Benjamin Ellingson1
1Radiological Sciences, University of California Los Angeles, Los Angeles, United States
Synopsis
Keywords: Image acquisition: Fast imaging, Neuro: Brain, Image acquisition: Sequences
Motivation: Echoplanar imaging (EPI) is instrumental to neuroimaging and applications that require high speed imaging including DTI and BOLD functional MRI.
Goal(s): In this lecture, we will discuss additional sequence modifications and advanced applications beyond DTI and BOLD with the specific goal of characterizing the brain tumor microenvironment (i.e. vascularity, hypoxia, acidity, and salinity).
Approach: The lecture will discuss the use of standard and modified EPI techniques for DSC perfusion imaging, pH-weighted amine CEST, and interleaved multinuclear imaging.
Results: New EPI and image contrasts can be combined to increase spatiotemporal resolution, optimize image acquisition, and provide critical information into brain tumor biology.
Impact: EPI has been instrumental to neuroimaging and applications that require high speed imaging including diffusion and BOLD-based functional MRI. In this lecture, we will discuss sequence modifications with the goal of characterizing brain tumor biology within clinically realistic scan times.
Lecture Overview
Since its introduction in 19911, echoplanar imaging (EPI) has been instrumental to neuroimaging and applications that require high speed imaging including diffusion tensor imaging (DTI) and brain oxygen level dependent (BOLD) functional MRI. In this lecture, we will discuss additional sequence modifications and advanced applications beyond DTI and BOLD with the specific goal of characterizing the brain tumor microenvironment (i.e. vascularity, hypoxia, acidity, and salinity).
The lecture will start by first discussing the use of standard, single-shot EPI in dynamic susceptibility contrast (DSC) perfusion imaging2. Then, we will demonstrate spatiotemporal acceleration of DSC perfusion through the use of simultaneous multi-slice (SMS)-EPI3. We will then describe the use of a multi-echo spin-and-gradient echo (SAGE)-EPI sequence to characterize a wide range of vascular-specific parameters4,5.
Next, we will describe the use of a pH-sensitive imaging technique utilizing amine proton chemical exchange saturation transfer (CEST)-EPI6,7 in brain tumors and how we can get similar improvements in acquisition speed using SMS applied to CEST-EPI. We will then demonstrate how this approach can similarly be combined with SAGE-EPI leading to a single sequence that can provide simultaneous pH- and oxygen-sensitive images (CEST-SAGE-EPI)8.
Lastly, we will show how X-nuclei imaging (e.g. sodium) can be interleaved between proton EPI acquisitions to optimize and accelerate multinuclear image acquisition and provide important information into the brain tumor microenvironment.Acknowledgements
No acknowledgement found.References
1 Stehling MK et al., Science 1991; 254:43-50.
2 Rosen BR et al., Magn Reson Med 1990; 14: 249-65.
3 Chakhoyan A et al., AJNR Am J Neuroradiol 2018; 39(1): 43-45.
4 Sanvito F et al., Eur Radiol 2023
5 Chakhoyan A et al., Sci Rep 2019; 9(1): 2846.
6 Cho NS et al., NMR Biomed 2023; 36(6): e4785.
7 Harris RJ et al., NMR Biomed 2016;29(11): 1563-76.
8 Harris RJ et al., Magn Reson Med 2018; 80(5): 1962-78.