Objective To quantitatively assess the damage of blood-retinal barrier (BRB) in rats with diabetic retinopathy using dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI). Methods Forty 3-week-old Sprague-Dawley (SD) rats were randomly divided into experiment and control group. The rats in experiment group underwent intraperitoneal injection of streptozotocin. The rats with blood glucose over 16.65 mmol/L and ldquo;+++rdquo; of urine glucose were considered as diabetes and were further divided into four subgroups according to the course of diabetes mellitus (2, 4, 6, and 8 months).The rats in control group underwent intraperitoneal injection with the same volume of buffer and were divided into four subgroups (with 5 rats in each subgroup) according to the coordinate age of rats in experimental group.All of the eyeballs were scanned by DCE MRI and enucleation was performed after intraperitoneal injection with pentobarbitone.The data were analyzed by SPSS 12.0 statistical software.Results All the rats in experiment group became diabetic models. There was no obvious BRB permeability in control group and in 2- and 4-months experiment group.The average BRB permeability rate in 6 and 8 month experiment groups were (0.1399plusmn;0.0065) and (0.1816plusmn;0.2756) mm3/min respectively (Z=-2.121, Plt;0.05). Retinal edema and cellular disorganization appeared at 4 months and became more severe when diabetes course extended.Conclusions DCE MRI can measure the BRB permeability rate accurately and assess the extent of BRB damage quantitatively in rats with diabetic retinopathy.