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Tissue-mimicking gel phantoms for thermal therapy studies

Dabbagh A, Abdullah BJ, Ramasindarum C, Abu Kasim NH

Ultrason Imaging, 2014 Oct;36(4):291-316.
PMID: 24626566 DOI: 10.1177/0161734614526372

Tissue-mimicking phantoms that are currently available for routine biomedical applications may not be suitable for high-temperature experiments or calibration of thermal modalities. Therefore, design and fabrication of customized thermal phantoms with tailored properties are necessary for thermal therapy studies. A multitude of thermal phantoms have been developed in liquid, solid, and gel forms to simulate biological tissues in thermal therapy experiments. This article is an attempt to outline the various materials and techniques used to prepare thermal phantoms in the gel state. The relevant thermal, electrical, acoustic, and optical properties of these phantoms are presented in detail and the benefits and shortcomings of each type are discussed. This review could assist the researchers in the selection of appropriate phantom recipes for their in vitro study of thermal modalities and highlight the limitations of current phantom recipes that remain to be addressed in further studies.

Matched MeSH terms: Hyperthermia, Induced/methods*
Feasibility of A-mode ultrasound attenuation as a monitoring method of local hyperthermia treatment

Manaf NA, Aziz MN, Ridzuan DS, Mohamad Salim MI, Wahab AA, Lai KW, et al.

Med Biol Eng Comput, 2016 Jun;54(6):967-81.
PMID: 27039402 DOI: 10.1007/s11517-016-1480-2

Recently, there is an increasing interest in the use of local hyperthermia treatment for a variety of clinical applications. The desired therapeutic outcome in local hyperthermia treatment is achieved by raising the local temperature to surpass the tissue coagulation threshold, resulting in tissue necrosis. In oncology, local hyperthermia is used as an effective way to destroy cancerous tissues and is said to have the potential to replace conventional treatment regime like surgery, chemotherapy or radiotherapy. However, the inability to closely monitor temperature elevations from hyperthermia treatment in real time with high accuracy continues to limit its clinical applicability. Local hyperthermia treatment requires real-time monitoring system to observe the progression of the destroyed tissue during and after the treatment. Ultrasound is one of the modalities that have great potential for local hyperthermia monitoring, as it is non-ionizing, convenient and has relatively simple signal processing requirement compared to magnetic resonance imaging and computed tomography. In a two-dimensional ultrasound imaging system, changes in tissue microstructure during local hyperthermia treatment are observed in terms of pixel value analysis extracted from the ultrasound image itself. Although 2D ultrasound has shown to be the most widely used system for monitoring hyperthermia in ultrasound imaging family, 1D ultrasound on the other hand could offer a real-time monitoring and the method enables quantitative measurement to be conducted faster and with simpler measurement instrument. Therefore, this paper proposes a new local hyperthermia monitoring method that is based on one-dimensional ultrasound. Specifically, the study investigates the effect of ultrasound attenuation in normal and pathological breast tissue when the temperature in tissue is varied between 37 and 65 °C during local hyperthermia treatment. Besides that, the total protein content measurement was also conducted to investigate the relationship between attenuation and tissue denaturation level at different temperature ranges. The tissues were grouped according to their histology results, namely normal tissue with large predominance of cells (NPC), cancer tissue with large predominance of cells (CPC) and cancer with high collagen fiber content (CHF). The result shows that the attenuation coefficient of ultrasound measured following the local hyperthermia treatment increases with the increment of collagen fiber content in tissue as the CHF attenuated ultrasound at the highest rate, followed by NPC and CPC. Additionally, the attenuation increment is more pronounced at the temperature over 55 °C. This describes that the ultrasound wave experienced more energy loss when it propagates through a heated tissue as the tissue structure changes due to protein coagulation effect. Additionally, a significant increase in the sensitivity of attenuation to protein denaturation is also observed with the highest sensitivity obtained in monitoring NPC. Overall, it is concluded that one-dimensional ultrasound can be used as a monitoring method of local hyperthermia since its attenuation is very sensitive to the changes in tissue microstructure during hyperthermia.

Matched MeSH terms: Hyperthermia, Induced/methods*
Polyethylene glycol-coated porous magnetic nanoparticles for targeted delivery of chemotherapeutics under magnetic hyperthermia condition

Dabbagh A, Hedayatnasab Z, Karimian H, Sarraf M, Yeong CH, Madaah Hosseini HR, et al.

Int J Hyperthermia, 2019;36(1):104-114.
PMID: 30428737 DOI: 10.1080/02656736.2018.1536809

PURPOSE: Although magnetite nanoparticles (MNPs) are promising agents for hyperthermia therapy, insufficient drug encapsulation efficacies inhibit their application as nanocarriers in the targeted drug delivery systems. In this study, porous magnetite nanoparticles (PMNPs) were synthesized and coated with a thermosensitive polymeric shell to obtain a synergistic effect of hyperthermia and chemotherapy.
MATERIALS AND METHODS: PMNPs were produced using cetyltrimethyl ammonium bromide template and then coated by a polyethylene glycol layer with molecular weight of 1500 Da (PEG1500) and phase transition temperature of 48 ± 2 °C to endow a thermosensitive behavior. The profile of drug release from the nanostructure was studied at various hyperthermia conditions generated by waterbath, magnetic resonance-guided focused ultrasound (MRgFUS), and alternating magnetic field (AMF). The in vitro cytotoxicity and hyperthermia efficacy of the doxorubicin-loaded nanoparticles (DOX-PEG1500-PMNPs) were assessed using human lung adenocarcinoma (A549) cells.
RESULTS: Heat treatment of DOX-PEG1500-PMNPs containing 235 ± 26 mg·g-1 DOX at 48 °C by waterbath, MRgFUS, and AMF, respectively led to 71 ± 4%, 48 ± 3%, and 74 ± 5% drug release. Hyperthermia treatment of the A549 cells using DOX-PEG1500-PMNPs led to 77% decrease in the cell viability due to the synergistic effects of magnetic hyperthermia and chemotherapy.
CONCLUSION: The large pores generated in the PMNPs structure could provide a sufficient space for encapsulation of the chemotherapeutics as well as fast drug encapsulation and release kinetics, which together with thermosensitive characteristics of the PEG1500 shell, make DOX-PEG1500-PMNPs promising adjuvants to the magnetic hyperthermia modality.

Matched MeSH terms: Hyperthermia, Induced/methods*
A new mechanism of thermal sensitivity for rapid drug release and low systemic toxicity in hyperthermia and thermal ablation temperature ranges

Dabbagh A, Abdullah BJ, Abu Kasim NH, Abdullah H, Hamdi M

Int J Hyperthermia, 2015 Jun;31(4):375-85.
PMID: 25716769 DOI: 10.3109/02656736.2015.1006268

The aim of this paper was to introduce a new mechanism of thermal sensitivity in nanocarriers that results in a relatively low drug release at physiological temperature and rapid release of the encapsulated drug at hyperthermia and thermal ablation temperature range (40-60 °C).

Matched MeSH terms: Hyperthermia, Induced/methods*
Prostalase: basic clinical research and preliminary clinical results with laser thermotherapy for symptomatic benign prostatic hyperplasia

Liong ML, Suzuki T, Yamanaka H, Kurokawa K, Daikuzono N, Nakazato M

J Clin Laser Med Surg, 1994 Apr;12(2):85-92.
PMID: 10151050

Prostalase¿ has a probe that emits a laser beam at 360 degrees . Targeted obstructive prostatic adenoma tissue was heated to above the cytotoxic threshold temperature of 45 degrees C. After successful canine prostate study, from September 1992 to April 1993, 45 patients were treated. This paper reports the 9 months results of this initial cohort of patients. Prostatic and periprostatic temperature mapping showed the mean temperature within the adenoma zone was 49 degrees C, while the periprostatic tissue remained within the safety level of less than 42.5 degrees C. The mean prostate volume reductions at 3, 6, and 9 months were 36, 33, and 38%, respectively. Those patients whose surgery was unsuccessful had prostatic tissue removed by TURP at 2 to 3 months. This tissue revealed a definite zone of coagulative necrosis. For the clinical assessment, patients were divided into urine retention (UR) and nonretention (NR) subgroups. At 9 months, 20 of the 32 UR subgroup and 10 of the 13 NR subgroup patients were available for assessment. Due to poor response or complications, 6 of the 26 UR patients (23%) required ancillary treatment. Hence, 20 of the 26 cases (77%) remained catheter free and their mean maximum uroflow +/- SE was 9.6 +/- 0.7 ml/sec. Based on a Siroky normogram only 7 of these 26 patients (27%) became unobstructed. Two of the 12 NR subgroup patients (17%) required ancillary treatment. The mean maximum uroflow +/- SE was 10.7 +/- 1.2 ml/sec.(ABSTRACT TRUNCATED AT 250 WORDS)

Matched MeSH terms: Hyperthermia, Induced/methods
Synthesis of enriched boron nitride nanocrystals: A potential element for biomedical applications

Ahmad P, Khandaker MU, Muhammad N, Rehman F, Ullah Z, Khan G, et al.

Appl Radiat Isot, 2020 Dec;166:109404.
PMID: 32956924 DOI: 10.1016/j.apradiso.2020.109404

The shortcomings in Boron neutron capture therapy (BNCT) and Hyperthermia for killing the tumor cell desired for the synthesis of a new kind of material suitable to be first used in BNCT and later on enable the conditions for Hyperthermia to destroy the tumor cell. The desire led to the synthesis of large band gap semiconductor nano-size Boron-10 enriched crystals of hexagonal boron nitride (10BNNCs). The contents of 10BNNCs are analyzed with the help of x-ray photoelectron spectroscopy (XPS) and counter checked with Raman and XRD. The 10B-contents in 10BNNCs produce 7Li and 4He nuclei. A Part of the 7Li and 4He particles released in the cell is allowed to kill the tumor (via BNCT) whereas the rest produce electron-hole pairs in the semiconductor layer of 10BNNCs suggested to work in Hyperthermia with an externally applied field.

Matched MeSH terms: Hyperthermia, Induced/methods