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Purpose To evaluate the feasibility of leveraging serial low-dose CT (LDCT) scans to develop a radiomics-based reinforcement learning (RRL) model for improving early diagnosis of lung cancer at baseline screening. Materials and Methods In this retrospective study, 1951 participants (female patients, 822; median age, 61 years [range, 55-74 years]) (male patients, 1129; median age, 62 years [range, 55-74 years]) were randomly selected from the National Lung Screening Trial between August 2002 and April 2004. An RRL model using serial LDCT scans (S-RRL) was trained and validated using data from 1404 participants (372 with lung cancer) containing 2525 available serial LDCT scans up to 3 years. A baseline RRL (B-RRL) model was trained with only LDCT scans acquired at baseline screening for comparison. The 547 held-out individuals (150 with lung cancer) were used as an independent test set for performance evaluation. The area under the receiver operating characteristic curve (AUC) and the net reclassification index (NRI) were used to assess the performances of the models in the classification of screen-detected nodules. Results Deployment to the held-out baseline scans showed that the S-RRL model achieved a significantly higher test AUC (0.88 [95% CI: 0.85, 0.91]) than both the Brock model (AUC, 0.84 [95% CI: 0.81, 0.88]; P = .02) and the B-RRL model (AUC, 0.86 [95% CI: 0.83, 0.90]; P = .02). Lung cancer risk stratification was significantly improved by the S-RRL model as compared with Lung CT Screening Reporting and Data System (NRI, 0.29; P < .001) and the Brock model (NRI, 0.12; P = .008). Conclusion The S-RRL model demonstrated the potential to improve early diagnosis and risk stratification for lung cancer at baseline screening as compared with the B-RRL model and clinical models. Keywords: Radiomics-based Reinforcement Learning, Lung Cancer Screening, Low-Dose CT, Machine Learning © RSNA, 2024 Supplemental material is available for this article.

The ACR Incidental Findings Committee presents recommendations for managing incidentally detected lung findings on thoracic CT. The Chest Subcommittee is composed of thoracic radiologists who endorsed and developed the provided guidance. These recommendations represent a combination of current published evidence and expert opinion and were finalized by informal iterative consensus. The recommendations address commonly encountered incidental findings in the lungs and are not intended to be a comprehensive review of all pulmonary incidental findings. The goal is to improve the quality of care by providing guidance on management of incidentally detected thoracic findings., (Copyright © 2021 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Lung cancer screening with a low radiation dose chest CT scan is the standard of care for screening-eligible individuals. The net benefit of screening may be optimized by delivering high-quality care, capable of maximizing the benefit and minimizing the harms of screening. Valid, feasible, and relevant indicators of the quality of lung cancer screening may help programs to evaluate their current practice and to develop quality improvement plans. The purpose of this project was to develop quality indicators related to the processes and outcomes of screening. Potential quality indicators were explored through surveys of multidisciplinary lung cancer screening experts. Those that achieved predefined measures of consensus for each of the validity, feasibility, and relevance domains are proposed as quality indicators. Each of the proposed indicators is described in detail, with guidance on how to define, measure, and improve program performance within the indicator., (Copyright © 2021 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

In 2014, the American College of Radiology (ACR) created Lung-RADS 1.0. The system was updated to Lung-RADS 1.1 in 2019, and further updates are anticipated as additional data become available. Lung-RADS provides a common lexicon and standardized nodule follow-up management paradigm for use when reporting lung cancer screening (LCS) low-dose CT (LDCT) chest examinations and serves as a quality assurance and outcome monitoring tool. The use of Lung-RADS is intended to improve LCS performance and lead to better patient outcomes. To date, the ACR's Lung Cancer Screening Registry is the only LCS registry approved by the Centers for Medicare & Medicaid Services and requires the use of Lung-RADS categories for reimbursement. Numerous challenges have emerged regarding the use of Lung-RADS in clinical practice, including the timing of return to LCS after planned follow-up diagnostic evaluation; potential substitution of interval diagnostic CT for future LDCT; role of volumetric analysis in assessing nodule size; assessment of nodule growth; assessment of cavitary, subpleural, and category 4X nodules; and variability in reporting of the S modifier. This article highlights the major updates between versions 1.0 and 1.1 of Lung-RADS, describes the system's ongoing challenges, and summarizes current evidence and recommendations.

Background: Lung cancer risk prediction models do not routinely incorporate imaging metrics available on low-dose CT (LDCT) imaging of the chest ordered for lung cancer screening., Research Question: What is the association between quantitative emphysema measured on LDCT imaging and lung cancer incidence and mortality, all-cause mortality, and airflow obstruction in individuals who currently or formerly smoked and are undergoing lung cancer screening?, Study Design and Methods: In 7,262 participants in the CT arm of the National Lung Screening Trial, percent low attenuation area (%LAA) was defined as the percentage of lung volume with voxels less than -950 Hounsfield units on the baseline examination. Multivariable Cox proportional hazards models, adjusting for competing risks where appropriate, were built to test for association between %LAA and lung cancer incidence, lung cancer mortality, and all-cause mortality with censoring at 6 years. In addition, multivariable logistic regression models were built to test the cross-sectional association between %LAA and airflow obstruction on spirometry, which was available in 2,700 participants., Results: The median %LAA was 0.8% (interquartile range, 0.2%-2.7%). Every 1% increase in %LAA was independently associated with higher hazards of lung cancer incidence (hazard ratio [HR], 1.02; 95% CI, 1.01-1.03; P = .004), lung cancer mortality (HR, 1.02; 95% CI, 1.00-1.05; P = .045), and all-cause mortality (HR, 1.01; 95% CI, 1.00-1.03; P = .042). Among participants with spirometry, 892 had airflow obstruction. The likelihood of airflow obstruction increased with every 1% increase in %LAA (odds ratio, 1.07; 95% CI, 1.06-1.09; P < .001). A %LAA cutoff of 1% had the best discriminative accuracy for airflow obstruction in participants aged > 65 years., Interpretation: Quantitative emphysema measured on LDCT imaging of the chest can be leveraged to improve lung cancer risk prediction and help diagnose COPD in individuals who currently or formerly smoked and are undergoing lung cancer screening., (Copyright © 2020 American College of Chest Physicians. All rights reserved.)

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., Competing Interests: We have the following interests. 1. This study was partly supported by Novartis Institutes for Biomedical Research, Cambridge, MA, USA, from which Terry E. Robinson received a research grant. 2. Charles R. Hatt is an employee and stock option holder at Imbio LLC. There are no patents, products in development or marketed products to declare. This does not alter our adherence to all the PLOS ONE policies on sharing the data and materials.

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease and the traditional variables extracted from computed tomography (CT) images may not be sufficient to describe all the topological features of lung tissues in COPD patients. We employed an unsupervised three-dimensional (3D) convolutional autoencoder (CAE)-feature constructor (FC) deep learning network to learn from CT data and derive tissue pattern-clusters jointly. We then applied exploratory factor analysis (EFA) to discover the unobserved latent traits (factors) among pattern-clusters. CT images at total lung capacity (TLC) and residual volume (RV) of 541 former smokers and 59 healthy non-smokers from the cohort of the SubPopulations and Intermediate Outcome Measures in the COPD Study (SPIROMICS) were analyzed. TLC and RV images were registered to calculate the Jacobian (determinant) values for all the voxels in TLC images. 3D Regions of interest (ROIs) with two data channels of CT intensity and Jacobian value were randomly extracted from training images and were fed to the 3D CAE-FC model. 80 pattern-clusters and 7 factors were identified. Factor scores computed for individual subjects were able to predict spirometry-measured pulmonary functions. Two factors which correlated with various emphysema subtypes, parametric response mapping (PRM) metrics, airway variants, and airway tree to lung volume ratio were discriminants of patients across all severity stages. Our findings suggest the potential of developing factor-based surrogate markers for new COPD phenotypes.

