Magnetic resonance imaging in real time: advances using radial FLASH.
OBJECTIVE
To develop technical advances for real-time magnetic resonance imaging (MRI) that allow for improved image quality and high frame rates.


METHODS
The approach is based on a combination of fast low-angle shot (FLASH) MRI sequences with radial data sampling and view sharing of successive acquisitions. Gridding reconstructions provide images free from streaking or motion artifacts and with a flexible trade-off between spatial and temporal resolution. Immediate image reconstruction and online display is accomplished with the use of an unmodified 3 T MRI system. For receive coils with a large number of elements this process is supported by a user-selectable channel compression that is based on a principal component analysis and performed during initial preparation scans.


RESULTS
In preliminary applications to healthy volunteers, real-time radial FLASH MRI visualized continuous movements of the temporomandibular joint during voluntary opening and closing of the mouth at high spatial resolution (0.75 mm in-plane) and monitored cardiac functions at high temporal resolution (20 images per second) during free breathing and without synchronization to the electrocardiogram.


CONCLUSIONS
Real-time radial FLASH MRI emerges as a simple and versatile tool for a large range of clinical applications.
Zhang
Shuo
S
Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany.
Block
Kai Tobias
KT
Frahm
Jens
J
D000465:Algorithms; D003199:Computer Systems; D044962:Data Compression / Q000379:methods*; D006321:Heart / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted