(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.

Rapid echo planar imaging and high-performance MRI gradient systems create fast-switching magnetic fields that can stimulate muscle and nerve tissues produced by either changing the electrical resistance or the potential of the excitation. There are apparently no effects on the conduction of impulses in the nerve fiber up to field strength of 0.1 T. A preliminary study has indicated neurological effects by exposition to a whole body imager at 4.0 T. Theoretical examinations argue that field strengths of 24 T are required to produce a 10% reduction of nerve impulse conduction velocity.
Nerve stimulations during MRI scans can be induced by very rapid changes of the magnetic field. This stimulation may occur for example during diffusion weighted sequences or diffusion tensor imaging and can result in muscle contractions caused by effecting motor nerves. The so-called magnetic phosphenes are attributed to magnetic field variations and may occur in a threshold field change of between 2 and 5 T/s. Phosphenes are stimulations of the optic nerve or the retina, producing a flashing light sensation in the eyes. They seem not to cause any damage in the eye or the nerve.
Varying magnetic fields are also used to stimulate bone-healing in non-unions and pseudarthroses. The reasons why pulsed magnetic fields support bone-healing are not completely understood. The mean threshold levels for various stimulations are 3600 T/s for the heart, 900 T/s for the respiratory system, and 60 T/s for the peripheral nerves.
Guidelines in the United States limit switching rates at a factor of three below the mean threshold for peripheral nerve stimulation. In the event that changes in nerve conductivity happens, the MRI scan parameters should be adjusted to reduce dB/dt for nerve stimulation.

An implantable medical device that stimulates nerves.

Depending on the used MRI field strength not necessarily a contraindication, but the examination may damage or impair it. In mid to high field MRI machines the reduction of the SAR value during the scan is necessary to avoid the risk of heating.

Hydrogen nuclei magnetic moments are randomly oriented in the absence of an external magnetic field and are considered to have a net magnetization of zero. Once hydrogen protons are placed in the presence of an external magnetic field, they align themselves in one of two directions, parallel or anti parallel to the net magnetic field, which is commonly referred to as the vector B0. The parallel and anti parallel protons cancel each other out, only the small number of low energy protons left aligned with the magnetic field create the overall net magnetization, this difference is all that counts. The magnetic moments of these protons are added together and are referred to as net magnetization vector (NMV) or the symbol 'M'.

See also Magnetization Transfer Contrast.

An uncharged neutral particle located in the nucleus of most atoms, which serves as a stabilizer.