biostudies-literatureSebek JNIBIB NIH HHS584-594https://www.ebi.ac.uk/biostudies/studies/S-EPMC9717487biostudies-literatureUnknown39(1)<h4>Purpose</h4>Bio-effects following thermal treatments are a function of the achieved temperature profile in tissue, which can be estimated across tumor volumes with real-time MRI thermometry (MRIT). Here, we report on expansion of a previously developed small-animal microwave hyperthermia system integrated with MRIT for delivering thermal ablation to subcutaneously implanted tumors in mice.<h4>Methods</h4>Computational models were employed to assess suitability of the 2.45 GHz microwave applicators for delivering ablation to subcutaneous tumor targets in mice. Phantoms and <i>ex-vivo</i> tissues were heated to temperatures in the range 47-67 °C with custom-made microwave applicators for validating MRIT with the proton resonance frequency shift method against fiberoptic thermometry. HAC15 tumors implanted in nude mice (<i>n</i> = 6) were ablated <i>in vivo</i> and monitored with MRIT in multiple planes. One day post ablation, animals were euthanized, and excised tumors were processed for viability assessment.<h4>Results</h4>Average absolute error between temperatures from fiberoptic sensors and MRIT was 0.6 °C across all <i>ex-vivo</i> ablations. During <i>in-vivo</i> experiments, tumors with volumes ranging between 5.4-35.9 mm³ (mean 14.2 mm³) were ablated (duration: 103-150 s) to achieve 55 °C at the tumor boundary. Thermal doses ≥240 CEM43 were achieved across 90.7-98.0% of tumor volumes for four cases. Ablations were incomplete for remaining cases, attributed to motion-affected thermometry. Thermal dose-based ablative tumor coverage agreed with viability assessment of excised tumors.<h4>Conclusions</h4>We have developed a system for delivering microwave ablation to subcutaneous tumors in small animals under MRIT guidance and demonstrated its performance <i>in</i>-<i>vivo</i>.International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia GroupSystem for delivering microwave ablation to subcutaneous tumors in small-animals under high-field MRI thermometry guidance.PMC9717487R01 EB028848Basel MTFaridi PZeinali NTimmerman SAPyle MPrakash PSebek JO'Halloran MMali IBossmann SHPayne MChamani FShrestha TBDennedy MCfalseSystem for delivering microwave ablation to subcutaneous tumors in small-animals under high-field MRI thermometry guidance.<h4>Purpose</h4>Bio-effects following thermal treatments are a function of the achieved temperature profile in tissue, which can be estimated across tumor volumes with real-time MRI thermometry (MRIT). Here, we report on expansion of a previously developed small-animal microwave hyperthermia system integrated with MRIT for delivering thermal ablation to subcutaneously implanted tumors in mice.<h4>Methods</h4>Computational models were employed to assess suitability of the 2.45 GHz microwave applicators for delivering ablation to subcutaneous tumor targets in mice. Phantoms and <i>ex-vivo</i> tissues were heated to temperatures in the range 47-67 °C with custom-made microwave applicators for validating MRIT with the proton resonance frequency shift method against fiberoptic thermometry. HAC15 tumors implanted in nude mice (<i>n</i> = 6) were ablated <i>in vivo</i> and monitored with MRIT in multiple planes. One day post ablation, animals were euthanized, and excised tumors were processed for viability assessment.<h4>Results</h4>Average absolute error between temperatures from fiberoptic sensors and MRIT was 0.6 °C across all <i>ex-vivo</i> ablations. During <i>in-vivo</i> experiments, tumors with volumes ranging between 5.4-35.9 mm³ (mean 14.2 mm³) were ablated (duration: 103-150 s) to achieve 55 °C at the tumor boundary. Thermal doses ≥240 CEM43 were achieved across 90.7-98.0% of tumor volumes for four cases. Ablations were incomplete for remaining cases, attributed to motion-affected thermometry. Thermal dose-based ablative tumor coverage agreed with viability assessment of excised tumors.<h4>Conclusions</h4>We have developed a system for delivering microwave ablation to subcutaneous tumors in small animals under MRIT guidance and demonstrated its performance <i>in</i>-<i>vivo</i>.2022-01-01T00:00:00Z20222025-04-19T04:42:44.675Z2025-04-19T04:42:44.675ZS-EPMC97174873543507810.1080/02656736.2022.2061727