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

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.

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..

Vessel wall MRI with intravascular (IV) detectors can produce superior local signal-to-noise ratios (SNR) and generate high-resolution T₁, T₂, and proton density (PD) maps that could be used to automatically classify atherosclerotic lesion stage. However, long acquisition times potentially limit multi-parametric mapping. Here, for the first time, spectroscopy with linear algebraic modeling (SLAM) is applied to yield accurate compartment-average T₁, T₂ and PD measures at least 10 times faster compared to a standard full k-space reconstructed MIX-TSE sequence at 3T. Simple phase and magnitude sensitivity corrections are incorporated into the SLAM reconstruction to compensate for IV detector non-uniformity.

CEST MRI can provide valuable molecular level information in vivo, but its translation to routine clinics is hindered by long imaging times. Regional average CEST measurements often suffice for quantitative evaluation, diagnosis, and treatment assessment, while allowing much shorter scan times. Recently, the spectroscopy with linear algebraic modeling (SLAM) method was adapted for CEST MRI in two dimensions (2D), directly obtaining compartmental-average measurements manifold faster than conventional CEST. Here, the SLAM CEST method is extended from 2D to 3D, and applied to patients with brain tumors with acceleration factors of up to 98-fold.

CEST imaging has numerous applications, but its widespread clinical use is hampered by relatively long acquisition times. Here, a novel variably-accelerated sensitivity encoding (vSENSE) method is proposed that provides faster CEST acquisitions than conventional SENSE. The vSENSE approach undersamples k-space variably for images acquired at different saturation frequencies to maximize acquisition speed. vSENSE was validated in a phantom and in 8 patients with brain tumors studied at 3T. The vSENSE method provided a 4-fold acceleration, compared to conventional SENSE which permitted only a 2-fold acceleration, with both compared to a full k-space reconstruction.