In vivo DTI assessment of hepatic ischemia reperfusion injury in an experimental rat model.
OBJECTIVE
To investigate hepatic ischemia reperfusion injury (IRI) using diffusion tensor imaging (DTI).


METHODS
Ten Sprague-Dawley rats were scanned at 7 Tesla (T) with DTI using b-value of 1000 s/mm(2) and 6 gradient directions before, 2 h, and 1 day after 30-min total hepatic IRI. Apparent diffusion coefficient or mean diffusivity (MD), directional diffusivities and fractional anisotropy (FA) were measured. Seven of the animals were also examined with spin-echo echo-planar diffusion-weighted imaging (DWI) with seven b-values up to 2000 s/mm(2) to estimate the true diffusion coefficient (D), blood pseudodiffusion coefficient (D), and perfusion fraction (f) using a bi-compartmental model.


RESULTS
MD 2 h after IRI (0.77 +/- 0.07 x 10(-3) mm(2)/s) was significantly lower (P < 0.01) than that before (1.03 +/- 0.07 x 10(-3) mm(2)/s) and 1 day after IRI (1.01 +/- 0.05 x 10(-3) mm(2)/s). Meanwhile, FA 2 h after IRI (0.33 +/- 0.03) was significantly higher (P < 0.01) than that before (0.21 +/- 0.02) and 1 day after IRI (0.20 +/- 0.02). The bi-compartmental model analysis revealed the transient decrease in D, D and f 2 h after IRI. Liver histology showed the multifocal cell swelling 3 h after IRI and widespread cell necrosis/apoptosis 1 day after IRI. Sinusoidal narrowing and congestion of erythrocytes were also observed 3 h and 1 day after IRI.


CONCLUSIONS
DTI can characterize hepatic IRI by detecting the transient change in both MD and FA.
Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China.
Jerry S
JS
Cheung
Shu Juan
SJ
Fan
April M
AM
Chow
Edward S
ES
Hui
Ed X
EX
Wu
D000818:Animals; D016880:Anisotropy; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004195:Disease Models, Animal; D005260:Female; D008099:Liver / Q000098:blood supply*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000175:diagnosis*; D012680:Sensitivity and Specificity