The cardiovascular magnetic resonance machine: Hardware and software requirements

The flexibility of cardiac magnetic resonance imaging (MRI) includes faster imaging for applications such as stress tests, ventricular function, myoca rdial perfusion and coronary artery imaging. Faster imaging makes greater d emands on the hardware and software. Although some cardiac imaging can be p erformed at 0.5 T, some of the faster techniques demand the higher signal-t o-noise ratio of higher main field, and fat suppression in cardiac images i s more easily achieved at higher field. Main field inhomogeneity affects ra pid imaging and performance in open-access magnets. High gradient performan ce, low eddy currents and surface receiver coils are essential for fast car diac imaging and the hardware of these systems including interventional ima ging is discussed. The use of ECG signals for prospective and retrospective cardiac synchronization of MRI is examined. Techniques for reducing the ma jor problem of respiratory motion in MRI are surveyed. Flexibility in the c omputer architecture of the scanner and the electronics generating the puls e sequence and controlling data acquisition is vital in cardiac imaging, fo r retrospective cardiac gating, respiratory navigator-controlled imaging an d "real-time interactive'' imaging in a similar manner to ultrasound imagin g. Automated measurements from MR images remain under development. The purs e sequences and image display functions a cardiovascular MRI system should support for basic cardiac imaging applications and current clinical researc h areas are summarized.