Quantitative Macromolecular Proton Fraction Imaging using Pulsed Spin-Lock

Fuente: arXiv
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Main Authors: Shan, Qianxue, Yu, Ziqiang, Jiang, Baiyan, Hou, Jian, Shen, Qiuyi, Chu, Winnie CW, Wong, Vincent WS, Chen, Weitian
Format: Preprint
Published: 2025
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author Shan, Qianxue
Yu, Ziqiang
Jiang, Baiyan
Hou, Jian
Shen, Qiuyi
Chu, Winnie CW
Wong, Vincent WS
Chen, Weitian
author_facet Shan, Qianxue
Yu, Ziqiang
Jiang, Baiyan
Hou, Jian
Shen, Qiuyi
Chu, Winnie CW
Wong, Vincent WS
Chen, Weitian
contents Purpose: Recent studies have shown that spin-lock MRI can simplify quantitative magnetization transfer (MT) by eliminating its dependency on water pool parameters, removing the need for a T1 map in macromolecular proton fraction (MPF) quantification. However, its application is often limited by the requirement for long radiofrequency (RF) pulse durations, which are constrained by RF hardware capabilities despite remaining within specific absorption rate (SAR) safety limits. Methods: To address this challenge, we propose a novel method, MPF mapping using pulsed spin-lock (MPF-PSL). MPF-PSL employs a pulsed spin-lock train with intermittent free precession periods, enabling extended total spin-lock durations without exceeding hardware and specific absorption rate limits. A comprehensive analytical framework was developed to model the magnetization dynamics of the two-pool MT system under pulsed spin-lock, demonstrating that MPF-PSL achieves MT-specific quantification while minimizing confounding effects from the water pool. The proposed method is validated with Bloch-McConnell simulations, phantoms, and in vivo studies at 3T. Results: Both Bloch-McConnell simulations and phantom validation demonstrated that MPF-PSL exhibits robust insensitivity to water pool parameters while enabling high-SNR MPF quantification. In vivo validation studies confirmed the method's clinical utility in detecting collagen deposition in patients with liver fibrosis. Conclusion: MPF-PSL presents a practical solution for quantitative MT imaging, with strong potential for clinical applications.
format Preprint
id arxiv_https___arxiv_org_abs_2505_21853
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantitative Macromolecular Proton Fraction Imaging using Pulsed Spin-Lock
Shan, Qianxue
Yu, Ziqiang
Jiang, Baiyan
Hou, Jian
Shen, Qiuyi
Chu, Winnie CW
Wong, Vincent WS
Chen, Weitian
Medical Physics
Applied Physics
Purpose: Recent studies have shown that spin-lock MRI can simplify quantitative magnetization transfer (MT) by eliminating its dependency on water pool parameters, removing the need for a T1 map in macromolecular proton fraction (MPF) quantification. However, its application is often limited by the requirement for long radiofrequency (RF) pulse durations, which are constrained by RF hardware capabilities despite remaining within specific absorption rate (SAR) safety limits. Methods: To address this challenge, we propose a novel method, MPF mapping using pulsed spin-lock (MPF-PSL). MPF-PSL employs a pulsed spin-lock train with intermittent free precession periods, enabling extended total spin-lock durations without exceeding hardware and specific absorption rate limits. A comprehensive analytical framework was developed to model the magnetization dynamics of the two-pool MT system under pulsed spin-lock, demonstrating that MPF-PSL achieves MT-specific quantification while minimizing confounding effects from the water pool. The proposed method is validated with Bloch-McConnell simulations, phantoms, and in vivo studies at 3T. Results: Both Bloch-McConnell simulations and phantom validation demonstrated that MPF-PSL exhibits robust insensitivity to water pool parameters while enabling high-SNR MPF quantification. In vivo validation studies confirmed the method's clinical utility in detecting collagen deposition in patients with liver fibrosis. Conclusion: MPF-PSL presents a practical solution for quantitative MT imaging, with strong potential for clinical applications.
title Quantitative Macromolecular Proton Fraction Imaging using Pulsed Spin-Lock
topic Medical Physics
Applied Physics
url https://arxiv.org/abs/2505.21853