Laser Ablation for Cancer: Past, Present and Future

Photoactivated Gas-Generating Nanocontrast Agents for Long-Term Ultrasonic Imaging-Guided Combined Therapy of Tumors

To date, long-term and continuous ultrasonic imaging for guiding the puncture biopsy remains a challenge. In order to address this issue, a multimodality imaging and therapeutic method was developed in the present study to facilitate long-term ultrasonic and fluorescence imaging-guided precision diagnosis and combined therapy of tumors. In this regard, certain types of photoactivated gas-generating nanocontrast agents (PGNAs), capable of exhibiting both ultrasonic and fluorescence imaging ability along with photothermal and sonodynamic function, were designed and fabricated. The advantages of these fabricated PGNAs were then utilized against tumors in vivo, and high therapeutic efficacy was achieved through long-term ultrasonic imaging-guided treatment. In particular, the as-prepared multifunctional PGNAs were applied successfully for the fluorescence-based determination of patient tumor samples collected through puncture biopsy in clinics, and superior performance was observed compared to the clinically used SonoVue contrast agents that are incapable of specifically distinguishing the tumor in ex vivo tissues.

Computed tomography guided electromagnetic navigation system in percutaneous laser ablation for treating primary lung cancer: a case report

Background

The majority of patients of lung cancer have already lost the chance of surgery at the time of diagnosis. Percutaneous local thermal ablation is a precise minimally invasive technique and a viable alternative to surgical treatment. Compared with radiofrequency ablation and microwave ablation, percutaneous laser ablation for the treatment of lung tumors is less commonly used and reported, especially for primary lung cancer.

Case presentation

A 63-year-old male patient with mixed pulmonary nodules selected computed tomography-guided electromagnetic navigation system for percutaneous biopsy and laser ablation therapy. The puncture point was determined through Computed tomography scanning, along with the placement of the electromagnetic navigation system locators. After rapid on-site evaluation and pathological examination of the puncture tissue specimen, the diagnosis of lung adenocarcinoma was confirmed. A 980-nanometer wavelength semiconductor laser fiber was inserted into the appropriate position guided by the electromagnetic navigation system. Subsequently, a power of 7 watt was applied to ablate the tumor for 30 seconds, then pause for 60 seconds before repeating the procedure. Positron emission tomography-Computed tomography examination was performed 1 month after operation, suggesting complete response of the tumor.

Conclusion

Here, we present a case of percutaneous laser ablation treatment for primary lung cancer guided by computed tomography-electromagnetic navigation system. As a more precise, shorter duration, impedance-independent, safe and effective minimally invasive thermal ablation method, it is expected to gain wider application and become a novel alternative for surgical treatment.

Tissue Ablation: Applications and Perspectives

Tissue ablation techniques have emerged as a critical component of modern medical practice and biomedical research, offering versatile solutions for treating various diseases and disorders. Percutaneous ablation is minimally invasive and offers numerous advantages over traditional surgery, such as shorter recovery times, reduced hospital stays, and decreased healthcare costs. Intra-procedural imaging during ablation also allows precise visualization of the treated tissue while minimizing injury to the surrounding normal tissues, reducing the risk of complications. Here, the mechanisms of tissue ablation and innovative energy delivery systems are explored, highlighting recent advancements that have reshaped the landscape of clinical practice. Current clinical challenges related to tissue ablation are also discussed, underlining unmet clinical needs for more advanced material-based approaches to improve the delivery of energy and pharmacology-based therapeutics.

Light exposure and its applications in human health

Light exposure has been proven to have a significant impact on human health. As a result, researchers are increasingly exploring its potential benefits and drawbacks. With advancements in understanding light and the manufacturing of light sources, modern health lighting has become widely utilized in daily life and plays a critical role in the prevention and treatment of various illnesses. The use of light in healthcare is a global trend, with many countries actively promoting the development and application of relevant scientific research and medical technology. This field has gained worldwide attention and support from scientists and doctors alike. In this review, we examine the application of lighting in human health and recent breakthroughs in light exposure related to pathology, therapeutic strategies, molecular changes, and more. Finally, we also discuss potential future developments and areas of application.

Shining Light in Mechanobiology: Optical Tweezers, Scissors, and Beyond

Mechanobiology helps us to decipher cell and tissue functions by looking at changes in their mechanical properties that contribute to development, cell differentiation, physiology, and disease. Mechanobiology sits at the interface of biology, physics and engineering. One of the key technologies that enables characterization of properties of cells and tissue is microscopy. Combining microscopy with other quantitative measurement techniques such as optical tweezers and scissors, gives a very powerful tool for unraveling the intricacies of mechanobiology enabling measurement of forces, torques and displacements at play. We review the field of some light based studies of mechanobiology and optical detection of signal transduction ranging from optical micromanipulation-optical tweezers and scissors, advanced fluorescence techniques and optogenentics. In the current perspective paper, we concentrate our efforts on elucidating interesting measurements of forces, torques, positions, viscoelastic properties, and optogenetics inside and outside a cell attained when using structured light in combination with optical tweezers and scissors. We give perspective on the field concentrating on the use of structured light in imaging in combination with tweezers and scissors pointing out how novel developments in quantum imaging in combination with tweezers and scissors can bring to this fast growing field.

Comparative efficacies and safeties of cylindrical interstitial laser ablation and radiofrequency ablation on swine pancreas

Laser ablation (LA) has been evaluated for the minimally invasive thermal treatment of various cancers, but conventional unidirectional endoscopic ultrasound (EUS)-guided LA has limitations. Therefore, we developed a cylindrical laser diffuser to overcome the limitations of unidirectional EUS-guided LA. The purpose of this study was to compare the efficacies and safeties of EUS-guided LA using a novel cylindrical laser diffuser and radiofrequency ablation (RFA) in vivo in swine pancreas. EUS-guided RFA (15 W, 30 s, 450 J) and cylindrical interstitial LA (CILA) (5 W, 90 s, 450 J) were applied to normal pancreatic tissue in six anesthetized pigs (three per group). Laboratory tests were performed at baseline, immediately after ablation (day 0), and 2 days after procedures (day 2). Two days after procedures, all pigs were sacrificed, and histopathological safety and efficacy assessments were performed. Technically, EUS-guided RFA and CILA were performed successfully in all cases. No major complications, including perforation or acute pancreatitis, occurred during the experiment in either group. All animals remained in excellent condition throughout the experimental period, and laboratory tests provided no evidence of a major complication. Average necrotic volumes in the RFA and CILA groups were 424.2 mm3 and 3747.4 mm3, respectively, and average necrotic volume was significantly larger in CILA group (p < 0.001). EUS-guided RFA and CILA had acceptable safety profiles in the normal swine pancreas model. Our findings indicate EUS-guided CILA has potential for the effective local treatment of pancreatic cancer as an alternative to EUS-guided RFA.

The State-of-the-Art and Perspectives of Laser Ablation for Tumor Treatment

Tumors significantly impact individuals' physical well-being and quality of life. With the ongoing advancements in optical technology, information technology, robotic technology, etc., laser technology is being increasingly utilized in the field of tumor treatment, and laser ablation (LA) of tumors remains a prominent area of research interest. This paper presents an overview of the recent progress in tumor LA therapy, with a focus on the mechanisms and biological effects of LA, commonly used ablation lasers, image-guided LA, and robotic-assisted LA. Further insights and future prospects are discussed in relation to these aspects, and the paper proposed potential future directions for the development of tumor LA techniques.

A photothermal driven chemotherapy for the treatment of metastatic melanoma

Solid tumors are abnormal mass of tissue, which affects the organs based on its malignancy and leads to the dysfunction of the affected organs. The major problem associated with treatment of solid tumors is delivering anticancer therapeutics to the deepest layers/core of the solid tumor. Deposition of excessive extracellular matrix (ECM) hinders the therapeutics to travel towards the core of the tumor. Therefore, conventional anticancer therapeutics can only reduce the tumor size and that also for a limited duration, and tumor recurrence occurs once the therapy is discontinued. Additionally, by the time the cancer is diagnosed, the cancer cells already started affecting the major organs of the body such as lung, liver, spleen, kidney, and brain, due to their ability to metastasize and lung is the primary site for them to be infiltrated. To facilitate the anticancer therapeutics to penetrate the deeper layers of tumor, and to provide concurrent treatment of both the solid tumor and metastasis, we have designed and developed a Bimodal Light Assisted Skin Tumor and Metastasis Treatment (BLAST), which is a combination of photothermal and chemotherapeutic moieties. The BLAST is composed of 2D boron nitride (BN) nanosheet with adsorbed molecules of BCL-2 inhibitor, Navitoclax (NAVI) on its surface, that can breakdown excessive ECM network and thereby facilitate dissociation of the solid tumor. The developed BLAST was evaluated for its ability to penetrate solid tumors using 3D spheroids for the uptake, cytotoxicity, growth inhibition, reactive oxygen species (ROS) detection, penetration, and downregulation of proteins upon laser irradiation. The in vivo therapeutic studies on a skin cancer mice model revealed that the BLAST with and without laser were able to penetrate the solid tumor, reduce tumor volume in mice, dissociate the protein network, and prevent lung metastasis as confirmed by immunohistochemistry and western blot analysis. Post analysis of serum and blood components revealed the safety and efficacy of BLAST in mice. Hence, the developed BLAST holds strong promise in solid tumor treatment and metastasis prevention simultaneously.

