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A real-time interactive MRI system capable of localizing coronary arteries and imaging arrhythmic hearts in real-time is described. Non-2DFT acquisition strategies such as spiral-interleaf, spiral-ring, and circular echo-planar imaging provide short scan times on a conventional scanner. Real-time gridding reconstruction at 8-20 images/s is achieved by(More)
Parallel excitation uses multiple transmit channels and coils, each driven by independent waveforms, to afford the pulse designer an additional spatial encoding mechanism that complements gradient encoding. In contrast to parallel reception, parallel excitation requires individual power amplifiers for each transmit channel, which can be cost prohibitive.(More)
A real-time interactive color flow MRI system capable of rapidly visualizing cardiac and vascular flow is described. Interleaved spiral phase contrast datasets are acquired continuously, while real-time gridding and phase differencing is used to compute density and velocity maps. These maps are then displayed using a color overlay similar to what is used by(More)
High polarization of nuclear spins in liquid state through dynamic nuclear polarization has enabled the direct monitoring of 13C metabolites in vivo at very high signal-to-noise, allowing for rapid assessment of tissue metabolism. The abundant SNR afforded by this hyperpolarization technique makes high-resolution 13C 3D-MRSI feasible. However, the number of(More)
Hyperpolarized 13C MR spectroscopic imaging can detect not only the uptake of the pre-polarized molecule but also its metabolic products in vivo, thus providing a powerful new method to study cellular metabolism. Imaging the dynamic perfusion and conversion of these metabolites provides additional tissue information but requires methods for efficient(More)
In parallel excitation, the computational speed of numerical radiofrequency (RF) pulse design methods is critical when subject dependencies and system nonidealities need to be incorporated on-the-fly. One important concern with optimization-based methods is high peak RF power exceeding hardware or safety limits. Hence, online controllability of the peak RF(More)
Hyperpolarized [1-(13)C]-pyruvate is an exciting new agent for the in vivo study of cellular metabolism and a potential cancer biomarker. The nature of the hyperpolarized signal poses unique challenges because of its short duration and the loss of magnetization with every excitation. In this study, we applied a novel and efficient time-resolved MR(More)
Large-tip-angle multidimensional radio-frequency (RF) pulse design is a difficult problem, due to the nonlinear response of magnetization to applied RF at large tip-angles. In parallel excitation, multidimensional RF pulse design is further complicated by the possibility for transmit field patterns to change between subjects, requiring pulses to be designed(More)
The Bloch-Siegert (B-S) B1+ mapping method has been shown to be fast and accurate, yet it suffers from high Specific Absorption Rate (SAR) and moderately long echo time. An adiabatic RF pulse design is introduced here for optimizing the off-resonant B-S RF pulse to achieve more B-S B1+ measurement sensitivity for a given pulse width. The extra sensitivity(More)
In many applications of dynamic MR imaging, only a portion of the field-of-view (FOV) exhibits considerable variations in time. In such cases, a prior knowledge of the static part of the image allows a partial-FOV reconstruction of the dynamic section using only a fraction of the raw data. This method of reconstruction generally results in higher temporal(More)