Purpose: Develop a quantitative image analysis method to characterize the heterogeneous patterns of nodule components for the classification of pathological categories of nodules., Materials and Methods: With IRB approval and permission of the National Lung Screening Trial (NLST) project, 103 subjects with low dose CT (LDCT) were used in this study. We developed a radiomic quantitative CT attenuation distribution descriptor (qADD) to characterize the heterogeneous patterns of nodule components and a hybrid model (qADD+) that combined qADD with subject demographic data and radiologist-provided nodule descriptors to differentiate aggressive tumors from indolent tumors or benign nodules with pathological categorization as reference standard. The classification performances of qADD and qADD + were evaluated and compared to the Brock and the Mayo Clinic models by analysis of the area under the receiver operating characteristic curve (AUC)., Results: The radiomic features were consistently selected into qADDs to differentiate pathological invasive nodules from (1) preinvasive nodules, (2) benign nodules, and (3) the group of preinvasive and benign nodules, achieving test AUCs of 0.847 ± 0.002, 0.842 ± 0.002 and 0.810 ± 0.001, respectively. The qADD + obtained test AUCs of 0.867 ± 0.002, 0.888 ± 0.001 and 0.852 ± 0.001, respectively, which were higher than both the Brock and the Mayo Clinic models., Conclusion: The pathologic invasiveness of lung tumors could be categorized according to the CT attenuation distribution patterns of the nodule components manifested on LDCT images, and the majority of invasive lung cancers could be identified at baseline LDCT scans., Competing Interests: Declaration of Competing Interest The authors and authors’ institutions have no conflicts of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Quantitative computed tomographic (QCT) imaging-based metrics enable to quantify smoking induced disease alterations and to identify imaging-based clusters for current smokers. We aimed to derive clinically meaningful sub-groups of former smokers using dimensional reduction and clustering methods to develop a new way of COPD phenotyping., Methods: An imaging-based cluster analysis was performed for 406 former smokers with a comprehensive set of imaging metrics including 75 imaging-based metrics. They consisted of structural and functional variables at 10 segmental and 5 lobar locations. The structural variables included lung shape, branching angle, airway-circularity, airway-wall-thickness, airway diameter; the functional variables included regional ventilation, emphysema percentage, functional small airway disease percentage, Jacobian (volume change), anisotropic deformation index (directional preference in volume change), and tissue fractions at inspiration and expiration., Results: We derived four distinct imaging-based clusters as possible phenotypes with the sizes of 100, 80, 141, and 85, respectively. Cluster 1 subjects were asymptomatic and showed relatively normal airway structure and lung function except airway wall thickening and moderate emphysema. Cluster 2 subjects populated with obese females showed an increase of tissue fraction at inspiration, minimal emphysema, and the lowest progression rate of emphysema. Cluster 3 subjects populated with older males showed small airway narrowing and a decreased tissue fraction at expiration, both indicating air-trapping. Cluster 4 subjects populated with lean males were likely to be severe COPD subjects showing the highest progression rate of emphysema., Conclusions: QCT imaging-based metrics for former smokers allow for the derivation of statistically stable clusters associated with unique clinical characteristics. This approach helps better categorization of COPD sub-populations; suggesting possible quantitative structural and functional phenotypes.

Rationale and Objectives: Chronic obstructive pulmonary disease is a heterogeneous disease characterized by small airway abnormality and emphysema. We hypothesized that a voxel-wise computed tomography analytic approach would identify patterns of disease progression in smokers., Materials and Methods: We analyzed 725 smokers in spirometric GOLD stages 0-4 with two chest CTs 5 years apart. Baseline inspiration, follow-up inspiration and follow-up expiration images were spatially registered to baseline expiration so that each voxel had correspondences across all time points and respiratory phases. Voxel-wise Parametric Response Mapping (PRM) was then generated for the baseline and follow-up scans. PRM classifies lung as normal, functional small airway disease (PRM fSAD ), and emphysema (PRM EMPH )., Results: Subjects with low baseline PRM fSAD and PRM EMPH predominantly had an increase in PRM fSAD on follow-up; those with higher baseline PRM fSAD and PRM EMPH mostly had increases in PRM EMPH . For GOLD 0 participants (n = 419), mean 5-year increases in PRM fSAD and PRM EMPH were 0.3% for both; for GOLD 1-4 participants (n = 306), they were 0.6% and 1.6%, respectively. Eighty GOLD 0 subjects (19.1%) had overall radiologic progression (30.0% to PRM fSAD , 52.5% to PRM EMPH , and 17.5% to both); 153 GOLD 1-4 subjects (50.0%) experienced progression (17.6% to PRM fSAD , 48.4% to PRM EMPH , and 34.0% to both). In a multivariable model, both baseline PRM fSAD and PRM EMPH were associated with development of PRM EMPH on follow-up, although this relationship was diminished at higher levels of baseline PRM EMPH ., Conclusion: A voxel-wise longitudinal PRM analytic approach can identify patterns of disease progression in smokers with and without chronic obstructive pulmonary disease., (Copyright © 2018. Published by Elsevier Inc.)

Lung cancer remains the leading cause of cancer death in both men and women. Smoking is the single greatest risk factor for the development of lung cancer. For patients between the age of 55 and 80 with 30 or more pack years smoking history who currently smoke or who have quit within the last 15 years should undergo lung cancer screening with low-dose CT. In patients who do not meet these criteria but who have additional risk factors for lung cancer, lung cancer screening with low-dose CT is controversial but may be appropriate. Imaging is not recommended for lung cancer screening of patient younger than 50 years of age or patients older than 80 years of age or patients of any age with less than 20 packs per year history of smoking and no additional risk factor (ie, radon exposure, occupational exposure, cancer history, family history of lung cancer, history of COPD, or history of pulmonary fibrosis). 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 include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment., (Copyright © 2018 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Background: Classification of COPD is usually based on the severity of airflow, which may not sensitively differentiate subpopulations. Using a multiscale imaging-based cluster analysis (MICA), we aim to identify subpopulations for current smokers with COPD., Methods: Among the SPIROMICS subjects, we analyzed computed tomography images at total lung capacity (TLC) and residual volume (RV) of 284 current smokers. Functional variables were derived from registration of TLC and RV images, e.g. functional small airways disease (fSAD%). Structural variables were assessed at TLC images, e.g. emphysema and airway wall thickness and diameter. We employed an unsupervised method for clustering., Results: Four clusters were identified. Cluster 1 had relatively normal airway structures; Cluster 2 had an increase of fSAD% and wall thickness; Cluster 3 exhibited a further increase of fSAD% but a decrease of wall thickness and airway diameter; Cluster 4 had a significant increase of fSAD% and emphysema. Clinically, Cluster 1 showed normal FEV1/FVC and low exacerbations. Cluster 4 showed relatively low FEV1/FVC and high exacerbations. While Cluster 2 and Cluster 3 showed similar exacerbations, Cluster 2 had the highest BMI among all clusters., Conclusions: Association of imaging-based clusters with existing clinical metrics suggests the sensitivity of MICA in differentiating subpopulations.

