Short name: SHU 555 C, preliminary trade name: Supravist™
An ultrasmall superparamagnetic iron oxide under development as a positive enhancing blood pool agent (MRI contrast agent phase III, Bayer Schering Pharma AG). Supravist™ can be administered as an iv. bolus up to doses of 80 μmol/kg.

See also Ultrasmall Superparamagnetic Iron Oxide and Blood Pool Agents.

(VSOP = very small superparamagnetic iron oxide particles) This new class of contrast agents with smaller particle size than SPIO offers advantages for MR angiography. SPIO particles are usually coated with an organic polymer such as dextran, carboxydextran or polyethylene glycol, which limits the minimal overall particle size that can be obtained. VSOP-C184 consists of an aqueous solution of superparamagnetic iron oxide particles with a citrate coating and the overall particle size of 4-8 nm.
Short name: VSOP-C184, central moiety: Fe, concentration: 29 g Fe/l, relaxivity: R1=20.1, R2=37.1, B0=0.94 T.

Any abnormal reaction of a patient to an examination or procedure, like for example claustrophobia or side effects of MRI contrast agents.
A claustrophobic attack is MRI scanner dependent and more rare with an open MRI. An adverse reaction with magnetic resonance imaging contrast medium is very infrequent. In general, adverse reactions increase with the quantity of contrast media (usual dose of paramagnetic contrast agents is 0.1 mmol/kg) and also with the osmolarity of the compound.
Most frequently encountered adverse reactions are heat sensation, dizziness, nausea, hypotension due to vasodilatation, which can progress to hypotensive shock and anaphylactic reactions.
See also MRI Safety, Contrast Enhanced MRI, Breast MRI, and Cardiac MR imaging.

The brain tissue is provided with a tight endothelial layer on vessels that acts as a filter for substances that reach the brain through the blood stream. This filter is called the blood brain barrier.
The blood brain barrier is responsible for the absence of contrast agent enhancement in normal brain tissue after administration of the iodinated or paramagnetic contrast media used in brain MRI and computed tomography (CT) diagnostic. The absence of contrast uptake in normal tissue provides the basis for differentiation from pathological brain tissue, which is conversely characterized by a disruption of the blood brain barrier.

See also Contrast Enhanced MRI, MRI Safety, Adverse Reaction.

A bolus is a rapid infusion of high dose contrast agent. Dynamic and accumulation phase imaging can be performed after bolus injection. Since the transit time of the bolus through the tissue is only a few seconds, high temporal resolution imaging can be required to obtain sequential images during the wash in and wash out of the contrast material and, therefore, resolve the first pass of the tracer.
For the same injected dose of contrast agent the injection rate (and, consequently, the total injected volume) modifies the bolus peak profile. Increasing the injection rate produces a sharpening of the peak (Cmax increase, Tmax decrease, peak length decrease). At a low injection rate, the first pass presents a plateau form. Substantial changes in the gadolinium concentrations during signal acquisition induce artifacts. Furthermore, the haemodynamic parameters (cardiac output, blood pressure) influence the bolus profile. The characteristics of gadolinium agents are favorable in the early bolus phase, whereas the advantages of large complexes (e.g. blood pool agents) and ultrasmall superparamagnetic iron oxide (USPIO) are most evident in the distribution phase.