Dose and Time Response of Mn²⁺-enhanced Magnetic Resonance Imaging for Tracing Visual Pathway in vivo

Abstract

Purpose : To explore time and dose response of Mn²⁺-enhanced MRI for tracing visual pathway in vivo using intravitreal MnCl₂ injection.

Methods : 36 rabbits were randomly divided into six groups (each group, n=6). 25μl MnCl₂ in various concentrations (2, 5, 10, 15, 20, 40 mmol/L) was injected into vitreous of left eyes for each group respectively. MRI was performed to examine the imaging of visual pathway at 4, 6, 8, 12, 24 hours, and 2, 4, 7 days after intravitreal MnCl₂ injection. The signal-noise ratio (SNR) of MRI in visual pathway was calculated and compared among different groups and time points.

Results : 2 mmol/L of MnCl₂ just could induce optical nerve enhancement, but no image of lateral geniculate body and superior colliculus enhanced was found. In 5 - 40 mmol/L groups, the visual pathway from retina to contralateral superior colliculus were enhanced significantly [Fig.1]. However, no signal was enhanced in visual cortex in each group. The images were enhanced strongest at 24 h, and then the signals attenuated gradually from 24 h to 7 days.

Conclusions : Manganese-enhanced MRI for tracing visual pathway is related with time and dose of intravitreal Mn²⁺ injection.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.