with SSc who had right heart catheterisation (RHC) were included. We compared the prior PH definition to the updated PH definition. The prior definition classified PH as mean pulmonary arterial pressure (mPAP) ≥25 mmHg and further divided into pre-capillary PH (PAH and PH due to lung disease and/or hypoxia), post-capillary PH, and combined pre- and post-capillary PH groups. For the updated definition, PH was classified as mPAP >20 mmHg and further divided into the different groups. We validated our findings in the DETECT cohort. RESULTS: Between 2005 and March 2019, 268 RHCs were performed in this single-centre cohort. Using the prior definition, 137 (51%) were diagnosed with PH, with 89 classified as pre-capillary PH (56 with PAH and 33 with PH due to lung disease and/or hypoxia), 29 as post-capillary PH, and 19 as combined pre- and post-capillary PH. When the updated definition was applied to the cohort, seven out of 131 (5%) with no PH were reclassified to pre-capillary PH (PAH (n=1), PH due to lung disease (n=3) and post-capillary PH (n=3)). In those with mPAP 21-24 mmHg, with no left heart or significant lung disease, one out of 28 (4%) in our cohort and four out of 36 (11%) in the DETECT cohort were reclassified as PAH. CONCLUSION: The updated PH definition does not appear to have a significant impact on the diagnosis of PH in two different screening cohorts.

Management of connective tissue diseases associated interstitial lung disease: a review of the published literature.

PURPOSE OF REVIEW: Interstitial lung disease (ILD), though a common and often a severe manifestation of many connective tissue diseases (CTD), is challenging to manage because of its variable presentation and the relative lack of guidelines to assist the clinician. In this review, we discuss the approach to diagnosis, treatment, and monitoring patients with CTD-associated ILD, with a focus on systemic sclerosis (SSc), rheumatoid arthritis (RA), and idiopathic inflammatory myopathy (IIM). RECENT FINDINGS: High-resolution computed tomography scan and pulmonary function testing can be reliably used to diagnose ILD and monitor progression, and often to determine its likely histologic subtype and severity. In SSc-ILD, randomized controlled trials show ILD stabilization with cyclophosphamide treatment; preliminary data from another randomized controlled trial demonstrates similar findings with mycophenolate. There are no robust clinical trials supporting specific treatments for RA-ILD or IIM-ILD, but rituximab in RA-ILD, and cyclophosphamide, mycophenolate and calcineurin inhibitors in IIM-ILD show promise. SUMMARY: Though ILD contributes substantially to morbidity and mortality in patients with CTD, there are minimal data to guide its management except in SSc-ILD.

Imaging pulmonary infection: classic signs and patterns.

OBJECTIVE: The purposes of this article are to describe common and uncommon imaging signs and patterns of pulmonary infections and to discuss their underlying anatomic and pathophysiologic basis. CONCLUSION: Imaging plays an integral role in the diagnosis and management of suspected pulmonary infections and may reveal useful signs on chest radiographs and CT scans. Detected early, these signs can often be used to predict the causative agent and pathophysiologic mechanism and possibly to optimize patient care.

Abdominal CT in COVID-19 patients: incidence, indications, and findings.

PURPOSE: The purpose of this study was to evaluate the frequency, indications, and findings of abdominal CTs ordered in the initial evaluation of patients who had a positive COVID-19 test performed in our institution. METHODS: Retrospective chart review was performed on all patients who had a positive test for COVID-19 performed at a single quaternary care center from 1/20/2020 through 5/8/2020. In a subset of patients undergoing abdominal CT as part of the initial evaluation, the demographics, suspected COVID-19 status at the time of scan, presenting complaints, and abdominal CT findings were recorded. Cardiothoracic radiologists reviewed and scored the visualized lung bases for the likelihood of COVID-19. RESULTS: Only 43 (4.1%) of 1057 COVID-19 patients presented with abdominal complaints sufficient to warrant an abdominal CT. Of these 43 patients, the vast majority (39, 91%) were known or suspected to have COVID-19 at the time of the scan. Most (27/43, 63%) scans showed no acute abdominal abnormality, and those that were positive did not share a discernable pattern of abnormalities. Lung base abnormalities were common, and there was moderate inter-reviewer reliability. CONCLUSION: A minority of COVID-19 patients present with abdominal complaints sufficient to warrant a dedicated CT of the abdomen, and most of these studies will be negative or have abdominal findings not associated with COVID-19. Appropriate lung base findings are a more consistent indication of COVID-19 infection than abdominal findings.

Performance of the DETECT Algorithm for Pulmonary Hypertension Screening in a Systemic Sclerosis Cohort.