High-resolution computed tomography (HRCT) may be useful for diagnosing hypersensitivity pneumonitis. Here, we develop and validate a radiological diagnosis model and model-based points score.Patients with interstitial lung disease seen at the University of Michigan Health System (derivation cohort) or enrolling in the Lung Tissue Research Consortium (validation cohort) were included. A thin-section, inspiratory HRCT scan was required. Thoracic radiologists documented radiological features.The derivation cohort comprised 356 subjects (33.9% hypersensitivity pneumonitis) and the validation cohort comprised 424 subjects (15.5% hypersensitivity pneumonitis). An age-, sex- and smoking status-adjusted logistic regression model identified extent of mosaic attenuation or air trapping greater than that of reticulation ("MA-AT>Reticulation"; OR 6.20, 95% CI 3.53-10.90; p<0.0001) and diffuse axial disease distribution (OR 2.33, 95% CI 1.31-4.16; p=0.004) as hypersensitivity pneumonitis predictors (area under the receiver operating characteristic curve 0.814). A model-based score >2 (1 point for axial distribution, 2 points for "MA-AT>Reticulation") has specificity 90% and positive predictive value (PPV) 74% in the derivation cohort and specificity 96% and PPV 44% in the validation cohort. Similar model performance is seen with population restriction to those reporting no exposure (score >2: specificity 91%).When radiological mosaic attenuation or air trapping are more extensive than reticulation and disease has diffuse axial distribution, hypersensitivity pneumonitis specificity is high and false diagnosis risk low (<10%), but PPV is diminished in a low-prevalence setting., Competing Interests: Conflict of interest: M.L. Salisbury reports salary funding from a departmental National Institutes of Health (NIH) training grant. B.J. Bartholmai reports other support from the NIH/National Heart, Lung, and Blood Institute for research related to the Lung Tissue Research Consortium (LTRC), previous to the conduct of the study. S. Murray reports that NIH sponsored grants pay for statistical work carried out for the Pulmonary Division. F.J. Martinez has received grants for chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) studies from NIH, has participated in steering committees for IPF studies for Bayer, Centocor, Gilead and Promedior, has received personal fees (IPF advisory board) from Ikaria, Genentech, Nycomed/Takeda, Pfizer and Vertex, personal fees (IPF CME programmes) from the American Thoracic Society, MedScape and National Association for Continuing Education, personal fees (IPF grand rounds) from Inova Health System, Spectrum Health System and University of Texas Southwestern, personal fees (IPF study DSMB) from Stromedix/Biogen, personal fees (IPF teleconference consultation) from Axon Communications, Johnson & Johnson and Genzyme, personal fees (IPF advisory board) from Boehringer Ingelheim, and personal fees (IPF diagnostic advisor) from Veracyte, during the conduct of the study; and has received personal fees (steering committee COPD study) from Forest, Janssen, GSK and Nycomed/Takeda, personal fees (COPD PRO development) from Amgen, personal fees (COPD advisory board) from Actelion, AstraZeneca, CSA Medical, Ikaria/Bellerophon, Forest, Genentech, GSK, Janssen, Merck, Pearl, Nycomed/Takeda, Pfizer, Roche and Sudler & Hennessey, personal fees (COPD CME programmes) from the American College of Chest Physicians, CME Incite, Center for Healthcare Education, MedScape, Miller Medical, National Association for Continuing Education, Paradigm, Peer Voice, Projects in Knowledge, UpToDate, Wayne State University and Annenberg, personal fees (COPD grand rounds) from Inova Health System, St John's Hospital, St Mary's Hospital and University of Illinois Chicago, personal fees (COPD study DSMB) from GSK, personal fees (COPD FDA mock presentation) from Boehringer Ingelheim, GSK and Ikaria, personal fees (European Respiratory Society (ERS) bronchiectasis presentation) from Bayer, personal fees (ERS COPD presentation) from Nycomed/Takeda, personal fees (COPD consulting teleconference) from Grey Healthcare and Merion, personal fees (COPD book royalties) from Informa, and personal fees (speaking on COPD) from GSK and Forest, outside the submitted work. K.R. Flaherty reports grants from NIH, during the conduct of the study; and reports personal fees for consultancy on IPF from Boehringer Ingelheim, Fibrogen, Genentech, Ikaria, ImmuneWorks, MedImmune, Novartis, Takeda, Vertex, Veracyte, Roche and Biogen, personal fees for consultancy and DSMB on IPF from Gilead, personal fees for employment from Pulmonary Fibrosis Foundation, personal fees for consultancy and grants for clinical trials on IPF from Intermune, and grants for clinical trials on IPF from Bristol-Myers Squibb, outside the submitted work., (Copyright ©ERS 2018.)

The ACR Incidental Findings Committee presents recommendations for managing incidentally detected mediastinal and cardiovascular findings found on CT. The Chest Subcommittee was composed of thoracic radiologists who developed the provided guidance. These recommendations represent a combination of current published evidence and expert opinion and were finalized by informal iterative consensus. The recommendations address the most commonly encountered mediastinal and cardiovascular incidental findings and are not intended to be a comprehensive review of all incidental findings associated with these compartments. Our goal is to improve the quality of care by providing guidance on how to manage incidentally detected thoracic findings., (Copyright © 2018 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Lung cancer is the leading cause of cancer-related mortality in the United States and worldwide. Early detection of lung cancer is an important opportunity for decreasing mortality. Data support using low-dose computed tomography (LDCT) of the chest to screen select patients who are at high risk for lung cancer. Lung screening is covered under the Affordable Care Act for individuals with high-risk factors. The Centers for Medicare & Medicaid Services (CMS) covers annual screening LDCT for appropriate Medicare beneficiaries at high risk for lung cancer if they also receive counseling and participate in shared decision-making before screening. The complete version of the NCCN Guidelines for Lung Cancer Screening provides recommendations for initial and subsequent LDCT screening and provides more detail about LDCT screening. This manuscript focuses on identifying patients at high risk for lung cancer who are candidates for LDCT of the chest and on evaluating initial screening findings., (Copyright © 2018 by the National Comprehensive Cancer Network.)

In response to the recommendation of the U.S. Preventive Services Task Force and the coverage decision by the Centers for Medicare and Medicaid Services for lung cancer screening (LCS) computed tomography (CT), the American College of Radiology introduced the Lung CT Screening Reporting and Data System (Lung-RADS) in 2014 to standardize the reporting and management of screening-detected lung nodules. As with many first-edition guidelines, questions arise when such reporting systems are used in daily practice. In this article, a collection of 15 LCS-related scenarios are presented that address situations in which the Lung-RADS guidelines are unclear or situations that are not currently addressed in the Lung-RADS guidelines. For these 15 scenarios, the authors of this article provide the reader with recommendations that are based on their collective experiences, with the hope that future versions of Lung-RADS will provide additional guidance, particularly as more data from widespread LCS are collected and analyzed. © RSNA, 2017.

Purpose To evaluate associations between pulmonary function and both quantitative analysis and visual assessment of thin-section computed tomography (CT) images at baseline and at 15-month follow-up in subjects with idiopathic pulmonary fibrosis (IPF). Materials and Methods This retrospective analysis of preexisting anonymized data, collected prospectively between 2007 and 2013 in a HIPAA-compliant study, was exempt from additional institutional review board approval. The extent of lung fibrosis at baseline inspiratory chest CT in 280 subjects enrolled in the IPF Network was evaluated. Visual analysis was performed by using a semiquantitative scoring system. Computer-based quantitative analysis included CT histogram-based measurements and a data-driven textural analysis (DTA). Follow-up CT images in 72 of these subjects were also analyzed. Univariate comparisons were performed by using Spearman rank correlation. Multivariate and longitudinal analyses were performed by using a linear mixed model approach, in which models were compared by using asymptotic χ 2 tests. Results At baseline, all CT-derived measures showed moderate significant correlation (P < .001) with pulmonary function. At follow-up CT, changes in DTA scores showed significant correlation with changes in both forced vital capacity percentage predicted (ρ = -0.41, P < .001) and diffusing capacity for carbon monoxide percentage predicted (ρ = -0.40, P < .001). Asymptotic χ 2 tests showed that inclusion of DTA score significantly improved fit of both baseline and longitudinal linear mixed models in the prediction of pulmonary function (P < .001 for both). Conclusion When compared with semiquantitative visual assessment and CT histogram-based measurements, DTA score provides additional information that can be used to predict diminished function. Automatic quantification of lung fibrosis at CT yields an index of severity that correlates with visual assessment and functional change in subjects with IPF. © RSNA, 2017.

The Society of Cardiovascular Computed Tomography (SCCT) and the Society of Thoracic Radiology (STR) have jointly produced this document. Experts in this subject have been selected from both organizations to examine subject-speci&filig;c data and write this guideline in partnership. A formal literature review, weighing the strength of evidence has been performed. When available, information from studies on cost was considered. Computed tomography (CT) acquisition, CAC scoring methodologies and clinical outcomes are the primary basis for the recommendations in this guideline. This guideline is intended to assist healthcare providers in clinical decision making. The recommendations re&fllig;ect a consensus after a thorough review of the best available current scienti&filig;c evidence and practice patterns of experts in the &filig;eld and are intended to improve patient care while acknowledging that situations arise where additional information may be needed to better inform patient care.

Objectives: This study retrospectively analyses the screening CT examinations and outcomes of the National Lung Screening Trial (NLST) participants who had interval lung cancer diagnosed within 1 year after a negative CT screen and before the next annual screen., Methods: The screening CTs of all 44 participants diagnosed with interval lung cancer (cases) were matched with negative CT screens of participants who did not develop lung cancer (controls). A majority consensus process was used to classify each CT screen as positive or negative according to the NLST criteria and to estimate the likelihood that any abnormalities detected retrospectively were due to lung cancer., Results: By retrospective review, 40/44 cases (91%) and 17/44 controls (39%) met the NLST criteria for a positive screen (P < 0.001). Cases had higher estimated likelihood of lung cancer (P < 0.001). Abnormalities included pulmonary nodules ≥4 mm (n = 16), mediastinal (n = 8) and hilar (n = 6) masses, and bronchial lesions (n = 6). Cancers were stage III or IV at diagnosis in 32/44 cases (73%); 37/44 patients (84%) died of lung cancer, compared to 225/649 (35%) for all screen-detected cancers (P < 0.0001)., Conclusion: Most cases met the NLST criteria for a positive screen. Awareness of missed abnormalities and interpretation errors may aid lung cancer identification in CT screening., Key Points: • Lung cancer within a year of a negative CT screen was rare. • Abnormalities likely due to lung cancer were identified retrospectively in most patients. • Awareness of error types may help identify lung cancer sooner.

