Phase-Incrementing MRSI for Resolving Overlapping Biomarker Images
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Solution Overview
Problem
Current MRSI imaging techniques face challenges in resolving overlapping biomarker images due to spatial distribution overlap and the inability to simultaneously image ZQ→DQ and DQ→ZQ coherence pathways, leading to signal loss and prolonged imaging times.
Innovation Solution
The phase-incrementing Magnetic Resonance Spectroscopic Imaging (pi-MRSI) method, which involves applying phase-selective RF pulses and varying phase encoding gradients to induce and encode multiple quantum coherences, allowing for simultaneous detection of ZQ→DQ and DQ→ZQ coherence pathways and reducing image overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Chemical Shift Imaging (CSI) techniques are used to resolve overlapping biomarker MRSI images, then image resolution is improved, but imaging time increases significantly
Solution Approach 1:
The patent applies parameter changes by modifying the phase encoding gradient parameters and RF pulse phase parameters to create opposite image offsets for different biomarkers. This allows fast k-space mapping techniques to be used simultaneously for multiple biomarkers without overlapping, resolving the contradiction between image resolution and imaging time by enabling parallel acquisition of multiple biomarker images using parameter differentiation.
2Measurement precision
If only one coherence pathway (ZQ→DQ or DQ→ZQ) is imaged at a time using Sel-MQC method, then signal overlap is reduced, but signal intensity is lost by a factor of one half
Solution Approach 1:
The patent merges the imaging of both ZQ→DQ and DQ→ZQ coherence pathways by applying phase incrementing to RF pulses in combination with phase encoding gradients. This allows simultaneous detection of both coherence pathways with opposite image offsets, combining the signal intensity from both pathways while maintaining signal clarity through spatial separation, thus resolving the contradiction between signal clarity and signal intensity.
3Productivity
If fast k-space mapping techniques are employed for single biomarker imaging, then imaging speed is improved, but simultaneous imaging of multiple biomarkers cannot be achieved due to image overlapping
Solution Approach 1:
The patent applies local quality by assigning different phase encoding gradient parameters and RF pulse phase parameters to different biomarkers, creating distinct local imaging characteristics (opposite image offsets) for each biomarker. This enables fast k-space mapping techniques to be simultaneously applied to multiple biomarkers with differentiated local parameters, resolving the contradiction between imaging speed and multi-biomarker capability.
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 effectively resolves overlapping biomarker images, recovers lost signal, and significantly reduces imaging time, enabling faster and more accurate detection of biomarkers like lactate and choline in both phantom and in vivo samples.
Implementation Method 1
applying frequency-selective RF pulses at frequencies in a first set of frequencies to an RF coil of a magnetic resonance imaging (MRI) spectrometer to induce a single-quantum transition(s) or multiple-quantum coherences
Implementation Method 2
applying a phase encoding gradient to gradient coils to phase encode signals generated by the multiple quantum coherences or the single-quantum transitions induced
Data Source
AI summary
Phase-incrementing MRSI (pi-MRSI) method has resolved overlapping biomarker images in the presence of a read-gradient. On a Bruker 9.4T MRI spectrometer, the pi-SEE-HSelMQC sequence was implemented. The choline-selective and lactate CH-selective RF pulses were phase incremented by 10° in opposite signs, synchronized with the phase-encoding steps. The lactate and choline images from a yogurt phantom displayed opposite image offsets without image overlapping. In vivo one-dimensional pi-SEE-HSelMQC CSI images of lactate and choline, acquired from the MDA-MB-231 human breast cancer xenograft in a nude mouse, as well as two-dimensional pi-SEE-HSelMQC imaging of lactate and choline acquired from the PC3 human prostate cancer xenograft in a nude mouse, also had opposite image offsets, shifted away from the spurious residual water signals in the image center. The pi-SEE-HSelMQC method completely suppresses lipid and water with potential clinical applications in disease diagnosis and therapeutic interventions.