Ultra-Short Echo Time MRI Pulse Sequence for Short T2 Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional MRI techniques fail to effectively produce images of objects with short T2 relaxation times, such as certain tissues and cells in the human body, due to limitations in echo time and signal decay, leading to artifacts and prolonged acquisition times.
Innovation Solution
A pulse sequence incorporating a slab-selective RF pulse, slab-selective gradient pulse, variable duration slice encoding gradient pulses, and spirally encoded and phase encoded magnetic resonance signals is applied, allowing for concurrent detection and reconstruction of images with ultra-short echo times, reducing signal decay and acquisition time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MRI pulse sequences with long echo times are used, then image acquisition is possible, but signal decay occurs for objects with short T2 relaxation times leading to poor image quality
Solution Approach 1:
The patent changes the echo time parameter from conventional long echo times to ultra-short echo times (≤10 ms), and modifies the pulse sequence parameters including using a hard pulse instead of a sinc pulse, and implementing a 3D radial projection imaging trajectory. These parameter changes allow the system to capture signals from tissues with short T2 relaxation times before significant signal decay occurs, thereby improving image quality for such tissues.
2Loss of time
If 3D radial projection imaging is used with hard pulse excitation, then data acquisition is almost immediate with reduced signal loss, but the field of view is passively defined by receiver coil sensitivity maps
Solution Approach 1:
The patent implements dynamic control of the field of view by allowing the FOV to be actively defined through the 3D radial projection imaging trajectory and phase encoding gradients, rather than being passively constrained by coil sensitivity maps. The system dynamically adjusts the imaging parameters including the radial projection angle and phase encoding steps to achieve the desired FOV and spatial resolution, providing operational flexibility while maintaining ultra-short echo time advantages.
3Measurement precision
If the number of radial projections is increased to meet Nyquist sampling requirement, then spatial resolution is improved, but total acquisition time increases significantly
Solution Approach 1:
The patent applies partial sampling strategies where the number of radial projections is optimized to meet the minimum Nyquist sampling requirement for the desired spatial resolution, rather than using excessive numbers of projections. By carefully selecting the number of projections based on the specific imaging requirements and using efficient 3D radial projection trajectories, the system achieves adequate spatial resolution with reduced acquisition time compared to conventional approaches that use more projections for safety margins.
Data Source
AI summary
A method for producing a magnetic resonance image using an ultra-short echo time. The method includes applying a pulse sequence to an object, detecting a spirally encoded and phase encoded magnetic resonance signal associated with the object, and reconstructing the magnetic resonance image based on the spirally encoded and phase encoded magnetic resonance signal. The pulse sequence includes a slab-selective radiofrequency pulse, a slab-selective gradient pulse, a plurality of variable duration slice encoding gradient pulses, a plurality of first spiral encoding gradient pulses, and a plurality of second spiral encoding gradient pulses. The detection of the spirally encoded and phase encoded magnetic resonance signal occurs concurrently with the application of one of the plurality of first spiral encoding gradient pulses and with the application of one of the plurality of second spiral encoding gradient pulses.