Pulse sequences, designed to be insensitive to flow, e.g. at every even echo, a spin echo sequence is not flow sensitive. Velocity compensation is achieved by using gradients, which are either symmetrical around a 180° pulse and switched on twice as is the case for motion compensated spin echo pulse sequences, or two antisymmetrical gradient lobes without 180° pulse, which is the way to produce a velocity compensated gradient echo pulse sequence.
The signal of the second echo (and all other even echoes) is independent of the velocity of the object. Thus, velocity-based motion effects stemming from the entire voxel or from spins within a voxel (intravoxel incoherent motion) are suppressed with such pulse sequences.
If higher order motion is relevant, as it may be in turbulent jets across valves, acceleration and jerk effects can also be compensated for by the use of appropriate combinations of gradient- and radio frequency pulses.
With the increasingly stronger gradients, echo times in MR systems can be shortened to the point at which effects other than velocity effects hardly ever become relevant.

Categories of negative oral contrast agents:
Negative oral contrast media are usually based on superparamagnetic particles and act by inducing local field inhomogeneities, which results in shortening of both T1 and T2 relaxation times. Superparamagnetic contrast agents have predominant T2 weighted effects. Biphasic contrast media are agents that have different signal intensities on different sequences, depending on the concentration at which they are used.
Suitable materials for oral contrast agents should have little or no absorption by the stomach or intestines, complete excretion, no motion or susceptibility artifacts, affordability, and uniform marking of the gastrointestinal tract. Benefits of negative oral contrast agents are the reduction of ghosting artifacts caused by the lack of signal. Superparamagnetic iron oxides produce also in low concentrations a noticeable signal loss; but can generate susceptibility artifacts especially in gradient echo sequences. Perfluorochemicals do not dilute in the bowel because they are not miscible with water.
High cost, poor availability, and limited evaluations of side effects are possible disadvantages.
Negative oral contrast agents are used e.g., in MRCP, where the ingestion of 600-900 ml of SPIO cancels out the signal intensity of the lumen (in addition after the injection of a gadolinium-based contrast medium, the enhancement of the inflammatory tissues is clearer seen), and in MR abdominal imaging of Crohn's disease in combination with mannitol.

Blueberry or pineapple juices are useable for examinations of the pancreas (MRCP, upper abdominal imaging) as cheep contrast agents, because of the content of magnetic substances (e.g. manganese).

See also Ferristene, Ferumoxsil, Oral Magnetic Particles, Gastrointestinal Imaging.

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the Panorama 0.23 T, providing a new design optimized for patient comfort, faster reconstruction time than before (300 images/second) and new gradient specifications. Philips' Panorama 0.23 T I/T supports MR-guided interventions, resulting in minimally invasive procedures, more targeted surgery, reduced recovery time and shorter hospital stays. Optional OptoGuide functionality enables real-time needle tracking. Philips' Panorama 0.23 TPanorama 0.2 R/T is the first and only open MRI system to enable radiation therapy planning using MR data sets. The Panorama also features the new and consistent Philips User Interface, an essential element of the Vequion clinical IT family of products and services.

From Philips Medical Systems;
Panorama 0.6 T is the Philips Mid-Field Open MRI system. It is the most open MR scanner in the market, optimized for patient comfort and faster reconstruction time.

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this active shielded member of the Panorama product line combines the advantages of one 1.0 T system's with the possibilities of an open MRI system. The open design helps ease anxiety for claustrophobic patients and increased patient comfort whereby the field strength provides spectacular image quality and fast patient throughput.