Metal detector coils can be used to find hidden ferromagnetic materials inside of clothes or the body of persons before entering a scanning room. Magnetic fields attract ferromagnetic objects with forces, which can be dangerous for humans and MRI machines.

The paramagnetic water-soluble metallofullerenes (Gd-fullerenols), which have strong T1 shortening effect, can be used as a novel core material of MRI contrast agents. Gadolinium endohedral metallofullerenes have been synthesized as polyhydroxyl forms (Gd@C82(OH)n, Gd-fullerenes) with the evaluation of their paramagnetic properties. The modification to the water-soluble forms is essential for the biomedical application of the metallofullerenes. The in vitro water proton relaxivity, R1 (the effect on 1/T1), of Gd-fullerenes is significantly higher (20-folds) than that of commercial MRI contrast agents - e.g. Gd-DTPA.

Porphyrins occur naturally in plants and animals. All porphyrin molecules feature an aromatic macrocycle ring with a central binding site. This site accommodates transition metals, which are held in place by inward-facing nitrogen atoms. Metalloporphyrins have usually a low toxicity and a potential of a selective uptake in tumors or necrosis. These properties are advantageous for a use as MRI tumor specific agents with positive enhancement. These contrast agents enhance tumors on T1 weighted sequences, which are isointense to surrounding tissues. Porphyrin-based compounds have also necrosis avid properties; they can depict the extent of myocardial infarction as defined by histopathology.
Metalloporphyrins are also used in photodynamic therapy of tumors. The compounds contain a 'lone star' metal atom at the center of the ring and are 'bigger than the average porphyrin'. They contain five N atoms in the central chelating core and this allows them to form complexes with large trivalent lanthanide metals, which have useful cancer therapy properties.

See also Classifications, Characteristics, etc., Gadophrin, MnIIITPPS4, Necrosis Avid Contrast Agent.

(m) The SI base unit of distance.
Definition: 1983 defined as the distance traveled by light in a vacuum during the time interval of 1/299 792 458 of a second.
The speed of light in a vacuum, c, is one of the fundamental constants of nature.

1 meter (m) is equal to approximately 39.370 079 inches (in)
1 meter is equal to approximately 3.280 840 feet (ft)
1 meter is equal to approximately 1.093 613 3 yard (yd)
1 square meter (m²) is equal to approximately 10.763911 square feet (ft²)
1 inch = 2.54 centimeters
Smaller or larger units are, e.g.:
1 (m) = 1 000 millimeter (mm)
1 kilometer (km) = 1 000 (m)
1 kilometer (km) = 0.62137 (statute) miles (mi)

(MINIP) A projection image, which is obtained from a 3D data set by selecting the minimum intensity along lines or rays that cut through the 3D image volume. This function is used as a postprocessing method for black blood MRA images.