Miniaturised dual-modality all-optical ultrasound probe for laser interstitial thermal therapy (LITT) monitoring

All-optical ultrasound (OpUS) has emerged as an imaging paradigm well-suited to minimally invasive imaging due to its ability to provide high resolution imaging from miniaturised fibre optic devices. Here, we report a fibre optic device capable of concurrent laser interstitial thermal therapy (LITT) and real-time in situ all-optical ultrasound imaging for lesion monitoring. The device comprised three optical fibres: one each for ultrasound transmission, reception and thermal therapy light delivery. This device had a total lateral dimension of <1 mm and was integrated into a medical needle. Simultaneous LITT and monitoring were performed on ex vivo lamb kidney with lesion depth tracked using M-mode OpUS imaging. Using one set of laser energy parameters for LITT (5 W, 60 s), the lesion depth varied from 3.3 mm to 8.3 mm. In all cases, the full lesion depth could be visualised and measured with the OpUS images and there was a good statistical agreement with stereomicroscope images acquired after ablation (t=1.36, p=0.18). This work demonstrates the feasibility and potential of OpUS to guide LITT in tumour resection.

Combining energy-based focal ablation and immune checkpoint inhibitors: preclinical research and clinical trials

Energy-based focal therapy (FT) uses targeted, minimally invasive procedures to destroy tumors while preserving normal tissue and function. There is strong emerging interest in understanding how systemic immunity against the tumor can occur with cancer immunotherapy, most notably immune checkpoint inhibitors (ICI). The motivation for combining FT and ICI in cancer management relies on the synergy between the two different therapies: FT complements ICI by reducing tumor burden, increasing objective response rate, and reducing side effects of ICI; ICI supplements FT by reducing local recurrence, controlling distal metastases, and providing long-term protection. This combinatorial strategy has shown promising results in preclinical study (since 2004) and the clinical trials (since 2011). Understanding the synergy calls for understanding the physics and biology behind the two different therapies with distinctive mechanisms of action. In this review, we introduce different types of energy-based FT by covering the biophysics of tissue-energy interaction and present the immunomodulatory properties of FT. We discuss the basis of cancer immunotherapy with the emphasis on ICI. We examine the approaches researchers have been using and the results from both preclinical models and clinical trials from our exhaustive literature research. Finally, the challenges of the combinatory strategy and opportunities of future research is discussed extensively.

Real-time automatic temperature regulation during in vivo MRI-guided laser-induced thermotherapy (MR-LITT)

Precise control of tissue temperature during Laser-Induced Thermotherapy (LITT) procedures has the potential to improve the clinical efficiency and safety of such minimally invasive therapies. We present a method to automatically regulate in vivo the temperature increase during LITT using real-time rapid volumetric Magnetic Resonance thermometry (8 slices acquired every second, with an in-plane resolution of 1.4 mmx1.4 mm and a slice thickness of 3 mm) using the proton-resonance frequency (PRF) shift technique. The laser output power is adjusted every second using a feedback control algorithm (proportional-integral-derivative controller) to force maximal tissue temperature in the targeted region to follow a predefined temperature-time profile. The root-mean-square of the difference between the target temperature and the measured temperature ranged between 0.5 °C and 1.4 °C, for temperature increases between + 5 °C to + 30 °C above body temperature and a long heating duration (up to 15 min), showing excellent accuracy and stability of the method. These results were obtained on a 1.5 T clinical MRI scanner, showing a potential immediate clinical application of such a temperature controller during MR-guided LITT.

Photoresponsive Inorganic Nanomaterials in Oncology

The diagnosis and treatment of cancer are continuously evolving in search of more efficient, safe, and personalized approaches. Therapies based on nanoparticles or physical stimuli-responsive substances have shown great potential to overcome the inherent shortcomings of conventional cancer therapies. In fact, nanoparticles may increase the half-life of chemotherapeutic agents or promote the targeting in cancer tissues while physical stimuli-responsive substances are more effective and safer with respect to traditional chemotherapeutic agents because of the possibility to be switched on only when needed. These 2 approaches can be combined by exploiting the ability of some inorganic nanomaterials to be activated by light, ultrasounds, magnetic fields, or ionizing radiations. Albeit the development of stimuli-responsive materials is still at the early stages, research in this field is rapidly growing since they have important advantages with respect to organic nanoparticles or molecular substances, like higher stability, and higher efficiency in converting the stimulus in heat or, in some cases, reactive oxygen species. On the other hand, the translation process is slowed down by issues related to safety and quality of the formulations. This literature review summarizes the current advancements in this research field, analysing the most promising materials and applications.

Optical Fiber Distributed Sensing Network for Thermal Mapping in Radiofrequency Ablation Neighboring a Blood Vessel

Radiofrequency ablation (RFA) is a minimally invasive form of thermotherapy with great potential in cancer care, having the capability of selectively ablating tumoral masses with a surface area of several cm². When performing RFA in the proximity of a blood vessel, the heating profile changes due to heat dissipation, perfusion, and impedance changes. In this work, we provide an experimental framework for the real-time evaluation of 2D thermal maps in RFA neighboring a blood vessel; the experimental setup is based on simultaneous scanning of multiple fibers in a distributed sensing network, achieving a spatial resolution of 2.5 × 4 mm² in situ. We also demonstrate an increase of ablating potential when injecting an agarose gel in the tissue. Experimental results show that the heat-sink effect contributes to a reduction of the ablated region around 30-60% on average; however, the use of agarose significantly mitigates this effect, enlarging the ablated area by a significant amount, and ablating an even larger surface (+15%) in the absence of blood vessels.

Nanoparticles-based phototherapy systems for cancer treatment: Current status and clinical potential

Remarkable progress in phototherapy has been made in recent decades, due to its non-invasiveness and instant therapeutic efficacy. In addition, with the rapid development of nanoscience and nanotechnology, phototherapy systems based on nanoparticles or nanocomposites also evolved as an emerging hotspot in nanomedicine research, especially in cancer. In this review, first we briefly introduce the history of phototherapy, and the mechanisms of phototherapy in cancer treatment. Then, we summarize the representative development over the past three to five years in nanoparticle-based phototherapy and highlight the design of the innovative nanoparticles thereof. Finally, we discuss the feasibility and the potential of the nanoparticle-based phototherapy systems in clinical anticancer therapeutic applications, aiming to predict future research directions in this field. Our review is a tutorial work, aiming at providing useful insights to researchers in the field of nanotechnology, nanoscience and cancer.

Endoscopic Ultrasound-Guided Pancreatic Interstitial Laser Ablation Using a Cylindrical Laser Diffuser: A Long-Term Follow-Up Study

BACKGROUND AND AIMS

Local ablative treatment is another option for improving outcomes and has been evaluated for locally advanced pancreatic cancer. We previously suggested endoscopic ultrasound (EUS)-guided interstitial laser ablation using a cylindrical laser diffuser (CILA) might be a feasible therapeutic option based on experiments performed on pancreatic cancer cell lines and porcine model with a short follow-up (3 days). The aim of this study was to investigate the safety of EUS-CILA performed using optimal settings in porcine pancreas with a long-term follow-up (2 weeks).

METHODS

EUS-CILA (laser energy of 450 J; 5 W for 90 s) was applied to normal pancreatic tissue in porcine (n = 5) under EUS guidance. Animals were observed clinically for 2 weeks after EUS-CILA to evaluate complications. Computed tomography and laboratory tests were carried out to evaluate safety. Two weeks after EUS-CILA, all pigs were sacrificed, and histopathological safety and efficacy evaluations were conducted.

RESULTS

EUS-CILA was technically successful in all five cases. No major complications occurred during the follow-up period. Body weight of porcine did not change during the study period without any significant change in feed intake. Animals remained in excellent condition throughout the experimental period, and laboratory tests and computed tomography (CT) scans provided no evidence of a major complication. Histopathological evaluation showed complete ablation in the ablated area with clear delineation of surrounding normal pancreatic tissue. Mean ablated volume was 55.5 mm² × 29.0 mm and mean ablated areas in the pancreatic sections of the five pigs were not significantly different (p = 0.368).

CONCLUSIONS

In conclusion, our experimental study suggests that EUS-CILA is safe and has the potential to be an effective local treatment modality. No major morbidity or mortality occurred during the study period. Further evaluations are warranted before clinical application.

Current Trends in Anticancer Drug Delivery System for Oral Cancer- A PRISMA complaint Systematic Review

Background:

Oral cancer is a deadly disease affecting worldwide. Despite developments of conventional cancer therapy, there has been little improvement in the survival rates. This culminated in the evolution of a targeted. New Drug Delivery System, discovering novel objectives for successful drug delivery and synergistic combination of anticancer agents to minimize side effects.

Objective:

The main focus was on understanding the various aspects of different targeted drug delivery vehicles used in the treatment of oral cancer including advantages, disadvantages, and future perspectives.

Materials and Methods:

A literature search was accomplished from 2005 to 2020 via Google scholar. PubMed, EBSCO, Embase, and Scopus databases along with Clinical trials registries using the terms oral buccal thin films, Hyperthermia and Thermoablation, Intra-tumoral, Photodynamic, Immunotherapy, photothermal, and ultrasound therapy in oral cancer. The articles were scrutinized and those which were not relevant to our search were omitted. Clinical trials on targeted drug delivery systems for Oral Cancer being conducted or completed around the world from various registries of clinical trials have also been searched out and the findings were tabulated in the end. The PRISMA 2020 guidelines were followed.

Results:

The treatment of oral squamous cell carcinoma (OSCC) mostly depends upon the location, type, and stage of the tumor. Vivid targeted drug delivery systems are being used in the therapeutic interventions of oral cancer as they aim for specific target site delivery and are the most appropriate treatment. Active Pharmacological Ingredient (API) is taken to the targeting site, sparing non-target organs or cells, triggering selective and efficient localization, thereby maximizing the therapeutic index with minimizing toxicity. The successful targeted drug delivery system works on four principles i.e. Retain, Evade, Target and Release, which means loading of sufficient drug into a suitable drug carrier, does not affect body secretions, long duration in circulation, reaching the targeted site and, drug release within the time for effective functioning of the drug. All techniques described in this paper have proven to show effective results.

Conclusion:

Oral Cancer is an emerging public health problem worldwide. Various conventional therapies are used for treating oral cancer, but they enclose variable degrees of side effects both on the body as well as the cellular microenvironment. With advanced technology, many other aids have been introduced in the field of oncology to treat oral cancer with minimal side effects. All techniques described in this paper have proven to show effective results in the therapeutic interventions of oral cancer. Moreover, they can be used even in combination with conventional drug therapy to show beneficial outcomes. Several clinical trials are being conducted and completed in this aspect to investigate definite results of these therapies, yet robust research is needed for further confirmation.

Guide mapping for effective superficial photothermal coagulation of the esophagus using computer simulations with ex vivo sheep model validation study

OBJECTIVES

The transfer and widespread acceptance of laser-induced thermal therapy into gastroenterology remain a topic of interest. However, a practical approach to the quantitative effect of photothermal injury in the esophagus needs further investigation. Here, we aim to perform computer simulations that simulate laser scanning and calculate the laser-induced thermal damage area. The simulation engine offers the results in a guide map for laser coagulation with a well-confined therapeutic area according to laser irradiance and surface scanning speed. The study also presents validation experiments that include histology analyses in an ex vivo sheep esophagus model.

METHODS

The simulation engine was developed based on the Monte-Carlo method and the Arrhenius damage integral. The computational model mimicked laser scanning by shifting the position of the calculated heat source in the grating system along the axis to be scanned. The performance of the simulations was tested in an ex vivo sheep esophagus model at a laser wavelength of 1505 nm. Histological analysis, hematoxylin-eosin staining, light microscope imaging, and block-face scanning electron microscopy were used to assess thermal damage to the tissue model.

