Comparison of the DWI and Gd-EOB-DTPA-enhanced MRI on assessing the hepatic ischemia and reperfusion injury after partial hepatectomy

Abstract

Objective: To compare two different imaging media, diffusion weighted imaging (DWI) with apparent diffusion coefficient (ADC) and Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) with perfusion parameters K^trans, K^ep, and relative contrast enhancement index (RCEI), in assessing the liver function via ischemia/perfusion injury (IRI) + partial hepatectomy rat model.

Methods: Rats underwent 0, 30 and 60min of ischemia/reperfusion with 30% of hepatectomy before subjected to Gd-EOB-DTPA-enhanced MRI in addition to ^99mTc-GSA scintigraphy. For ^99mTc-GSA scintigraphy test, the receptor index LHL15, modified receptor index and the blood clearance index HH15 were recorded. Apparent diffusion coefficient (ADC) was evaluated by using both mono- and bi-exponential models, and perfusion parameters K^trans, K^ep, and RCEI were measured. Liver function is tested by measuring activity of serum ALT, AST and PT. Histological analysis was performed by H&E and Ki-67 staining.

Results: ^99mTc-GSA dynamic imaging analysis demonstrated that LHL15 was increased and HH15 was decreased as the extension of ischemia/reperfusion time. ADC value estimated by MRI was significantly increased (P<0.05) in 30min IRI group compared with 0min and 60min IRI groups, respectively. K^trans value was gradually and significantly decreased (P<0.05) as the extension of IRI time, but there was no significant difference (P>0.05) in K^ep value between at 30min and 60min IRI, and RCEI value was significantly higher (P<0.05) in 30min IR compared with 0min and 60min IRI group. Serum level of ALT, AST and PT were gradually and significantly (P<0.05) increased as the extension of IRI time. Histological analysis showed that there was a remarkable difference between 30min and 60min IRI, as protein expression of Ki-67 was significantly higher (P<0.05) in 30min IRI group.

Conclusion: Fast ADC bi-exponential model in DWI and RCEI in Gd-EOB-DTPA-enhanced MRI showed the good correlation in assessment of liver function after partial hepatectomy, showing consistency with our histological findings. The K^trans in Gd-EOB-DTPA-enhanced MRI could be a potent parameter for assessing the early ischemic injury, but not the severity of the hepatic injury, in accordance with the correlation with our biochemical findings.

Keywords: Ischemia/reperfusion injury; Liver; Magnetic resonance imaging.