Proceedings of the International Society for Magnetic Resonance in Medicine ... Scientific Meeting and Exhibition. International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition最新文献

Previous work has suggested fitting joint AFI/FLASH data for T1 and B1+ by minimizing the 2-norm of the difference between the signal model and measurements will produce unbiased estimates of T1. We demonstrate that, contrary to previous results, the estimator has a substantial bias that varies with both the true T1 and B1+, and the receive channel count. We also demonstrate that the correct ML estimator removes the effect of channel count, and that the choice of AFI protocol has a larger impact of the quality of estimates than the addition of an extra FLASH scan.

We propose a prospective motion correction approach for background suppressed (BS) segmented 3D GRASE pCASL using volumetric EPI-based navigators (vNavs), which causes minimal contrast change and no extra time. vNavs reduced motion artifacts effectively and increased temporal signal-to-noise ratio (t-SNR). Principle component analysis (PCA) is able to further reduce residual motion artifacts and restore the details of gyral structure in perfusion weighted images..

An intravascular MRI (IMRI) loopless antenna is combined for the first time with an intravascular water-cooled ultrasound ablation transducer as a possible tool for providing high-resolution MRI-guided ablations of pathological tissue via intravascular access. High resolution anatomical MRI, and real-time MRI thermometry were used to monitor ablation delivery in phantoms and tissue specimens. Results show that IMRI can guide IVUS-mediated directional ablation with minimal image artifacts. This permits the monitoring of thermal dose and therapy titration while minimizing potential thermal damage to the vessel wall.

Low-resolution, whole-head volumes can be acquired rapidly with EPI-based volumetric navigators (vNavs). vNavs interspersed in a longer scan are widely used for prospective motion correction in a variety of sequences. To further improve the accuracy and flexibility of vNavs, we present a novel registration algorithm, tailored specifically for the vNavs application. Accuracy of the algorithm is tested on navigator volumes acquired with human volunteers at three isotropic resolutions, 6.4mm, 8mm, and 10mm, using a series of field of view (FOV) rotations and translations to provide ground truth rigid "motion".

MRF is a new quantitative MR imaging technique, which can provide rapid and simultaneous measurement of multiple tissue properties. Compared to the fast speed for data acquisition, the post-processing to extract tissue properties with MRF is relatively slow and often requires a large memory for the storage of both image dataset and MRF dictionary. In this study, a convolutional neural network was developed, which can provide rapid estimation of multiple tissue properties in 0.1 sec. The T1 and T2 values obtained in white matter and gray matter are also in a good agreement with the results from pattern matching.

The clinical use of amide proton transfer (APT) imaging is hindered by long scan times. Accuracy generally limits the use of conventional sensitivity encoding (SENSE) methods in APT, to an acceleration factor of 2. A novel variably-accelerated sensitivity encoding (vSENSE) method can provide more accurate results and therefore substantially higher overall acceleration factors than conventional SENSE. Here, vSENSE is further developed to eliminate the requirement that one fully-sampled APT frame be acquired, and extended to three dimensions (3D). Furthermore, we combine vSENSE with parallel transmit saturation, and apply it proactively to three normal volunteers and eleven patients with brain tumors.

Image contrast afforded by tissue longitudinal (T₁) and transverse (T₂) relaxation times is central to the success of modern MRI. Here, a recently-proposed 'spectroscopy with linear algebraic modeling' (SLAM) method is adapted to dramatically accelerate relaxation time imaging at 3 Tesla in phantoms, the abdomens of six volunteers and in six brain tumor patients.. SLAM is validated by omitting up to 15/16^ths (94%) of the data acquired retroactively from inversion recovery and multi-echo spin-echo sequences, and proactively applied to accelerate abdominal and brain tumor T₁ and T₂ measurements by up to 16-fold in humans..