(FIESTA) The fast imaging employing steady state acquisition sequence provides images of fluid filled structures with very short acquisition times. The FIESTA sequence uses the T2 steady state contrast mechanism to provide high SNR images with strong signal from fluid tissues while suppressing background tissue for contrast and anatomic detail of small structures. In addition, the ultra short TR and TE enable extremely short acquisition times - shorter than FSE - and the images can be post processed using MIP, volume rendering, or 3D navigator techniques.

See Steady State Free Precession.

(TrueFISP) True fast imaging with steady state precession is a coherent technique that uses a fully balanced gradient waveform. The image contrast with TrueFISP is determined by T2*//T1 properties and mostly depending on TR. The speed and relative motion insensitivity of acquisition help to make the technique reliable, even in patients who have difficulty with holding their breath.
Recent advances in gradient hardware have led to a decreased minimum TR. This combined with improved field shimming capabilities and signal to noise ratio, has allowed TrueFISP imaging to become practical for whole-body applications. There's mostly T2* weighting. With the used ultrashort TR-times T1 weighting is almost impossible. One such application is cardiac cine MR with high myocardium-blood contrast. Spatial and temporal resolution can be substantially improved with this technique, but contrast on the basis of the ratio of T2* to T1 is not sufficiently high in soft tissues. By providing T1 contrast, TrueFISP could then document the enhancement effects of T1 shortening contrast agents. These properties are useful for the anatomical delineation of brain tumors and normal structures. With an increase in SNR ratio with minimum TR, TrueFISP could also depict the enhancement effect in myoma uteri. True FSIP is a technique that is well suited for cardiac MR imaging. The imaging time is shorter and the contrast between the blood and myocardium is higher than that of FLASH.

See Steady State Free Precession.

(FLASH) A fast sequence producing signals called gradient echo with low flip angles. FLASH sequences are modifications, which incorporate or remove the effects of transverse coherence respectively.
FLASH uses a semi-random spoiler gradient after each echo to spoil the steady state (to destroy any remaining transverse magnetization) by causing a spatially dependent phase shift. The transverse steady state is spoiled but the longitudinal steady state depends on the T1 values and the flip angle. Extremely short TR times are possible, as a result the sequence provides a mechanism for gaining extremely high T1 contrast by imaging with TR times as brief as 20 to 30 msec while retaining reasonable signal levels. It is important to keep the TE as short as possible to suppress susceptibility artifacts.
The T1 contrast depends on the TR as well as on flip angle, with short TE.
Small flip angles and short TR results in proton density, and long TR in T2* weighting.
With large flip angles and short TR result T1 weighted images.

TR and flip angle adjustment:
TR 3000 ms, Flip Angle 90°
TR 1500 ms, Flip Angle 45°
TR 700 ms, Flip Angle 25°
TR 125 ms, Flip Angle 10°

The apparent ability to trade TR against flip angle for purposes of contrast and the variation in SNR as the scan time (TR) is reduced.

See also Gradient Echo Sequence.

In every MR examination, a large static magnetic field is applied. Field strengths for clinical equipment can vary between 0.2 and 3 T; experimental imaging units have a field strength of up to 11 T, depending on the MRI equipment used. In MRS, field strengths up to 12 T are currently used. The field strength of the magnet will influence the quality of the MR image regarding chemical shift artifacts, the signal to noise ratio (SNR), motion sensitivity and susceptibility artifacts.

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

The use of MR spectroscopy for acquiring functional activation of the brain.
There are two possible approaches:
In the first, localized spectra of brain water are acquired and subtle changes in these spectra reflect the biophysical water environment. Changes in T2 due to deoxyhaemoglobin concentration may be detected in this way. The disadvantages of poor spatial resolution are to some extent offset by the high signal to noise ratio SNR of the spectroscopic data.
An alternative approach is to use MR spectroscopy directly to detect metabolites that are altered by brain activation. These include lactate and glucose. Such experiments have inherently poor spatial and temporal resolution, but do give a direct indication of the metabolic response of the brain to functional activation.