Thriving In and Out of the Reading Room: A Faculty Development Workshop.

RATIONALE AND OBJECTIVES: Given the immense time and energy radiologists dedicate to their profession, the experience at work should be a major contributor to a meaningful and fulfilling life. In pursuit of this vision, our department launched a novel faculty development workshop entitled "Thriving In and Out of the Reading Room: What They Didn't Teach Us in Training." We report on the design, implementation and initial outcomes of this faculty development workshop. MATERIALS AND METHODS: The workshop drew upon positive psychology research and the PERMA model of well-being, which encompasses five key elements: Positive emotion, Engagement, Relationships, Meaning, and Achievement. These elements have been shown to enhance work satisfaction and foster resilience. Using interactive, small group exercises, the workshop provided strategies for incorporating PERMA elements into daily life. At the conclusion of each workshop, an anonymous voluntary electronic survey was distributed to participants. RESULTS: The final version of the workshop was offered to 58 faculty over eight sessions between September 2022 and May 2023. Survey results indicate that participants found the workshop to be highly valuable and practical. They also found the workshop to promote camaraderie and peer learning. Developing the workshop internally allowed us to customize it to our faculty's unique experiences and engage a large number of participants. CONCLUSION: The workshop shows promise in improving job satisfaction and addressing burnout among academic radiologists.

Practice patterns in reporting interstitial lung abnormality at a tertiary academic medical center.

PURPOSE: Interstitial lung abnormality (ILA) is a common finding on chest CTs and is associated with higher all-cause mortality. The 2020 Fleischner Society position paper standardized the terminology and definition of ILA. Despite these published guidelines, the extent to which radiologists use this term is unknown. We evaluated practice patterns for identification of ILAs among radiologists at a tertiary academic medical center. METHODS: In this retrospective review, we identified 157 radiology reports between January 1, 2010 through December 31, 2021 containing the phrase "interstitial lung abnormality" or "interstitial abnormality". After exclusions, 125 CT scans were reviewed by thoracic-trained radiologists using the sequential reading method. RESULTS: Seventy-seven (62%) patients were found to have ILA (69% subpleural fibrotic, 19% subpleural non-fibrotic, and 6% non-subpleural), nine (7%) were equivocal for ILA and 39 (31%) had no ILA. The term ILA was used exclusively by thoracic-trained radiologists except for two cases. Use of the term ILA has rapidly increased since the position paper publication (none from 2010-2017, one case in 2018, 20 cases in 2019, 41 cases in 2020, and 73 cases in 2021), and cases were typically very mild (1-25% of the lung). CONCLUSION: While there has been increased use of the term ILA among thoracic-trained radiologists, non-thoracic radiologists have essentially not begun to use the term. Almost one-third of cases labeled ILA on clinical reads were re-classified as not having ILA on research reads.

How Does Pruning Impact Long-Tailed Multi-Label Medical Image Classifiers?

Pruning has emerged as a powerful technique for compressing deep neural networks, reducing memory usage and inference time without significantly affecting overall performance. However, the nuanced ways in which pruning impacts model behavior are not well understood, particularly for long-tailed, multi-label datasets commonly found in clinical settings. This knowledge gap could have dangerous implications when deploying a pruned model for diagnosis, where unexpected model behavior could impact patient well-being. To fill this gap, we perform the first analysis of pruning's effect on neural networks trained to diagnose thorax diseases from chest X-rays (CXRs). On two large CXR datasets, we examine which diseases are most affected by pruning and characterize class "forgettability" based on disease frequency and co-occurrence behavior. Further, we identify individual CXRs where uncompressed and heavily pruned models disagree, known as pruning-identified exemplars (PIEs), and conduct a human reader study to evaluate their unifying qualities. We find that radiologists perceive PIEs as having more label noise, lower image quality, and higher diagnosis difficulty. This work represents a first step toward understanding the impact of pruning on model behavior in deep long-tailed, multi-label medical image classification. All code, model weights, and data access instructions can be found at https://github.com/VITA-Group/PruneCXR.

