ABLAVAR™ (formerly named Vasovist™) is a blood pool agent for magnetic resonance angiography (MRA), which opens new medical imaging possibilities in the evaluation of aortoiliac occlusive disease (AIOD) in patients with suspected peripheral vascular disease.
ABLAVAR™ binds reversibly to blood albumin, providing imaging with high spatial resolution up to 1 hour after injection, due to its high relaxivity and to the long lasting increased signal intensity of blood.
As with other contrast media: the possibility of serious or life-threatening anaphylactic or anaphylactoid reactions, including cardiovascular, respiratory and/or cutaneous manifestations, should always be considered.

WARNING:
NEPHROGENIC SYSTEMIC FIBROSIS Gadolinium-based contrast agents increase the risk for nephrogenic systemic fibrosis (NSF) in patients with acute or chronic severe renal insufficiency (glomerular filtration rate less than 30 mL/min/1.73m²), or acute renal insufficiency of any severity due to the hepato-renal syndrome or in the perioperative liver transplantation period.

See also Cardiovascular Imaging, Adverse Reaction, Molecular Imaging, and MRI Safety.

This method synchronize the heartbeat with the beginning of the TR, whereat the r wave is used as the trigger. Cardiac gating times the acquisition of MR data to physiological motion in order to minimize motion artifacts. ECG gating techniques are useful whenever data acquisition is too slow to occur during a short fraction of the cardiac cycle.
Image blurring due to cardiac-induced motion occurs for imaging times of above approximately 50 ms in systole, while for imaging during diastole the critical time is of the order of 200-300 ms. The acquisition of an entire image in this time is only possible with using ultrafast MR imaging techniques. If a series of images using cardiac gating or real-time echo planar imaging EPI are acquired over the entire cardiac cycle, pixel-wise velocity and vascular flow can be obtained.
In simple cardiac gating, a single image line is acquired in each cardiac cycle. Lines for multiple images can then be acquired successively in consecutive gate intervals. By using the standard multiple slice imaging and a spin echo pulse sequence, a number of slices at different anatomical levels is obtained. The repetition time (TR) during a ECG-gated acquisition equals the RR interval, and the RR interval defines the minimum possible repetition time (TR). If longer TRs are required, multiple integers of the RR interval can be selected. When using a gradient echo pulse sequence, multiple phases of a single anatomical level or multiple slices at different anatomical levels can be acquired over the cardiac cycle.
Also called cardiac triggering.

The Dixon technique is a MRI method used for fat suppression and/or fat quantification. The difference in magnetic resonance frequencies between fat and water-bound protons allows the separation of water and fat images based on the chemical shift effect.
This imaging technique is named after Dixon, who published in 1984 the basic idea to use phase differences to calculate water and fat components in postprocessing. Dixon's method relies on acquiring an image when fat and water are 'in phase', and another in 'opposed phase' (out of phase). These images are then added together to get water-only images, and subtracted to get fat-only images. Therefore, this sequence type can deliver up to 4 contrasts in one measurement: in phase, opposed phase, water and fat images. An additional benefit of Dixon imaging is that source images and fat images are also available to the diagnosing physician.
The original two point Dixon sequence (number of points means the number of images acquired at different TE) had limited possibilities to optimize the echo time, spatial resolution, slice thickness, and scan time; but Dixon based fat suppression can be very effective in areas of high magnetic susceptibility, where other techniques fail. This insensitivity to magnetic field inhomogeneity and the possibility of direct image-based water and fat quantification have currently generated high research interests and improvements to the basic method (three point Dixon).
The combination of Dixon with gradient echo sequences allows for example liver imaging with 4 image types in one breath hold. With Dixon TSE/FSE an excellent fat suppression with high resolution can be achieved, particularly useful in imaging of the extremities.
For low bandwidth imaging, chemical shift correction of fat images can be made before recombination with water images to produce images free of chemical shift displacement artifacts. The need to acquire more echoes lengthens the minimum scan time, but the lack of fat saturation pulses extends the maximum slice coverage resulting in comparable scan time.

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'

[This entry is marked for removal.]

Hitachi Medical Systems America, Inc. (HMSA), was a major provider of magnetic resonance imaging systems in the United States. Hitachi had more than 2300 installed permanent magnet MR imaging systems worldwide. As a full-line supplier of medical imaging equipment in Japan, Hitachi Medical Corporation (HMC) founded HMSA to provide a direct link to the U.S. marketplace. Altaire™ , the open MR system from Hitachi, extends the family of open MRI products.

In December 2019 Japan's Fujifilm announced the acquisition of Hitachi's diagnostic imaging business for 179 billion yen ($1.63 billion). This includes Hitachi’s CT, MRI, X-ray, and ultrasound imaging operations, also its electronic health record business. Fujifilm expects the deal to close in July 2020 subject to regulatory clearances.

MRI Scanners:

0.3T to 0.7T:
1.5T: