Modelling heating of liver tumours with heterogeneous magnetic microsphere deposition

Abstract

Ferromagnetic embolization hyperthermia (FEH) is a novel treatment for liver cancer. Magnetic microspheres are injected into the hepatic artery and cluster in the periphery of tumours and are heated with externally applied magnetic fields. In order to more accurately simulate FEH, we modelled a three-dimensional heterogeneous distribution of heat sources. We constructed a fractal model of the vasculature in the periphery of a tumour. We used this model to compute the spatial distribution of the microspheres that lodge in capillaries. We used the distribution model as input to a finite-element heat transfer model of the FEH treatment. The overall appearance of the vascular tree is subjectively similar to that of the disorganized vascular network which encapsulates tumours. The microspheres are distributed in the tumour periphery in similar patterns to experimental observations. We expect the vasculature and microsphere deposition models to also be of interest to researchers of any targeted cancer therapies such as localized intra-arterial chemotherapy and selective internal radiotherapy. Our results show that heterogeneous microsphere distributions give significantly different results to those for a homogeneous model and thus are preferable when accurate results are required.

Accurate measurement of the specific absorption rate using a suitable adiabatic magnetothermal setup

“…SAR highly depends on field parameters and on material properties, since different heating mechanisms can be involved. 5,6 So accurate measurements are necessary for the studies on correlation between the SAR and material properties, 7-11 simulations of temperature distributions in tissues or phantoms, 12,13 and the optimization of hyperthermia therapies. 1,2 SAR can be estimated by calorimetric methods as SAR = ͑1 / m͒C͑⌬T / ⌬t͒, where m is the mass of the dissipating material, C the heat capacity of the whole sample, and ⌬T the sample temperature increase during the ac-field application interval ⌬t.…”

Parametric investigation of heating due to magnetic fluid hyperthermia in a tumor with blood perfusion

“…The blood perfusion in a smaller tumor located inside muscular or fatty tissues is typically lower than in an organ such as the liver where it varies between 5 and 30 kg m 3 s À 1 [34].…”

Future of Nanoparticles in the Field of Medicine

“…Based on the different research models given, we used the theory according to which the tumor in the affected area can be removed by heating it up to temperatures [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], in the range of 41-46°C. It was proposed that if the power ranges 2.75-6.5 W, when applied to the magnetic nanoparticles (present at the tumor site), for duration of (up to) 10 s, a tumor having diameter of size 5 cm can be successfully/efficiently removed.…”

“…We explore the variation in applied power within which the desired results can be obtained, which in turn leads to minimizing the running cost and undue heating of healthy tissue/cell in the vicinity of the affected area. The study presented is based on the model suggested by Tsafnat et al [19] for heating of liver tumors. According to their study, the affected area demonstrates lower levels of blood perfusion than a healthy one.…”