How Does Pruning Impact Long-Tailed Multi-label Medical Image Classifiers?

Pruning has emerged as a powerful technique for compressing deep neural networks, reducing memory usage and inference time without significantly affecting overall performance. However, the nuanced ways in which pruning impacts model behavior are not well understood, particularly for long-tailed, multi-label datasets commonly found in clinical settings. This knowledge gap could have dangerous implications when deploying a pruned model for diagnosis, where unexpected model behavior could impact patient well-being. To fill this gap, we perform the first analysis of pruning's effect on neural networks trained to diagnose thorax diseases from chest X-rays (CXRs). On two large CXR datasets, we examine which diseases are most affected by pruning and characterize class "forgettability" based on disease frequency and co-occurrence behavior. Further, we identify individual CXRs where uncompressed and heavily pruned models disagree, known as pruning-identified exemplars (PIEs), and conduct a human reader study to evaluate their unifying qualities. We find that radiologists perceive PIEs as having more label noise, lower image quality, and higher diagnosis difficulty. This work represents a first step toward understanding the impact of pruning on model behavior in deep long-tailed, multi-label medical image classification. All code, model weights, and data access instructions can be found at https://github.com/VITA-Group/PruneCXR.

Screening Chest CT Prior to Allogenic Hematopoietic Stem Cell Transplantation.

Pulmonary complications constitute a major cause of morbidity and mortality in the post-allogenic hematopoietic stem cell transplantation (alloHSCT) period. Although chest X-ray (CXR) is customarily used for screening, we have used chest computed tomography (CT) scans. To characterize the prevalence of abnormalities and explore their impact on alloHSCT eligibility and outcomes post-transplantation, we conducted a retrospective analysis using real-world data collected at our center for adult patients who were evaluated for alloHSCT between January 2013 and December 2020 and identified 511 eligible patients. The most common primary disease was acute myeloid leukemia, in 49% of patients, followed by myelodysplastic syndrome (23%), lymphoma (11%), and acute lymphocytic leukemia (10%). Abnormal screening chest CT results were found in 199 patients (39%). The most frequent detected abnormality was pulmonary nodule, in 78 patients (35%), followed by consolidation in 42 (19%), ground-glass opacification in 33 (15%), bronchitis and bronchiolitis in 25 (11%), pleural effusions in 14 (6%), and new primary cancer in 7 (2%). CXR detected abnormalities in only approximately one-half of the patients (48%) with an abnormal chest CT scan. Among the 199 patients with an abnormal chest CT scan, 98 (49%) underwent further assessment and/or intervention before transplantation. The most common workup was pulmonary consultation in 32%, followed by infectious diseases consultation in 24%. Lung biopsy was obtained in 20%, and antimicrobial therapy was initiated after confirming an infection diagnosis in 20%. Patients with an abnormal chest CT scan demonstrated worse overall survival (P = .032), nonrelapse mortality (P = .015), and pulmonary-related mortality (P < .001) compared to those with a normal chest CT scan. Our study suggests that pretransplantation screening chest CT is beneficial in uncovering invasive infections and underlying malignancies and allows for appropriate interventions before alloHSCT to prevent potentially serious post-transplantation complications without causing a delay in alloHSCT. Nevertheless, abnormal CT findings prior to transplantation may be associated with overall worse prognosis.

Incidence, clinical associations and outcomes of intrathoracic complications with and without ARDS in COVID-19 pneumonia.

PURPOSE: To determine the incidence and clinical predictors of intrathoracic complications in COVID-19 patients, and the association with outcomes. METHODS: In this retrospective cross-sectional study, we included 976 patients (age 61 ± 17 years, 62% male) who tested positive for SARS-CoV-2 between March 3-April 4, 2020 and underwent chest imaging. 3836 radiographs from 976 patients and 105 CTs from 88 patients were reviewed for intrathoracic complications, including pneumothorax, pneumomediastinum, pneumopericardium, lobar collapse, pleural effusion, and pneumatocele formation. RESULTS: There was a high rate of intrathoracic complications (197/976, 20%). Pleural effusion was the most common complication (168/976, 17%). Pneumothorax (30/976, 3%) and pneumatoceles (9/88, 10%) were also frequent. History of hypertension and high initial CXR severity score were independent risk factors for complications. Patients with any intrathoracic complication during admission had an over 11-fold risk of ICU admission (adjusted odds ratio [aOR] 11.2, p < 0.0001) and intubation (aOR 12.4, p < 0.0001), over 50% reduction in successful extubation (aOR 0.49, p = 0.02) and longer length of stay (median 13 versus 5 days, p < 0.0001). There was no difference in overall survival between patients with and without any complication (log-rank p = 0.94). CONCLUSION: In COVID-19 patients who underwent chest imaging, 1 in 5 patients have an intrathoracic complication, which are associated with higher level of care and prolonged hospital stay. Hypertension history and high CXR severity score confer an increased risk of complication. SUMMARY: Intrathoracic complications in COVID-19 are common and are predictive of ICU admission, need for intubation, less successful extubation, and longer length of stay but are not predictive of mortality.

Management of Incidental Pulmonary Nodules: Influencing Patient Care Through Subspecialized Imaging Review.

OBJECTIVE: To evaluate whether thoracic radiologist review of computed tomography-detected incidental pulmonary nodules initially reported by non-thoracic imagers would change management recommendations. MATERIALS AND METHODS: The Radiology Consultation Service identified 468 computed tomography scans (one per patient) performed through the adult emergency department from August 2018 through December 2020 that mentioned the presence of a pulmonary nodule. Forty percent (186/468) were read by thoracic radiologists and 60% (282/468) were read by non-thoracic radiologists. The Radiology Consultation Service contacted all patients in order to assess risk factors for lung malignancy. Sixty-seven patients were excluded because they were unreachable, declined participation, or were actively followed by a pulmonologist or oncologist. A thoracic radiologist assessed the nodule and follow up recommendations in all remaining cases. RESULTS: A total of 215 cases were re-reviewed by thoracic radiologists. The thoracic radiologist disagreed with the initial nodule recommendations in 38% (82/215) of cases and agreed in 62% (133/215) of cases. All discordant cases resulted in a change in management by the thoracic radiologist with approximately one-third (33%, 27/82) decreasing imaging utilization and two-thirds (67%, 55/82) increasing imaging utilization. Nodules were deemed benign and follow up eliminated in 11% (9/82) of discordant cases. DISCUSSION: Our study illustrates that nodule review by thoracic radiologists results in a change in management in a large percentage of patients. Continued research is needed to determine whether subspecialty imaging review results in increased or more timely lung cancer detection.

Imaging of the rare cystic lung diseases.

When discussing cystic lung diseases, a certain group of diseases tends to receive the majority of attention. Other less frequently discussed cystic lung diseases are also important causes of morbidity in patients. Etiologies include genetic syndromes, lymphoproliferative diseases, infections, exogenous exposures, and a developmental abnormality. This review article focuses on the clinical and imaging features of these other cystic lung diseases.

The Design and Preliminary Experience with a Virtual Diversity Visiting Student Acting Internship in Radiology for Underrepresented Minority Medical Students.

OBJECTIVE: Benefits of a diverse physician workforce are numerous and the impact of a lack of diversity has been highlighted with the COVID-19 pandemic. Despite the commitment of professional societies such as the American College of Radiology to diversity in Radiology, the field and its residency training programs remain the least diverse. With COVID-19 related suspension of in-person medical student rotations, our Department of Radiology redesigned and implemented a virtual radiology internship for underrepresented minority (URM) medical students. METHODS: A four-week virtual radiology internship was designed to provide clinical exposure to radiology and to allow students to gain an understanding of what a career in radiology entails. Course design included videoconference patient care sessions, didactic lectures, online modules, mentoring, and extra-clinical curriculum. Feedback from students was collected using online surveys assessing pre- and postcourse attitudes and understanding of a career in radiology and the students' perceived aptitude for such a career, as well as course component evaluation. RESULTS: Three participants were enrolled in the inaugural clerkship. All noted exceptional educational course content and ample opportunities to build connections with faculty and residents-with mentoring seen as the highlight of the course. All indicated a significant shift in perception of the field and in declaring interest in pursuing a career in radiology. CONCLUSION: Virtual radiology internship for URM students is a feasible paradigm to address potential impediments to diversification of the specialty by both engaging interested URM medical students in a career in radiology and arming them with the tools for a successful application to radiology residency.

Central paradiaphragmatic middle lobe involvement in nonspecific interstitial pneumonia.

OBJECTIVES: Nonspecific interstitial pneumonia (NSIP) lacks specific diagnostic guidelines or criteria for imaging diagnosis, and the need for more reliable computed tomography (CT) characterization remains. We hypothesized that central paradiaphragmatic middle lobe (ML) involvement is present in most patients with NSIP. The purpose of this study was to evaluate the prevalence of ML involvement and thus to assess its potential as a unique feature of NSIP. METHODS: We conducted a retrospective CT-imaging review of 40 patients with biopsy-proven (7/40, 18%) or clinically established (33/40, 82%) NSIP. Three subspecialty-trained thoracic radiologists reviewed CTs for ML involvement both independently and in consensus, and additional CT findings previously described in NSIP independently. RESULTS: ML involvement was present in most cases (70%, 28/40, independent review, 78%, 31/40, consensus reading), with substantial agreement among all three readers (κ = 0.65). Fibrosis was present in almost all cases (93%, 37/40). Subpleural sparing occurred in one-third of patients (30%, 12/40). Homogeneity (48%, 19/40), central bronchiectasis (45%, 18/40), and peripheral bronchiectasis (53%, 21/40) were present in about half of patients. Apart from substantial inter-reader agreement on fibrosis (κ = 0.65), the above-mentioned imaging characteristics had fair to slight universal agreement (κ = 0.07-0.30). CONCLUSIONS: Central paradiaphragmatic ML ground glass attenuation superimposed on reticulation and traction bronchiectasis occurs in most patients with NSIP, with high interobserver agreement. KEY POINTS: • Central paradiaphragmatic middle lobe ground glass attenuation superimposed on reticulation and traction bronchiectasis is common in nonspecific interstitial pneumonia (NSIP). • This finding occurs more frequently than subpleural sparing and has a better interobserver agreement.

Thoracic Manifestations of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is one of the most common chronic systemic inflammatory diseases and the most common chronic inflammatory arthritis. Classically a progressive symmetric polyarthritis, RA is characterized by inflammation, erosions, bone loss, and joint destruction. Up to half of patients with RA exhibit extra-articular manifestations (EAMs), which may precede articular disease and are more common in patients with seropositive RA (patients with detectable serum levels of rheumatoid factor and/or anticitrullinated peptide antibodies). Cardiovascular and pulmonary EAMs are the largest contributors to morbidity and mortality in RA and may be especially devastating. Imaging has a significant role in diagnosing these EAMs and assessing response to treatment. Although treatment with disease-modifying antirheumatic drugs has redefined the natural history of RA and helped many patients achieve low disease activity, patients are at risk for treatment-related complications, as well as infections. The clinical features of drug-induced lung disease and infection can overlap considerably with those of EAMs, presenting a diagnostic challenge. Radiologists, by recognizing the imaging characteristics and evolution of these various processes, are essential in diagnosing and distinguishing among EAMs, treatment-related complications, and unrelated processes and formulating an appropriate differential diagnosis. Moreover, recognizing these disease processes at imaging and contextualizing imaging findings with clinical information and laboratory and pathologic findings can facilitate definitive diagnosis and proper treatment. The authors review the articular and extra-articular thoracic imaging manifestations of RA, including cardiovascular, respiratory, and pleural diseases, as well as treatment-related complications and common infections. ©RSNA, 2021.

