Laser-induced Thermal Therapy Research Articles

Direct reconstruction of tissue temperature fields during thermal therapy by dynamic response matching and steady-state correction

In the field of oncology thermotherapy technology, online and real-time reconstruction of biological tissue temperature field is a fundamental work with important practical needs. In this paper, we proposed a new method for direct reconstruction of biological tissue temperature field by dynamic response feature matching and steady-state correction. Based on the bioheat transfer equation, the step response model of tissue temperature field during thermal therapy is established, and the dynamic response eigenvectors of biological tissue temperature and the steady-state gain of temperature response are determined offline. According to the optimal matching principle between the temperature dynamic response of the observation point and the internal space point of tissue, the optimal matching matrix of the dynamic response features between the observation point temperature and the internal temperature field of tissue is determined with the use of the dynamic response eigenvectors. Further, through the weighted synthesis of observation point temperature response by using the optimal matching matrix of dynamic response features, the tissue transient temperature field pre-estimation model is established. Finally, by correcting the tissue temperature field pre-estimation model with steady-state gain correction factor, the direct reconstruction scheme of temperature field based on dynamic response feature matching and steady-state gain correction is established. In this work, the non-destructive reconstruction of the internal temperature field of biological tissues during laser-induced thermal therapy is achieved based on the above direct reconstruction scheme. Numerical simulation experiments are performed to investigated the effects of pre-estimation time domain, the number of measurement points, laser irradiation form and measurement error on the temperature field reconstruction results.

Non-destructive estimation of temperature field during laser-induced tumor hyperthermia based on Kalman filtering

Laser-induced thermal therapy (LITT) is an emerging minimally invasive treatment technique for tumors. Non-destructive acquisition of the transient temperature field in the target tissue is a key in studying and developing LITT technology. In this paper, a non-destructive temperature field estimation scheme based on Kalman filtering theory is proposed to address the challenge of temperature field monitoring during the LITT process. This scheme establishes a state space model that corresponds to the fundamental equations of heat transfer in biological tissues. Subsequently, the real-time estimation of the transient temperature field within the target tissue is conducted by integrating the temperature observations on the surface of the tissue with the state space model of heat transfer in biological tissues and the Kalman filtering theory. Numerical experiments are conducted in this study to estimate the transient temperature field inside the target tissue during the therapy of LITT. The effect of the number of temperature observation points on the surface of the target tissue, laser irradiation conditions, and measurement noise on the estimation results of the transient temperature field within the target tissue is also discussed.

Numerical modeling of skin tumors subjected to gold nanoparticle assisted laser-induced thermal therapy

Gold nanoparticle (GNP) laser-induced thermal therapy (LITT) for cancer tumor treatment, is a promising therapeutic procedure. It combines the laser deep penetration when operating in near-infrared band and the contrast agent high absorption at the considered wavelengths. Nevertheless, the treatment success is highly sensitive to the nanoparticles spatial/temporal distribution. Therefore, in this work we investigate the LITT effectiveness under conditions of non-uniform GNPs arrangement. In particular, the impact of gold nanoparticles diffusion mass transfer for different waiting periods between the GNPs injection and the treatment start was assessed. Moreover, the inoculated contrast agent concentration effect on the thermal therapy was also evaluated. Therefore, a numerical solver relying on foam-extend v.5.0 library was developed for modeling: (i) realistic intra-tumor injection. (ii) GNPs diffusion in the target area. (iii) thermal effects on skin tumors by means of LITT. It was found that a waiting period of about 24 h between the contrast agent inoculation and the treatment start is recommended. Lastly, injected GNPs concentration has to be also accurately calibrated to guarantee LITT success.

Advances in hypothalamic hamartoma research over the past 30 years (1992-2021): a bibliometric analysis.

