Magnetic resonance imaging detects intestinal barrier dysfunction in a rat model of acute mesenteric ischemia/reperfusion injury.
OBJECTIVE
To develop an in vivo intestinal permeability assay applying magnetic resonance imaging (MRI) to monitor real-time gut barrier defects in animal models of acute mesenteric ischemia/reperfusion (I/R) insult.


METHODS
Twenty Wistar rats were divided to 2 groups for I/R challenge or sham controls. I/R rats received occlusion of superior mesenteric artery for 20 minutes and reperfusion for 1 hour. Sham-operation controls received laparotomy without manipulation of artery. To assess gut permeability, a 10-cm jejunal sac was created distal to the ligament of Treitz in both groups of rats after laparotomy, and a contrast agent (gadodiamide) was injected into the lumen of the ligated intestinal sac. The signals produced by gadodamide in the liver, kidney, and plasma before and after the start of reperfusion were examined by 1.5 Tesla MRI (GE Signa Excite), and the increment of signal-to-noise ratio (SNR) in these organs that parallels the luminal-to-serosal flux rate of the probe was used as an indicator of gut permeability. At the end of procedures, jejunal tissues and mucosal scrapings were collected for histologic examination and Western blotting for epithelial tight junctional proteins. Moreover, liver and spleen homogenates were cultured on fresh blood agar plates to measure the bacterial colony-forming units per gram of tissue.


RESULTS
In I/R rats, disrupted villous structure and decreased epithelial tight junctional expression were seen in the jejunum associated with massive enteric bacterial translocation to the liver and spleen. The SNR in the liver of I/R rats was higher than sham controls (2.65 +/- 0.56 vs. 0.65 +/- 0.26, P < 0.01) at 15 minutes postreperfusion. Elevation of SNR in the kidney was also found in I/R rats compared with sham controls (11.61 +/- 2.07 vs. 3.06 +/- 1.15, P < 0.05). The plasma gadodiamide concentration in I/R rats was significantly increased compared with sham controls (0.220 +/- 0.044 vs. 0.006 +/- 0.004 mM, P < 0.01) at 15 minutes postreperfusion.


CONCLUSIONS
This novel MRI-based intestinal permeability assay has shown a significant increase in the signal intensity in liver, kidney, and plasma samples that correlated with mucosal barrier defects in experimental models of acute mesenteric I/R.
Department of Medical Imaging, National Taiwan University Hospital, Taipei, Taiwan; and daggerGraduate Institute of Physiology, National Taiwan University College of Medicine, Taipei, Taiwan.
Jong-Kai
JK
Hsiao
Ching-Ying
CY
Huang
Yen-Zhen
YZ
Lu
Chung-Yi
CY
Yang
Linda Chia-Hui
LC
Yu
D000208:Acute Disease; D000818:Animals; D004195:Disease Models, Animal; D006801:Humans; D007410:Intestinal Diseases / Q000175:diagnosis* / Q000209:etiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008638:Mesenteric Arteries / Q000473:pathology*; D008641:Mesenteric Vascular Occlusion / Q000150:complications* / Q000175:diagnosis*; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000150:complications* / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity