Experimental measurement of microwave ablation heating pattern and comparison to computer simulations

Assessment of thermochromic phantoms for characterizing microwave ablation devices

BACKGROUND AND PURPOSE

Thermochromic gel phantoms provide a controlled medium for visual assessment of thermal ablation device performance. However, there are limited studies reporting on the comparative assessment of ablation profiles assessed in thermochromic gel phantoms against those in ex vivo tissue. The objective of this study was to compare microwave ablation zones in a thermochromic tissue-mimicking gel phantom and ex vivo bovine liver and to report on measurements of the temperature-dependent dielectric and thermal properties of the phantom.

METHODS

Thermochromic polyacrylamide phantoms were fabricated following a previously reported protocol. Phantom samples were heated to temperatures in the range of 20°C-90°C in a temperature-controlled water bath, and colorimetric analysis of images of the phantom taken after heating was used to develop a calibration between color changes and the temperature to which the phantom was heated. Using a custom, 2.45 GHz water-cooled microwave ablation antenna, ablations were performed in fresh ex vivo liver and phantoms using 65 W applied for 5 min or 10 min (n = 3 samples in each medium for each power/time combination). Broadband (500 MHz-6 GHz) temperature-dependent dielectric and thermal properties of the phantom were measured over the temperature range of 22°C-100°C.

RESULTS

Colorimetric analysis showed that the sharp change in gel phantom color commences at a temperature of 57°C. Short and long axes of the ablation zone in the phantom (as assessed by the 57°C isotherm) for 65 W, 5 min ablations were aligned with the extents of the ablation zone observed in ex vivo bovine liver. However, for the 65 W, 10 min setting, ablations in the phantom were on average 23.7% smaller in the short axis and 7.4 % smaller in the long axis than those observed in ex vivo liver. Measurements of the temperature-dependent relative permittivity, thermal conductivity, and volumetric heat capacity of the phantom largely followed similar trends to published values for ex vivo liver tissue.

CONCLUSION

Thermochromic tissue-mimicking phantoms provides a controlled, and reproducible medium for comparative assessment of microwave ablation devices and energy delivery settings. However, ablation zone size and shapes in the thermochromic phantom do not accurately represent ablation sizes and shapes observed in ex vivo liver tissue for high energy delivery treatments (65 W, 10 min). One cause for this limitation is the difference in temperature-dependent thermal and dielectric properties of the thermochromic phantom compared to ex vivo bovine liver tissue, as reported in the present study.

Assessment of thermochromic phantoms for characterizing microwave ablation devices

Background and Purpose

Thermochromic gel phantoms provide a controlled medium for visual assessment of thermal ablation device performance. However, there are limited studies reporting on the comparative assessment of ablation profiles assessed in thermochromic gel phantoms against those in ex vivo tissue. The objective of this study was to compare microwave ablation zones in a thermochromic tissue mimicking gel phantom and ex vivo bovine liver, and to report on measurements of the temperature dependent dielectric and thermal properties of the phantom.

Methods

Thermochromic polyacrylamide phantoms were fabricated following a previously reported protocol. Phantom samples were heated to temperatures in the range of 20 - 90 °C in a temperature-controlled water bath, and colorimetric analysis of images of the phantom taken after heating were used to develop a calibration between color changes and temperature to which the phantom was heated. Using a custom, 2.45 GHz water-cooled microwave ablation antenna, ablations were performed in fresh ex vivo liver and phantoms using 65 W applied for 5 min or 10 min ( n = 3 samples in each medium for each power/time combination). Broadband (500 MHz - 6 GHz) temperature-dependent dielectric and thermal properties of the phantom were measured over the temperature range 22 - 100 °C.

Results

Colorimetric analysis showed that the sharp change in gel phantom color commences at a temperature of 57 °C. Short and long axes of the ablation zone in the phantom (as assessed by the 57 °C isotherm) for 65 W, 5 min ablations were aligned with extents of the ablation zone observed in ex vivo bovine liver. However, for the 65 W, 10 min setting, ablations in the phantom were on average 23.7% smaller in short axis and 7.4 % smaller in long axis than those observed in ex vivo liver. Measurements of the temperature dependent relative permittivity, thermal conductivity, and volumetric heat capacity of the phantom largely followed similar trends to published values for ex vivo liver tissue.

Conclusion

Thermochromic tissue mimicking phantoms provide a controlled, and reproducible medium for comparative assessment of microwave ablation devices and energy delivery settings, though ablation zone size and shapes may not accurately represent ablation sizes and shapes observed in ex vivo liver tissue under similar conditions.

Adaptive simulation of 3D thermometry maps for interventional MR-guided tumor ablation using Pennes' bioheat equation and isotherms

Minimally-invasive thermal ablation procedures have become clinically accepted treatment options for tumors and metastases. Continuous and reliable monitoring of volumetric heat distribution promises to be an important condition for successful outcomes. In this work, an adaptive bioheat transfer simulation of 3D thermometry maps is presented. Pennes' equation model is updated according to temperature maps generated by uniformly distributed 2D MR phase images rotated around the main axis of the applicator. The volumetric heat diffusion and the resulting shape of the ablation zone can be modelled accurately without introducing a specific heat source term. Filtering the temperature maps by extracting isotherms reduces artefacts and noise, compresses information of the measured data and adds physical a priori knowledge. The inverse heat transfer for estimating values of the simulated tissue and heating parameters is done by reducing the sum squared error between these isotherms and the 3D simulation. The approach is evaluated on data sets consisting of 13 ex vivo bio protein phantoms, including six perfusion phantoms with simulated heat sink effects. Results show an overall average Dice score of 0.89 ± 0.04 (SEM < 0.01). The optimization of the parameters takes 1.05 ± 0.26 s for each acquired image. Future steps should consider the local optimization of the simulation parameters instead of a global one to better detect heat sinks without a priori knowledge. In addition, the use of a proper Kalman filter might increase robustness and accuracy if combined with our method.

Predicting the coagulation volume induced by microwave ablation of hepatocellular carcinoma: the role of deposited energy, ex-vivo bovine liver charts and central hyperdense area on post-treatment CT

PURPOSE

To study the correlation between the overall coagulation zone (A) attained in percutaneous microwave ablation (MWA) of hepatocellular carcinomas (HCC) and: (1) the hyperdense zone (C) visible in the central part of zone A on post-treatment unenhanced CT scans; (2) the deposited energy; (3) the coagulation zones observed on ex-vivo bovine liver.

MATERIALS AND METHODS

The post-procedural computed tomography (CT) scans of HCCs treated with a single energy deployment through the same 2450 MHz MWA system were retrospectively analyzed, retrieving the dimensions of A and C zones and the deposited energy (E). Ex-vivo bovine liver MWA with the same system were performed and analyzed to determine the same quantities by gross-pathologic examination and CT imaging.

RESULTS

A total of 101 HCC treatments were analyzed. The average coagulation volumes increased linearly with deposited energy (1.11 cc/kJ, R² = 0.90, 4.2 kJ ≤ E ≤ 48 kJ), similarly to ex-vivo findings (1.38 cc/kJ, R² =0.97, 7.2 kJ ≤ E ≤ 144 kJ). The long axis (L) and short axis (D) of zones A and C held a fairly constant ratio both in-vivo (L_C/L_A=0.43 ± 0.13; D_C/D_A=0.42 ± 0.10) and ex-vivo (L_C/L_A = 0.49 ± 0.07; D_C/D_A = 0.28 ± 0.06).

CONCLUSIONS

The average dimensions of the ablation zone induced by the considered system on HCC increase linearly with the deposited energy and are fairly well predicted by the corresponding ex-vivo dimensions. The ratio between each linear dimension of A and C zones was found to be roughly constant over a large deposited energy span, both ex-vivo and in-vivo.

Temperature-dependent dielectric properties of human uterine fibroids over microwave frequencies

Microwave ablation is under investigation as a minimally-invasive treatment for uterine fibroids. Computational models play a vital role in the development, evaluation and characterization of candidate ablation devices. The temperature-dependent dielectric properties of fibroid tissue are essential for accurate computational modeling.Objective:To measure the broadband temperature-dependent dielectric properties of uterine fibroids excised during hysterectomy procedures.Methods: The open-ended coaxial probe method was employed for measuring the broadband dielectric properties of freshly excised human uterine fibroid samples (n = 6) obtained from an IRB-approved tissue bank. The dielectric properties (relative permittivity,ε_r, and effective electrical conductivity,σ_eff) were evaluated at temperatures ranging from 23 °C-150 °C, over the frequency range of 0.5-6 GHz. Linear piecewise parametrization with respect to temperature and quadratic parametrization with respect to frequency was applied to characterize broadband temperature-dependent dielectric properties of fibroid tissue.Results: The baseline room temperature values ofε_rvary from 57.5 ± 5.29 to 44.5 ± 5.77 units andσ_effchanges from 0.91 ± 0.19 to 6.02 ± 0.7 S m^-1over the frequency range of 0.5-6 GHz. At temperatures close to the water vaporization point,ε_r, drops considerably i.e. to 12%-14% of its baseline value for all measured frequencies.σ_effvalues initially rise till 98 °C and then fall to 11%-13% of their baseline values at 125 °C for frequencies ≤2.45 GHz. Theσ_efffollows a decreasing trend for frequencies >2.45 GHz and drops to ∼6 % of their baseline room temperature values.Conclusion:The temperature dependent dielectric properties of uterine fibroid tissues over microwave frequency range are reported for the first time in this study. Parametric models of uterine fibroid dielectric properties are also presented for incorporation within computational models of microwave ablation of fibroids.

Computer simulations of an irrigated radiofrequency cardiac ablation catheter and experimental validation by infrared imaging

PURPOSE

To develop and validate a three-dimensional (3-D) computer model based on accurate geometry of an irrigated cardiac radiofrequency (RF) ablation catheter with microwave radiometry capability, and to test catheter performance.

METHODS

A computer model was developed based on CAD geometry of a RF cardiac ablation catheter prototype to simulate electromagnetic heating, heat transfer, and computational fluid dynamics (blood flow, open irrigation, and natural convection). Parametric studies were performed; blood flow velocity (0-25 cm/s) and irrigation flow (0-40 ml/min) varied, both with perpendicular (PE) and parallel (PA) catheter orientations relative to tissue. Tissue Agar phantom studies were performed under similar conditions, and temperature maps were recorded via infrared camera. Computer model simulations were performed with constant voltage and with voltage adjusted to achieve maximum tissue temperatures of 95-105 °C.

RESULTS

Model predicted thermal lesion width at 5 W power was 5.8-6.4 mm (PE)/6.5-6.6 mm (PA), and lesion depth was 4.0-4.3 mm (PE)/4.0-4.1 mm (PA). Compared to phantom studies, the mean errors of the computer model were as follows: 6.2 °C(PE)/4.3 °C (PA) for maximum gel temperature, 0.7 mm (10.9%) (PE)/0.1 mm (0.8%) (PA) for lesion width, and 0.3 mm (7.7%)(PE)/0.7 mm (19.1%) (PA) for lesion depth. For temperature-controlled ablation, model predicted thermal lesion width was 7-9.2 mm (PE)/8.6-9.2 mm (PA), and lesion depth was 4.3-5.5 mm (PE)/3.4-5.4 mm (PA).

CONCLUSIONS

Computer models were able to reproduce device performance and to enable device evaluation under varying conditions. Temperature controlled ablation of irrigated catheters enables optimal tissue temperatures independent of patient-specific conditions such as blood flow.

Transcervical microwave ablation in type 2 uterine fibroids via a hysteroscopic approach: analysis of ablation profiles

Type 2 uterine fibroids are challenging to resect surgically as ≥ 50% volume of myoma lies within the myometrium. A hysteroscopic approach for ablating fibroids is minimally-invasive, but places a considerable burden on the operator to accurately place the ablation applicator within the target. We investigated the sensitivity of transcervical microwave ablation outcome with respect to position of the ablation applicator within 1 - 3 cm type 2 fibroids.Methods:A finite element computer model was developed to simulate 5.8 GHz microwave ablation of fibroids and validated with experiments inex vivotissue. The ablation outcome was evaluated with respect to applicator insertion angles (30°, 45°, 60°) , depth and offset from the fibroid center (±2 mm for 3 cm fibroid and ±1 mm for 1 cm fibroid) with 35 W and 15 W applied power for 3 cm and 1 cm fibroids, respectively. Power deposition was stopped when thermal dose of 40 cumulative equivalent minutes at 43 °C (CEM43) was accrued in adjacent myometrium.Results:Within the range of all evaluated insertion angles, depths and offsets, the ablation coverage was less sensitive to variation in angle as compared to depth and offset, and ranged from 34.9 - 83.6% for 3 cm fibroid in 140 - 400 s and 34.1 - 67.9% for 1 cm fibroid in 30 - 50 s of heating duration. Maximum achievable ablation coverage in both fibroid cases reach ∼ 90% if thermal dose is allowed to exceed 40 CEM43 in myometrium.Conclusion:The study demonstrates the technical feasibility of transcervical microwave ablation for fibroid treatment and the relationship between applicator position within the fibroid and fraction of fibroid that can be ablated while limiting thermal dose in adjacent myometrium.

A review of antenna designs for percutaneous microwave ablation

Microwave (MW) antenna is a key element in microwave ablation (MWA) treatments as the means that energy is delivered in a focused manner to the tumor and its surrounding area. The energy delivered results in a rise in temperature to a lethal level, resulting in cell death in the ablation zone. The delivery of energy and hence the success of MWA is closely dependent on the structure of the antennas. Therefore, three design criteria, such as expected ablation zone pattern, efficiency of energy delivery, and minimization of the diameter of the antennas have been the focus along the evolution of the MW antenna. To further improve the performance of MWA in the treatment of various tumors through inventing novel antennas, this article reviews the state-of-the-art and summarizes the development of MW antenna designs regarding the three design criteria.

Evaluation of the performance of designed coaxial antennas for hyperthermia using simulation and experimental methods

Introduction: Antenna geometries and tissue properties affect microwave energy distributions during microwave ablation procedures. There is paucity information on the potential of antenna fabricated from a thick semi-rigid coaxial cable in the field of microwave thermal therapy. This study aimed at comparing the performance of two dual-slot antennas designed from different semi-rigid coaxial cables for the ablation of a liver tumour using numerical simulation and experimental validation methods.

Materials and Methods: COMSOL Multiphysics software was used for designing dual-slot antennas and as well as to evaluate microwave energy deposition and heat distribution in the liver tissue. Experimental validations were conducted on the ex-vivo bovine livers to validate the simulation results.

Results: Thick antenna developed in this study produced a higher sphericity index, larger ablation diameter and reduced backward heating along the antenna shaft than the existing one. The experimental validation results also indicate significant differences between the two antennas in terms of ablation diameters (p = 0.04), ablation lengths (p = 0.02) and aspect ratios (p = 0.02).

Conclusion: Based on the findings in this study, antenna fabricated from a thick coaxial cable has a higher potential of localizing microwave energy in the liver than conventional antennas.

Robot-assisted ultrasound navigation platform for 3D HIFU treatment planning: Initial evaluation for conformal interstitial ablation

Interstitial Ultrasound-guided High Intensity Focused Ultrasound (USgHIFU) therapy has the potential to deliver ablative treatments which conform to the target tumor. In this study, a robot-assisted US-navigation platform has been developed for 3D US guidance and planning of conformal HIFU ablations. The platform was used to evaluate a conformal therapeutic strategy associated with an interstitial dual-mode USgHIFU catheter prototype (64 elements linear-array, measured central frequency f = 6.5 MHz), developed for the treatment of HepatoCellular Carcinoma (HCC). The platform included a 3D navigation environment communicating in real-time with an open research dual-mode US scanner/HIFU generator and a robotic arm, on which the USgHIFU catheter was mounted. 3D US-navigation was evaluated in vitro for guiding and planning conformal HIFU ablations using a tumor-mimic model in porcine liver. Tumor-mimic volumes were then used as targets for evaluating conformal HIFU treatment planning in simulation. Height tumor-mimics (ovoid- or disc-shaped, sizes: 3-29 cm³) were created and visualized in liver using interstitial 2D US imaging. Robot-assisted spatial manipulation of these images and real-time 3D navigation allowed reconstructions of 3D B-mode US images for accurate tumor-mimic volume estimation (relative error: 4 ± 5%). Sectorial and full-revolution HIFU scanning (angular sectors: 88-360°) could both result in conformal ablations of the tumor volumes, as soon as their radii remained ≤ 24 mm. The presented US navigation-guided HIFU procedure demonstrated advantages for developing conformal interstitial therapies in standard operative rooms. Moreover, the modularity of the developed platform makes it potentially useful for developing other HIFU approaches.

Experimental assessment of microwave ablation computational modeling with MR thermometry

PURPOSE

Computational models are widely used during the design and characterization of microwave ablation (MWA) devices, and have been proposed for pretreatment planning. Our objective was to assess three-dimensional (3D) transient temperature and ablation profiles predicted by MWA computational models with temperature profiles measured experimentally using magnetic resonance (MR) thermometry in ex vivo bovine liver.

MATERIALS AND METHODS

We performed MWA in ex vivo tissue under MR guidance using a custom, 2.45 GHz water-cooled applicator. MR thermometry data were acquired for 2 min prior to heating, during 5-10 min microwave exposures, and for 3 min following heating. Fiber-optic temperature sensors were used to validate the accuracy of MR temperature measurements. A total of 13 ablation experiments were conducted using 30-50 W applied power at the applicator input. MWA computational models were implemented using the finite element method, and incorporated temperature-dependent changes in tissue physical properties. Model-predicted ablation zone extents were compared against MRI-derived Arrhenius thermal damage maps using the Dice similarity coefficient (DSC).

RESULTS

Prior to heating, the observed standard deviation of MR temperature data was in the range of 0.3-0.7°C. Mean absolute error between MR temperature measurements and fiber-optic temperature probes during heating was in the range of 0.5-2.8°C. The mean DSC between model-predicted ablation zones and MRI-derived Arrhenius thermal damage maps for 13 experimental set-ups was 0.95. When comparing simulated and experimentally (i.e. using MRI) measured temperatures, the mean absolute error (MAE %) relative to maximum temperature change was in the range 5%-8.5%.

CONCLUSION

We developed a system for characterizing 3D transient temperature and ablation profiles with MR thermometry during MWA in ex vivo liver tissue, and applied the system for experimental validation of MWA computational models.

Use of microwave ablation for thermal treatment of solid tumors with different shapes and sizes-A computational approach

Microwave Ablation (MWA) is one of the most recent developments in the field of thermal therapy. This approach is an effective method for thermal tumor ablation by increasing the temperature above the normal physiological threshold to kill cancer cells with minimum side effects to surrounding organs due to rapid heat dispersive tissues. In the present study, the effects of the shape and size of the tumor on MWA are investigated. To obtain the temperature gradient, coupled bio-heat and electromagnetic equations are solved using a three-dimensional finite element method (FEM). To extract cellular response at different temperatures and times, the three-state mathematical model was employed to achieve the ablation zone size. Results show that treatment of larger tumors is more difficult than that of smaller ones. By doubling the diameter of the tumor, the percentage of dead cancer cells is reduced by 20%. For a spherical tumor smaller than 2 cm, applying 50 W input power compared to 25 W has no significant effects on treatment efficiency and only increases the risk of damage to adjacent tissues. However, for tumors larger than 2 cm, it can increase the ablation zone up to 21%. In the spherical and oblate tumors, the mean percentage of dead cells at 6 GHz is nearly 30% higher than that at 2.45GHz, but for prolate tumors, treatment efficacy is reduced by 10% at a higher frequency. Moreover, the distance between two slots in the coaxial double slot antenna is modified based on the best treatment of prolate tumors. The findings of this study can be used to choose the optimum frequency and the best antenna design according to the shape and size of the tumor.

Conformal coverage of liver tumors by the thermal coagulation zone in 2450-MHz microwave ablation

Purpose: To optimize treatment schemes using 2450-MHz microwave ablation (MWA), a novel conformal coverage method based on bipolar-angle mapping is proposed that determines whether a liver tumor is completely encompassed by thermal coagulation zones. Materials and methods: Firstly, three-dimensional (3-D) triangular mesh data of liver tumors were reconstructed from clinical computed tomography (CT) slices using the Marching cubes (MC) algorithm. Secondly, characterization models of thermal coagulation zones were established based on finite element simulation results of 40, 45, 50, 55, and 60 W ablations. Finally, coagulation zone models and tumor surface data were mapped and fused on a two-dimensional (2-D) plane to achieve conformal coverage of liver tumors by comparing the corresponding polar radii. Results: Optimal parameters for ablation treatment of liver tumors were efficiently obtained with the proposed conformal coverage method. Fifteen liver tumors were obtained with maximal diameters of 12.329-78.612 mm (mean ± standard deviation, 39.094 ± 19.447 mm). The insertion positions and orientations of the MWA antenna were determined based on 3-D reconstruction results of these tumors. The ablation patterns and durations of tumors were planned according to the minimum mean standard deviations between the ablative margin and tumor surface. Conclusion: The proposed method can be applied to computer-assisted MWA treatment planning of liver tumors, and is expected to guide clinical procedures in future.

Numerical Analysis of Human Cancer Therapy Using Microwave Ablation

Microwave ablation is one type of hyperthermia treatment of cancer that involves heating tumor cells. This technique uses electromagnetic wave effects to kill cancer cells. A micro-coaxial antenna is introduced into the biological tissue. The radiation emitted by the antenna is absorbed by the tissue and leads to the heating of cancer cells. The diffuse increase in temperature should reach a certain value to achieve the treatment of cancer cells but it should be less than a certain other value to avoid damaging normal cells. This is why hyperthermia treatment should be carefully monitored. A numerical simulation is useful and may provide valuable information. The bio-heat equation and Maxwell’s equations are solved using the finite element method. Electro-thermal effects, temperature distribution profile, specific absorption rate (SAR), and fraction of necrotic tissue within cancer cells are analyzed. The results show that SAR and temperature distribution are strongly affected by input microwave power. High microwave power causes a high SAR value and raises the temperature above 50 °C, which may destroy healthy cells. It is revealed that with a power of 10 W, the tumor cells will be killed without damaging the surrounding tissue.