OBJECTIVE: Pulmonary arterial hypertension (PAH) is one of the leading causes of mortality in systemic sclerosis (SSc). This study was undertaken to assess predictive accuracies of the DETECT algorithm and the 2015 European Society of Cardiology/European Respiratory Society (ESC/ERS) guidelines in SSc patients who underwent right-sided heart catheterization (RHC) for pulmonary hypertension (PH) evaluation. METHODS: Patients with SSc who had diagnostic RHC, had no PH or had PAH, and had available data on variables to allow application of the DETECT and 2015 ESC/ERS guidelines were included for analysis. PH classification was based on hemodynamics using the 2018 revised criteria and extent of lung fibrosis shown on high-resolution computed tomography. Sensitivity and predictive accuracies of the DETECT algorithm and 2015 ESC/ERS guidelines were calculated, including analysis of subjects with a diffusing capacity for carbon monoxide (DLco) of ≥60% predicted. RESULTS: Sixty-eight patients with SSc had RHC, of whom 58 had no PH and 10 had PAH. The mean age was 60.0 years, and 58.8% had limited cutaneous SSc. The DETECT algorithm had a sensitivity of 1.00 (95% confidence interval [95% CI] 0.69-1.00) and a negative predictive value (NPV) of 1.00 (95% CI 0.80-1.00), whereas the 2015 ESC/ERS guidelines had a sensitivity of 0.80 (95% CI 0.44-0.97) and an NPV of 0.94 (95% CI 0.81-0.99). In patients with a DLco of ≥60% (n = 27), the DETECT algorithm had a sensitivity of 1.00 (95% CI 0.29-1.00) and an NPV of 1.00 (95% CI 0.59-1.00), whereas the 2015 ESC/ERS guidelines had a sensitivity of 0.67 (95% CI 0.09-0.99) and an NPV of 0.94 (95% CI 0.71-1.00). CONCLUSION: The DETECT algorithm has high sensitivity and NPV for diagnosis of PAH, including among individuals with a DLco of ≥60%.

Interstitial lung disease in systemic sclerosis quantification of disease classification and progression with high-resolution computed tomography: An observational study.

Introduction: Systemic sclerosis-associated interstitial lung disease accounts for up to 20% of mortality in these patients and has a highly variable prognosis. Functional respiratory imaging, a quantitative computed tomography imaging technique which allows mapping of regional information, can provide a detailed view of lung structures. It thereby shows potential to better characterize this disease. Purpose: To evaluate the use of functional respiratory imaging quantitative computed tomography in systemic sclerosis-associated interstitial lung disease staging, as well as the relationship between short-term changes in pulmonary function tests and functional respiratory imaging quantitative computed tomography with respect to disease severity. Materials and methods: An observational cohort of 35 patients with systemic sclerosis was retrospectively studied by comparing serial pulmonary function tests and in- and expiratory high-resolution computed tomography over 1.5-year interval. After classification into moderate to severe lung disease and limited lung disease (using a hybrid method integrating quantitative computed tomography and pulmonary function tests), post hoc analysis was performed using mixed-effects models and estimated marginal means in terms of functional respiratory imaging parameters. Results: At follow-up, relative mean forced vital capacity percentage change was not significantly different in the limited (6.37%; N = 13; p = 0.053) and moderate to severe disease (-3.54%; N = 16; p = 0.102) groups, respectively. Specific airway resistance decreased from baseline for both groups. (Least square mean changes -25.11% predicted (p = 0.006) and -14.02% predicted (p = 0.001) for limited and moderate to severe diseases.) In contrast to limited disease from baseline, specific airway radius increased in moderate to severe disease by 8.57% predicted (p = 0.011) with decline of lower lobe volumes of 2.97% predicted (p = 0.031). Conclusion: Functional respiratory imaging is able to differentiate moderate to severe disease versus limited disease and to detect disease progression in systemic sclerosis.

Improved detection of air trapping on expiratory computed tomography using deep learning.

