Perfusion characteristics of oleic acid--injured canine lung on Gd-DTPA--enhanced dynamic magnetic resonance imaging.
OBJECTIVE
We conducted an animal study to describe and interpret the perfusion characteristics of oleic acid (OA)-injured lungs on gadopentetate dimeglumine (Gd-DTPA)-enhanced dynamic perfusion magnetic resonance (MR) imaging.


METHODS
Fourteen dogs received an intravenous OA infusion in the supine (n = 4), prone (n = 4), and right lateral decubitus (n = 6) positions, and 10 minutes later these animals in the same postures underwent the dynamic MR study. Regional Gd-DTPA kinetics was analyzed by the time-signal intensity (SI) curves and by qualitative functional map images of the mean transit time that was representative of the mean circulation time in the vascular bed and the average cumulative sum of the relative increases in SI representative of Gd-DTPA distribution volume during Gd-DTPA first pass. The results were compared with those in six control animals and in another six animals that underwent the MR study 3 minutes (n = 3) and 60 minutes (n = 3) after OA infusion. The MR findings were correlated with the distribution of lung damage and the infused OA particles as assessed by histology.


RESULTS
The dynamic MR study showed postural shifts on the gravity-dependent perfusion map of normal lungs. Contrast enhancement during Gd-DTPA first pass in the lung was lower and more heterogeneous in the OA-injured lung models than in controls but was followed by conversely greater and persistent enhancement during the Gd-DTPA redistribution phase. Regardless of the postures for OA infusion, these abnormalities were predominant in the dependent lungs and became more pronounced with time after OA infusion, where more prominent capillary obstruction with OA droplets and alveolar/interstitial edema were histologically observed. On the functional map images, greater mean transit time and the average cumulative sum of the relative increases in SI values were also predominantly distributed in the dependent lungs.


CONCLUSIONS
Low and heterogeneous enhancement was observed during Gd-DTPA first pass but was followed by persistent enhancement during the Gd-DTPA redistribution phase, and predominant abnormalities in the dependent lungs may be characteristic features of the perfusion of OA-injured lungs. The histological correlations indicate that these abnormalities may reflect OA-induced pathophysiologies associated with capillary OA obstruction, increased vascular resistance, and capillary permeability/extravascular spaces and that lung damage may be gravity dependent.
Suga
K
K
Department of Radiology, Yamaguchi University School of Medicine, Ube, Japan.
Ogasaware
N
N
Matsunaga
N
N
Sasai
K
K
D000818:Animals; D003287:Contrast Media; D004195:Disease Models, Animal; D004285:Dogs; D019786:Gadolinium DTPA; D007089:Image Enhancement; D008168:Lung / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D008171:Lung Diseases / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019301:Oleic Acid; D011187:Posture; D011652:Pulmonary Circulation; D011654:Pulmonary Edema / Q000209:etiology; D011859:Radiography; D012039:Regional Blood Flow
D003287:Contrast Media; D019301:Oleic Acid; D019786:Gadolinium DTPA