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.

From Hitachi Medical Systems America Inc.;
Hitachi expanded its portfolio with the Echelon™ 1.5T. The MRI scanner combines a compact magnet and a scalable 8-channel RF system with high-performance gradients and slew rate to select short echo times, small field of views, high matrices and thin slices. Standard features of the Echelon MRI system include higher-order active shim, RAPID (parallel imaging for use on brain MRI, body, cardiovascular imaging, and orthopedic coils), multiple coil ports, and an advanced reconstruction engine.

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General Electric (GE) agreed to buy diagnostic systems maker Lunar Corp. for $150m. in March 2000. In 2004/05 it seems that the integration process into GE Healthcare has been completed. (GE Medical Systems and Amersham announced in April 2004 the completion of a share exchange acquisition of Amersham Health by GE. The result of this acquisition is the new GE Healthcare, based in the UK, totally owned by General Electric (GE).

The U.S.-based company developed bone densitometers and scanning machines that measure bone density as a way of diagnosing osteoporosis and other metabolic bone diseases. GE Lunar marketed these products worldwide.
GE Lunar announced a distribution agreement with MagneVu for domestic sales of the MagneVu 1000, a portable MRI device for orthopedic use, under the trade name Applause™.
GE Lunar was the exclusive U.S. distributor of MR-devices manufactured by Esaote S.p.A. These compact in-office MRI™ machines are designed to fit all practice sizes in orthopedic imaging and complete the range of diagnostic imaging systems.

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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:

The quality of magnetic resonance imaging is particularly dependent on image resolution (matrix, field of view, slice thickness), contrast (TE, TR), signal to noise ratio (bandwidth, signal averaging) and lack of artifacts. These MRI parameters are affected by the field homogeneity, the field strength, the coil, the pulse sequence type and imaging techniques like parallel imaging.

See also Image Contrast Characteristics.