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MRI Characterization of Thermoembolization, a Novel Transarterial Intervention

SJ Fahrenholtz1*, C Guo2 , Christopher MacLellan1 , J Yung1 , K Hwang1 , RJ Stafford1 , E Cressman2 , (1) Imaging Physics Dept., UT MD Anderson Cancer Center, Houston, TX (2) Interventional Radiology Dept., UT MD Anderson Cancer Center, Houston, TX


(Monday, 7/30/2018) 4:30 PM - 5:30 PM

Room: Exhibit Hall | Forum 2

Purpose: Thermoembolization is a pre-clinical transarterial intervention for solid tumors, conceived for liver and kidney. The treatment introduces an acid-chloride mixed in mineral oil, occluding arteries and hydrolyzing the acid-chloride in situ. The hydrolytic reaction produces acid and ablative temperatures – about twice the heat release to the comparable acid-base reaction. In summary, thermoembolization aims to create a durable treatment through thermal ablation, ischemia, and chemical insults. In order understand treatment outcomes, we propose using a multiparametric MRI pulse sequence that provides data on temperature, signal amplitude, and R2*.

Methods: One recently harvested porcine kidney’s artery was flushed. A temperature probe was inserted into the kidney’s interpolar region. The injection was 5 mL of mineral oil with a 2 M concentration of an acid-chloride, dichloroacetyl chloride (DCACl). The injection was into the renal artery. Prior to, during, and after DCACl injection, an MRI acquisition—multi-echo fast gradient-recalled echo (MFGRE)—provided magnitude, proton resonance frequency (PRF) shift, and R2* data.

Results: The temperature probe recorded an increase of 2.5°C over approximately 2 minutes post injection; the temperature only reduced by 0.5°C over the next 15 minutes. Meanwhile, the MRFGRE sequence’s PRF-based thermometry indicated heating in several foci in the renal cortex and vasculature, ranging from 10-30°C. The MR thermometry also reports elevated temperature. The R2* data demonstrates the kidney’s vasculature and has some temporal changes consistent with the injection timing and subsequent heating.

Conclusion: The MR thermometry and probe agree that the temperature increases and remains so. In comparison to other ablative heat sources (e.g., laser and focused ultrasound), the elevated temperature lingering in time is surprising. Speculatively, it may indicate that the DCACl reacts over time, and not immediately upon injection.


Interventional MRI, Thermal Ablation, Thermometry


IM/TH- Image-guided surgery: General (most aspects)

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