RESULTS

The developed simulation engine estimated the photothermal coagulation area for a surface scanning speed range of 0.5-8 mm/second and laser power of up to 0.5 W at a 0.9-nm laser diameter in a tissue model with a volume of 4 × 4 × 4 mm³ . For example, the optimum laser irradiation for effective photothermal coagulation in the mucosa and superficial submucosa depths was estimated to be between 16.4 and 31.8 W/cm² , 23.2 and 38.1 W/cm² at 0.5 and 1 mm/second, respectively. The computational results, summarized as a guide map, were directly compared with the results of ex vivo tissue experiments. In addition, it was pointed out that the comparative theoretical and experimental data overlap significantly in terms of energy density.

CONCLUSIONS

Our results suggest that the developed simulation approach could be a seed algorithm for further preclinical and clinical trials and a complementary tool to the laser-induced photothermal coagulation technique for superficial treatments in the gastrointestinal tract. In future preclinical studies, it is thought that the simulation engine can be enriched by combining it with an in vivo model for different laser wavelengths.

Present Status of Thyroid Ablation in Europe: An International Survey among the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) Members

AIM

To evaluate the effective spread of image-guided thermal ablation in thyroid gland and to characterize its current perceptions among European interventional radiologists.

MATERIALS AND METHODS

A questionnaire with 29 multiple choice questions about thyroid ablation was sent as an E-blast to 4752 CIRSE members. Only those who completed the survey in all its parts were included in the study.

RESULTS

242/4752 (5.09%) participants (212 males and 30 females) completed and submitted the survey. A total of 160 subjects (66.1%) were familiar with any image-guided thermal ablations, but only 63 (26% of total population) usually perform thermal ablation for thyroid gland. Only 19.5% of the interviewed sample treats micropapillary thyroid tumours and the vast majority routinely uses radiofrequency ablation (84.4%).

CONCLUSION

There is a significant mismatch between thyroid ablation as reported by the literature and the relatively low percentage of interventional radiology actively performing such procedure in Europe. A considerable effort is required by the Cardiovascular and Interventional Radiological Society of Europe to fill this lack.

Laser ablation of pancreatic cancer using a cylindrical light diffuser

Pancreatic cancer (PC) is a leading cause of cancer death and its incidence and mortality have shown an increasing trend. Despite improvements in outcomes, another treatment option is required for PC. Laser ablation (LA) has been evaluated for the treatment of various types of cancer. The aim of this study was to assess the safety and feasibility of a novel cylindrical light diffuser in a xenograft model of PC. This study was performed using a customized high-power laser system. PANC-1 cells and BALB/c mice were used for experiments at a laser power of 5 W for 40 to 200 s at five different energy levels (n = 30). There was no acute bleeding or major complication. Using the cylindrical light diffuser, tumors were irradiated with similar size in each energy group. A correlation between laser dose and tumor necrosis was observed. Pearson's correlation for the relation between the amount of necrosis area and laser ablation energy on day 3 was 0.78 (p < 0.01). No statistical difference of necrosis area was exhibited when the necrosis area of each harvested tumor analyzed by dividing into 5 specimens for each energy. The study demonstrates that LA treatment using a cylindrical light diffuser induced remarkable tumor necrosis at histopathologic examinations. Laser ablation dosage and tumor response were strongly correlated, and the ablation procedure resulted in homogeneous tissue necrosis. No adverse event was encountered. These findings suggest that the devised cylindrical light diffuser offers a safe and effective means of treating pancreatic cancer.

Dual-modality fibre optic probe for simultaneous ablation and ultrasound imaging

All-optical ultrasound (OpUS) is an emerging high resolution imaging paradigm utilising optical fibres. This allows both therapeutic and imaging modalities to be integrated into devices with dimensions small enough for minimally invasive surgical applications. Here we report a dual-modality fibre optic probe that synchronously performs laser ablation and real-time all-optical ultrasound imaging for ablation monitoring. The device comprises three optical fibres: one each for transmission and reception of ultrasound, and one for the delivery of laser light for ablation. The total device diameter is < 1 mm. Ablation monitoring was carried out on porcine liver and heart tissue ex vivo with ablation depth tracked using all-optical M-mode ultrasound imaging and lesion boundary identification using a segmentation algorithm. Ablation depths up to 2.1 mm were visualised with a good correspondence between the ultrasound depth measurements and visual inspection of the lesions using stereomicroscopy. This work demonstrates the potential for OpUS probes to guide minimally invasive ablation procedures in real time.

Novel Tumor-Targeting Nanoparticles for Cancer Treatment—A Review

Being one of the leading causes of death and disability worldwide, cancer represents an ongoing interdisciplinary challenge for the scientific community. As currently used treatments may face limitations in terms of both efficiency and adverse effects, continuous research has been directed towards overcoming existing challenges and finding safer specific alternatives. In particular, increasing interest has been gathered around integrating nanotechnology in cancer management and subsequentially developing various tumor-targeting nanoparticles for cancer applications. In this respect, the present paper briefly describes the most used cancer treatments in clinical practice to set a reference framework for recent research findings, further focusing on the novel developments in the field. More specifically, this review elaborates on the top recent studies concerning various nanomaterials (i.e., carbon-based, metal-based, liposomes, cubosomes, lipid-based, polymer-based, micelles, virus-based, exosomes, and cell membrane-coated nanomaterials) that show promising potential in different cancer applications.

Modeling and ex vivo experimental validation of liver tissue carbonization with laser ablation

OBJECTIVE

The purpose of this study was to model the process of liver tissue carbonization with laser ablation (LA).

METHODS

A dynamic heat source model was proposed and combined with the light distribution model as well as bioheat transfer model to predict the development of tissue carbonization with laser ablation (LA) using an ex vivo porcine liver tissue model. An ex vivo laser ablation experiment with porcine liver tissues using a custom-made 1064 nm bare fiber was then used to verify the simulation results at 3, 5, and 7 W laser administrations for 5 min. The spatiotemporal temperature distribution was monitored by measuring the temperature changes at three points close the fiber during LA. Both the experiment and simulation of the temperature, tissue carbonization zone, and ablation zone were then compared.

RESULTS

Four stages were recognized in the development of liver tissue carbonization during LA. The growth of the carbonization zone along the fiber axial and radial directions were different in the four stages. The carbonization zone along the fiber axial direction (L2) grew in the four stages with a sharp increase in the initial period and a minor increase in Stage 4. However, the change in the carbonization zone along the fiber radial direction (D2) increased dramatically (Stage 1) to a long-time plateau (Stages 2 and 3) followed by a slow growth in Stage 4. An acceptable agreement between the computer simulation and ex vivo experiment in the temperature changes at the three points was found at all three testing laser administrations. A similar result was also obtained for the dimensions of coagulation zone and ablation zone between the computer simulation and ex vivo experiment (carbonization zone: 2.99± 0.10 vs. 2.78 mm², 67.39± 0.09 vs. 63.53 mm², and 90.53± 0.11 vs. 85.15 mm²; ablation zone: 68.95± 0.28 vs. 65.29 mm², 182.11± 0.24 vs. 213.81 mm², and 244.80± 0.06 vs. 251.79 mm² at 3, 5, and 7 W, respectively).

CONCLUSION

This study demonstrates that the proposed dynamic heat source model combined with the light distribution model as well as bioheat transfer model can predict the development of liver tissue carbonization with an acceptable accuracy. This study contributes to an improved understanding of the LA process in the treatment of liver tumors.

Photothermally-Heated Superparamagnetic Polymeric Nanocomposite Implants for Interstitial Thermotherapy

Photothermally-heated polymer-based superparamagnetic nanocomposite (SNC) implants have the potential to overcome limitations of the conventional inductively-heated ferromagnetic metallic alloy implants for interstitial thermotherapy (IT). This paper presents an assessment of a model SNC—poly-dimethylsiloxane (PDMS) and Fe3O4 nanoparticles (MNP)—implant for IT. First, we performed structural and optical characterization of the commercially purchased MNPs, which were added to the PDMS to prepare the SNCs (MNP weight fraction =10 wt.%) that were used to fabricate cubic implants. We studied the structural properties of SNC and characterized the photothermal heating capabilities of the implants in three different media: aqueous solution, cell (in-vitro) suspensions and agarose gel. Our results showed that the spherical MNPs, whose optical absorbance increased with concentration, were uniformly distributed within the SNC with no new bond formed with the PDMS matrix and the SNC implants generated photothermal heat that increased the temperature of deionized water to different levels at different rates, decreased the viability of MDA-MB-231 cells and regulated the lesion size in agarose gel as a function of laser power only, laser power or exposure time and the number of implants, respectively. We discussed the opportunities it offers for the development of a smart and efficient strategy that can enhance the efficacy of conventional interstitial thermotherapy. Collectively, this proof-of-concept study shows the feasibility of a photothermally-heated polymer-based SNC implant technique.

