Related Experiment Video
Updated: Jun 27, 2026
Registered Bioimaging of Nanomaterials for Diagnostic and Therapeutic Monitoring
Published on: December 9, 2010
FID sampling superior to spin-echo sampling for T2*-based quantification of holmium-loaded microspheres: theory and
Peter R Seevinck1, Jan-Henry Seppenwoolde, Jaco J M Zwanenburg
1Image Sciences Institute, Department of Radiology, University Medical Center Utrecht, The Netherlands. p.seevinck@umcutrecht.nl
Abstract:
This work demonstrates both theoretically and experimentally that multiple gradient-echo sampling of free induction decay (MGEFID) is superior to MGE sampling of spin echo (MGESE) for T2*-based quantification of holmium-loaded microspheres (HoMS). An interleaved sampling strategy was applied in great detail to characterize the MR signal behavior of FID and SE signals of gels and perfused rabbit livers containing HoMS in great detail. Diffusion sensitivity was demonstrated for MGESE sampling, resulting in non-exponential signal decay on both sides of the SE peak and in an underestimation of the HoMS concentration. Other than MGESE sampling, MGEFID sampling was demonstrated to be insensitive to diffusion, to exhibit exponential signal decay, and to allow accurate T2*-based quantification of HoMS. Furthermore, a fit procedure was proposed extending the upper limit of quantifiable R2* relaxation rates to at least 1500 sec(-1). With this post-processing step incorporated, MGEFID was shown to correctly estimate the integral amount of inhomogeneously distributed HoMS in liver tissue, up to a clinically relevant limit. All experimental findings could be explained with the theory of nuclear magnetic resonance (NMR) signal behavior in magnetically inhomogeneous tissues. HoMS were shown to satisfy the static dephasing regime when investigated with MGEFID and to violate the static dephasing conditions for MGESE at longer echo times typically used in SE.
Insights
Multiple gradient-echo sampling of free induction decay (MGEFID) accurately quantifies holmium-loaded microspheres (HoMS) by being insensitive to diffusion. This method surpasses MGE sampling of spin echo (MGESE) for reliable T2*-based concentration measurements.
Area of Science:
- Magnetic Resonance Imaging
- Biomedical Engineering
- Materials Science
Background:
- Accurate quantification of holmium-loaded microspheres (HoMS) is crucial for various biomedical applications.
- Traditional magnetic resonance imaging (MRI) techniques face challenges in precisely measuring HoMS concentrations due to diffusion effects.
Purpose of the Study:
- To compare the efficacy of multiple gradient-echo sampling of free induction decay (MGEFID) versus MGE sampling of spin echo (MGESE) for T2*-based HoMS quantification.
- To investigate the influence of diffusion on MR signal decay and its impact on HoMS concentration measurements.
- To develop and validate an improved method for accurate HoMS quantification in biological tissues.
Main Methods:
- Interleaved sampling strategy to characterize MR signal behavior of FID and SE signals.
- Experimental and theoretical analysis of gels and perfused rabbit livers containing HoMS.
- Development of a novel fit procedure to extend the quantification limit of R2* relaxation rates.
Main Results:
- MGEFID sampling demonstrated insensitivity to diffusion, resulting in exponential signal decay and accurate HoMS quantification.
- MGESE sampling exhibited diffusion sensitivity, leading to non-exponential signal decay and underestimation of HoMS concentration.
- The proposed fit procedure extended the quantifiable R2* relaxation rate limit to 1500 sec(-1), enabling accurate quantification of inhomogeneously distributed HoMS in liver tissue.
Conclusions:
- MGEFID is superior to MGESE for T2*-based HoMS quantification due to its insensitivity to diffusion.
- The developed MGEFID method with the extended fit procedure allows for accurate and clinically relevant HoMS concentration measurements in inhomogeneous tissues.
- Experimental findings align with the theory of NMR signal behavior in magnetically inhomogeneous tissues, with HoMS satisfying the static dephasing regime under MGEFID conditions.
