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Development of a Pre-Clinical MR-Guided Radiotherapy Model to Assess Gadolinium-Induced Renal Toxicity

M Petronek1*, E Steinbach1, A Kalen1, C Callaghan1, D Hyer1, R Flynn1, D Spitz1, J Buatti1, V Magnotta1, D Zepedo-orozco2, J St-Aubin1, B Allen1 (1) University of Iowa, Iowa City, IA, (2) Ohio State University, Columbus, OH

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: pre-clinical MRI-guided radiotherapy (MRIgRT) system, where MRI acquisitions and radiation delivery are performed in rapid succession was developed to assess the effect of gadolinium-based contrast agents (GBCAs) during MRIgRT in a flank tumor bearing animal model. Despite generally being considered safe, new literature suggests that GBCAs are capable of contrast induced acute kidney injury. We investigated the impact of GBCAs during MRIgRT on renal function.


Methods: bearing mice with normal kidney function were injected with GBCA and treated with 2 Gy, 8 Gy, or 18 Gy ionizing radiation in a single fraction. Pre-irradiation T1-weighted images of the tumors were acquired pre- and post-initial gadolinium injection using a GE 7T small animal MRI scanner. One representative mouse from each dose group was imaged following radiation to confirm gadolinium presence during RT. Mice were irradiated on the Xstrahl small animal radiation research platform (SARRP) with the tumors aligned to isocenter using the onboard laser system. Tumors were treated to a depth of 1.5 mm using a 10 x 10 mm2 collimator with doses validated within 8% using TLD dosimetry.


Results: mean time to treatment following the administration of gadolinium was 18 ± 3 min while MRI data acquisition following RT was 28 ± 1 min. No clinically relevant changes in renal function, assessed via blood urea nitrogen (BUN)/creatinine 3- and 7-days post-treatment, were observed in any combination of GBCA and radiation dose.


Conclusion: developed an efficient method for pre-clinical studies of MR-guided radiotherapy. From these data, we conclude that gadolinium, in combination with ionizing radiation, does not increase the risk for acute renal injury in the absence of renal impairment.

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Keywords

MRI, Radiation Therapy, Radiobiology

Taxonomy

TH- Small Animal RT: Development (new technology and techniques)

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