(NSF) Nephrogenic systemic fibrosis is a rare and highly debilitating disorder that involves extensive thickening and hardening of the skin with fibrotic nodules and plaques.
MRI contrast media have very low side effects, but accumulating data indicate that gadolinium-based contrast agents increase the risk for the development of NSF among patients with severe renal insufficiency or renal dysfunction due to the hepato-renal syndrome or in the perioperative liver transplantation period.
Due to this reason, gadolinium contrast agents are now considered contraindicated in patients with an estimated glomerular filtration rate fewer than 30 mL/min/1.73m². In these patients, avoid use of gadolinium-based contrast agents unless the diagnostic information is essential and not available with non-contrast enhanced magnetic resonance imaging (MRI).

Recognized or possibly associated factors for NSF:
When administering a gadolinium-based contrast agent, do not exceed the recommended dose and allow a sufficient period of time for elimination of the contrast medium from the body prior to any readminstration. Screen all patients for renal dysfunction by obtaining a history and/or laboratory tests.

See also Contrast Medium, Adverse Reaction, MRI Risks, MRI Safety, Ionic Intravenous Contrast Agents, Nonionic Intravenous Contrast Agents, and Contraindications.

General MRI of the abdomen can consist of T1 or T2 weighted spin echo, fast spin echo (FSE, TSE) or gradient echo sequences with fat suppression and contrast enhanced MRI techniques. The examined organs include liver, pancreas, spleen, kidneys, adrenals as well as parts of the stomach and intestine (see also gastrointestinal imaging). Respiratory compensation and breath hold imaging is mandatory for a good image quality.
T1 weighted sequences are more sensitive for lesion detection than T2 weighted sequences at 0.5 T, while higher field strengths (greater than 1.0 T), T2 weighted and spoiled gradient echo sequences are used for focal lesion detection. Gradient echo in phase T1 breath hold can be performed as a dynamic series with the ability to visualize the blood distribution. Phases of contrast enhancement include the capillary or arterial dominant phase for demonstrating hypervascular lesions, in liver imaging the portal venous phase demonstrates the maximum difference between the liver and hypovascular lesions, while the equilibrium phase demonstrates interstitial disbursement for edematous and malignant tissues.
Out of phase gradient echo imaging for the abdomen is a lipid-type tissue sensitive sequence and is useful for the visualization of focal hepatic lesions, fatty liver (see also Dixon), hemochromatosis, adrenal lesions and renal masses. The standards for abdominal MRI vary according to clinical sites based on sequence availability and MRI equipment. Specific abdominal imaging coils and liver-specific contrast agents targeted to the healthy liver tissue improve the detection and localization of lesions.
See also Hepatobiliary Contrast Agents, Reticuloendothelial Contrast Agents, and Oral Contrast Agents.

For Ultrasound Imaging (USI) see Abdominal Ultrasound at Medical-Ultrasound-Imaging.com.

Blood pool agents (intravascular contrast agents) remain in the blood for a prolonged time compared with conventional contrast agents, which diffuse quickly into the interstitial space. Magnetic resonance angiography (MRA), cardiovascular imaging, or contrast enhanced MRIs are possible over an hour or more. This advantage over conventional MRI contrast media allows also higher resolution MRA of several territories using respiratory or cardiac gating techniques with a single contrast bolus.
Different types of blood pool contrast agents:
Blood pool MRI contrast agents with their longer intravascular circulation can be designed to be targeted to necrotic myocardium, to assess myocardial viability, or tumor directed to provide better diagnostic information for various tumors. A disadvantage of the use of blood pool agents for MRA is that the separation of arteries and veins is more difficult because they are present in both and the overlapping of those vessels is disturbing. This can be solved by e.g. different MIP segmentation algorithms.

See also Necrosis Avid Contrast Agent, Tumor Specific Agents, Feruglose, Gadofosveset Trisodium (Vasovist), Ultrasmall Superparamagnetic Iron Oxide and Contrast Medium.

Ferrioxamines are potential iron oxide-based intravascular contrast agents. Ferrioxamine methanesulfonate, ferrioxamine-B, and hydroxyethyl-starch-ferrioxamine have been tested as MRI contrast agents, partly in clinical trials.
Ferrioxamine methanesulfonate was tested as a paramagnetic agent for the imaging of the kidney and the urogenital system. Hydroxyethyl-starch-ferrioxamine has the potential to provide information regarding myocardial vascular flow and ferrioxamine-B derivatives may be used as hepatobiliary contrast agents.

See also Superparamagnetic Iron Oxide, Hepatobiliary Contrast Agents.

Tumor specific MRI contrast agents are in development to provide better delineation and progression information for various tumors. Clinical oncology has a need for contrast agents that can identify tumors and metastases at a size of 100,000 cells rather than 1,000,000,000 cells. This level of sensitivity requires excellent tumor targeting of imaging agents and a high MRI signal.
Tumor specific agents accumulate at pathological tissues by passive or active targeting mechanisms. Passive targeting agents use e.g., the natural defense mechanisms in which phagocytic cells remove foreign particles from the body. Active targeting is based on a ligand-directed, site-specific accumulation of contrast agents. The availability of macromolecular contrast agents such as feruglose and ultrasmall superparamagnetic iron oxide (USPIO), which permit the assessment of tissue permeability, may also improve the detection of tumor grade, tumor type, and response to drugs that target angiogenesis.

See also Monoclonal Antibodies, Metalloporphyrins, Nitroxides and Ferrioxamine.