Resovist® is an organ-specific MRI contrast agent, used for the detection and characterization of especially small focal liver lesions.
Resovist® consists of superparamagnetic iron oxide (SPIO) nanoparticles coated with carboxydextran, which are accumulated by phagocytosis in cells of the reticuloendothelial system (RES) of the liver. The uptake of Resovist® Injection in the reticuloendothelial cells results in a decrease of the signal intensity of normal liver parenchyma on both T2- and T1 weighted images.
Most malignant liver tumors do not contain RES cells and therefore do not uptake the iron particles. The resulting imaging effect is an improved contrast between the tumor (bright) and the surrounding tissue (dark).
Resovist® can be injected as an intravenous bolus, which allows immediate imaging of the liver and reduces the overall examination time. A dynamic imaging strategy after bolus injection supports to characterize lesions. In comprehensive clinical trials, it demonstrated an excellent safety profile.
In 2001, Resovist® was approved for the European market.

See also Superparamagnetic Iron Oxide.

Resovist® competed with Primovist™, the other liver imaging agent of Bayer Schering Pharma AG. Due to this reason, the production of Resovist® has been abandoned in 2009.

Respiratory compensation reduces motion artifacts due to breathing. The approach is to reassign the echoes that are sensitive to respiratory motion in the central region of k-space. The outer lines of phase encoding normally contain the echoes where the motion from expiration is the greatest. The central portion of k-space will have encoded the echoes where inspiration and expiration are minimal. By a bellows device fixed to the abdomen, monitoring of the diaphragm excursion is possible. Respiratory compensation does not increase scan time with most systems.
An advantage of very fast sequences is the possibility of breath holding during the acquisition to eliminate motion artifacts. Breath hold is commonly used on most abdominal studies where images are acquired using gradient echo-based sequences during a brief inspiratory period (20-30 seconds). To enhance the breath holding endurance of the patient, connecting the patient to oxygen at a 1-liter flow rate via a nasal cannula has been shown to be helpful.
Also called PEAR, Respiratory Trigger, Respiratory Gating, PRIZE, FREEZE, Phase Reordering.

See also Phase Encoding Artifact Reduction, Respiratory Ordered Phase Encoding.

Respiratory gating is a respiratory motion reduction technique with reordering of the phase encoding matrix.

See Gating.

Respiratory synchronization that acquires image data at regular times independent of the respiratory cycle, but chooses the sequence of phase encoding data acquisition so as to minimize the respiratory motion-induced artifacts in the resulting image. For example, choosing the sequence of phase encoding such that adjacent samples in the final full data set have minimal differences in respiratory phase will minimize the spacing of ghosting artifacts in the final image.

(FREEZE) See Respiratory Ordered Phase Encoding.