• Takuga Hinoshita, Gabriel Motta Ribeiro, Tilo Winkler, Nicolas de Prost, Mauro R Tucci, Costa Eduardo Leite Vieira ELV Hospital das Clínicas, Faculdade de Medicina, São Paulo, Brasil., Tyler J Wellman, Soshi Hashimoto, Congli Zeng, Alysson R Carvalho, and Melo Marcos Francisco Vidal MFV Massachusetts General Hospital, Department of Anesthesia, Critical Care and Pain Medicine, 55 Fruit St. Boston, MA..
• Massachusetts General Hospital, Department of Anesthesia, Critical Care and Pain Medicine, 55 Fruit St. Boston, MA; Tokyo Medical and Dental University, Department of Intensive Care Medicine, Tokyo, Japan. Electronic address: dr.takuga@gmail.com.
• Acad Radiol. 2020 Dec 1; 27 (12): 1679-1690.

Rationale And ObjectivesPulmonary atelectasis presumably promotes and facilitates lung injury. However, data are limited on its direct and remote relation to inflammation. We aimed to assess regional 2-deoxy-2-[18F]-fluoro-D-glucose (18F-FDG) kinetics representative of inflammation in atelectatic and normally aerated regions in models of early lung injury.Materials And MethodsWe studied supine sheep in four groups: Permissive Atelectasis (n = 6)-16 hours protective tidal volume (VT) and zero positive end-expiratory pressure; Mild (n = 5) and Moderate Endotoxemia (n = 6)- 20-24 hours protective ventilation and intravenous lipopolysaccharide (Mild = 2.5 and Moderate = 10.0 ng/kg/min), and Surfactant Depletion (n = 6)-saline lung lavage and 4 hours high VT. Measurements performed immediately after anesthesia induction served as controls (n = 8). Atelectasis was defined as regions of gas fraction <0.1 in transmission or computed tomography scans. 18F-FDG kinetics measured with positron emission tomography were analyzed with a three-compartment model.Results18F-FDG net uptake rate in atelectatic tissue was larger during Moderate Endotoxemia (0.0092 ± 0.0019/min) than controls (0.0051 ± 0.0014/min, p = 0.01). 18F-FDG phosphorylation rate in atelectatic tissue was larger in both endotoxemia groups (0.0287 ± 0.0075/min) than controls (0.0198 ± 0.0039/min, p = 0.05) while the 18F-FDG volume of distribution was not significantly different among groups. Additionally, normally aerated regions showed larger 18F-FDG uptake during Permissive Atelectasis (0.0031 ± 0.0005/min, p < 0.01), Mild (0.0028 ± 0.0006/min, p = 0.04), and Moderate Endotoxemia (0.0039 ± 0.0005/min, p < 0.01) than controls (0.0020 ± 0.0003/min).ConclusionAtelectatic regions present increased metabolic activation during moderate endotoxemia mostly due to increased 18F-FDG phosphorylation, indicative of increased cellular metabolic activation. Increased 18F-FDG uptake in normally aerated regions during permissive atelectasis suggests an injurious remote effect of atelectasis even with protective tidal volumes.Copyright © 2020 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

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