BACKGROUND: Radiologic evidence of air trapping (AT) on expiratory computed tomography (CT) scans is associated with early pulmonary dysfunction in patients with cystic fibrosis (CF). However, standard techniques for quantitative assessment of AT are highly variable, resulting in limited efficacy for monitoring disease progression. OBJECTIVE: To investigate the effectiveness of a convolutional neural network (CNN) model for quantifying and monitoring AT, and to compare it with other quantitative AT measures obtained from threshold-based techniques. MATERIALS AND METHODS: Paired volumetric whole lung inspiratory and expiratory CT scans were obtained at four time points (0, 3, 12 and 24 months) on 36 subjects with mild CF lung disease. A densely connected CNN (DN) was trained using AT segmentation maps generated from a personalized threshold-based method (PTM). Quantitative AT (QAT) values, presented as the relative volume of AT over the lungs, from the DN approach were compared to QAT values from the PTM method. Radiographic assessment, spirometric measures, and clinical scores were correlated to the DN QAT values using a linear mixed effects model. RESULTS: QAT values from the DN were found to increase from 8.65% ± 1.38% to 21.38% ± 1.82%, respectively, over a two-year period. Comparison of CNN model results to intensity-based measures demonstrated a systematic drop in the Dice coefficient over time (decreased from 0.86 ± 0.03 to 0.45 ± 0.04). The trends observed in DN QAT values were consistent with clinical scores for AT, bronchiectasis, and mucus plugging. In addition, the DN approach was found to be less susceptible to variations in expiratory deflation levels than the threshold-based approach. CONCLUSION: The CNN model effectively delineated AT on expiratory CT scans, which provides an automated and objective approach for assessing and monitoring AT in CF patients.

Prevalence, Treatment, and Outcomes of Coexistent Pulmonary Hypertension and Interstitial Lung Disease in Systemic Sclerosis.

OBJECTIVE: Systemic sclerosis (SSc) is associated with interstitial lung disease (ILD) and pulmonary hypertension (PH). This study was undertaken to determine the prevalence, characteristics, treatment, and outcomes of PH in a cohort of patients with SSc-associated ILD. METHODS: Patients with SSc-associated ILD on high-resolution computed tomography (HRCT) were included in a prospective observational cohort. Patients were screened for PH based on a standardized screening algorithm and underwent right-sided heart catheterization (RHC) if indicated. PH classification was based on hemodynamic findings and the extent of ILD on HRCT. Summary statistics and survival using the Kaplan-Meier method were calculated. RESULTS: Of the 93 patients with SSc-associated ILD included in the study, 76% were women and 65.6% had diffuse cutaneous SSc. The mean age was 54.9 years, and the mean SSc disease duration was 8 years. Twenty-nine patients (31.2%) had RHC-proven PH; of those 29 patients, 24.1% had PAH, 55.2% had World Health Organization (WHO) Group III PH, 34.5% had WHO Group III PH with pulmonary vascular resistance >3.0 Wood units, 48.3% had a PH diagnosis within 7 years of SSc onset, 82.8% received therapy for ILD, and 82.8% received therapy for PAH. The survival rate 3 years after SSc-associated ILD diagnosis for all patients was 97%. The survival rate 3 years after PH diagnosis for those with SSc-associated ILD and PH was 91%. CONCLUSION: In a large cohort of patients with SSc-associated ILD, a significant proportion of patients had coexisting PH, which often occurs early after SSc diagnosis. Most patients were treated with ILD and PAH therapies, and survival was good. Patients with SSc-associated ILD should be evaluated for coexisting PH.

Augmenting the National Institutes of Health Chest Radiograph Dataset with Expert Annotations of Possible Pneumonia.

This dataset is intended to be used for machine learning and is composed of annotations with bounding boxes for pulmonary opacity on chest radiographs which may represent pneumonia in the appropriate clinical setting.

Cross-sectional Imaging Review of Tuberous Sclerosis.

Tuberous sclerosis complex (TSC) is a multisystem, genetic disorder characterized by development of hamartomas in the brain, abdomen, and thorax. It results from a mutation in one of 2 tumor suppressor genes that activates the mammalian target of rapamycin pathway. This article discusses the origins of the disorder, the recently updated criteria for the diagnosis of TSC, and the cross-sectional imaging findings and recommendations for surveillance. Familiarity with the diverse radiological features facilitates diagnosis and helps in treatment planning and monitoring response to treatment of this multisystem disorder.

Incidence of nonconfounded post-computed tomography acute kidney injury in hospitalized patients with stable renal function receiving intravenous iodinated contrast material.

