Multiband RF Pulse for Simultaneous MR Elastography Slices
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Solution Overview
Problem
Current Magnetic Resonance (MR) elastography techniques are time-consuming and uncomfortable for patients due to the need for repeated breath-holds to acquire multiple slices, which prolongs the acquisition time without significantly improving image quality.
Innovation Solution
Implementing multi-band acquisition techniques in MR elastography, where a multiband RF pulse and motion encoding gradients are used to induce shear waves and image multiple slices simultaneously during a single breath-hold, allowing for the acquisition of multiple slices in a single imaging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-slice gradient recalled echo sequence is used for MR elastography, then high quality images are produced, but acquisition time becomes excessively long requiring multiple repeated breath-holds
Solution Approach 1:
The patent divides the acquisition into multiple simultaneous slices using multiband RF pulses, allowing parallel acquisition of multiple slices instead of sequential acquisition. This segmentation of the imaging process enables concurrent data collection across multiple slices, dramatically reducing total acquisition time while maintaining image quality through optimized multiband factors and slice-specific parameter tuning.
Solution Approach 2:
The patent introduces the temporal dimension by acquiring multiple slices simultaneously during a single breath-hold period using multiband techniques. This transforms the traditional sequential acquisition approach (acquiring one slice at a time across multiple breath-holds) into a parallel acquisition approach where multiple slices are captured in the same temporal window, effectively adding a dimensional aspect to the acquisition process.
2Adaptability or versatility
If multiple repeated breath-holds are performed to acquire multiple slices, then complete multi-slice coverage is achieved, but patient comfort deteriorates and acquisition time increases
Solution Approach 1:
The patent merges the acquisition of multiple slices into a single breath-hold event by using multiband RF pulses that simultaneously excite multiple slices. This combining of multiple slice acquisitions into one temporal event eliminates the need for repeated breath-holds, thereby improving patient comfort while maintaining complete multi-slice coverage through the multiband factor and slice selection gradient design.
3Adaptability or versatility
If conventional single-slice acquisition is repeated for multiple slices, then all slice positions are covered, but productivity decreases due to time consumption
Solution Approach 1:
The patent applies preliminary action by using multiband RF pulses and slice selection gradients to pre-configure and simultaneously excite multiple slices before the actual data acquisition begins. This preliminary setup enables the system to acquire multiple slices in parallel during a single breath-hold, significantly improving productivity and acquisition efficiency while ensuring comprehensive slice position coverage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the overall scan time, decreases patient discomfort, and maintains high-quality image acquisition by enabling the depiction of liver stiffness in a single breath-hold period, improving spatial coverage and efficiency.
Implementation Method 1
applying a multiband Radio Frequency (RF) pulse to the anatomical region of interest
Implementation Method 2
The produced waveform is synchronized to a motion encoding gradient in the MR imaging sequence to encode tissue displacement as phase in the reconstructed images
Implementation Method 3
inducing shear waves at a shear wave frequency value (e.g., between 25-500 Hz) in the anatomical region of interest using an external driver
Data Source
AI summary
A method for performing multi-slice MR Elastography on an anatomical region of interest associated with a patient includes inducing shear waves at a shear wave frequency value (e.g., between 25-500 Hz) in the anatomical region of interest using an external driver. Next, the anatomical region of interest is imaged during a single patient breath-hold using an MRI acquisition process. Following the MRI acquisition process(es), phase images of the anatomical region of interest are generated based on an acquired RF signal. These phase images may then be processed (e.g., using an inversion algorithm) to generate one or more quantitative images depicting stiffness of the anatomical region of interest. In some embodiments, a wave image is also generated showing propagation of the plurality of shear waves through the anatomical region of interest based on the phase images.