A Case-Based Review of Vaping-Induced Injury-Pulmonary Toxicity and Beyond.

The last 10 years has seen a steady rise in the use of electronic cigarettes ("e-cigarettes" or ECIGs) or "vape pens." Though initially developed to assist with smoking cessation, use among adolescents has been particularly high. A concomitant rise in ECIG-related injuries disproportionately affecting young patients has been recognized. This unique case series highlights both pulmonary and extra-pulmonary ECIG-induced injuries including vape tip ingestion, maxillofacial fractures after vape pen explosion, myocarditis, and several different manifestations of vaping-associated lung injury. Becoming familiar with expected imaging findings in the wide array of ECIG-induced complications will help radiologists recognize these findings, recommend further imaging as needed, facilitate early diagnosis by help referring clinicians elicit the relevant history from patients, and expedite appropriate treatment.

Potential impact of dynamic automated CT aortic annular measurements on outcomes for transcatheter aortic valve replacement sizing.

To determine the potential impact of automated computed tomography (CT) software used for aortic annular sizing for transcatheter aortic valve replacement (TAVR) on paravalvular leak (PVL) and major adverse cardiovascular events (MACE) as compared to standard CT manual measurement. In 60 TAVR patients (84 ± 7 years, 60% male), we evaluated the preprocedural CT scans. For the standard manual measurement, we measured the perimeter and area from a single cardiac phase deemed to be of maximum systolic opening. Valve type and size were determined by a multidisciplinary TAVR team per clinical routine. From the dynamic automated software, we determined the aortic annular perimeter and area as the maximum value from an entire cardiac cycle. Valve size was readjudicated by a blinded interventional cardiologist who was provided with valve type and automated values. Clinical endpoints were adjudicated for presence of at least mild PVL and MACE at 30 days. There were 16 (28%) patients with PVL and 4 (7%) with 30-day MACE. When reclassifying valve size using dynamic automated values, 12 (20%) patients were undersized and 3 (5%) patients were oversized. Undersized patients were more likely to have mild-to-moderate PVL at 30 days (27% vs 4%, p = 0.04) than those not undersized. Of the 5 (45%) undersized patients with at least mild PVL, all were balloon-expandable valves. Automated dynamic CT annular measurements have the potential to reclassify patients with PVL with larger TAVR valve size, particularly balloon-expandable valves.

Imaging Utilization and Outcomes in Vulnerable Populations during COVID-19 in New York City.

BACKGROUND: Coronavirus disease 2019 (COVID-19) affects vulnerable populations (VP) adversely. PURPOSE: To evaluate overall imaging utilization in vulnerable subgroups (elderly, racial/ethnic minorities, socioeconomic status [SES] disadvantage) and determine if a particular subgroup has worse outcomes from COVID-19. MATERIALS/METHODS: Of 4110 patients who underwent COVID-19 testing from March 3-April 4, 2020 at NewYork-Presbyterian Hospital (NYP) health system, we included 1121 COVID-19 positive adults (mean age 59±18 years, 59% male) from two academic hospitals and evaluated imaging utilization rates and outcomes, including mortality. RESULTS: Of 897 (80%) VP, there were 465 (41%) elderly, 380 (34%) racial/ethnic minorities, and 479 (43%) SES disadvantage patients. Imaging was performed in 88% of patients and mostly portable/bedside studies, with 87% of patients receiving chest radiographs. There were 83% hospital admissions, 25% ICU admissions, 23% intubations, and 13% deaths. Elderly patients had greater imaging utilization, hospitalizations, ICU/intubation requirement, longer hospital stays, and >4-fold increase in mortality compared to non-elderlies (adjusted hazard ratio[aHR] 4.79, p<0.001). Self-reported minorities had fewer ICU admissions (p=0.03) and reduced hazard for mortality (aHR 0.53, p=0.004; complete case analysis: aHR 0.39, p<0.001 excluding "not reported"; sensitivity analysis: aHR 0.61, p=0.005 "not reported" classified as minorities) with similar imaging utilization, compared to non-minorities. SES disadvantage patients had similar imaging utilization and outcomes as compared to their counterparts. CONCLUSIONS: In a predominantly hospitalized New York City cohort, elderly patients are at highest mortality risk. Racial/ethnic minorities and SES disadvantage patients fare better or similarly to their counterparts, highlighting the critical role of access to inpatient medical care during the COVID-19 pandemic.