Rationale: The predominant cause of chronic lung allograft failure is small airway obstruction arising from bronchiolitis obliterans. However, clinical methodologies for evaluating presence and degree of small airway disease are lacking., Objectives: To determine if parametric response mapping (PRM), a novel computed tomography voxel-wise methodology, can offer insight into chronic allograft failure phenotypes and provide prognostic information following spirometric decline., Methods: PRM-based computed tomography metrics quantifying functional small airways disease (PRM fSAD ) and parenchymal disease (PRM PD ) were compared between bilateral lung transplant recipients with irreversible spirometric decline and control subjects matched by time post-transplant (n = 22). PRM fSAD at spirometric decline was evaluated as a prognostic marker for mortality in a cohort study via multivariable restricted mean models (n = 52)., Measurements and Main Results: Patients presenting with an isolated decline in FEV 1 (FEV 1 First) had significantly higher PRM fSAD than control subjects (28% vs. 15%; P = 0.005), whereas patients with concurrent decline in FEV 1 and FVC had significantly higher PRM PD than control subjects (39% vs. 20%; P = 0.02). Over 8.3 years of follow-up, FEV 1 First patients with PRM fSAD greater than or equal to 30% at spirometric decline lived on average 2.6 years less than those with PRM fSAD less than 30% (P = 0.004). In this group, PRM fSAD greater than or equal to 30% was the strongest predictor of survival in a multivariable model including bronchiolitis obliterans syndrome grade and baseline FEV 1% predicted (P = 0.04)., Conclusions: PRM is a novel imaging tool for lung transplant recipients presenting with spirometric decline. Quantifying underlying small airway obstruction via PRM fSAD helps further stratify the risk of death in patients with diverse spirometric decline patterns.

Rationale: Adaptive multiple features method (AMFM) lung texture analysis software recognizes high-resolution computed tomography (HRCT) patterns., Objectives: To evaluate AMFM and visual quantification of HRCT patterns and their relationship with disease progression in idiopathic pulmonary fibrosis., Methods: Patients with idiopathic pulmonary fibrosis in a clinical trial of prednisone, azathioprine, and N-acetylcysteine underwent HRCT at study start and finish. Proportion of lung occupied by ground glass, ground glass-reticular (GGR), honeycombing, emphysema, and normal lung densities were measured by AMFM and three radiologists, documenting baseline disease extent and postbaseline change. Disease progression includes composite mortality, hospitalization, and 10% FVC decline., Measurements and Main Results: Agreement between visual and AMFM measurements was moderate for GGR (Pearson's correlation r = 0.60, P < 0.0001; mean difference = -0.03 with 95% limits of agreement of -0.19 to 0.14). Baseline extent of GGR was independently associated with disease progression when adjusting for baseline Gender-Age-Physiology stage and smoking status (hazard ratio per 10% visual GGR increase = 1.98, 95% confidence interval [CI] = 1.20-3.28, P = 0.008; and hazard ratio per 10% AMFM GGR increase = 1.36, 95% CI = 1.01-1.84, P = 0.04). Postbaseline visual and AMFM GGR trajectories were correlated with postbaseline FVC trajectory (r = -0.30, 95% CI = -0.46 to -0.11, P = 0.002; and r = -0.25, 95% CI = -0.42 to -0.06, P = 0.01, respectively)., Conclusions: More extensive baseline visual and AMFM fibrosis (as measured by GGR densities) is independently associated with elevated hazard for disease progression. Postbaseline change in AMFM-measured and visually measured GGR densities are modestly correlated with change in FVC. AMFM-measured fibrosis is an automated adjunct to existing prognostic markers and may allow for study enrichment with subjects at increased disease progression risk.

Purpose: This study aimed to investigate the breast dose reduction potential of a breast-positioning (BP) technique for thoracic CT examinations with organ-based tube current modulation (OTCM)., Methods: This study included 13 female anthropomorphic computational phantoms (XCAT, age range: 27-65 y.o., weight range: 52-105.8 kg). Each phantom was modified to simulate three breast sizes in standard supine geometry. The modeled breasts were then morphed to emulate BP that constrained the majority of the breast tissue inside the 120° anterior tube current (mA) reduction zone. The OTCM mA value was modeled using a ray-tracing program, which reduced the mA to 20% in the anterior region with a corresponding increase to the posterior region. The organ doses were estimated by a validated Monte Carlo program for a typical clinical CT system (SOMATOM Definition Flash, Siemens Healthcare). The simulated organ doses and organ doses normalized by CTDI vol were used to compare three CT protocols: attenuation-based tube current modulation (ATCM), OTCM, and OTCM with BP (OTCM BP )., Results: On average, compared to ATCM, OTCM reduced breast dose by 19.3 ± 4.5%, whereas OTCM BP reduced breast dose by 38.6 ± 8.1% (an additional 23.8 ± 9.4%). The dose saving of OTCM BP was more significant for larger breasts (on average 33, 38, and 44% reduction for 0.5, 1, and 2 kg breasts, respectively). Compared to ATCM, OTCM BP also reduced thymus and heart dose by 15.1 ± 7.4% and 15.9 ± 6.2% respectively., Conclusions: In thoracic CT examinations, OTCM with a breast-positioning technique can markedly reduce unnecessary exposure to radiosensitive organs in anterior chest wall, specifically breast tissue. The breast dose reduction is more notable for women with larger breasts., (© 2016 American Association of Physicists in Medicine.)

