(CE MRA) Contrast enhanced MR angiography is based on the T1 values of blood, the surrounding tissue, and paramagnetic contrast agent.
T1-shortening contrast agents reduces the T1 value of the blood (approximately to 50 msec, shorter than that of the surrounding tissues) and allow the visualization of blood vessels, as the images are no longer dependent primarily on the inflow effect of the blood. Contrast enhanced MRA is performed with a short TR to have low signal (due to the longer T1) from the stationary tissue, short scan time to facilitate breath hold imaging, short TE to minimize T2* effects and a bolus injection of a sufficient dose of a gadolinium chelate.
Images of the region of interest are performed with 3D spoiled gradient echo pulse sequences. The enhancement is maximized by timing the contrast agent injection such that the period of maximum arterial concentration corresponds to the k-space acquisition. Different techniques are used to ensure optimal contrast of the arteries e.g., bolus timing, automatic bolus detection, bolus tracking, care bolus. A high resolution with near isotropic voxels and minimal pulsatility and misregistration artifacts should be striven for. The postprocessing with the maximum intensity projection (MIP) enables different views of the 3D data set.
Unlike conventional MRA techniques based on velocity dependent inflow or phase shift techniques, contrast enhanced MRA exploits the gadolinium induced T1-shortening effects. CE MRA reduces or eliminates most of the artifacts of time of flight angiography or phase contrast angiography. Advantages are the possibility of in plane imaging of the blood vessels, which allows to examine large parts in a short time and high resolution scans in one breath hold. CE MRA has found a wide acceptance in the clinical routine, caused by the advantages:

The magnetic memory of credit and similar cards, as well as magnetic devices such as tapes, will be erased by MR magnets.

European Medicines Agency (EMA) is a decentralised body of the European Union with headquarters in London.
'The EMA began its activities in 1995, when the European system for authorising medicinal products was introduced, providing for a centralised and a mutual recognition procedure. The EMA has a role in both, but is primarily involved in the centralised procedure. Where the centralised procedure is used, companies submit one single marketing authorisation application to the EMA. A single evaluation is carried out through the Committee for Medicinal Products for Human Use (CHMP) or Committee for Medicinal Products for Veterinary Use (CVMP). If the relevant Committee concludes that quality, safety and efficacy of the medicinal product is sufficiently proven, it adopts a positive opinion. This is sent to the Commission to be transformed into a single market authorisation valid for the whole of the European Union.'
'Its main responsibility is the protection and promotion of public and animal health, through the evaluation and supervision of medicines for human and veterinary use. The EMA coordinates the evaluation and supervision of medicinal products throughout the European Union. The Agency brings together the scientific resources of the 28 EU Member States in a network of over 40 national competent authorities. It cooperates closely with international partners, reinforcing the EU contribution to global harmonisation.'

Ultrasound imaging is the primary fetal monitoring modality during pregnancy, nevertheless fetal MRI is increasingly used to image anatomical regions and structures difficult to see with sonography. Given its long record of safety, utility, and cost-effectiveness, ultrasound will remain the modality of first choice in fetal screening. However, MRI is beginning to fill a niche in situations where ultrasound does not provide enough information to diagnose abnormalities before the baby's birth. Magnetic resonance imaging of the fetus provides multiplanar views also in sub-optimal positions, better characterization of anatomic details of e.g. the fetal brain, and information for planning the mode of delivery and airway management at birth.

Indications:
Modern fetal MRI requires no sedatives or muscle relaxants to control fetal movement. Ultrafast MRI techniques (e.g., single shot techniques like Half Fourier Acquisition Single shot Turbo spin Echo HASTE) enable images to be acquired in less than one second to eliminate fetal motion. Such technology has led to increased usage of fetal MRI, which can lead to earlier diagnosis of conditions affecting the baby and has proven useful in planning fetal surgery and designing postnatal treatments. As MR technology continues to improve, more advances in the prenatal diagnosis and treatment of fetal abnormalities are to expect. More advances in in-utero interventions are likely as well. Eventually, fetal MRI may replace even some prenatal tests that require invasive procedures such as amniocentesis.

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

(FDA) An agency of the US federal government established by Congress in 1912 and presently part of the US Department of Health and Human Services. The FDA gives classifications of medical devices according to potential risks and controls the safety of marketed drugs.

See also Class I II III Devices, Phase 1 2 3 4 Drug Trials and Legal Requirements.