Temperature mapping of exothermicin situchemistry: imaging of thermoembolization via MR

Abstract

Purpose: MR temperature imaging (MRTI) was employed for visualizing the spatiotemporal evolution of the exotherm of thermoembolization, an investigative transarterial treatment for solid tumors. Materials and Methods: Five explanted kidneys were injected with thermoembolic solutions, and monitored by MRTI. In three nonselective experiments, 5 mL of 4 mol/L dichloroacetyl chloride (DCA-Cl) solution in a hydrocarbon vehicle was injected via the main renal artery. For two of these three, MRTI temperature data were compared to fiber optic thermal probes. Another two kidneys received selective injections, treating only portions of the kidneys with 1 mL of 2 mol/L DCA-Cl. MRTI data were acquired and compared to changes in pre- and post-injection CT. Specimens were bisected and photographed for gross pathology 24 hours post-procedure. Results: MRTI temperature estimates were within ±1°C of the probes. In experiments without probes, MRTI measured increases of 30°C. Some regions had not reached peak temperature by the end of the >18 minutes acquisition. MRTI indicated the initial heating occurred in the renal cortex, gradually spreading more proximally toward the main renal artery. Gross pathology showed the nonselective injection denatured the entire kidney whereas in the selective injections, only the treated territory was coagulated. Conclusion: The spatiotemporal evolution of thermoembolization was visualized for the first time using non-invasive MRTI, providing unique insight into the thermodynamics of thermoembolization.

Contactless Thermometry by MRI and MRS: Advanced Methods for Thermotherapy and Biomaterials

“…In this way, thermoembolization has both thermoablative and antimetabolic effects. Recently, Fahrenholtz et al have presented the first in vivo test of liver thermoembolization in a swine model and have determined associated temperature changes in explanted kidney using phase PRFS-based MRT (a 2D multiple fast gradient-recalled echo or MFGRE sequence) at 3.0 T (Cressman and Guo, 2018;Fahrenholtz et al, 2019). MRT-measured temperature changes of up to 30 C were found to be within G1 C of reference values measured through fiber optic probes.…”

Mathematical modeling of mass and energy transport for thermoembolization

“…Ex vivo experimental measurements were used to provide an initial validation of our mathematical modeling approach. The experimental methods were described previously [40]. Briefly, experiments were conducted on fresh tissue acquired at necropsy under an Institutional Animal Care and Use Committee-approved protocol.…”

Combining Chemistry and Engineering for Hepatocellular Carcinoma: Nano-Scale and Smaller Therapies

“…The PRF image is a coronal slab that is essentially a chemically induced thermal angiogram that maps the energy release from the reaction in tissue. A more detailed and comprehensive investigation of thermal imaging with exothermic chemistry was recently published [59]. In vivo, delivery via the hepatic artery in a pig model has substantial effects both macroscopically and microscopically [60,61].…”