The referenceless correction enables robust single-scan imaging under changing conditions-such as patient motion and changes in shimming over time-without the need of ancillary navigators. This opens new options for real-time MRI and interactive scanning.

An approach delivering single-scan MRI with unprecedented resilience to field inhomogeneities, is proposed and illustrated. The method departs from conventional k-based scanning methods, and relies instead on spatiotemporally encoding the image being sought. Unlike hitherto proposed methods, however, this MRI image readout does not take place utilizing a magnetic field gradient along the direction being probed, but rather with the aid of an ancillary source of inhomogeneous frequency broadening. This ancillary dimension can arise from an orthogonal field gradient, from susceptibility-or shift-imposed frequency distributions, from intrinsic spin anisotropies, or from a combination of these all. By allowing such broadenings to act as the agents that spatiotemporally encode and readout the desired imaging information, the ensuing MR images become insensitive to the presence of field inhomogeneities or internal shifts. Even when dealing with notably distorted spin-echo multi-scan images acquired in low-homogeneity magnets or next to metallic objects, the new approach delivers unbiased single-shot images. The principles and characteristics of this new approach -compatible with existing scanners and free from the need to collect auxiliary information such as field maps-are presented and discussed, together with single-and multi-slice in vitro, ex vivo and in vivo MRI comparisons.

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.

SPEN-based sequences yielded diffusion-weighted breast images with minimal artifacts and distortions, enabling the calculation of improved ADC maps and the identification of decreased ADCs in malignant regions.

Recent studies described an alternative “ultrafast” scanning method based on spatiotemporal (SPEN) principles. SPEN demonstrates numerous potential advantages over EPI-based alternatives, at no additional expense in experimental complexity. An important aspect that SPEN still needs to achieve for providing a competitive acquisition alternative entails exploiting parallel imaging algorithms, without compromising its proven capabilities. The present work introduces a combination of multi-band frequency-swept pulses simultaneously encoding multiple, partial fields-of-view; together with a new algorithm merging a Super-Resolved SPEN image reconstruction and SENSE multiple-receiving methods. The ensuing approach enables one to reduce both the excitation and acquisition times of ultrafast SPEN acquisitions by the customary acceleration factor R, without compromises in either the ensuing spatial resolution, SAR deposition, or the capability to operate in multi-slice mode. The performance of these new single-shot imaging sequences and their ancillary algorithms were explored on phantoms and human volunteers at 3T. The gains of the parallelized approach were particularly evident when dealing with heterogeneous systems subject to major T2/T2* effects, as is the case upon single-scan imaging near tissue/air interfaces.