Coupled thermo-electro-mechanical models for thermal ablation of biological tissues and heat relaxation time effects

Thermal ablation is a widely applied electrosurgical process in medical treatment of soft biological tissues. Numerical modeling and simulations play an important role in prediction of temperature distribution and damage volume during the treatment planning stage of associated therapies. In this contribution we report a coupled thermo-electro-mechanical model, accounting for heat relaxation time, for more accurate and precise prediction of the temperature distribution, tissue deformation and damage volume during the thermal ablation of biological tissues. Finite element solutions are obtained for most widely used percutaneous thermal ablative techniques, viz., radiofrequency ablation (RFA) and microwave ablation (MWA). Importantly, both tissue expansion and shrinkage have been considered for modeling the tissue deformation in the coupled model of high temperature thermal ablation. The coupled model takes into account the non-Fourier effects, considering both single-phase-lag (SPL) and dual-phase-lag (DPL) models of bio-heat transfer. The temperature-dependent electrical and thermal parameters, damage-dependent blood perfusion rate and phase change effect accounting for tissue vaporization have been accounted for obtaining more clinically relevant model. The proposed model predictions are found to be in good agreement against the temperature distribution and damage volume reported by previous experimental studies. The numerical simulation results revealed that the non-Fourier effects cause a decrease in the predicted temperature distribution, tissue deformation and damage volume during the high temperature thermal ablative procedures. Furthermore, the effects of different magnitudes of phase lags of the heat flux and temperature gradient on the predicted treatment outcomes of the considered thermal ablative modalities are also quantified and discussed in detail.

Antenna Designs for Microwave Tissue Ablation

Microwave (MW) ablation has emerged as a minimally invasive therapeutic modality and is in clinical use for treatment of unresectable tumors and cardiac arrhythmias, neuromodulation, endometrial ablation, and other applications. Components of image-guided MW ablation systems include high-power MW sources, ablation applicators that deliver power from the generator to the target tissue, cooling systems, energy-delivery control algorithms, and imaging guidance systems tailored to specific clinical indications. The applicator incorporates a MW antenna that radiates MW power into the surrounding tissue. A variety of antenna designs have been developed for MW ablation with the objective of efficiently transferring MW power to tissue, with a radiation pattern well matched to the size and shape of the targeted tissue. Here, we survey advances in percutaneous, endocavitary, and endoscopic antenna designs as an integral element of MW ablation applicators for a diverse set of clinical applications.

Localized delivery of therapeutic doxorubicin dose across the canine blood-brain barrier with hyperthermia and temperature sensitive liposomes

Most drugs cannot penetrate the blood–brain barrier (BBB), greatly limiting the use of anti-cancer agents for brain cancer therapy. Temperature sensitive liposomes (TSL) are nanoparticles that rapidly release the contained drug in response to hyperthermia (>40 °C). Since hyperthermia also transiently opens the BBB, we hypothesized that localized hyperthermia can achieve drug delivery across the BBB when combined with TSL. TSL-encapsulated doxorubicin (TSL-Dox) was infused intravenously over 30 min at a dose of 0.94 mg/kg in anesthetized beagles (age ∼17 months). Following, a hyperthermia probe was placed 5–10 mm deep through one of four 3-mm skull burr holes. Hyperthermia was performed randomized for 15 or 30 min, at either 45 or 50 °C. Blood was drawn every 30 min to measure TSL-Dox pharmacokinetics. Nonsurvival studies were performed in four dogs, where brain tissue at the hyperthermia location was extracted following treatment to quantify doxorubicin uptake via high-performance liquid chromatography (HPLC) and to visualize cellular uptake via fluorescence microscopy. Survival studies for 6 weeks were performed in five dogs treated by a single hyperthermia application. Local doxorubicin delivery correlated with hyperthermia duration and ranged from 0.11 to 0.74 μg/g of brain tissue at the hyperthermia locations, with undetectable drug uptake in unheated tissue. Fluorescence microscopy demonstrated doxorubicin delivery across the BBB. Histopathology in Haematoxylin & Eosin (H&E) stained samples demonstrated localized damage near the probe. No animals in the survival group demonstrated significant neurological deficits. This study demonstrates that localized doxorubicin delivery to the brain can be facilitated by TSL-Dox with localized hyperthermia with no significant neurological deficits.