» Articles » PMID: 32999735

Simulation-based Design and Characterization of a Microwave Applicator for MR-guided Hyperthermia Experimental Studies in Small Animals

Overview
Date 2020 Oct 1
PMID 32999735
Citations 4
Authors
Affiliations
Soon will be listed here.
Abstract

Purpose: The objective of this study was to design and characterize a 2.45 GHz microwave hyperthermia applicator for delivering hyperthermia in experimental small animals to 2 - 4 mm diameter targets located 1 - 3 mm from the skin surface, with minimal heating of the surrounding tissue, under 14.1 T MRI real-time monitoring and feedback control.

Materials And Methods: An experimentally validated 3D computational model was employed to design and characterize a non-invasive directional water-cooled microwave hyperthermia applicator. We assessed the effects of: reflector geometry, monopole shape, cooling water temperature, and flow rate on spatial-temperature profiles. The system was integrated with real-time MR thermometry and feedback control to monitor and maintain temperature elevations in the range of 4 - 5 °C at 1 - 3 mm from the applicator surface. The quality of heating was quantified by determining the fraction of the target volume heated to the desired temperature, and the extent of heating in non-targeted regions.

Results: Model-predicted hyperthermic profiles were in good agreement with experimental measurements (Dice Similarity Coefficient of 0.95 - 0.99). Among the four considered criteria, a reflector aperture angle of 120 °, S-shaped monopole antenna with 0.6 mm displacement, and coolant flow rate of 150 ml/min were selected as the end result of the applicator design. The temperature of circulating water and input power were identified as free variables, allowing considerable flexibility in heating target sizes within varying distances from the applicator surface. 2 - 4 mm diameter targets positioned 1 - 3 mm from the applicator surface were heated to hyperthermic temperatures, with target coverage ratio ranging between 76 - 93 % and 11 - 26 % of non-targeted tissue heated.

Conclusion: We have designed an experimental platform for MR-guided hyperthermia, incorporating a microwave applicator integrated with temperature-based feedback control to heat deep-seated targets for experimental studies in small animals.

Citing Articles

System for delivering microwave ablation to subcutaneous tumors in small-animals under high-field MRI thermometry guidance.

Sebek J, Shrestha T, Basel M, Chamani F, Zeinali N, Mali I Int J Hyperthermia. 2022; 39(1):584-594.

PMID: 35435078 PMC: 9717487. DOI: 10.1080/02656736.2022.2061727.


Preclinical Studies in Small Animals for Advanced Drug Delivery Using Hyperthermia and Intravital Microscopy.

Priester M, Curto S, Seynhaeve A, Perdomo A, Amin M, Agnass P Cancers (Basel). 2021; 13(20).

PMID: 34680296 PMC: 8534089. DOI: 10.3390/cancers13205146.


Nanomaterials responding to microwaves: an emerging field for imaging and therapy.

Wilson A, Rahman M, Kosmas P, Thanou M Nanoscale Adv. 2021; 3(12):3417-3429.

PMID: 34527861 PMC: 8388194. DOI: 10.1039/d0na00840k.


Experimental assessment of microwave ablation computational modeling with MR thermometry.

Faridi P, Keselman P, Fallahi H, Prakash P Med Phys. 2020; 47(9):3777-3788.

PMID: 32506550 PMC: 7719571. DOI: 10.1002/mp.14318.

References
1.
Frey B, Weiss E, Rubner Y, Wunderlich R, Ott O, Sauer R . Old and new facts about hyperthermia-induced modulations of the immune system. Int J Hyperthermia. 2012; 28(6):528-42. DOI: 10.3109/02656736.2012.677933. View

2.
Centelles M, Wright M, So P, Amrahli M, Xu X, Stebbing J . Image-guided thermosensitive liposomes for focused ultrasound drug delivery: Using NIRF-labelled lipids and topotecan to visualise the effects of hyperthermia in tumours. J Control Release. 2018; 280:87-98. DOI: 10.1016/j.jconrel.2018.04.047. View

3.
Bing C, Staruch R, Tillander M, Kohler M, Mougenot C, Ylihautala M . Drift correction for accurate PRF-shift MR thermometry during mild hyperthermia treatments with MR-HIFU. Int J Hyperthermia. 2016; 32(6):673-87. PMC: 5045807. DOI: 10.1080/02656736.2016.1179799. View

4.
Hew J, Solon-Biet S, McMahon A, Ruohonen K, Raubenheimer D, Ballard J . The Effects of Dietary Macronutrient Balance on Skin Structure in Aging Male and Female Mice. PLoS One. 2016; 11(11):e0166175. PMC: 5104383. DOI: 10.1371/journal.pone.0166175. View

5.
Sebek J, Curto S, Bortel R, Prakash P . Analysis of minimally invasive directional antennas for microwave tissue ablation. Int J Hyperthermia. 2016; 33(1):51-60. DOI: 10.1080/02656736.2016.1195519. View