Experimental Study of Ultrafine Superparamagnetic Iron Oxide-Enhanced MRI in an Atherosclerotic Plaque Model

Unstable atherosclerotic (AS) plaques contain numerous macrophages that can phagocytose a specific contrast agent, namely ultrafine superparamagnetic iron oxide (USPIO). This study prepared USPIO nanoparticles, defined their physical and magnetic properties and transmission characteristics, explored the feasibility of their use as a magnetic resonance negative contrast agent, and used them to detect unstable AS plaque as a specific marker of macrophages. We randomly divided 20 healthy male New Zealand white rabbits into two groups, experimental and control (n = 10 each). The experimental group was fed pure high-fat feed. The magnetic resonance imaging (MRI) performance of arterial plaque before and after USPIO enhancement compare with pathological results. The experimental group successfully established a rabbit AS plaque model, and 8 of 10 rabbits developed AS plaque. USPIO-enhanced T2W1 sequence showed that the central signal of the plaque was reduced, and the signal-to-noise ratio of the vascular wall was the lowest at 96 h. The control group showed no change in the wall signal before and after enhancement. The USPIO-enhanced PJN2D-TOF sequence showed dotted filling defects on the tube wall. Pathological examination showed that USPIO nanoparticles were mainly deposited under the arterial intima. A simple high-fat diet can establish a rabbit AS plaque model, and USPIO-enhanced MRI reflects the condition of rabbit AS plaque, which is helpful in evaluating AS lesion diagnosis.