Background: Idiopathic pulmonary fibrosis (IPF) can be diagnosed confidently and non-invasively when clinical and computed tomography (CT) criteria are met. Many do not meet these criteria due to absence of CT honeycombing. We investigated predictors of IPF and combinations allowing accurate diagnosis in individuals without honeycombing., Methods: We utilized prospectively collected clinical and CT data from patients enrolled in the Lung Tissue Research Consortium. Included patients had no honeycombing, no connective tissue disease, underwent diagnostic lung biopsy, and had CT pattern consistent with fibrosing ILD (n = 200). Logistic regression identified clinical and CT variables predictive of IPF. The probability of IPF was assessed at various cut-points of important clinical and CT variables., Results: A multivariable model adjusted for age and gender found increasingly extensive reticular densities (OR 2.93, CI 95% 1.55-5.56, p = 0.001) predicted IPF, while increasing ground glass densities predicted a diagnosis other than IPF (OR 0.55, CI 95% 0.34-0.89, p = 0.02). The model-based probability of IPF was 80% or greater in patients with age at least 60 years and extent of reticular density one-third or more of total lung volume; for patients meeting or exceeding these clinical thresholds the specificity for IPF is 96% (CI 95% 91-100%) with 21 of 134 (16%) biopsies avoided., Conclusions: In patients with suspected fibrotic ILD and absence of CT honeycombing, extent of reticular and ground glass densities predict a diagnosis of IPF. The probability of IPF exceeds 80% in subjects over age 60 years with one-third of total lung having reticular densities., Competing Interests: Dr. Salisbury reports grants from NIH during the conduct of the study. Ms. Xia has nothing to disclose. Dr. Murray reports grants from NIH during the conduct of the study. Dr. Bartholmai reports other support from the NIH/NHLBI for research related to the LTRC, previous to the conduct of the study. Dr. Kazerooni has nothing to disclose. Dr. Meldrum has nothing to disclose. Dr. Martinez reports grants from National Institutes of Health, non-financial support from Bayer, non-financial support from Centocor, non-financial support from Gilead, non-financial support from Promedior, personal fees from Ikaria, personal fees from Genentech, personal fees from Nycomed/Takeda, personal fees from Pfizer, personal fees from Vertex, personal fees from American Thoracic Society, personal fees from Inova Health System, personal fees from MedScape, personal fees from Spectrum Health System, personal fees from University of Texas Southwestern, personal fees from Stromedix/Biogen, personal fees from Axon Communications, from Johnson & Johnson, from Genzyme, personal fees from National Association for Continuing Education, personal fees from Boehringer Ingelheim, personal fees from Veracyte, during the conduct of the study; personal fees from Forest, personal fees from Janssens, personal fees from GSK, personal fees from Nycomed/Takeda, personal fees from Actelion, personal fees from Amgen, personal fees from Astra Zeneca, personal fees from CSA Medical, personal fees from Ikaria/Bellerophon, personal fees from Forest, personal fees from Genentech, personal fees from GSK, personal fees from Janssens, personal fees from Merck, personal fees from Pearl, personal fees from Nycomed/Takeda, personal fees from Pfizer, personal fees from Roche, personal fees from Sudler & Hennessey, personal fees from American College of Chest Physicians, personal fees from CME Incite, personal fees from Center for Healthcare Education, personal fees from Inova Health System, personal fees from MedScape, personal fees from Miller Medical, personal fees from National Association for Continuing Education, personal fees from Paradigm, personal fees from Peer Voice, personal fees from Projects in Knowledge, personal fees from St. John’s Hospital, personal fees from St. Mary’s Hospital, personal fees from University of Illinois Chicago, personal fees from UpToDate, personal fees from Wayne State University, personal fees from GSK, personal fees from Boehringer Ingelheim, personal fees from GSK, personal fees from Ikaria, personal fees from Bayer, personal fees from Nycomed/Takeda, personal fees from Grey Healthcare, personal fees from Merion, personal fees from Informa, personal fees from Annenberg, personal fees from GSK, personal fees from Forest, outside the submitted work. Dr. Flaherty reports grants from NIH, during the conduct of the study; personal fees from Boehringer Ingelheim, personal fees from Fibrogen, personal fees from Genentech, personal fees from Gilead, personal fees from Ikaria, personal fees from ImmuneWorks, personal fees from MedImmune, personal fees from Novartis, personal fees from Takeda, personal fees from Vertex, personal fees from Veracyte, personal fees from Roche, personal fees from Pulmonary Fibrosis Foundation, grants from ImmuneWorks, grants and personal fees from Intermune, grants from Bristol-Myers Squibb, outside the submitted work., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Purpose: The aim of this study was to assess the appropriateness of utilization and diagnostic yields of CT pulmonary angiography (CTPA), comparing two commonly applied decision rules, the pulmonary embolism (PE) rule-out criteria (PERC) and the modified Wells criteria (mWells), in the emergency department (ED) setting., Methods: Institutional review board approval was obtained for this HIPAA-compliant, prospective-cohort, academic single-center study. Six hundred two consecutive adult ED patients undergoing CTPA for suspected PE formed the study population. The outcome was positive or negative for PE by CTPA and at 6-month follow-up. PERC and mWells scores were calculated. A positive PERC score was defined as meeting one or more criteria and a positive mWells score as >4. The percentage of CT pulmonary angiographic examinations that could have been avoided and the diagnostic yield of CTPA using PERC, mWells, and PERC applied to a negative mWells score were calculated., Results: The diagnostic yield of CTPA was 10% (61 of 602). By applying PERC, mWells, and PERC to negative mWells score, 17.6% (106 of 602), 45% (273 of 602), and 17.1% (103 of 602) of CT pulmonary angiographic examinations, respectively, could have been avoided. The diagnostic yield in PERC-positive patients was higher than in mWells-positive patients (10% [59 of 602] vs 8% [49 of 602], P < .0001). Among PERC-negative and mWells-negative patients, the diagnostic yields for PE were 1.9% (2 of 106) and 4% (12 of 273), respectively (P = .004). The diagnostic yield of a negative PERC score applied to a negative mWells score was 1.9% (2 of 103)., Conclusions: The use of PERC in the ED has the potential to significantly reduce the utilization of CTPA and misses fewer cases of PE compared with mWells, and it is therefore a more efficient decision tool., (Copyright © 2015 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

The Quantitative Imaging Biomarker Alliance (QIBA) is a multidisciplinary consortium sponsored by the RSNA to define processes that enable the implementation and advancement of quantitative imaging methods described in a QIBA profile document that outlines the process to reliably and accurately measure imaging features. A QIBA profile includes factors such as technical (product-specific) standards, user activities, and relationship to a clinically meaningful metric, such as with nodule measurement in the course of CT screening for lung cancer. In this report, the authors describe how the QIBA approach is being applied to the measurement of small pulmonary nodules such as those found during low-dose CT-based lung cancer screening. All sources of variance with imaging measurement were defined for this process. Through a process of experimentation, literature review, and assembly of expert opinion, the strongest evidence was used to define how to best implement each step in the imaging acquisition and evaluation process. This systematic approach to implementing a quantitative imaging biomarker with standardized specifications for image acquisition and postprocessing for a specific quantitative measurement of a pulmonary nodule results in consistent performance characteristics of the measurement (eg, bias and variance). Implementation of the QIBA small nodule profile may allow more efficient and effective clinical management of the diagnostic workup of individuals found to have suspicious pulmonary nodules in the course of lung cancer screening evaluation., (Copyright © 2015 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Rationale and Objectives: The longitudinal relationship between regional air trapping and emphysema remains unexplored. We have sought to demonstrate the utility of parametric response mapping (PRM), a computed tomography (CT)-based biomarker, for monitoring regional disease progression in chronic obstructive pulmonary disease (COPD) patients, linking expiratory- and inspiratory-based CT metrics over time., Materials and Methods: Inspiratory and expiratory lung CT scans were acquired from 89 COPD subjects with varying Global Initiative for Chronic Obstructive Lung Disease (GOLD) status at 30 days (n = 13) or 1 year (n = 76) from baseline as part of the Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS) clinical trial. PRMs of CT data were used to quantify the relative volumes of normal parenchyma (PRM(Normal)), emphysema (PRM(Emph)), and functional small airways disease (PRM(fSAD)). PRM measurement variability was assessed using the 30-day interval data. Changes in PRM metrics over a 1-year period were correlated to pulmonary function (forced expiratory volume at 1 second [FEV1]). A theoretical model that simulates PRM changes from COPD was compared to experimental findings., Results: PRM metrics varied by ∼6.5% of total lung volume for PRM(Normal) and PRM(fSAD) and 1% for PRM(Emph) when testing 30-day repeatability. Over a 1-year interval, only PRM(Emph) in severe COPD subjects produced significant change (19%-21%). However, 11 of 76 subjects showed changes in PRM(fSAD) greater than variations observed from analysis of 30-day data. Mathematical model simulations agreed with experimental PRM results, suggesting fSAD is a transitional phase from normal parenchyma to emphysema., Conclusions: PRM of lung CT scans in COPD patients provides an opportunity to more precisely characterize underlying disease phenotypes, with the potential to monitor disease status and therapy response., (Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.)

The ACR recognizes that low-dose CT for lung cancer screening has the potential to significantly reduce mortality from lung cancer in the appropriate high-risk population. The ACR supports the recommendations of the US Preventive Services Task Force and the National Comprehensive Cancer Network for screening patients. To be effective, lung cancer screening should be performed at sites providing high-quality low-dose CT examinations overseen and interpreted by qualified physicians using a structured reporting and management system. The ACR has developed a set of tools necessary for radiologists to take the lead on the front lines of lung cancer screening. The ACR Lung Cancer Screening Center designation is built upon the ACR CT accreditation program and requires use of Lung-RADS or a similar structured reporting and management system. This designation provides patients and referring providers with the assurance that they will receive high-quality screening with appropriate follow-up care., (Copyright © 2015 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

The management of bronchiolitis obliterans syndrome (BOS) after hematopoietic cell transplantation presents many challenges, both diagnostically and therapeutically. We developed a computed tomography (CT) voxel-wise methodology termed parametric response mapping (PRM) that quantifies normal parenchyma, functional small airway disease (PRM(fSAD)), emphysema, and parenchymal disease as relative lung volumes. We now investigate the use of PRM as an imaging biomarker in the diagnosis of BOS. PRM was applied to CT data from 4 patient cohorts: acute infection (n = 11), BOS at onset (n = 34), BOS plus infection (n = 9), and age-matched, nontransplant control subjects (n = 23). Pulmonary function tests and bronchoalveolar lavage were used for group classification. Mean values for PRM(fSAD) were significantly greater in patients with BOS (38% ± 2%) when compared with those with infection alone (17% ± 4%, P < .0001) and age-matched control subjects (8.4% ± 1%, P < .0001). Patients with BOS had similar PRM(fSAD) profiles, whether a concurrent infection was present or not. An optimal cut-point for PRM(fSAD) of 28% of the total lung volume was identified, with values >28% highly indicative of BOS occurrence. PRM may provide a major advance in our ability to identify the small airway obstruction that characterizes BOS, even in the presence of concurrent infection., (Copyright © 2014 American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.)

Introduction: Left ventricular (LV) and right ventricular (RV) volumetric and functional parameters are important biomarkers for morbidity and mortality in patients with heart failure., Purpose: To retrospectively determine reference mean values of LV and RV volume, function and mass normalised by age, gender and body surface area (BSA) from retrospectively electrocardiographically gated 64-slice cardiac computed tomography (CCT) by using automated analysis software in healthy adults., Materials and Methods: The study was approved by the institutional review board with a waiver of informed consent. Seventy-four healthy subjects (49% female, mean age 49.6 ± 11) free of hypertension and hypercholesterolaemia with a normal CCT formed the study population. Analyses of LV and RV volume (end-diastolic, end-systolic and stroke volumes), function (ejection fraction), LV mass and inter-rater reproducibility were performed with commercially available analysis software capable of automated contour detection. General linear model analysis was performed to assess statistical significance by age group after adjustment for gender and BSA. Bland-Altman analysis assessed the inter-rater agreement., Results: The reference range for LV and RV volume, function, and LV mass was normalised to age, gender and BSA. Statistically significant differences were noted between genders in both LV mass and RV volume (P-value < 0.0001). Age, in concert with gender, was associated with significant differences in RV end-diastolic volume and LV ejection fraction (P-values 0.027 and 0.03). Bland-Altman analysis showed acceptable limits of agreement (±1.5% for ejection fraction) without systematic error., Conclusion: LV and RV volume, function and mass normalised to age, gender and BSA can be reported from CCT datasets, providing additional information important for patient management., (© 2014 The Royal Australian and New Zealand College of Radiologists.)

Imaging is paramount in the setting of blunt trauma and is now the standard of care at any trauma center. Although anteroposterior radiography has inherent limitations, the ability to acquire a radiograph in the trauma bay with little interruption in clinical survey, monitoring, and treatment, as well as radiography's accepted role in screening for traumatic aortic injury, supports the routine use of chest radiography. Chest CT or CT angiography is the gold-standard routine imaging modality for detecting thoracic injuries caused by blunt trauma. There is disagreement on whether routine chest CT is necessary in all patients with histories of blunt trauma. Ultimately, the frequency and timing of CT chest imaging should be site specific and should depend on the local resources of the trauma center as well as patient status. Ultrasound may be beneficial in the detection of pneumothorax, hemothorax, and pericardial hemorrhage; transesophageal echocardiography is a first-line imaging tool in the setting of suspected cardiac injury. In the blunt trauma setting, MRI and nuclear medicine likely play no role in the acute setting, although these modalities may be helpful as problem-solving tools after initial assessment. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment., (Copyright © 2014 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Objective: The purpose of this article is to review both expected and unexpected thoracic CT manifestations of nonsurgical breast cancer treatment with multimodality imaging correlation. Specific topics include the spectrum of posttherapy changes attributed to chemotherapy and radiation therapy and the spread of breast cancer., Conclusion: Thoracic CT is an important tool commonly used for breast cancer staging and surveillance and for diagnostic indications such as shortness of breath and chest pain. Imaging findings can be related to progression of disease or to associated conditions, such as pulmonary embolism. The hallmarks of breast cancer spread in the thorax include pulmonary nodules, enlarged lymph nodes, pleural effusions, thickening or nodularity, and sclerotic or lytic skeletal lesions. Less common findings including pulmonary lymphangitic tumor spread and pericardial metastasis. The findings also may represent the sequelae of surgery, radiation therapy, or chemotherapy for breast cancer. Knowledge of various treatment methods and their expected and unexpected CT findings is important for recognizing treatment-related abnormalities to avoid confusion with breast cancer spread and thereby minimize the risk that unnecessary further diagnostic imaging will be performed.

Interstitial lung diseases (ILDs) are increasingly recognized in patients with systemic diseases. Patients with early ILD changes may be asymptomatic. Features of ILD overlap among systemic diseases and with idiopathic variety. High-resolution computed tomography plays a central role in diagnosing ILDs. Imaging features are often nonspecific. Therapy- and complication-related lung changes would pose difficulty in diagnosing and classifying an ILD. Biology and prognosis of secondary ILDs may differ between different disease-related ILDs and idiopathic variety. Combination of clinical features, serological tests, pulmonary and extrapulmonary imaging findings, and pathology findings may help to diagnose ILDs., (© 2013 Published by Elsevier Inc.)

Objective: The purpose of this article is to discuss the surgical treatment of breast cancer and its resultant thoracic CT and multimodality imaging manifestations., Conclusion: Many breast cancer patients undergo cross-sectional imaging at some point during or after treatment. Thoracic CT is an important modality performed for staging and surveillance. Thoracic CT examinations often show findings related to patients' surgical or adjuvant treatment. The postsurgical changes visible on thoracic CT may include those related to lumpectomy, mastectomy, breast reconstruction, and axillary surgery. Postsurgical complications may also be seen, including fluid collections, infection, fat necrosis, and lymphedema. Recognition and appropriate interpretation of the posttherapeutic spectrum of findings are important to avoid unnecessary diagnostic imaging and minimize patient anxiety.

Lung cancer screening with low dose computed tomography (CT) is the only method ever proven to reduce lung cancer-specific mortality in high-risk current and former cigarette smokers. Radiation exposure from annual screening CT examinations and subsequent CT and nuclear medicine testing to further evaluate positive screening CTs is sometimes raised as a reason to avoid screening and is often misunderstood. With all testing, there are potential benefits and risks. As we sit on the brink of widespread adoption of lung cancer screening CT, we aim to explain why the risks associated with radiation exposure from lung cancer screening are very low and should not be used to avoid screening or dissuade individuals who qualify for screening CT to participate in a lung cancer screening program., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Rationale and Objectives: To determine the impact of coronary computed tomography angiography (CCTA) on treatment decisions made by cardiac surgeons and to explore barriers to implementation of CCTA as first-line imaging workup before coronary artery bypass., Materials and Methods: Tertiary academic medical center retrospective cohort study. Questionnaires administered to three cardiac surgeons regarding diagnosis and treatment decisions with level of confidence in decision making for 30 chest pain patients, after reviewing deidentified catheter coronary angiogram (CCA) and CCTA images on the same patients, several weeks apart., Results: All surgeons tended to report more severe disease with CCTA than CCA (P < .05). Treatment decisions differed in 12 (40%), 14 (47%), and 18 (60%) patients within each individual surgeon based on CCTA images compared to CCA images (P = .11, .01, and .02, respectively). Confidence levels were significantly higher with CCA for the diagnosis and treatment of coronary artery disease for all three surgeons (P < .05). There was a tendency toward more invasive treatment choices (angioplasty, stent insertion, or coronary artery bypass graft) when making treatment decisions based upon CCTA images., Conclusions: Severity of disease may be overestimated by cardiac surgeons when using CCTA as a decision-making test, tending toward more invasive treatment choices compared to CCA. Additionally, cardiac surgeons may be more confident with their diagnosis and treatment based on CCA. These may be important limitations in the application of CCTA in clinical practice and may reflect the maturation of CCTA use in practice, diffusion of the technology and/or a reflection of the technology itself., (Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.)

Rationale and Objectives: The aims of the study were: 1) to assess the baseline health-related quality of life (HRQOL) of patients with coronary artery disease (CAD) using the standard gamble; 2) to evaluate and compare patients' preference for catheter versus computed tomography (CT) coronary angiography using the wait tradeoff (WTO) and rating scales; and 3) to calculate test disutility for catheter and CT coronary angiography., Materials and Methods: Thirty patients with CAD who underwent both CT and catheter angiography were interviewed by telephone within 6 months of testing. Patients were asked about their baseline symptoms and quality of life, their experience preparing for both CT and catheter angiography, their desire to undergo CT or catheter angiography, and immediate treatment versus having a waiting period between test results and treatment for a hypothetical "ideal test" with no side effects. Test disutility for CT and catheter angiography were calculated and compared., Results: The mean and median baseline HRQOL utility values were 0.72 and 0.91. The patients were willing to wait a mean (median) time of 12 (3) days after the ideal test for the test results to avoid undergoing CT angiography. They were willing to wait a mean (median) of 7 (3) days after the ideal test for test results, to avoid undergoing catheter angiography. There was no significant difference between waiting times or between patients' rating for their experience preparing for the two tests. Test disutility for CT angiography was 1.30 quality-adjusted life days (QALD) versus 2.16 QALD for catheter angiography (P > .05)., Conclusion: There was no significant difference in patient preference and test disutility between CT and catheter angiography in our small series. Future rigorously planned and adequately powered studies are required to confirm these findings in larger patient populations., (Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.)

Purpose: Lung segmentation is a fundamental step in many image analysis applications for lung diseases and abnormalities in thoracic computed tomography (CT). The authors have previously developed a lung segmentation method based on expectation-maximization (EM) analysis and morphological operations (EMM) for our computer-aided detection (CAD) system for pulmonary embolism (PE) in CT pulmonary angiography (CTPA). However, due to the large variations in pathology that may be present in thoracic CT images, it is difficult to extract the lung regions accurately, especially when the lung parenchyma contains extensive lung diseases. The purpose of this study is to develop a new method that can provide accurate lung segmentation, including those affected by lung diseases., Methods: An iterative neutrosophic lung segmentation (INLS) method was developed to improve the EMM segmentation utilizing the anatomic features of the ribs and lungs. The initial lung regions (ILRs) were extracted using our previously developed EMM method, in which the ribs were extracted using 3D hierarchical EM segmentation and the ribcage was constructed using morphological operations. Based on the anatomic features of ribs and lungs, the initial EMM segmentation was refined using INLS to obtain the final lung regions. In the INLS method, the anatomic features were mapped into a neutrosophic domain, and the neutrosophic operation was performed iteratively to refine the ILRs. With IRB approval, 5 and 58 CTPA scans were collected retrospectively and used as training and test sets, of which 2 and 34 cases had lung diseases, respectively. The lung regions manually outlined by an experienced thoracic radiologist were used as reference standard for performance evaluation of the automated lung segmentation. The percentage overlap area (POA), the Hausdorff distance (Hdist), and the average distance (AvgDist) of the lung boundaries relative to the reference standard were used as performance metrics., Results: The proposed method achieved larger POAs and smaller distance errors than the EMM method. For the 58 test cases, the average POA, Hdist, and AvgDist were improved from 85.4±18.4%, 22.6±29.4 mm, and 3.5±5.4 mm using EMM to 91.2±6.7%, 16.0±11.3 mm, and 2.5±1.0 mm using INLS, respectively. The improvements were statistically significant (p<0.05). To evaluate the accuracy of the INLS method in the identification of the lung boundaries affected by lung diseases, the authors separately analyzed the performance of the proposed method on the cases with versus without the lung diseases. The results showed that the cases without lung diseases were segmented more accurately than the cases with lung diseases by both the EMM and the INLS methods, but the INLS method achieved better performance than the EMM method in both cases., Conclusions: The new INLS method utilizing the anatomic features of the rib and lung significantly improved the accuracy of lung segmentation, especially for the cases affected by lung diseases. Improvement in lung segmentation will facilitate many image analysis tasks and CAD applications for lung diseases and abnormalities in thoracic CT, including automated PE detection.

Background: Whether African Americans (AA) are more susceptible to COPD than non-Hispanic Whites (NHW) and whether racial differences in disease phenotype exist is controversial. The objective is to determine racial differences in the extent of emphysema and airway remodeling in COPD., Methods: First, 2,500 subjects enrolled in the COPDGene study were used to evaluate racial differences in quantitative CT (QCT) parameters of% emphysema, air trapping and airway wall thickness. Independent variables studied included race, age, gender, education, BMI, pack-years, smoking status, age at smoking initiation, asthma, previous work in dusty job, CT scanner and center of recruitment., Results: Of the 1,063 subjects with GOLD Stage II-IV COPD, 200 self-reported as AA. AAs had a lower mean% emphysema (13.1% vs. 16.1%, p = 0.005) than NHW and proportionately less emphysema in the lower lung zones. After adjustment for covariates, there was no statistical difference by race in air trapping or airway wall thickness. Measured QCT parameters were more predictive of poor functional status in NHWs compared to AAs., Conclusions: AAs have less emphysema than NHWs but the same degree of airway disease. Additional factors not easily assessed by current QCT techniques may account for the poor functional status in AAs.

Screening with low-dose computed tomography reduces mortality from lung cancer in high-risk patients. Lung cancer screening with chest radiography alone or in combination with sputum analysis is currently not recommended. The feasibility and impact of screening in patients with a low or moderate risk for primary lung cancer are currently not known. A standardized framework for testing and management in a multidisciplinary fashion is necessary to provide lung cancer screening. The National Comprehensive Cancer Network and the American Lung Association have recently issued guidelines for lung cancer screening with computed tomography in high-risk patients., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Knowledge of the anatomy of the coronary sinus (CS) and cardiac venous drainage is important because of its relevance in electrophysiologic procedures and cardiac surgeries. Several procedures make use of the CS, such as left ventricular pacing, mapping and ablation of arrhythmias, retrograde cardioplegia, targeted drug delivery, and stem cell therapy. As a result, it is more important for physicians interpreting the results of computed tomographic (CT) examinations dedicated to the heart or including the heart to be able to identify normal variants and congenital anomalies and to understand their clinical importance. Abnormalities of the CS range from anatomic morphologic variations to hemodynamically significant anomalies such as an unroofed CS, anomalous pulmonary venous connection to the CS, and coronary artery-CS fistula. It can be important to identify some anatomic variations, even though they are clinically occult, to ensure appropriate preprocedural planning. Both CT and magnetic resonance imaging provide excellent noninvasive depiction of the anatomy and anomalies of the CS. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.324105220/-/DC1.

Purpose: To document the natural history of branch artery pseudoaneurysms (BAPs), which are sequelae of aortic dissection with false lumen thrombosis that have been distinguished anatomically from penetrating ulcers., Materials and Methods: Serial computed tomography (CT) scans in 50 patients with at least two CT scans greater than 1 month apart were retrospectively studied. Mean follow-up was 29 months, with longitudinal analyses of 119 BAPs. Changes in BAPs, false lumen thrombosis, and aortic diameter were assessed., Results: No patient had an aortic rupture or other poor outcome. All BAPs eventually disappeared (ie, thrombosed), with 50% thrombosed within 18 months. Aortas were ectatic, with a mean diameter of 36 mm. There was no statistically significant change in total aortic diameters; however, there was a significant increase in true lumen diameters (P < .0001) and a significant decrease in false lumen thickness (P < .0001) at the level of the BAP over time (mean 50% reduction in maximum thickness of thrombosed false lumen). There were no significant associations between BAP thrombosis and vertebral level, presence of more than one BAP, presence of branch artery in communication with the BAP, history of smoking, diabetes mellitus or hypertension, or treatment with β-blockers, other antihypertensive medication, statins, or anticoagulation therapy. After controlling for other variables, BAPs were less likely to thrombose if an ulcerlike projection was present (P = .003), in men (P = .02), in subjects with hypertension (P = .04), and in older patients (P = .05)., Conclusions: Most BAPs spontaneously thrombose, and associated intramural hematoma regresses/disappears. Isolated BAPs were not associated with poor clinical outcomes., (Copyright © 2012 SIR. Published by Elsevier Inc. All rights reserved.)

