Contrast Agents for Cerebral Dynamic Susceptibility MRI Hemodynamic Effects after Intravenous Bolus Injection

Abstract

We investigated the effects of IV bolus injection of three MRI contrast agents, i.e., Gadolinium-DTPA, polylysine-Gd-DTPA and superpara-magnetic iron particles (SPIO) on arterial blood pressure and cerebral blood flow (CBF). In 56 anesthetized rats a single fiber laser Doppler flowmetry (LDF) probe was placed intracerebrally. CBF and mean arterial blood pressure (MABP) were measured before (baseline), during and up to 30 minutes after IV bolus administration of the three contrast agents: 0.1 mmol/kg and 0.3 mmol/kg Gd-DTPA (n = 18 per group), respectively, 0.3 mmol/kg polylysine-Gd-DTPA (n ? 10) and 0.03 mmol/kg SPIO (n = 10). Neither the higher nor the lower dose of Gd-DTPA had any statistically significant effect on CBF. There were no changes in blood pressure during administration of Gd-DTPA at both dose levels. Administration of polylysine-Gd-DTPA caused a transient drop in blood pressure in two animals; marked in one animal (decrease to 21% of preinjection values/baseline) and mild in another (84% of baseline). After administration of SPIO a significant decrease in blood pressure occurred in one animal (41 % of baseline). Despite this decrease in MABP, there were no statistically significant changes in CBF after administration of polylysine-Gd-DTPA and SPIO. Our results suggest that bolus injection of these contrast agents in clinically relevant doses causes no significant alteration in cerebral blood flow. We conclude that at least Gd-DTPA is well suited for cerebral MR perfusion imaging without inherent influence on CBF. The same is probably also true for polylysine-Gd-DTPA and superparamagnetic iron particles.