Skip to main content

Volume 3 Supplement 1


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


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.


  1. Gattinoni L: Intensive Care Med. 2005, 31 (6): 776-84. 10.1007/s00134-005-2627-z.

    PubMed  Article  Google Scholar 

  2. Mead J: J Appl Physiol. 1970, 28 (5): 596-608.

    PubMed  CAS  Google Scholar 

  3. Patlak CS: J Cereb Blood Flow Metab. 1983, 3 (1): 1-7. 10.1038/jcbfm.1983.1.

    PubMed  CAS  Article  Google Scholar 

  4. Cressoni M: Am J Respir Crit Care Med. 2013

    Google Scholar 

Download references

Author information

Authors and Affiliations


Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Cressoni, M., Chiumello, D., Brioni, M. et al. Lung inhomogeneities, inflation and [18F]FDG uptake rate in ards. ICMx 3 (Suppl 1), A90 (2015).

Download citation

  • Published:

  • DOI:


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