(MRI-CA, MRCA) The noninvasive imaging of the coronary arteries using magnetic resonance imaging of the heart.
For cardiac MRI-CA, high performance machines are necessary with minimum 40mT/m and 300μsec slew rate.
2D and 3D acquisition are used for fast gradient echo sequences with techniques for minimizing cardiac and respiratory motion and suppressing the high signal of pericardial fat. The optimal sequences seem to be trueFISP, Balanced FFE or FIESTA with SMASH and SENSE techniques. Respiratory motion is minimized for 3D acquisitions by using respiratory gating, especially using navigator echoes (Navigator Technique) to track diaphragmatic and cardiac movement. Optimization of MR technique can provide mapping of long segments of the coronary arteries.
Blood pool agents are being applied to improve the reliability of coronary MR angiography. The major current clinical indication is the identification of coronary artery anomalies because the diagnostic accuracy's for identifying haemodynamically significant stenoses are variable depending of the image quality.

See also Magnetic Resonance Angiography, and Cardiac MRI.

(EPI) Echo planar imaging is one of the early magnetic resonance imaging sequences (also known as Intascan), used in applications like diffusion, perfusion, and functional magnetic resonance imaging. Other sequences acquire one k-space line at each phase encoding step. When the echo planar imaging acquisition strategy is used, the complete image is formed from a single data sample (all k-space lines are measured in one repetition time) of a gradient echo or spin echo sequence (see single shot technique) with an acquisition time of about 20 to 100 ms. The pulse sequence timing diagram illustrates an echo planar imaging sequence from spin echo type with eight echo train pulses. (See also Pulse Sequence Timing Diagram, for a description of the components.)
In case of a gradient echo based EPI sequence the initial part is very similar to a standard gradient echo sequence. By periodically fast reversing the readout or frequency encoding gradient, a train of echoes is generated.
EPI requires higher performance from the MRI scanner like much larger gradient amplitudes. The scan time is dependent on the spatial resolution required, the strength of the applied gradient fields and the time the machine needs to ramp the gradients.
In EPI, there is water fat shift in the phase encoding direction due to phase accumulations. To minimize water fat shift (WFS) in the phase direction fat suppression and a wide bandwidth (BW) are selected. On a typical EPI sequence, there is virtually no time at all for the flat top of the gradient waveform. The problem is solved by "ramp sampling" through most of the rise and fall time to improve image resolution.
The benefits of the fast imaging time are not without cost. EPI is relatively demanding on the scanner hardware, in particular on gradient strengths, gradient switching times, and receiver bandwidth. In addition, EPI is extremely sensitive to image artifacts and distortions.

Founded in 1969, Elscint is headquartered in Haifa, Israel. Elscint developed advanced computerized imaging systems in Computed Tomography (CT), Magnetic Resonance Imaging (MRI), Nuclear Medicine (NM) and Mammography (MAM) for international markets.
In November 1998, General Electric Medical Systems (GEMS) acquired the Nuclear Medicine and MRI divisions of Elscint, including an unique MRI gradient system concept and technology (twin gradient system).
Elscint Ltd. signs definitive agreement to sell its Nuclear Medicine and Magnetic Resonance Imaging Businesses for $100 Million. Elscint's shareholders approved the sale of its NM, and MRI division to GE (now GE Healthcare). Picker International acquires the Computed Tomography Division of Elscint Ltd. in the same year.

See also Marconi Medical Systems.

The company is a leading manufacturer and developer of magnetic resonance imaging (MRI) scanners. The Patient Friendly MRI Company, formed in 1978, is engaged in the business of inventing, manufacturing, selling and servicing magnetic resonance imaging (MRI) scanners. FONAR is the oldest MRI company in the world. After receiving hundreds of millions in a windfall from protecting their MRI patents, they made a MRI scanner that no other MRI manufacturer has. One that the patient stands in and they call Indomitable, the Stand-Up MRI. Patients like it because it is the least claustrophobic, most comfortable MRI on the market. Doctors like it because of its superior image quality and for the first time, the patient can be scanned in the weight-bearing position, or the position of pain or symptom. In October of 2004, the company changed the product name of the Stand-Up MRI to the Upright MRI. Fonar introduced the first "open" MRI scanner in 1980 and is the originator of the iron-core nonsuperconductive and permanent magnet technology.

MRI Scanners:

- 0.6T: