A novel method for detecting striatal hypoperfusion in Parkinson disease ‐Saturated Iron oxide Nanoparticle Contrast (SINC) MRI (LB79)

Abstract

Striatal dopaminergic denervation is a major characteristic of Parkinson’s disease (PD). Such neuronal damage may lead to disrupted perfusion that reflects changes in regional metabolism and neural activity. Current imaging findings regarding striatal perfusion alterations in PD remain inconclusive. The present study proposed a new perfusion weighted MRI technique that takes advantage of saturated iron oxide nanoparticle contrast (SINC) to estimate cerebral blood flow (CBF), cerebral blood volume (CBV) , and the mean transit time (MTT) in a PD rat model induced by 6‐hydroxydopamine. This SINC‐MRI method uses a high dose of iron oxide nanoparticles (IRON) for inducing signal changes on gradient echo T2* images acquired repeatedly over 60 time frames. As soon as IRON is injected, the signal decreases rapidly from a baseline to an undershoot, and then reaches a saturated steady state. CBV is represented directly by ΔR2* between the baseline and the steady state. Moreover, the derivative of the measured signal changes was modeled as the delta function of impulse response by fitting pixelwisely the signal‐to‐time curve using the piecewise Hermite polynomial function. The modeled signal was then deconvoluted through a local arterial input function to obtain the tissue concentration of the contrast agent so as to estimate CBF and MTT. Our results showed that, in the lesioned striatum, there were consistent decreases in the CBV and CBF by approximately 4‐7% as compared to the intact striatum. Importantly, this difference was not found by conventional dynamic susceptibility contrast MRI method. SINC‐MRI appears as a reliable and sensitive approach in detecting subtle perfusion changes.