Objectives: To combine the intravoxel incoherent motion MRI and blood oxygen level-dependent MRI for assessment of the renal allograft pathological process undergoing acute rejection and differentiation from acute tubular necrosis and acute calcineurin inhibitor toxicity caused by cyclosporine A in rat models.

Materials and Methods: AR was induced by transplantation of DA donor kidneys into Lewis recipients (allogenic ktx). Lewis rat that received Lewis kidneys served as controls (syngenic ktx). Lewis rats developed IRI after ligation of the left renal artery for 45 min and calcineurin inhibitor toxicity was induced in Lewis rats by the application of CSA (50mg/kg/BW i.p.) for 2days. AR group performed MRI at POD 1,4,7; ATN, CSA, and syngeneic group performed at POD 4. Histopathological evaluation and PCR were performed.

Results: According to the T2 map and gross appearance, we can hardly distinguish the boundary of cortex and medulla in the AR group while it's very clear in the control group. A progressive reduction was shown for MRI parameters both the cortex and medulla in an early stage of AR. In the cortex, D values were strongly correlated with ADC; D* and f were strongly correlated with R2*. Animals developed acute rejection which was confirmed by histological analysis and the severity of AR increased progressively over time. Immunohistochemistry shows significant CD3-positive lymphocytes and CD68-positive macrophages infiltration in grafts undergoing AR, starting on POD1 with a further increase to POD7 while absent in other groups. MRI parameters significantly correlated with the Banff score and the amount of cellular infiltration as well as the mRNA expression.Conclusions: IVIM imaging coupled with BOLD MR imaging is an effective tool for monitoring progress of AR and may help us differentiating AR from ATN and CSA in rat models.

CITATION INFORMATION: Zeng S, Hu X. Intravoxel Incoherent Motion MRI Is an Effective Way to Monitor Acute Allograft Rejection in Rat Models. Am J Transplant. 2017;17 (suppl 3).

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