Magnetic resonance imaging provides sensitive in vivo assessment of experimental ventilator-induced lung injury.
Animal models play a critical role in the study of acute respiratory distress syndrome (ARDS) and ventilator-induced lung injury (VILI). One limitation has been the lack of a suitable method for serial assessment of acute lung injury (ALI) in vivo. In this study, we demonstrate the sensitivity of magnetic resonance imaging (MRI) to assess ALI in real time in rat models of VILI. Sprague-Dawley rats were untreated or treated with intratracheal lipopolysaccharide or PBS. After 48 h, animals were mechanically ventilated for up to 15 h to induce VILI. Free induction decay (FID)-projection images were made hourly. Image data were collected continuously for 30 min and divided into 13 phases of the ventilatory cycle to make cinematic images. Interleaved measurements of respiratory mechanics were performed using a flexiVent ventilator. The degree of lung infiltration was quantified in serial images throughout the progression or resolution of VILI. MRI detected VILI significantly earlier (3.8 ± 1.6 h) than it was detected by altered lung mechanics (9.5 ± 3.9 h, P = 0.0156). Animals with VILI had a significant increase in the Index of Infiltration (P = 0.0027), and early regional lung infiltrates detected by MRI correlated with edema and inflammatory lung injury on histopathology. We were also able to visualize and quantify regression of VILI in real time upon institution of protective mechanical ventilation. Magnetic resonance lung imaging can be utilized to investigate mechanisms underlying the development and propagation of ALI, and to test the therapeutic effects of new treatments and ventilator strategies on the resolution of ALI.
ABQMR Inc., Albuquerque, New Mexico; Lovelace Respiratory Research Institute, Albuquerque, New Mexico; and.
Dean O
DO
Kuethe
Lovelace Respiratory Research Institute, Albuquerque, New Mexico; and Division of Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
Piotr T
PT
Filipczak
Lovelace Respiratory Research Institute, Albuquerque, New Mexico; and.
Jeremy M
JM
Hix
Lovelace Respiratory Research Institute, Albuquerque, New Mexico; and.
Andrew P
AP
Gigliotti
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
Raúl San José
RS
Estépar
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
George R
GR
Washko
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
Rebecca M
RM
Baron
Division of Pulmonary and Critical Care Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts lfredenburgh@rics.bwh.harvard.edu.
Laura E
LE
Fredenburgh
D000403:Airway Resistance; D000818:Animals; D008070:Lipopolysaccharides / Q000494:pharmacology; D008168:Lung / Q000000981:diagnostic imaging / Q000276:immunology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D020556:Neutrophil Infiltration; D017207:Rats, Sprague-Dawley; D012121:Respiration, Artificial; D055397:Ventilator-Induced Lung Injury / Q000000981:diagnostic imaging* / Q000276:immunology / Q000503:physiopathology
D008070:Lipopolysaccharides
ARDS; FID-projection imaging; MRI; VILI