Superparamagnetic Iron Oxide Enhanced MRI for Elekta Unity MR-Linac: A Pre-Clinical Phantom Study
D Lee1*, P Klepchick1, H Lee1, D Pavord1, S Oh1, J Sohn1,2, A Kirichenko1, (1) Allegheny Health Network, Pittsburgh, PA, (2) Drexel University College of Medicine, Philadelphia, PA
Presentations
PO-GePV-M-180 (Sunday, 7/25/2021) [Eastern Time (GMT-4)]
Purpose: This study aims to sufficiently visualize Super-Paramagnetic-Iron-Oxide enhanced MR images for Elekta Unity MR-Linac (Elekta; Stockholm, Sweden). Once IV of Ferumoxytol (Feraheme, AMAG Pharmaceuticals, Waltham, MA) injected as an alternative contrast media, it is prolonged hepatic blood pool phase and delayed intracellular uptake in liver Kupffer cells over a month. Then, it alters MR signals due to susceptibility effect. Hence, we performed a pre-clinical phantom study to investigate the sensitivity of Feraheme on MR images of Unity.
Methods: Varying concentrations of Feraheme and Gadobutrol (Gd, Gadavist, Bayer HealthCare) were diluted in water into clinically relevant concentrations and poured into cylindrical containers: (1) 10µg/mL, (2) 15µg/mL and (3) 30µg/mL of Feraheme, (4) 0.1mmol/kg Gd, and (5) distilled water only and an identical set with the same concentrations with 1% w/w agarose. The varying concentrations were imaged using CT and MRI (Siemens and Unity) with T1-Weighted, T2, Proton Density (PD) and T2* sequences. All MR images were visually inspected to evaluate signal enhancements.
Results: Feraheme successfully enhanced MR images but not for CT. Feraheme especially enhanced T1-Wighted (TR<8.0ms/TE<5ms) images brighter than Gd. Feraheme negatively enhanced T2 (TR/TE=1000.0/100.0ms) images but it is insufficient to differentiate the three Feraheme concentrations of contrast agents. Feraheme also negatively enhanced PD (TR/TE=1400.0/30.0ms) images, similar to the T2 images but it slightly differentiate them. In addition, Feraheme enhanced T2* (TR/TE=1074.7/5.8ms) images of Siemens but negatively-minimally enhanced T2* (TR/TE=1457.7/18.4ms) images of Unity. The 1% agarose resulted in signal reduction on only T2 images.
Conclusion: This study utilized a clinical range of concentrations of Feraheme to enhance MR images with positive or negative signal changes on T1, T2, PD and T2* images whilst compared to the ground truth of diagnostic images. It is evident that Feraheme can be applicable for Unity and clinical trials for investigations liver functional imaging.
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