From Siemens Medical Systems;
Received FDA clearance in 2012.
The MAGNETOM Spectra is a cost-optimized high field MRI system with Tim 4G and Dot technologies. The system consumes less energy compared to other 3 Tesla scanners. The magnet-cooling helium is contained in a closed loop, which prevents the gas from escaping and reduces the need for refills. TimTX includes innovative techniques in the radio frequency excitation hardware as well as new application and processing features enabling uniform RF distribution in all body regions.

From Siemens Medical Systems; Received FDA clearance in 2010.
MAGNETOM Skyra is a top-of-the-line, patient friendly wide bore 3 Tesla MRI system.
The system is equipped with the Tim 4G and Dot system (Total imaging matrix and Day optimizing throughput), to enhance both productivity and image quality with the complete range of advanced applications for clinical routine and research. Tim 4G features lighter, trimmer MRI coils that take up less space inside the magnet but deliver a high coil element density with increased signal to noise ratio and the possibility to use high iPAT factors.

The mobile intraoperative iMotion system produces real-time images used for MR guided surgery and offers functional magnetic resonance imaging, MR spectroscopy, perfusion imaging, and diffusion weighted imaging capabilities.
The iMotion 1.5 T magnet moves to the patient, gliding in and out of place as needed, without affecting surgical, anesthetic, and nursing management.

See also Intraoperative Magnetic Resonance Imaging, MR Guided Interventions.

From ISOL Technology
'RELAX is open type MRI system created by making up for the weakness of existing conventional MR systems and applying the strength and the application of the middle to high field MR without uncompromising the image quality.
RELAX offers you a premium mix of form, performance and functionality that are patient and user friendly beyond comparison. - New breed of MRI pursuing - patients comfort'

The schematic figures of a pulse sequence timing diagram illustrate the steps of basic hardware activity that are incorporated into a pulse sequence. Time during sequence execution is indicated along the horizontal axes. Each line belongs to a different hardware component. One line is needed for the radio frequency transmitter and also one for each gradient (G_s = slice selection gradient x, G_f = phase encoding gradient y, G_f = frequency encoding gradient z, also called readout gradient).
In picture 1, a timing diagram for a 2D pulse sequence is shown.
Slice selection and signal detection are repeated in duration, relative timing and amplitude, each time the sequence is repeated. A single phase encoding component is present each time the sequence is executed.
Additional lines are added for ADC (Analog to Digital Converter) and sampling. A gradient pulse is shown as a deviation above or below the horizontal line. Simultaneous component activities such as the RF pulse and slice selection gradient are indicated as a non-zero deviation from both lines at the same horizontal position. Simple deviations from zero show constant amplitude gradient pulse. Gradient amplitudes that change during the measurement, e.g. phase encoding are represented as hatched regions.

The second picture shows a timing diagram for a 3D pulse sequence.
Volume excitation and signal detection are repeated in duration, relative timing and amplitude, each time the sequence is repeated. Two phase encoding components are present, one in the phase encoding direction and the other in slice selection direction (irrespectively incremented in amplitude) in each time the sequence is executed. A description of the comparison of hardware activity between different pulse sequences.