System for delivering microwave ablation to subcutaneous tumors in small-animals under high-field MRI thermometry guidance.
Int J Hyperthermia
; 39(1): 584-594, 2022.
Article
in En
| MEDLINE
| ID: mdl-35435078
ABSTRACT
PURPOSE:
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.METHODS:
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 ex-vivo 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 (n = 6) were ablated in vivo and monitored with MRIT in multiple planes. One day post ablation, animals were euthanized, and excised tumors were processed for viability assessment.RESULTS:
Average absolute error between temperatures from fiberoptic sensors and MRIT was 0.6 °C across all ex-vivo ablations. During in-vivo 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.CONCLUSIONS:
We have developed a system for delivering microwave ablation to subcutaneous tumors in small animals under MRIT guidance and demonstrated its performance in-vivo.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Thermometry
/
Neoplasms
Type of study:
Guideline
Limits:
Animals
Language:
En
Journal:
Int J Hyperthermia
Journal subject:
NEOPLASIAS
/
TERAPEUTICA
Year:
2022
Document type:
Article
Affiliation country: