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Subpleural sparing: clinical, physiological, and radiological implications

Published:November 22, 2022DOI:https://doi.org/10.1016/j.amjms.2022.11.002

      Abstract

      The term “subpleural sparing” refers to computed tomography (CT) images that indicate that there is limited disease/infiltrate in the immediate subpleural location. This observation is often associated with nonspecific interstitial pneumonitis and is a characteristic that distinguishes this pathology from usual interstitial pneumonitis (idiopathic pulmonary fibrosis). Subpleural sparing can also occur in acute respiratory disorders, including pulmonary contusion in children, acute lung disease associated with electronic cigarettes (vaping), and aspiration of exogenous lipids. Potential explanations for this observation include nonuniform distribution of lung injury/inflammation, nonuniform clearing/resolution of injury, and variations in CT image acquisition and presentation. The subpleural region contains lymphatic structures on the interior surface of the visceral pleura and in interlobular septa. The density of subpleural lymphatics decreases in more interior zones of the lung that largely contain alveolar-capillary units. These lymphatics transfer fluid and other inflammatory mediators from the peripheral lung into central lymphatics and veins. Consequently, the density and distribution of lymphatics could explain preferential clearing of the subpleural regions during acute injury. The acquisition of CT images also depends on the configuration of detectors, slice thickness, and the energy of the electron beam. Clinicians should carefully consider the disease process, lymphatic function and other clearance mechanisms, and the vagaries in CT image acquisition when they evaluate patients with subpleural sparing.

      Key words

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      References

        • Chong WH
        • Saha BK
        • Austin A
        • Chopra A.
        The significance of subpleural sparing in ct chest: A state-of-the-art review.
        Am J Med Sci. 2021; 361: 427-435https://doi.org/10.1016/j.amjms.2021.01.008
        • Hansell DM
        • Bankier AA
        • MacMahon H
        • et al.
        Fleischner Society: glossary of terms for thoracic imaging.
        Radiology. 2008; 246: 697-722https://doi.org/10.1148/radiol.2462070712
        • Gruden JF
        • Naidich DP
        • Machnicki SC
        • et al.
        An algorithmic approach to the interpretation of diffuse lung disease on chest ct imaging: a theory of almost everything.
        Chest. 2020; 157: 612-635https://doi.org/10.1016/j.chest.2019.10.017
        • Panse PM
        • Feller FF
        • Butt YM
        • et al.
        Radiologic and pathologic correlation in EVALI.
        AJR Am J Roentgenol. 2020; 215: 1057-1064https://doi.org/10.2214/AJR.20.22836
        • Donnelly LF
        • Klosterman LA.
        Subpleural sparing: a CT finding of lung contusion in children.
        Radiology. 1997; 204 (In eng): 385-387https://doi.org/10.1148/radiology.204.2.9240524
        • Gondouin A
        • Manzoni P
        • Ranfaing E
        • et al.
        Exogenous lipid pneumonia: a retrospective multicentre study of 44 cases in France.
        Eur Respir J. 1996; 9: 1463-1469https://doi.org/10.1183/09031936.96.09071463
        • Imai R
        • Nishimura N
        • Takahashi O
        • Tamura T.
        High-resolution computed tomography for the prediction of mortality in acute respiratory distress syndrome: A retrospective cohort study.
        Health Sci Rep. 2021; 4: e418https://doi.org/10.1002/hsr2.418
        • Demirci NY DA
        • Tasci C
        • et al.
        Relationship between chest computed tomography findings and clinical conditions of coronavirus disease (COVID-19): A multicentre experience.
        International J of Clin Practice. 2021; 75: e14459
        • Silva CI
        • Müller NL
        • Hansell DM
        • et al.
        Nonspecific interstitial pneumonia and idiopathic pulmonary fibrosis: changes in pattern and distribution of disease over time.
        Radiology. 2008; 247: 251-259https://doi.org/10.1148/radiol.2471070369
        • Ebina M
        • Shibata N
        • Ohta H
        • et al.
        The disappearance of subpleural and interlobular lymphatics in idiopathic pulmonary fibrosis.
        Lymphat Res Biol. 2010; 8: 199-207https://doi.org/10.1089/lrb.2010.0008
        • Parra ER
        • Araujo CA
        • Lombardi JG
        • et al.
        Lymphatic fluctuation in the parenchymal remodeling stage of acute interstitial pneumonia, organizing pneumonia, nonspecific interstitial pneumonia and idiopathic pulmonary fibrosis.
        Braz J Med Biol Res. 2012; 45: 466-472https://doi.org/10.1590/s0100-879x2012007500055
        • Johkoh T.
        Nonspecific interstitial pneumonia and usual interstitial pneumonia: is differentiation possible by high-resolution computed tomography?.
        Semin Ultrasound CT MR. 2014; 35: 24-28https://doi.org/10.1053/j.sult.2013.10.004
        • Soni N
        • Williams P.
        Positive pressure ventilation: what is the real cost?.
        Br J Anaesth. 2008; 101: 446-457https://doi.org/10.1093/bja/aen240
        • O'Hagan LA
        • Windsor JA
        • Itkin M
        • et al.
        The lymphovenous junction of the thoracic duct: a systematic review of its structural and functional anatomy.
        Lymphat Res Biol. 2020; https://doi.org/10.1089/lrb.2020.0010
        • Ratnayake CBB
        • Escott ABJ
        • et al.
        The anatomy and physiology of the terminal thoracic duct and ostial valve in health and disease: potential implications for intervention.
        J Anat. 2018; 233: 1-14https://doi.org/10.1111/joa.12811
        • Kambouchner M
        • Bernaudin JF.
        Intralobular pulmonary lymphatic distribution in normal human lung using D2-40 antipodoplanin immunostaining.
        J Histochem Cytochem. 2009; 57: 643-648https://doi.org/10.1369/jhc.2009.953067
        • Robinson SK
        • Ramsden JJ
        • Warner J
        Correlative 3D imaging and microfluidic modelling of human pulmonary lymphatics using immunohistochemistry and high-resolution μCT.
        Sci Rep. 2019; 9: 6415https://doi.org/10.1038/s41598-019-42794-7
        • Weber E
        • Sozio F
        • Borghini A
        • et al.
        Pulmonary lymphatic vessel morphology: a review.
        Ann Anat. 2018; 218: 110-117https://doi.org/10.1016/j.aanat.2018.02.011
        • Aharinejad S
        • Nourani F
        • Lametschwandtner A
        • et al.
        Pulmonary lymphatic filling is increased in spontaneously hypertensive rats.
        Anat Embryol (Berl). 1999; 200: 425-432https://doi.org/10.1007/s004290050292
        • Schraufnagel DE
        • Basterra JL
        • Hainis K
        • et al.
        Lung lymphatics increase after hyperoxic injury. An ultrastructural study of casts.
        Am J Pathol. 1994; 144: 1393-1402
        • Schraufnagel DE
        • Agaram NP
        • Faruqui A
        • et al.
        Pulmonary lymphatics and edema accumulation after brief lung injury.
        Am J Physiol Lung Cell Mol Physiol. 2003; 284: L891-L897https://doi.org/10.1152/ajplung.00333.2002