Dynamic contrast-enhanced MRI for assessing therapeutic response of choroidal neovascularization in a rat model

We evaluated the potential of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) as a noninvasive biomarker of choroidal neovascularization (CNV) and its utility as a tool for monitoring therapeutic response in laser-induced rat CNV models.

CNV was induced in the right eyes of 14 rats using a laser. Rats (n = 7) were treated daily for 14 days with a candidate drug (KR-31831, 50 mg/kg of body weight) having antiangiogenic effects, whereas control rats (n = 7) were treated with the vehicle alone (10% cremophor, 10% absolute ethyl alcohol, and 80% saline). DCE-MRI examinations were performed on the day before surgery (D - 1), and 3, 7, and 14 days after surgery (D + 3, D + 7, and D + 14), from which pharmacokinetic parameters (K(trans), v(e), v(p)) were calculated. Angiography was performed to visualize CNV using FITC-labeled high molecular weight dextran after MRI on D + 14. The paired Wilcoxon test and Mann-Whitney U test were performed for statistical analysis.

The K(trans) and v(e) values of the CNV-induced right eyes were significantly higher than those of the intact eyes in control rats at D + 14 (P < 0.05). In the CNV-induced eyes, the relative K(trans) and v(e) values of the KR-31831-treated group were significantly lower than those of the nontreated group at D + 14 (P < 0.05). The angiography showed that decreased CNV was observed in rats treated with KR-31831.

Quantitative DCE-MRI produces noninvasive biomarker of CNV, thus allowing monitoring of therapeutic response of antiangiogenic drugs in neovascular age-related macular degeneration (AMD).