Background: The value of quantitative CT (QCT) to identify chronic obstructive pulmonary disease (COPD) phenotypes is increasingly appreciated. The authors hypothesised that QCT-defined emphysema and airway abnormalities relate to St George's Respiratory Questionnaire (SGRQ) and Body-Mass Index, Airflow Obstruction, Dyspnea and Exercise Capacity Index (BODE)., Methods: 1200 COPDGene subjects meeting Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria for COPD with QCT analysis were included. Total lung emphysema was measured using the density mask technique with a -950 Hounsfield unit threshold. An automated programme measured mean wall thickness (WT), wall area percentage (WA%) and 10 mm lumenal perimeter (pi10) in six segmental bronchi. Separate multivariate analyses examined the relative influence of airway measures and emphysema on SGRQ and BODE., Results: In separate models predicting SGRQ score, a 1 unit SD increase in each airway measure predicted higher SGRQ scores (for WT, 1.90 points higher, p=0.002; for WA%, 1.52 points higher, p=0.02; for pi10, 2.83 points higher p<0.001). The comparable increase in SGRQ for a 1 unit SD increase in emphysema percentage in these models was relatively weaker, significant only in the pi10 model (for emphysema percentage, 1.45 points higher, p=0.01). In separate models predicting BODE, a 1 unit SD increase in each airway measure predicted higher BODE scores (for WT, 1.07-fold increase, p<0.001; for WA%, 1.20-fold increase, p<0.001; for pi10, 1.16-fold increase, p<0.001). In these models, emphysema more strongly influenced BODE (range 1.24-1.26-fold increase, p<0.001)., Conclusion: Emphysema and airway disease both relate to clinically important parameters. The relative influence of airway disease is greater for SGRQ; the relative influence of emphysema is greater for BODE.

Background: Coronary computed tomography angiography (CCTA) is an emerging noninvasive anatomical method for evaluation of patients with suspected coronary artery disease (CAD). Multicenter clinical registries are key to efforts to establish the role of CCTA in CAD diagnosis and management. The Advanced Cardiovascular Imaging Consortium (ACIC) is a statewide, multicenter collaborative quality initiative with the intent to establish quality and appropriate use of CCTA in Michigan., Methods: The ACIC is sponsored by the Blue Cross Blue Shield of Michigan/Blue Care Network, and its 47 sites include imaging centers that offer CCTA and meet established structure and process standards for participation. Patients enrolled include those with suspected ischemia with or without known CAD, and individuals across the entire spectrum of CAD risk. Patient demographics, history, CCTA scan-related data and findings, and 90-day follow-up data are entered prospectively into a centralized database with strict validation tools and processes. Collaborative quality initiatives include radiation dose reduction and appropriate CCTA use by education and feedback to participating sites and referring physicians., Conclusions: Across a wide range of institutions, the ACIC permits evaluation of "real-world" utilization and effectiveness of CCTA and examines an alternative, nontraditional approach to utilization management wherein physicians and payers collaborate to address the growing problem of cardiac imaging overutilization., (Copyright © 2012 Mosby, Inc. All rights reserved.)

Rational and Objectives: To evaluate our prototype method for segmentation and tracking of the coronary arterial tree, which is the foundation for a computer-aided detection (CADe) system to be developed to assist radiologists in detecting non-calcified plaques in coronary CT angiography (cCTA) scans., Materials and Methods: The heart region was first extracted by a morphological operation and an adaptive thresholding method based on expectation-maximization (EM) estimation. The vascular structures within the heart region were enhanced and segmented using a multiscale coronary response (MSCAR) method that combined 3D multiscale filtering, analysis of the eigenvalues of Hessian matrices and EM estimation segmentation. After the segmentation of vascular structures, the coronary arteries were tracked by a 3D dynamic balloon tracking (DBT) method. The DBT method started at two manually identified seed points located at the origins of the left and right coronary arteries (LCA and RCA) for extraction of the arterial trees. The coronary arterial trees of a data set containing 20 ECG-gated contrast-enhanced cCTA scans were extracted by our MSCAR-DBT method and a clinical GE Advantage workstation. Two experienced thoracic radiologists visually examined the coronary arteries on the original cCTA scans and the rendered volume of segmented vessels to count the untracked false-negative (FN) segments and false positives (FPs) for both methods., Results: For the visible coronary arterial segments in the 20 cases, the radiologists identified that 25 segments were missed by our MSCAR-DBT method, ranging from 0 to 5 FN segments in individual cases, and that 55 artery segments were missed by the GE software, ranging from 0 to 7 FN segments in individual cases. 19 and 15 FPs were identified in our and the GE coronary trees, ranging from 0 to 4 FPs for both methods in individual cases, respectively., Conclusion: The preliminary study demonstrates the feasibility of our MSCAR-DBT method for segmentation and tracking coronary artery trees. The results indicated that both our method and GE software can extract coronary artery trees reasonably well and the performance of our method is superior to that of GE software in this small data set. Further studies are underway to develop methods for improvement of the segmentation and tracking accuracy., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The purpose of this study was to determine the normal distribution of aortic branch artery ostia. CT scans of 100 subjects were retrospectively reviewed. The angular distributions of the aorta with respect to the center of the T3 to L4 vertebral bodies, and of branch artery origins with respect to the center of the aorta were measured. At each vertebral body level the distribution of intercostal/lumbar arteries and other branch arteries were calculated. The proximal descending aorta is posteriorly placed becoming a midline structure, at the thoracolumbar junction, and remains anterior to the vertebral bodies within the abdomen. The intercostal and lumbar artery ostia have a distinct distribution. At each vertebral level from T3 caudally, one intercostal artery originates from the posterior wall of the aorta throughout the thoracic aorta, while the other intercostal artery originates from the medial wall of the descending thoracic aorta high in the chest, posteromedially from the mid-thoracic aorta, and from the posterior wall of the aorta low in the chest. Mediastinal branches of the thoracic aorta originate from the medial and anterior wall. Lumbar branches originate only from the posterior wall of the abdominal aorta. Aortic branch artery origins arise with a bimodal distribution and have a characteristic location. Mediastinal branches of the thoracic aorta originate from the medial and anterior wall. Knowing the location of aortic branch artery ostia may help distinguish branch artery pseudoaneurysms from penetrating ulcers., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To test the hypothesis-given the increasing emphasis on quantitative computed tomographic (CT) phenotypes of chronic obstructive pulmonary disease (COPD)-that a relationship exists between COPD exacerbation frequency and quantitative CT measures of emphysema and airway disease., Materials and Methods: This research protocol was approved by the institutional review board of each participating institution, and all participants provided written informed consent. One thousand two subjects who were enrolled in the COPDGene Study and met the GOLD (Global Initiative for Chronic Obstructive Lung Disease) criteria for COPD with quantitative CT analysis were included. Total lung emphysema percentage was measured by using the attenuation mask technique with a -950-HU threshold. An automated program measured the mean wall thickness and mean wall area percentage in six segmental bronchi. The frequency of COPD exacerbation in the prior year was determined by using a questionnaire. Statistical analysis was performed to examine the relationship of exacerbation frequency with lung function and quantitative CT measurements., Results: In a multivariate analysis adjusted for lung function, bronchial wall thickness and total lung emphysema percentage were associated with COPD exacerbation frequency. Each 1-mm increase in bronchial wall thickness was associated with a 1.84-fold increase in annual exacerbation rate (P = .004). For patients with 35% or greater total emphysema, each 5% increase in emphysema was associated with a 1.18-fold increase in this rate (P = .047)., Conclusion: Greater lung emphysema and airway wall thickness were associated with COPD exacerbations, independent of the severity of airflow obstruction. Quantitative CT can help identify subgroups of patients with COPD who experience exacerbations for targeted research and therapy development for individual phenotypes., (© RSNA, 2011.)

Objective: The purpose of this study was to retrospectively determine CT-based normal reference values of left atrial volume, function, and diameter normalized by age, sex, and body surface area., Materials and Methods: The study group consisted of 74 subjects with normal findings at ECG-gated coronary CT angiography performed with retrospective gating. Analysis of left atrial volume (end-diastolic, end-systolic, and stroke volume) and function (ejection fraction) was performed with the Simpson method. Left atrial diameter was measured in the anteroposterior dimension. General linear model analysis was performed to model the data and assess statistical significance by age group after adjustment for sex and body surface area., Results: The reference range for left atrial volume, function, and diameter was normalized (indexed) to age, sex, and body surface area in healthy subjects. A statistically significant difference was noted between left atrial volume and age without adjustment for sex and body surface area, but no statistically significant difference was found after adjustment for these variables. Sex and body surface area had a significant influence on left atrial volume, function, and diameter., Conclusion: Left atrial volume, function, and diameter normalized to age, sex, and body surface area can be reported from CTA datasets and may provide information important for patient care.