Since approval of the first magnetic resonance (MR) contrast agent was granted in 1988, there has been remarkable growth in the utilization of intravenous gadolinium (Gd)-based agents. Currently it is estimated that nearly half of all MR studies performed are contrast-enhanced. Despite containing a toxic heavy metal, these agents have proven to be not only an effective diagnostic adjunct to non-enhanced MRI, but also remarkably well tolerated and safe. As a result, conventional wisdom has been that MR contrast media are "biologically inert," a notion that is clearly false. Ultimately, it is the radiologist's responsibility to understand the potential adverse effects of Gd-based agents and the special situations in which they are likely to occur; however, the basic pharmacology of contrast agents is generally not included in medical school curricula or formally taught in residency. The purpose of this review is to discuss the mechanism of action of MR contrast agents and relevant aspects of their clinical pharmacology, including effects on the cardiovascular and renal systems, potential laboratory errors, and special situations involving women and children. We also briefly discuss the issue of nephrogenic systemic fibrosis (NSF).

Purpose: To determine if the phenomenon of transient normalization of T2 relaxation in the subacute stage of ischemic stroke is associated with either magnetic susceptibility effects secondary to hemorrhage or changes in tissue water content. Materials and Methods:We utilized a rat model of transient, focal, cerebral ischemia. The possibility of hemorrhage was evaluated with T2*-weighted (T2*W) imaging and histology. Changes in water content were assessed by brain wet-to-dry weight.Results: Susceptibility effects were not evident in T2*W images, and neither red blood cells nor unchelated Fe(III) was found in hematoxylin and eosin (H-E)-or Prussian Blue-stained sections, respectively. However, between the peak of T2 contrast and the point of transient T2 normalization, water content consistently decreased by an average of 3%. Conclusion:Transient T2 normalization is associated with normalization of water content and can occur without evidence of hemorrhage.

MRA prescreening in patients with PVD is an effective, novel adjunct to cardiac catheterization in selected patients that improves physician confidence and influences technical choices during coronary angiography from the femoral artery approach.

Stroke is a medical emergency and expeditious treatment is critical to reducing permanent disability or death. Acute management of patients suffering from acute ischemic stroke (AIS) requires early recognition of symptoms, rapid assessment and stabilization (hyperacute workup), and appropriate selection of patients for reperfusion with intravenous alteplase and/or mechanical thrombectomy. Established stroke protocols which involve both prehospital emergency medical services and in-hospital multidisciplinary stroke teams have been shown to be crucial to reducing the long term, devastating effects of stroke.