Performance of Dynamic Automated CT Annular Measurements Compared to Standard Manual Measurements for Transcatheter Aortic Valve Replacement Sizing.

PURPOSE: We sought to determine the performance of an automated computed tomography (CT) software that provides dynamic annular measurements of all available cardiac phases for transcatheter aortic valve replacement (TAVR) sizing as compared to the standard single manual measurement. MATERIALS AND METHODS: In 60 TAVR patients (84±7 years, 60% male) who underwent pre-procedural CT scans, we measured the aortic annular diameters, perimeter, and area using (1) the dynamic automated CT measurements and (2) standard single manual measurement from the cardiac phase of maximum systolic opening by visual estimate. RESULTS: The automated software was successful in providing annular measurements in 43/60 (72%) of cases, with the remainder requiring semi-automated contours. The maximum dynamic automated values were predominantly in systole (46/60[77%] for diameter, 44/60[73%] for perimeter, 48/60[80%] for area), and was a different phase from the standard manual phase in 46/60 (77%) cases. The maximum dynamic automated annular values were larger than the standard manual values measured (Δdiameter 0.35 mm, p=0.04; Δperimeter 1.71 mm, p<0.001; Δarea 15.6 mm2, p<0.001). When comparing standard manual to the same phase by automated measurements, while there was no difference in annular mean diameter (p=0.80), perimeter and area were larger with the automated measurements (Δperimeter 0.95 mm, p=0.002; Δarea 10.8 mm2, p=0.03). However, the maximum automated measurements were consistently larger than the same phase automated measurements (Δdiameter 0.13 mm, p<0.001; Δperimeter 0.42 mm, p<0.001; Δarea 4.4 mm2, p<0.001). CONCLUSIONS: Automated maximum dynamic CT annular measurements provide larger values than standard manual and same phase automated measurements.

Multilobulated thymoma with an acute angle: a new predictor of lung invasion.

OBJECTIVE: Imaging features of thymomas such as lobulation, infiltration into lung, and adjacent lung abnormality have been associated with lung invasion but are unreliable. The goal of this study was to develop a more objective and reproducible method for predicting lung invasion by thymomas. SUBJECTS AND METHODS: Fifty-four thymomas resected from 2007 to 2017 were included for analysis. Pre-operative CT scans for these thymomas were reviewed, and multiple features were evaluated, including the interface of each thymoma with the adjacent lung. A multilobulated thymoma with at least one acute angle between lobulations was considered suspicious for lung invasion. Two blinded radiologists then tested this hypothesis by reviewing all 54 CT scans and using this single criterion to predict lung invasion. RESULTS: Twelve thymomas invaded the lung. All lung-invasive thymomas were multilobulated. Twenty-nine thymomas had a multilobulated interface with the lung. Multilobulated thymomas were more likely to invade the lung than thymomas with a single lobulation or no lobulation (p = 0.0008). Using the criterion of multilobulation with at least one acute angle between lobulations to predict lung invasion, the two readers achieved a sensitivity of 67-83%, specificity of 93-98%, positive predictive value of 77-89%, and negative predicted value of 91-95%. Nine lung-invasive thymomas also invaded mediastinal structures or disseminated to the pleura. CONCLUSIONS: A multilobulated thymoma with at least one acute angle between lobulations predicts lung invasion with a high degree of accuracy. When lung invasion is suspected, the findings are indicative of a locally aggressive tumor, and the pleura and mediastinal structures should also be closely inspected for invasion. KEY POINTS: • A multilobulated thymoma with at least one acute angle between lobulations is predictive of lung invasion. • Coronal and sagittal reformations and thin sections are helpful in challenging cases. • Lung invasion indicates a locally aggressive tumor, and the pleura and other mediastinal structures should also be closely inspected for invasion.

Communication errors in radiology - Pitfalls and how to avoid them.

Communication failures are a common cause of patient harm and malpractice claims against radiologists. In addition to overt communication breakdowns among providers, it is also important to address the quality of communication to optimize patient outcomes. In this review, we describe common communication failures and potential solutions providing a framework for radiologists to improve health care delivery.

Screening for Lung Cancer: Communicating With Patients.

OBJECTIVE: The purposes of this article are to detail the experience of a single-center academic institution in applying the patient-centered approach to a lung cancer screening program and to examine how this approach can expand to other aspects of follow-up imaging of lung nodules. CONCLUSION: As the practice of patient-centered radiology gains attention, diagnostic radiologists are findings new ways to become more involved in patient care. A lung cancer screening program is one opportunity for radiologists to consult with and educate patients.

Dendriform Pulmonary Ossification in the Absence of Usual Interstitial Pneumonia: CT Features and Possible Association With Recurrent Acid Aspiration.

OBJECTIVE: Dendriform pulmonary ossification (DPO) is a rare lung disease in which mature bone is present in the peripheral interstitium of the lung. It typically occurs in patients with usual interstitial pneumonia (UIP). We assessed patients with CT findings of DPO without UIP to determine possible causative factors and to assess the clinical and CT course. We hypothesized that DPO without UIP would be a unique entity. MATERIALS AND METHODS: We retrospectively reviewed CT reports for the word "ossification." Two observers reviewed each examination for micronodules 1-5 mm in diameter in the peripheral interstitium (subpleural and perifissural spaces and interlobular septa), some of which had high attenuation on mediastinal windows, presence of contiguous clusters of nodules resulting in a branching pattern, and lack of findings of UIP or focal lung disease. We reviewed the electronic medical records and follow-up CT and clinical information in all eligible patients. RESULTS: The study population consisted of 52 men with a median age of 79 years old. Seventy-five percent of the patients had gastroesophageal reflux disease, obstructive sleep apnea, or a chronic neurologic disorder. No progressive pulmonary symptoms were attributed directly to DPO, and no patient developed pulmonary fibrosis or suffered clinical decline from DPO. CT showed minimal progression or remained stable at follow-up (77% for at least 1 year, 25% for over 4 years). CONCLUSION: DPO in the absence of UIP occurs in elderly men and appears to be associated with chronic aspiration of gastric acid. The course is indolent.

Pulmonary fibrosis on the lateral chest radiograph: Kerley D lines revisited.

The retrosternal clear space (RCS) is a lucent area on the lateral chest radiograph located directly behind the sternum. The two types of pathology classically addressed in the RCS are anterior mediastinal masses and emphysema. Diseases of the pulmonary interstitium are a third type of pathology that can be seen in the RCS. Retrosternal reticular opacities, known as Kerley D lines, were initially described in the setting of interstitial oedema. Pulmonary fibrosis is another aetiology of Kerley D lines, which may be more easily identified in the RCS than elsewhere on the chest radiograph. TEACHING POINTS: • The RCS is one of three lucent spaces on the lateral chest radiograph. • Reticular opacities in the RCS are known as Kerley D lines. • Pulmonary fibrosis can be seen in the RCS as Kerley D lines. • Kerley D lines should be further evaluated with chest CT.