Causative factors, imaging findings, and CT course of round atelectasis

Our plain-English summary of Causative factors, imaging findings, and CT course of round atelectasis, by L. Azour, T. Billah, M.M. Salvatore, et al (Clinical Imaging, 2018).

The study

• Authors: L. Azour, T. Billah, M.M. Salvatore, M.D. Cham, D.S. Mendelson, C.D. Eber, A.H. Jacobi
• Journal: Clinical Imaging
• Published: 2018;50:250-257
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: To assess causative factors, associated imaging findings, and CT course of round atelectasis (RA).

Materials And Methods: We retrospectively reviewed CT reports for "round" or "rounded atelectasis" over a 5-year time frame. Patients with at least 2 CT scans a minimum of 6 months apart were included. Electronic medical records and clinical and imaging follow-up was reviewed for all cases.

Results: Study population included 50 individuals with mean age of 63 years, and 59 unique instances of RA. The most commonly associated etiologies were hepatic hydrothorax (26%, n = 13) and asbestos exposure (26%), followed by post-infectious pleural inflammation (22%), congestive heart failure (12%), and end stage renal disease (8%). RA was found in the right lower lobe in over half of cases (n = 30). Association with one or more pleural abnormality was identified in all cases, including thickening (88%), fluid (60%), or calcification (40%). Nearly one third (n = 19) demonstrated intra-lesional calcification. In those who underwent PET/CT (20%), lesions demonstrated an average SUV of 2.2 (range 0-7.8). CT course over mean follow up of 32 months (range 6-126 months), demonstrated RA to remain stable (n = 26) or decrease (n = 26) in size in the majority (88%) of cases.

Conclusion: Round atelectasis may arise from diverse etiologies beyond asbestos, and will most often decrease or remain stable in size over serial exams. Accurate identification may obviate the need for added diagnostic interventions.

Copyright © 2018 Elsevier Inc. All rights reserved.

In plain English

This retrospective study by radiologists at Icahn School of Medicine at Mount Sinai in New York reviewed CT reports from January 2010 to January 2015 that described round atelectasis. Round atelectasis is a rounded area of collapsed lung against the pleura (the lung lining) that can resemble a mass on scans. The study included 50 patients (44 men) with 59 lesions, each with at least two CT scans 6 or more months apart. The most common causes identified were hepatic hydrothorax, which is fluid around the lung linked to liver disease (13 patients, 26%), and asbestos exposure (13 patients, 26%). These were followed by post-infectious pleural inflammation (22%), congestive heart failure (12%) and end stage renal disease (8%). Every patient had at least one pleural abnormality. Over an average of 32.3 months between first and last scans, 26 lesions stayed stable, 26 shrank and 7 grew. Biopsies in 8 patients were non-diagnostic or showed inflammatory cells. The authors concluded that round atelectasis may arise from diverse causes beyond asbestos and most often decreases or remains stable in size. The article gives no detail on the asbestos exposures.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective review of CT reports, medical records and follow-up imaging (case series)
• Who was studied: A database search for January 1, 2010 to January 1, 2015 found 225 CT exams reporting round or rounded atelectasis. Of these, 53 patients had at least 2 CT scans at least 6 months apart. After 3 were excluded, 50 individuals remained (44 men, 6 women; mean age 62.9, range 20 to 89), with 59 round atelectasis lesions. The authors are affiliated with Icahn School of Medicine at Mount Sinai, New York.
• Exposure: The study looked at the causes of round atelectasis. Asbestos exposure (asbestos-related pleural disease) was one attributed cause, in 13 of 50 patients. No fiber types, jobs, products or doses are reported, and the article does not say how asbestos exposure was determined.
• Main results:
  • Causes attributed among the 50 patients: hepatic hydrothorax 26% (13 patients), asbestos-related pleural disease 26% (13 patients), post-infectious pleural inflammation 22%, congestive heart failure 12%, and end stage renal disease 8%.
  • The authors found no significant relation between the cause and lesion size or progression.
  • Round atelectasis was found most often in the right lower lobe (51%), followed by the left lower lobe (31%).
  • All 50 patients had at least one pleural abnormality: pleural thickening in 88%, pleural fluid in 60%, and pleural calcification in 40%.
  • Pleural fluid was found in 60% of individuals and pleural calcification in 40%.
  • Small calcifications inside the lesion, most often punctate, were present in about one third of lesions (19 lesions).
  • Ten patients had PET/CT, and the lesions showed an average SUV (a measure of tracer uptake) of 2.2, ranging from 0 to 7.8.
  • Eight patients (16%) had a biopsy of the lesion. Pathology was either non-diagnostic or showed inflammatory cells.
  • In 6 patients whose lesion was visible on abdominal MRI, all lesions were bright on both diffusion weighted imaging and the apparent diffusion coefficient map.
  • Between first and last scans (mean 32.3 months, range 6 to 126 months), 26 lesions (44%) stayed stable (change of less than 0.5 cm).
  • Another 26 lesions decreased in size, by an average of 1.7 cm.
  • Seven lesions (12%) increased in size, by an average of 1.5 cm (range 0.9 to 2 cm).
  • The authors reported a weakly positive correlation (r=0.43) between the width of pleural thickening or fluid and lesion size.
• The authors' conclusion: The authors concluded that round atelectasis may arise from diverse causes beyond asbestos, and will most often decrease or remain stable in size over serial exams.
• Limitations the authors state:
  • The design was retrospective, and most cases had no histopathologic (tissue) confirmation of round atelectasis.
  • Measuring the lesions accurately was somewhat challenging because their boundaries are not always clear.
  • Volumetric analysis was not performed.
  • Round atelectasis caused by hepatic hydrothorax is likely more common in this group than in the general population, because the institution has a large liver transplant service.

Topics

Medical terms in this study, explained in our Lexicon: Atelectasis, Rounded Atelectasis, CT Scan, Asbestos Exposure, Inflammation.

Related studies

• Round atelectasis as a complication of Legionnella pneumonia — R. Kuno, D.J. Bower, et al. (1994)
• Round atelectasis and Metsovo lung — S.A. Papiris, M.A. Maniati, et al. (1993)
• Malignant pleural mesothelioma with osteoblastic heterologous elements: CT and MR imaging findings — G. Chave, L. Chalabreysse, et al. (2002)
• Rounded atelectasis of the lung — G.T. Stathopoulos, M.T. Karamessini, et al. (2005)
• Asbestos-related rounded atelectasis. Radiologic and mineralogic data in 23 cases — C. Voisin, F. Fisekci, et al. (1995)
• Rounded atelectasis. Clinical experience with 74 patients — G. Hillerdal (1989)

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