Short name: Gd-DTPA mesoporphyrin, generic name: gadophrin, central moiety: Gd2+
Gd-DTPA mesoporphyrin is a substance under development (Bayer Schering Pharma AG) as a positive enhancing myocardium- and necrosis- targeted MRI contrast agent.

See also Metalloporphyrins and Necrosis Avid Contrast Agent.

Hepatobiliary chelates used in MRI are paramagnetic contrast agents consisting of a metal ion bound to an organic ligand. Paramagnetic metal ions such as gadolinium improve the MRI signal, but the toxicity of these uncomplexed metal ions makes the use of a chelate to bind the metal ion essential. Due to the hepatocyte uptake of this chelate complex, the different contrast between normal parenchyma and liver lesions improves the detection and characterization of specific diseases. In addition, the hepatobiliary excretion allows the assessment of the hepatobiliary system.
Chelates for hepatobiliary imaging: MultiHance® (Gadobenate Dimeglumine), Teslascan® (Mangafodipir Trisodium), Gd-HIDA, Cr-HIDA, and Fe-EHPG IronIII or other derivatives.

See also Hepatobiliary Contrast Agents, Liver Imaging.

Perflubron® is a perfluorochemical for use as an oral contrast agent. Due to its insolubility in water it does not mix with intestinal secretions; thus bowel lumina appear homogeneously dark on MR images when Perflubron® replaces bowel contents. Filled bowel loops appear black with all pulse sequences because the contrast agent lacks mobile protons.
It is commercially available as Imagent GI. Because rapid transit through the gastrointestinal tract it reaches the rectum within 30 to 40 minutes in most patients. MR imaging of the upper abdominal region should begin within 15 minutes and of the pelvic region 15 to 60 minutes after ingestion of perflubron.

See also Classifications, Characteristics, etc.

Lung imaging is furthermore a challenge in MRI because of the predominance of air within the lungs and associated susceptibility issues as well as low signal to noise of the inflated lung parenchyma. Cardiac and respiratory triggered or breath hold sequences allow diagnostic imaging, however a comparable image quality with computed tomography is still difficult to achieve.
Assumptions for lung MRI:
The current trends in MRI are the use of new imaging technologies and increasingly powerful magnetic fields. Among these technologies are parallel imaging techniques as well as ventilation agents like hyperpolarized helium for the use as an inert inhalational contrast agent to study lung ventilation properties. With hyperpolarized gases clear images of the lungs can be obtained without using a large magnetic field (see also back projection imaging). Single shot sequences (e.g. TSE or Half Fourier Acquisition Single Shot Turbo Spin Echo HASTE) used in lung MR imaging benefits from parallel imaging techniques due to reduced relaxation time effects during the echo train and therefore reduced image blurring as well as reduced motion artifacts.
In the future, more effective contrast agents may provide an alternative solution to the need for high field MRI. Dynamic contrast enhanced MRI perfusion has demonstrated a potential in the diagnosis of pulmonary embolism or to characterize lung cancer and mediastinal tumors. 3D contrast enhanced magnetic resonance angiography of the thoracic vessel.

See also the related poll result: 'MRI will have replaced 50% of x-ray exams by'

Magnevist® enteral (Gadopentetate) is a Gd-DTPA solution for use as a gastrointestinal contrast agent to visualize the bowel in MRI scans.

See also Positive Oral Contrast Agents and Gadopentetate Gastrointestinal.