Quick Overview
Please note that there are different common names for this artifact.

Flow effects in MRI produce a range of artifacts, e.g. intravascular signal void by time of flight effects; turbulent dephasing and first echo dephasing, caused by flowing blood.
Through movement of the hydrogen nuclei (e.g. blood flow), there is a location change between the time these nuclei experience a radio frequency pulse and the time the emitted signal is received (because the repetition time is asynchronous with the pulsatile flow).
The blood flow occasionally produces intravascular high signal intensities due to flow related enhancement, even echo rephasing and diastolic pseudogating. The pulsatile laminar flow within vessels often produces a complex multilayered band that usually propagates outside the head in the phase encoded direction. Blood flow artifacts should be considered as a special subgroup of motion artifacts.

Artifacts can be reduced by reduction of phase shifts with flow compensation (gradient moment nulling), suppression of the blood signal with saturation pulses parallel to the slices, synchronization of the imaging sequence with the heart cycle (cardiac triggering) or can be flipped 90° by swapping the phase//frequency encoding directions.

See also Flow Related Enhancement and Flow Effects.

Short name: Gd-BOPTA, generic name: Gadobenate dimeglumine
A paramagnetic MRI contrast agent (small molecular weight Gd-chelate) with 0.5 and 0.25 molar concentration.
The albumin-mediated relaxation enhancement may result in advantages for Gd-BOPTA over Gd-DTPA and other gadolinium agents in poorly vascularized, small, or lesions with low enhancement and in tumors with high concentrations of albumin. The substance is excreted partly by the kidneys (75-90%), partly by the biliary system (10-25%). The uptake in the liver is about 5% in humans. It is bolus injectable.

See Contrast Agents and MultiHance®.

Short name: (Gd-DTPA)-17, 24 cascade polymer, generic name: Gadomer-17, 24, central moiety: Gd2+, relaxivity: r1=11.9, B0=1.0 T, r2=16.5, Dose: 0.05 mmol/kg
An intravascular macromolecular MRI contrast agent with positive enhancement under development (Bayer Schering Pharma AG) for MR angiography and tumor differentiation. The synthetic dendrimer with large molecular weight (17kD - limits agent to vascular space) is linked to Gadolinium. The renal excretion is slowed to intermediate molecular size. In MRA a longer lasting venous and arterial enhancement was seen with Gadomer-17 due to the particular pharmacokinetics of this agent.

See also Tumor Specific Agents, and Intravascular Contrast Agents.

Nitroxide radicals (or nitroxyl spin labels) are stable organic compounds with theoretical potential for use as a paramagnetic MRI contrast agent. Similar to gadolinium they have an unpaired electron, a property that provides enhancement in T1 based MRI, and a comparable pharmacokinetic. Depending on their structure and chemical bonding, different nitroxides formula may have the potential for use as cardiovascular imaging agents, to enhance the MR imaging on joints (e.g., dendrimer-linked nitroxides have a strong affinity for cartilage), to evaluate brain tumors and infarction, and as a contrast enhancement agent of body/abdominal NMR imaging. Nitroxides are rapidly enzymatically reduced in tissues to products that do not enhance the NMR signal, which can be a problem for MR imaging. In animal experiments with EPRI (electron paramagnetic resonance imaging), tissue redox studies show differences between tumors and normal tissues, which reflect their respective redox status consistent with the reduction/clearance of nitroxides.

OptiMARK® is a formulation of a nonionic gadolinium chelate of diethylenetriamine pentaacetic acid bismethoxyethylamide (gadoversetamide), for use as a paramagnetic MRI contrast agent. OptiMARK® (gadoversetamide injection) is to be administered by intravenous injection. OptiMARK® is indicated for MRI diagnostic procedures to provide increased enhancement and visualization of lesions of the brain, spine and liver, including tumors.

WARNING: NEPHROGENIC SYSTEMIC FIBROSIS Gadolinium-based contrast agents increase the risk for nephrogenic systemic fibrosis (NSF) in patients with acute or chronic severe renal insufficiency (glomerular filtration rate less than 30 mL/min/1.73m²), or acute renal insufficiency of any severity due to the hepato-renal syndrome or in the perioperative liver transplantation period.