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.
Cheung
Jerry S
JS
Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Pokfulam, Hong Kong, China.
Fan
Shu Juan
SJ
Chow
April M
AM
Hui
Edward S
ES
Wu
Ed X
EX
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