Interleaved multishot imaging by spatiotemporal encoding: A fast, self-referenced method for high-definition diffusion and functional MRI.
PURPOSE
Single-shot imaging by spatiotemporal encoding (SPEN) can provide higher immunity to artifacts than its echo planar imaging-based counterparts. Further improvements in resolution and signal-to-noise ratio could be made by rescinding the sequence's single-scan nature. To explore this option, an interleaved SPEN version was developed that was capable of delivering optimized images due to its use of a referenceless correction algorithm.


METHODS
A characteristic element of SPEN encoding is the absence of aliasing when its signals are undersampled along the low-bandwidth dimension. This feature was exploited in this study to segment a SPEN experiment into a number of interleaved shots whose inaccuracies were automatically compared and corrected as part of a navigator-free image reconstruction analysis. This could account for normal phase noises, as well as for object motions during the signal collection.


RESULTS
The ensuing interleaved SPEN method was applied to phantoms and human volunteers and delivered high-quality images even in inhomogeneous or mobile environments. Submillimeter functional MRI activation maps confined to gray matter regions as well as submillimeter diffusion coefficient maps of human brains were obtained.


CONCLUSION
We have developed an interleaved SPEN approach for the acquisition of high-definition images that promises a wider range of functional and diffusion MRI applications even in challenging environments.
['Schmidt|Rita|R|', 'Seginer|Amir|A|', 'Frydman|Lucio|L|']
D000465:Algorithms D001921:Brain D001940:Breast D038524:Diffusion Magnetic Resonance Imaging D017352:Echo-Planar Imaging D005260:Female D066128:Gray Matter D006801:Humans D007089:Image Enhancement D007090:Image Interpretation, Computer-Assisted D007091:Image Processing, Computer-Assisted D008279:Magnetic Resonance Imaging D015233:Models, Statistical D009038:Motion D019047:Phantoms, Imaging D015203:Reproducibility of Results D012815:Signal Processing, Computer-Assisted D059629:Signal-To-Noise Ratio
spatiotemporal encoding full refocusing high-definition fMRI high-resolution ADCs interleaved MRI referenceless reconstruction