Hypothalamic hamartoma (HH) is a rare intracranial disease whose manifestations include gelastic seizures and precocious puberty. The diagnosis and treatment of HH have changed substantially over the past three decades as medical care has improved. Bibliometrics can reveal the evolution and development of a scientific field. Documents on HH were retrieved from the Web of Science Core Collection (WoSCC) database on September 8, 2022. The search terms were as follows: "hypothalamic hamartoma" or "hamartoma of the hypothalamus" or "hypothalamic hamartomas." The types of documents were restricted to articles, case reports, and reviews. VOSviewer, CiteSpace, and the R package "bibliometrix" were used for a bibliometric analysis. A total of 667 independent documents on HH were obtained from the WoSCC database. The most common types of documents were articles (n = 498, 75%) and reviews (n = 103, 15%). The number of annual publications fluctuated but showed an upward trend overall, and the annual growth rate was 6.85%. The cumulative publication data indicated that the most influential journals in the HH field include Epilepsia, Epileptic Disorders, Child's Nervous System, Neurosurgery, and the Journal of Neurosurgery. Kerrigan JF, Ng YT, Rekate HL, Regis J, and Kameyama S were among the most prominent authors in the field of HH, with numerous publications and citations. American research institutions, especially the Barrow Neurological Institute, occupied a pivotal position in HH research. Other countries and institutions were catching up and producing considerable research results. Research on HH has steadily switched its emphasis from Pallister-Hall syndrome (PHS) and precocious puberty to epilepsy and new diagnostic and therapeutic techniques, including Gamma Knife, laser ablation, and interstitial thermal therapy. HH remains a special neurological disease with significant research prospects. The development of novel technologies, including MRI-guided laser-induced thermal therapy (MRg-LiTT) and stereotactic radiofrequency thermocoagulation (RF-TC), has enabled the efficient treatment of gelastic seizures in HH while minimizing the risks associated with craniotomies. Through bibliometric analysis, this study points out the direction for future HH research.

Reconstruction of surface laser power and internal temperature of biological tissue during laser-induced thermal therapy

In this article, the decentralized fuzzy inference method (DFIM) is applied to reconstruct the distributions of surface laser power and internal temperature of the biological tissue during laser-induced thermal therapy. The Pennes bioheat equation is used to describe the heat transfer in the tissue with laser irradiation, and it is solved by finite volume method. The reconstruction task is formulated as an inverse problem which is solved by the DFIM. Reconstruction results demonstrate that the DFIM can accurately reconstruct the surface laser power and internal temperature distribution of the tissue. Furthermore, the influences of the number of measurement points, laser irradiance form and measurement error on reconstruction results are discussed. Retrieval results showed that the DFIM is robust to reconstruct different forms of laser irradiances and internal temperature fields, even with noisy data.

The Rationale for "Laser-Induced Thermal Therapy (LITT) and Intratumoral Cisplatin" Approach for Cancer Treatment.

Cisplatin is one of the most widely used anticancer drugs in the treatment of various types of solid human cancers, as well as germ cell tumors, sarcomas, and lymphomas. Strong evidence from research has demonstrated higher efficacy of a combination of cisplatin and derivatives, together with hyperthermia and light, in overcoming drug resistance and improving tumoricidal efficacy. It is well known that the antioncogenic potential of CDDP is markedly enhanced by hyperthermia compared to drug treatment alone. However, more recently, accelerators of high energy particles, such as synchrotrons, have been used to produce powerful and monochromatizable radiation to induce an Auger electron cascade in cis-platinum molecules. This is the concept that makes photoactivation of cis-platinum theoretically possible. Both heat and light increase cisplatin anticancer activity via multiple mechanisms, generating DNA lesions by interacting with purine bases in DNA followed by activation of several signal transduction pathways which finally lead to apoptosis. For the past twenty-seven years, our group has developed infrared photo-thermal activation of cisplatin for cancer treatment from bench to bedside. The future development of photoactivatable prodrugs of platinum-based agents injected intratumorally will increase selectivity, lower toxicity and increase efficacy of this important class of antitumor drugs, particularly when treating tumors accessible to laser-based fiber-optic devices, as in head and neck cancer. In this article, the mechanistic rationale of combined intratumor injections of cisplatin and laser-induced thermal therapy (CDDP–LITT) and the clinical application of such minimally invasive treatment for cancer are reviewed.

342 Long-Term Follow-up of 54 Cases of Recurrent Glioblastoma Treated with Magnetic Resonance-Guided Laser Interstitial Thermal Therapy

INTRODUCTION: Magnetic resonance guided laser-induced thermal therapy (MRgLITT) is a novel minimally invasive procedural treatment for progressive cerebral lesions and cerebral edema related to post-radiation treatment effect. METHODS: We conducted a single-center retrospective study of pre-operative imaging, clinical characteristics and survival outcomes of 54 patients with previously treated (WHO Grade IV) between January 2013 to December 2020. RESULTS: The average age of patients was 58.7 ± 12.0 years. Patients underwent MRgLITT a median time of 21.6 ± 23.7 months from original diagnosis. 20% (n = 11) of patients had previous history of stereotactic radiosurgery, 61% (n = 33) intensity-modulated radiation therapy, and 80% (n = 43) chemotherapy. There was an average of 1.2 ± 0.7 prior surgical resections before MRgLITT was performed. 41% (n = 22) of patients were on dexamethasone at the time of treatment. The median pre-operative enhancing lesion volume on T1 gadolinium-enhanced magnetic resonance imaging (MRI) was 9.7 cm3 (standard error [SE], 2.0 cm3) and 27.0 cm3 (SE, 5.6 cm3) on T2 fluid-attenuated inversion recovery MRI. The pathology of the biopsies taken during MRgLITT confirmed tumor recurrence in 61% (n = 33) of patients, and treatment effect or reactive changes in 37% (n = 20) of patients. 67% (n = 28) experienced radiographic evidence of progression of the previously treated lesion, while 21% (n =9) and 12% (n = 5) experienced progression of a new lesion or both, respectively. Progression-free survival after MRgLITT was 3.5 months (standard error [SE], 0.6; 95% CI, 2.4-4.6). At the time of the study, 78% (n = 42) of patients were deceased. Mean overall survival time was 29.9 months (SE, 4.3; 95% CI, 21.4-38.3). Mean survival time after MRgLITT was 8.3 months (SE, 1.2; 95% CI, 5.9-10.6. Of the 12 remaining living patients, 36% (n = 4) had a decline in their clinical status at the time of last follow up, while 64% (n = 7) and 9% (n = 1) were stable or improved, respectively. Patients were followed for a mean time interval of 9.25 ± 12.2 months from MRgLITT. CONCLUSION: MRgLITT may be a viable, minimally invasive option for patients with glioblastoma but is associated with relatively short post-treatment progression-free survival.

Optimization and decision-making of novel laser-induced thermal therapy for deep-lying tumor based on multi-objective genetic algorithm and three-way decisions method

In this paper, we develop novel laser-induced thermal therapy (LITT) schemes, multiple and single rotating laser irradiation, for deep-lying breast tumor to maximize tumor killing while minimizing normal tissue damage and preventing the surface overheating without the aid of external media such as nanoparticles and photosensitizers. Combined with numerical simulation and multi-objective genetic algorithm (MOGA), the incident angle, radius, intensity and exposure time of the multiple laser irradiation, as well as the rotational period and exposure time of the single rotating laser irradiation are optimized based on the surface response model, and a series of Pareto-optimal solutions are obtained. The three-way decisions method is utilized to effectively manage the Pareto-optimal solutions and select the ideal solution with a comprehensive consideration of the risk preferences (aversion, proneness and neutralness) of the surgeon. Compared with the traditional LITT, the ideal solution selected by the operator with risk neutralness attitude makes the surface temperature maintain at an acceptable level, and the killing volume of normal tissue is reduced by 80.4% for the multiple laser irradiation and 99.74% for the single rotating laser irradiation in the case of complete tumor killing. Results obtained can be employed as a guideline for the selection of LITT regimens for deep-lying breast tumor under consideration of the surgeon’s risk preferences.

OD179 - MR-guided laser-induced thermal therapy: the role of medical physicist in implementation

OD179 - MR-guided laser-induced thermal therapy: the role of medical physicist in implementation

Blood-Brain Barrier in Brain Tumors: Biology and Clinical Relevance.

The presence of barriers, such as the blood–brain barrier (BBB) and brain–tumor barrier (BTB), limits the penetration of antineoplastic drugs into the brain, resulting in poor response to treatments. Many techniques have been developed to overcome the presence of these barriers, including direct injections of substances by intranasal or intrathecal routes, chemical modification of drugs or constituents of BBB, inhibition of efflux pumps, physical disruption of BBB by radiofrequency electromagnetic radiation (EMP), laser-induced thermal therapy (LITT), focused ultrasounds (FUS) combined with microbubbles and convection enhanced delivery (CED). However, most of these strategies have been tested only in preclinical models or in phase 1–2 trials, and none of them have been approved for treatment of brain tumors yet. Concerning the treatment of brain metastases, many molecules have been developed in the last years with a better penetration across BBB (new generation tyrosine kinase inhibitors like osimertinib for non-small-cell lung carcinoma and neratinib/tucatinib for breast cancer), resulting in better progression-free survival and overall survival compared to older molecules. Promising studies concerning neural stem cells, CAR-T (chimeric antigen receptors) strategies and immunotherapy with checkpoint inhibitors are ongoing.

Thermo-vibrational analyses of skin tissue subjected to laser heating source in thermal therapy

Laser-induced thermal therapy, due to its applications in various clinical treatments, has become an efficient alternative, especially for skin ablation. In this work, the two-dimensional thermomechanical response of skin tissue subjected to different types of thermal loading is investigated. Considering the thermoelastic coupling term, the two-dimensional differential equation of heat conduction in the skin tissue based on the Cattaneo–Vernotte heat conduction law is presented. The two-dimensional differential equation of the tissue displacement coupled with the two-dimensional hyperbolic heat conduction equation in the tissue is solved simultaneously to analyze the thermal and mechanical response of the skin tissue. The existence of mixed complicated boundary conditions makes the problem so complex and intricate. The Galerkin-based reduced-order model has been utilized to solve the two-sided coupled differential equations of vibration and heat transfer in the tissue with accompanying complicated boundary conditions. The effect of various types of heating sources such as thermal shock, single and repetitive pulses, repeating sequence stairs, ramp-type, and harmonic-type heating, on the thermomechanical response of the tissue is investigated. The temperature distribution in the tissue along depth and radial direction is also presented. The transient temperature and displacement response of tissue considering different relaxation times are studied, and the results are discussed in detail.

Potential surgical therapies for drug-resistant focal epilepsy.

Drug‐resistant focal epilepsy (DRFE), defined by failure of two antiepileptic drugs, affects 30% of epileptic patients. Epilepsy surgeries are alternative options for this population. Preoperative evaluation is critical to include potential candidates, and to choose the most appropriate procedure to maximize efficacy and simultaneously minimize side effects. Traditional procedures involve open skull surgeries and epileptic focus resection. Alternatively, neuromodulation surgeries use peripheral nerve or deep brain stimulation to reduce the activities of epileptogenic focus. With the advanced improvement of laser‐induced thermal therapy (LITT) technique and its utilization in neurosurgery, magnetic resonance‐guided LITT (MRgLITT) emerges as a minimal invasive approach for drug‐resistant focal epilepsy. In the present review, we first introduce drug‐resistant focal epilepsy and summarize the indications, pros and cons of traditional surgical procedures and neuromodulation procedures. And then, focusing on MRgLITT, we thoroughly discuss its history, its technical details, its safety issues, and current evidence on its clinical applications. A case report on MRgLITT is also included to illustrate the preoperational evaluation. We believe that MRgLITT is a promising approach in selected patients with drug‐resistant focal epilepsy, although large prospective studies are required to evaluate its efficacy and side effects, as well as to implement a standardized protocol for its application.

Anisotropic scattering characteristics of nanoparticles in different morphologies: improving the temperature uniformity of tumors during thermal therapy using forward scattering.

Precise control of the thermal damage area is the key issue during thermal therapy, which can be achieved by manipulating the light propagation in biological tissue. In the present work, a method is proposed to increase the uniformity of the specific absorption rate (SAR) distribution in tumors during laser-induced thermal therapy, which is proved to be effective in reducing the thermal damage of healthy tissue. In addition, a better way of manipulating light propagation in biological tissue is explored. It is found that the anisotropic scattering characteristics of nanoparticles are strongly dependent on their shapes, sizes, orientations, and incident wavelengths, which will strongly affect the light propagation in nanoparticle embedded biological tissue. Therefore, to obtain a better outcome from photothermal therapy, the scattering properties of nanoparticles are very important factors that need to be taken into consideration, along with the absorption efficiency. Further investigation finds that nanoparticles that predominantly scatter to the forward direction are favorable in obtaining a larger penetration depth of light, which will improve the uniformity of SAR and temperature distributions. This paper is meaningful for the application of nanoparticle-assisted laser-induced thermal therapy.

Functional Hemispherotomy Using Magnetic Resonance (MR)-Guided Laser Induced Thermal Therapy (LITT)

Functional Hemispherotomy Using Magnetic Resonance (MR)-Guided Laser Induced Thermal Therapy (LITT)

Passive control of temperature distribution in cancerous tissue during photothermal therapy using optical phase change nanomaterials

Thermal therapy is a very promising alternative treatment for benign tumor, in which the temperature control is a key issue to avoid unwanted thermal damage of healthy tissue. However, the active temperature control methods usually require the assistance of real-time and accurate temperature monitoring devices. Even though, the lag of temperature control is inevitable. Therefore, in the present work, a passive control method is proposed to improve the uniformity of temperature distribution inside tumorous tissue during laser induced thermal therapy (LITT). Optical phase change nanoparticles (O-PCNPs) are utilized to replace the commonly used noble metal nanoparticles to enhance and adjust the localized light absorption in tumor. In the early stage of LITT, the O-PCNPs is used to improve the specific absorption rate in the targeted region. However, after the local temperature reaches a certain level (phase transition temperature), the O-PCNPs convert from amorphous state to crystalline state. By carefully selecting the size, shape, and laser wavelength, the absorption cross section of O-PCNPs could drop dramatically after phase transition. Therefore, in the high temperature zone the local temperature increasing rate reduces due to the reduction of local heat generation rate. On the contrary, the temperature increasing rate rises in the low temperature zone since more energy is transferred to the deeper tissue. In the present work, results show that SiO2@VO2 nanoshells can be applied as thermal contrast agents to improve the temperature uniformity in tumor during LITT.

Proton Resonance Frequency Shift Thermometry: A Review of Modern Clinical Practices.

Magnetic resonance imaging (MRI) has become a popular modality in guiding minimally invasive thermal therapies, due to its advanced, nonionizing, imaging capabilities and its ability to record changes in temperature. A variety of MR thermometry techniques have been developed over the years, and proton resonance frequency (PRF) shift thermometry is the current clinical gold standard to treat a variety of cancers. It is used extensively to guide hyperthermic thermal ablation techniques such as high-intensity focused ultrasound (HIFU) and laser-induced thermal therapy (LITT). Essential attributes of PRF shift thermometry include excellent linearity with temperature, good sensitivity, and independence from tissue type. This noninvasive temperature mapping method gives accurate quantitative measures of the temperature evolution inside biological tissues. In this review, the current status and new developments in the fields of MR-guided HIFU and LITT are presented with an emphasis on breast, prostate, bone, uterine, and brain treatments. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 3.

Characterization of Magnetic Resonance Thermal Imaging Signal Artifact During Magnetic Resonance Guided Laser-Induced Thermal Therapy.

Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive procedure that utilizes intraoperative magnetic resonance thermal imaging (MRTI) to generate a thermal damage estimate (TDE) of the ablative area. In select cases, the MRTI contains a signal artifact or defect that distorts the ablative region. No study has attempted to characterize this artifact. To characterize MRTI signal the artifact in select cases to better understand its potential relevance and impact on the ablation procedure. All ablations were performed using the Visualase magnetic resonance imaging-guided laser ablation system (Medtronic). Patients were included if the MRTI contained signal artifact that distorted the ablative region during the first thermal dose delivered. Ablation artifact was quantified using MATLAB version R2018a (Mathworks Inc, Natick, Massachusetts). A total of 116 patients undergoing MRgLITT for various surgical indications were examined. MRTI artifact was observed in 37.0% of cases overall. Incidence of artifact was greater at higher powers (P<.001) and with longer ablation times (P=.024), though artifact size did not correlate with laser power or ablation duration. MRTI signal artifact is common during LITT. Higher powers and longer ablation times result in greater incidence of ablation artifact, though artifact size is not correlated with power or duration. Future studies should aim to evaluate effects of artifact on postoperative imaging and, most notably, patient outcomes.

Commentary: Characterization of Magnetic Resonance Thermal Imaging Signal Artifact During Magnetic Resonance Guided Laser-Induced Thermal Therapy.

Commentary: Characterization of Magnetic Resonance Thermal Imaging Signal Artifact During Magnetic Resonance Guided Laser-Induced Thermal Therapy.

Multiple Iterations of Magnetic Resonance-Guided Laser Interstitial Thermal Ablation of Brain Metastases: Single Surgeon's Experience and Review of the Literature.

Prior treatment with magnetic resonance-guided, laser-induced thermal therapy (LITT) is widely assumed not to be a contraindication for further treatment of brain lesions, including further iterations of LITT. However, the safety and efficacy of repeat LITT treatments have never been formally investigated. To evaluate treatment with multiple iterations of LITT. All patients treated with LITT at least twice at our institution were included in the study. Outcomes and neurological examinations from before and after surgery were retrospectively examined from clinic notes. Perilesonal edema was determined at various timepoints using volumetric data derived from manual tracings of fluid-attenuated inversion recovery (FLAIR) enhancement on magnetic resonance imaging (MRI). Finally, a literature review of prior cases of repeat LITT was performed. A total of 9 patients underwent 18 treatments with LITT; all but 1 of whom were treated for metastatic brain lesions. One patient had a transient cerebrospinal fluid leak, whereas a second patient had a superficial wound infection, both of which resolved with standard medical care. The remaining 7 patients tolerated all LITT procedures without complication. Analysis of perilesional edema volume demonstrated a correlation with the amount of energy delivered during LITT. Literature review found 5 published papers describing 9 patients who underwent LITT more than once, the majority of whom tolerated repeat LITT well. LITT is a safe and promising treatment modality and may be used multiple times without issue. There appears to be an association between the amount of energy delivered during a LITT session and the degree of postoperative perilesional edema.

Characteristic analysis of light and heat transfer in photothermal therapy using multiple-light-source heating strategy

Nanoparticles enhanced laser-induced thermal therapy (LITT) is an emerging method for early stage tumor treatment. One of the major issues challenging this technique is the accurate heating of the cancerous tissue without influencing the nearby healthy tissue. Owning to its outstanding optical, chemical, and biological properties, gold nanoparticles (GNPs) have been frequently applied to act as nanosource of heat for selective heating of tumor. In the present work, we studied the GNPs enhanced LITT theoretically. The bioheat transfer model under laser irradiation was established by the finite element method. The influences of laser intensity, GNPs volume fraction, anisotropic scattering characteristics of nanoparticles, convective heat transfer coefficient, and laser incident angle were investigated, respectively. On this basis, different treatment strategies, i.e. single heat source and multiple heat sources, were also explored. It is found that for single dose therapy, i.e. the whole tumor was damaged in one-time treatment, the efficacy is almost the same for oblique and vertical laser incident. However, for fractionated therapy, i.e. the tumor was totally damage after a series of treatments, the efficacy of oblique laser irradiation is better than that of vertical laser irradiation. Furthermore, the hyperthermia efficacy of multiple heat sources is much better than that of single heat source, which means that it can be applied in GNPs enhanced LITT to improve the photothermal therapy efficacy.