The principal advantage of MRI at high field is the increase in signal to noise ratio. This can be used to improve anatomic and/or temporal resolution and reduce scan time while preserving image quality. MRI devices for whole body imaging for human use are available up to 3 tesla (3T). Functional MRI (fMRI) and MR spectroscopy (MRS) benefit significantly. In addition, 3T machines have a great utility in applications such as TOF MRA and DTI. Higher field strengths are used for imaging of small parts of the body or scientific animal experiments. Higher contrast may permit reduction of gadolinium doses and, in some cases, earlier detection of disease.
Using high field MRI//MRS, the RF-wavelength and the dimension of the human body complicating the development of MR coils. The absorption of RF power causes heating of the tissue. The energy deposited in the patient's tissues is fourfold higher at 3T than at 1.5T. The specific absorption rate (SAR) induced temperature changes of the human body are the most important safety issue of high field MRI//MRS.
Susceptibility and chemical shift dispersion increase like T1, therefore high field MRI occasionally exhibits imaging artifacts. Most are obvious and easily recognized but some are subtle and mimic diseases. A thorough understanding of these artifacts is important to avoid potential pitfalls. Some imaging techniques or procedures can be utilized to remove or identify artifacts.

See also Diffusion Tensor Imaging.

See also the related poll result: 'In 2010 your scanner will probably work with a field strength of'

The period of time required to collect the image data. This time does not include the time necessary to reconstruct the image. The total time for performing a scan must take into consideration the additional image reconstruction time when determining how quickly the image may be viewed.

Imaging coils are radio frequency coils used in magnetic resonance imaging for sending and/or receiving electromagnetic radiation. Several MR imaging coils in different shapes and sizes are necessary for different body parts and to handle individual applications.
For Example:
Birdcage coils provide high homogeneity and good signal to noise ratio (SNR) in brain MRI scans.
Surface coils with small coil diameter and higher SNR enable to image the temporomandibular joints (TMJ).
The implemented body coil allows the scanning of body parts with large field of views.
Micro coils are available to image finger joints.
High performance phased array coils are today state-of-the-art for a wide range of applications from head, spine, knee or shoulder to cardiac MRI.
For different types of coils see Volume Coil, Sense Coil, Array Coil, Surface Coil, and Bird Cage Coil.

See also the related poll result: '3rd party coils are better than the original manufacturer coils'

Not necessarily a contraindication, but the examination may damage or impair it. An insulin pump can be disconnected easily for a period of time. Remove the pump while outside the 5 Gauss line, because the pump batteries and motor are magnetic.

Keyhole imaging is used for dynamic imaging with contrast medium. The advantage is that the keyhole technique increases temporal resolution without a loss of spatial resolution by limited data acquisition. Keyhole Fourier imaging updates the low spatial frequencies of the original full, high-resolution data set. The high spatial frequency content of the image is constant in time so that its updating would be unnecessary. The high spatial frequency data is acquired from a baseline image, for example, before injection of a contrast agent.
After contrast injection, only the lower spatial frequency data is acquired because, there is no change in the tissue that is responsible for the higher frequency spatial variation in the image.