OBJECTIVE: The purpose of our investigation was to determine the frequency of proximate acute and chronic confounding risk factors for acute kidney injury (AKI) in a cohort of adult hospitalized patients with stable renal function who developed AKI following an intravenous (IV) contrast-enhanced computed tomography (CT) examination. MATERIALS AND METHODS: Institutional review board approval was obtained for this retrospective, Health Insurance Portability and Accountability Act-compliant investigation. Overall, 100 adult inpatients (50 males [mean age = 61 years, range: 24-94 years] and 50 females [mean age = 60 years, range: 20-95 years]) with stable pre-CT renal function who developed post-CT AKI using the Acute Kidney Injury Network (AKIN) laboratory criteria following an IV contrast-enhanced CT examination comprised the study population. Electronic International Classification of Disease-9 analysis followed by a comprehensive manual electronic medical record review was systematically performed by 5 radiologists to identify known acute (n = 24, within 5 days before or 3 days after CT) and chronic (n = 21) risk factors for AKI other than contrast material administration that might confound a diagnosis of contrast-induced nephrotoxicity. Descriptive statistics were performed. RESULTS: Of 100 inpatients with post-CT AKI, 99 (99%) had 1 or more acute risk factor(s) for AKI other than contrast material administration (median = 3 risk factors, range: 0-8) and 86 (86%) had one or more chronic risk factor(s) for AKI (median = 2 risk factors, range: 0-7). The median number of risk factors (acute or chronic) per patient was 5 (range: 1-13). Only 1 inpatient (1%) developed post-CT AKI without a confounding acute risk factor (estimated glomerular filtration rate = 62-71 mL/min/1.73 m(2), 4 chronic risk factors, and CT 7 days after pancreaticoduodenectomy). The most common acute risk factors were nephrotoxic medications (83%) and parenteral blood product administration (30%). The most common chronic risk factors were hypertension (59%) and chronic kidney disease (56%). CONCLUSION: Nonconfounded post-CT AKI is rare in hospitalized adults with stable renal function who have been exposed to IV low- or iso-osmolality iodinated contrast material.

Evaluation and management of pulmonary nodules: state-of-the-art and future perspectives.

INTRODUCTION: The imaging evaluation of pulmonary nodules, often incidentally detected on imaging examinations performed for other clinical reasons, is a frequently encountered clinical circumstance. With advances in imaging modalities, both the detection and characterization of pulmonary nodules continue to evolve and improve. AREAS COVERED: This article will review the imaging modalities used to detect and diagnose benign and malignant pulmonary nodules, with a focus on computed tomography (CT), which continues to be the mainstay for evaluation. The authors discuss recent advances in the lung nodule management, and an algorithm for the management of indeterminate pulmonary nodules. EXPERT OPINION: There are set of criteria that define a benign nodule, the most important of which are the lack of temporal change for 2 years or more, and certain benign imaging criteria, including specific patterns of calcification or the presence of fat. Although some indeterminate pulmonary nodules are immediately actionable, generally those approaching 1 cm or larger in diameter, at which size the diagnostic accuracy of tools such as positron emission tomography (PET)/CT, single photon emission CT (SPECT) and biopsy techniques are sufficient to warrant their use. The majority of indeterminate pulmonary nodules are under 1 cm, for which serial CT examinations through at least 2 years for solid nodules and 3 years for ground-glass nodules, are used to demonstrate either benign biologic behavior or otherwise. The management of incidental pulmonary nodules involves a multidisciplinary approach in which radiology plays a pivotal role. Newer imaging and postprocessing techniques have made this a more accurate technique eliminating ambiguity and unnecessary follow-up.

Cardiac angiosarcoma: an unusual cause of coronary artery pseudoaneurysm.

Cardiac angiosarcoma is the most common of the cardiac sarcomas. It can infiltrate into adjacent structures in addition to seeding distant metastases. Coronary artery encasement is a rare but potentially life-threatening complication of cardiac angiosarcoma. We report a case of cardiac angiosarcoma encasing the right coronary artery with subsequent pseudoaneurysm formation with mural thrombus. Magnetic resonance first-pass, contrast-enhanced images are very useful for defining the communication between such lesions and underlying cardiac chambers. In the presence of distant metastases, there are limited treatment options. No intervention was attempted for the pseudoaneurysm, and thus far (12 mo) it has been stable.

Pseudolesion in segment IV A of the liver from vein of Sappey secondary to SVC obstruction.

Pseudolesions in the liver are caused by unusual/altered hemodynamics of the liver and can be confused with a true hepatic mass. In superior vena cava (SVC) obstruction. there is recruitment of the cavo-mammary-phrenic-hepatic-capsule-portal pathway. and the venous blood follows the internal mammary vein, the inferior phrenic vein, the hepatic capsule veins, and the intrahepatic portal system. causing a hypervascular pseudolesion in segment IV A of the liver. Recognizing the classic appearances of this hypervascular pseudolesion from the vein of Sappey in a CT study of the abdomen has prognostic implications in directing further evaluation of the chest for SVC obstruction. We present a case of a 54-year-old HIV-positive male smoker in whom identification of the hypervascular pseudolesion from the vein of Sappey on the abdominal CT led to the diagnosis of SVC syndrome.