(Gadolite® oral Suspension) An oral paramagnetic MRI contrast agent to enhance delineation of the bowel. Zeolites are hydrated aluminosilicates with large holes that can provide a temporary home for guest molecules like gadolinium. Zeolites modified with Gd (III) are effective positive MRI contrast agents for gastrointestinal application.

(HS) A method in which approximately one half of the acquisition matrix in the phase encoding direction is acquired. Half scan is possible because of symmetry in acquired data. Since negative values of phase encoded measurements are identical to corresponding positive values, only a little over half (more than 62.5%) of a scan actually needs to be acquired to replicate an entire scan. This results in a reduction in scan time at the expense of signal to noise ratio. The time reduction can be nearly a factor of two, but full resolution is maintained.
Half scan can be used when scan times are long, the signal to noise ratio is not critical and where full spatial resolution is required. Half scan is particularly appropriate for scans with a large field of view and relatively thick slices; and, in 3D scans with many slices. In some fast scanning techniques the use of Half scan enables a shorter TE thus improving contrast. For this reason, the Half scan parameter is located in the contrast menu.

More information about scan time reduction; see also partial fourier technique.

(Mn-DPDP) This agent, mangafodipir trisodium, is a hepatocyte specific MRI contrast agent. Manganese is very toxic, so it has to be chelated and put in the form of a vitamin B6 analog, which is taken up by normal hepatocytes to some extent.
Teslascan® was developed in the early 1980's, went through clinical trials in the early 1990's, and was approved in 1997. One problem with assessing the efficacy of this agent is the fact that the phase III trials finished in the early 1990's, and the techniques used for MR today are very different from the techniques used almost a decade ago.
This contrast agent shortens the T1 relaxation time. On T1 weighted pictures it makes a normal liver look brighter. Since metastases, for example, do not generally take up this agent, the contrast between the enhancing liver and the non-enhancing lesions will increase on T1 weighted pictures. It does not have much effect on T2 weighted images.

A limitation of abdominal MRI can be the assessment of malignancies by difficulties to distinguish bowel from other organs or malignant masses. The use of oral contrast agents can reduce this problem. Properties of an ideal oral contrast agent are little or no absorption by the stomach or intestines, complete excretion, no motion or susceptibility artifacts, and uniform marking of the GI tract.
Gastrointestinal MRI contrast agents are divided in materials with bright appearance or dark appearance. The choice of a negative or a positive oral contrast agent depends on the specific problem or the pulse sequence.

See also Positive Oral Contrast Agents, Negative Oral Contrast Agents, Gastrointestinal Diamagnetic Contrast Agents, Gastrointestinal Paramagnetic Contrast Agents and Gastrointestinal Superparamagnetic Contrast Agents.

See also the related poll result: 'The development of contrast agents in MRI is'

A solution of ferric ammonium citrate (Geritol) used to enhance the delineation of the bowel. With T1 weighted magnetic resonance imaging (MRI) the predominantly positive enhancement helps to distinguish organs and tissues that are adjacent to the upper regions of the gastrointestinal tract. Product name found as both Ferriseltz® and FerriSeltz®.