Program Information
Tracking Thermoembolization Via Multiparametric MRI
SJ Fahrenholtz1*, C Guo2, CJ MacLellan1, J Yung1, K Hwang1, RJ Stafford1, E Cressman2, (1) Imaging Physics, UT MD Anderson Cancer Center, Houston, TX, (2) Interventional Radiology, UT MD Anderson Cancer Center, Houston, TX
Presentations
TU-C2-GePD-J(B)-2 (Tuesday, August 1, 2017) 10:00 AM - 10:30 AM Room: Joint Imaging-Therapy ePoster Lounge - B
Purpose: Thermoembolization is a new minimally invasive technique for treating solid tumors. It combines targeted delivery of hyperthermia from an exothermic reaction with ischemia and a local pH change. In this procedure, the hydrolysis of the electrophile dichloroacetyl chloride (DCACl) yields twice the energy of acid/base neutralization. Delivered via catheter, DCACl reacts with water or other nucleophiles in situ. In addition to hyperthermia and ischemia, this novel method also rapidly generates a substantial amount of acid locally, increasing the endovascular ablative effect. MR measurements relating to temperature changes and tissue damage could be a key tool for understanding thermoembolization outcomes.
Methods: A fresh heparinized kidney was explanted and flushed with saline. The renal artery was cannulated and two fluoroptic MR-compatible temperature probes were placed in one pole and the interpolar region. 2 mL of 4 M DCACl in mineral oil was infused over 30 seconds.MRI images were obtained before and after delivery of DCACI. a multi-echo fast gradient-recalled echo (MFGRE) acquisition monitored changes over time in the chemical shift, amplitude, and T2* signals. The DCACl injection was during the MFGRE sequence to allow pre- and post-injection changes to be realized.
Results: The temperature probes increased 3-5°C over ~50 seconds after injection, then remained elevated by 3°C for 15 more minutes until the experiment ceased. The kidney visually appeared mottled minutes after injection; lesions coalesced hours post injection. On MRI, proton resonance frequency (PRF) shift-based thermometry shows large temperature shifts (~18°C), especially in the vessels. The parenchyma had smaller temperatures changes (~5°C), consistent with the temperature probes.
Conclusion: The temperature probes corroborate the MR thermometry at their measurement locations. However, the greater temperature changes may be captured with alternate probe locations. The dramatic temperature shifts measured by MRI may also be corroborated by examining the amplitude and T2*.
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