Quantitative Non-Contrast Perfusion Imaging Using Arterial Spin Labeled MRI

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2022-05

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Wang, Yiming

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Abstract

Arterial Spin Labeled (ASL) magnetic resonance imaging (MRI) is a promising non-contrast perfusion imaging method. ASL has been widely used in brains and has seen emerging applications in kidneys, lungs, and placentas. This work is focused on glioblastoma (GBM), a highly vascularized tumor, with median survival of less than a year and poor prognosis. Elevation of tumor perfusion is often seen in patients with GBM and perfusion may change in response to treatment. ASL-measured perfusion can be an early biomarker of treatment response in GBM patients and can assist in the assessment of their treatment responses. This work is focused on the technical developments of robust perfusion MRI method and its clinical applications in GBM. A k-space filtering approach was proposed and optimized to deblur the brain ASL images acquired with a previously developed 3D Cartesian TSE approach called CASPR, which is Cartesian Acquisition with Spiral Profile Recording. Significant deblurring effect was achieved in brain ASL images with this approach. To further improve the robustness and SNR, a novel ASL acquisition approach called VD-CASPR, which is Variable-Density sampling of CASPR, was proposed and optimized. VD-CASPR showed improved robustness and SNR in both brain and kidney ASL MRI and was combined with CS-SENSE to achieve improved spatial resolution in clinically feasible scan times. These techniques can also be potentially applied in GBM patients. A study was initiated and underway to evaluate treatment response using ASL measured perfusion in patients with GBM. So far, this study has recruited 14 patients with GBM and performed over 60 imaging sessions before, during, and after treatment. Preliminary results showed that perfusion reduction measured by ASL could be seen as early as the 3rd week after treatment initiation in treatment-responding patients, indicating ASL measured perfusion can act as an early biomarker to evaluate treatment response in GBM patients. In addition, we also performed intra-session reproducibility tests of ASL measured perfusion in GBM patients and healthy volunteers, and results showed good reproducibility. Reproducibility tests were also performed in a previously developed 3D-printed perfusion phantom over a 16-week period to demonstrate the reliability of ASL, which also showed good reproducibility.

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