Novel Microcatheters for Selective Intra-Arterial Injection of Fluid in the Rat Brain

Abstract

BACKGROUND AND PURPOSE: The internal carotid artery (ICA) in the rat has a single extracranial branch, which supplies the muscles of mastication. The rat ICA also has multiple intracranial branches including (from proximal to distal): multiple small perforating arteries which supply the hypothalamus and the anterior choroidal artery which supplies the choroid plexus and part of the basal ganglia. At the ICA terminus, the vessel bifurcates into the anterior and middle cerebral arteries. The purpose of this study was to demonstrate selective injection of ICA branches in the rat.

MATERIALS AND METHODS: Microcatheters (μcath1 and μcath2) were fabricated by plugging the tip of 169-μm outer diameter polyimide tubing and perforating the sidewalls. A 450-μm polydimethyl-siloxane cylinder was affixed to the distal tip of μcath2 but not μcath1. We evaluated the territory of μcath1 injection ex vivo using magnetization-prepared rapid acquisition of gradient echo MR imaging of brain specimens injected at necropsy. Territories of μcath1 and μcath2 injection were evaluated in vivo with dynamic susceptibility-weighted contrast-enhanced MR imaging. The territory of μcath2 also was evaluated in vivo with fused static microPET/T1 MR images performed after [¹⁸F] fluorodeoxyglucose (¹⁸FDG) injection. We evaluated additional catheterized and injected animals at 48 hours using physical examination, T2 MR images, and postmortem brain histologic specimens.

RESULTS: Gadolinium-diethylene-triamine pentaacetic acid (Gd-DTPA) and ¹⁸FDG injected through μcath1 selectively opacified the ipsilateral cerebral hemisphere, with no contralateral opacification. Gd-DTPA injected through μcath2 selectively opacified the territories of the hypothalamic perforating arteries, and anterior choroidal artery. There was no iatrogenic complication 48 hours after 20- to 25-minute injections performed with μcath1 or μcath2.

CONCLUSIONS: We have developed 2 microcatheters which can be placed in the ICA for selective injection of its branches. One microcatheter selectively injects the ipsilateral cerebral hemisphere. The other selectively injects only the hypothalamus and lateral thalamus.