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Volume 3 Supplement 1


  • Poster presentation
  • Open Access

Lung inhomogeneities, inflation and [18F]FDG uptake rate in ards

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Intensive Care Medicine Experimental20153 (Suppl 1) :A90

  • Published:


  • Lung Volume
  • Normal Lung
  • Lung Parenchyma
  • Stress Raiser
  • Actual Classification


In ARDS lung parenchyma presents great variability in inflation, lung inhomogeneities and [18F]FDG uptake. In fact, inflation progressively decreases along the sternum-vertebral axis[1] leading to further inhomogeneities that may act as “stress raiser”.[2] That can activate a local inflammatory response leading to edema.


We aimed to examine the voxel by voxel relationship between [18F]FDG uptake and inhomogeneity according to the actual classification of ARDS.


20 ARDS patients underwent a PET-CT scan at 10 cmH2O. [18F]FDG uptake was determined with the graphical Patlak approach[3] voxel by voxel. Lung inhomogeneities were determined by measuring the gas/tissue ratio in two contiguous lung regions. We defined inhomogeneities the fraction of lung volume whose inhomogeneities were greater than 1.61.[4]


5 patients presented mild, 12 moderate and 3 severe ARDS. In mild and moderate ARDS a consistent lung fraction is homogeneous with a high [18F]FDG metabolic activity (53 ± 14% and 53 ± 20%). Inhomogeneous lung fraction with a higher [18F]FDG uptake increases from mild to severe (12 ± 3%, 16 ± 9% and 27 ± 11%). On the other hand, the homogeneous parenchyma with normal [18F]FDG uptake decreases in worse ARDS (33 ± 14%, 26 ± 20% and 5 ± 9%).


Our findings indicate that the actual classification of ARDS from mild to severe reflects the underlying pathophysiology. In fact, while a similar sized homogeneous and inflamed/metabolically more active compartment is present in all the ARDS patients, in mild ARDS it is associated with a consistent fraction of normal lung while in severe ARDS is primarily associated with inhomogeneous, inflamed/metabolically more active lung tissue.

Authors’ Affiliations

Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Fondazione IRCCS Ca’ Granda-Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy
Dipartimento di Anestesia, Rianimazione ed Emergenza Urgenza, Fondazione IRCCS Ca' Granda-Ospedale Maggiore Policlinico, Milan, Italy


  1. Gattinoni L: Intensive Care Med. 2005, 31 (6): 776-84. 10.1007/s00134-005-2627-z.PubMedView ArticleGoogle Scholar
  2. Mead J: J Appl Physiol. 1970, 28 (5): 596-608.PubMedGoogle Scholar
  3. Patlak CS: J Cereb Blood Flow Metab. 1983, 3 (1): 1-7. 10.1038/jcbfm.1983.1.PubMedView ArticleGoogle Scholar
  4. Cressoni M: Am J Respir Crit Care Med. 2013Google Scholar


© Cressoni et al.; 2015

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.