A Review of In Vitro Instrumentation Platforms for Evaluating Thermal Therapies in Experimental Cell Culture Models

Thermal therapies, the modulation of tissue temperature for therapeutic benefit, are in clinical use as adjuvant or stand-alone therapeutic modalities for a range of indications, and are under investigation for others. During delivery of thermal therapy in the clinic and in experimental settings, monitoring and control of spatio-temporal thermal profiles contributes to an increased likelihood of inducing desired bioeffects. In vitro thermal dosimetry studies have provided a strong basis for characterizing biological responses of cells to heat. To perform an accurate in vitro thermal analysis, a sample needs to be subjected to uniform heating, ideally raised from, and returned to, baseline immediately, for a known heating duration under ideal isothermal condition. This review presents an applications-based overview of in vitro heating instrumentation platforms. A variety of different approaches are surveyed, including external heating sources (i.e., CO2 incubators, circulating water baths, microheaters and microfluidic devices), microwave dielectric heating, lasers or the use of sound waves. We discuss critical heating parameters including temperature ramp rate (heat-up phase period), heating accuracy, complexity, peak temperature, and technical limitations of each heating modality.

Recent Progress of Sub-Nanometric Materials in Photothermal Energy Conversion

Sub-nanometric materials (SNMs) are an attractive scope in recent years due to their atomic-level size and unique properties. Among various performances of SNMs, photothermal energy conversion is one of the most important ones because it can efficiently utilize the light energy. Herein, the SNMs with photothermal energy conversion behaviors and their applications are reviewed. First, a hydrothermal/solvothermal method for the synthesis of SNMs is systematically discussed, including the LaMer pathway and the cluster-nuclei coassembly pathway. Based on this synthetic strategy, many kinds of SNMs with different morphologies are successfully prepared, such as nanorings, nanowires, nanosheets, and nanobelts. These SNMs exhibit excellent photothermal performance under the laser or solar irradiation according to their different light absorption ranges. These enhanced absorption performances of SNMs are induced by the mechanism of plasmonic localized heating or nonradiative relaxation. Finally, the applications of the photothermal SNMs are illustrated. The SNMs with photothermal behaviors can be widely applied in the fields of solar vapor generation, biomedicine, and light-responsive composites construction. It is hoped that this review can provide new viewpoints and profound understanding to the SNMs in photothermal energy conversion.

Radiofrequency ablation and related ultrasound-guided ablation technologies for treatment of benign and malignant thyroid disease: An international multidisciplinary consensus statement of the American Head and Neck Society Endocrine Surgery Section with the Asia Pacific Society of Thyroid Surgery, Associazione Medici Endocrinologi, British Association of Endocrine and Thyroid Surgeons, European Thyroid Association, Italian Society of Endocrine Surgery Units, Korean Society of Thyroid Radiology, Latin American Thyroid Society, and Thyroid Nodules Therapies Association

BACKGROUND

The use of ultrasound-guided ablation procedures to treat both benign and malignant thyroid conditions is gaining increasing interest. This document has been developed as an international interdisciplinary evidence-based statement with a primary focus on radiofrequency ablation and is intended to serve as a manual for best practice application of ablation technologies.

METHODS

A comprehensive literature review was conducted to guide statement development and generation of best practice recommendations. Modified Delphi method was applied to assess whether statements met consensus among the entire author panel.

RESULTS

A review of the current state of ultrasound-guided ablation procedures for the treatment of benign and malignant thyroid conditions is presented. Eighteen best practice recommendations in topic areas of preprocedural evaluation, technique, postprocedural management, efficacy, potential complications, and implementation are provided.

CONCLUSIONS

As ultrasound-guided ablation procedures are increasingly utilized in benign and malignant thyroid disease, evidence-based and thoughtful application of best practices is warranted.

Image-guided locoregional non-intravascular interventional treatments for hepatocellular carcinoma: Current status

Hepatocellular carcinoma (HCC) is one of the most deadly and frequent cancers worldwide, although great advancement in the treatment of this malignancy have been made within the past few decades. It continues to be a major health issue due to an increasing incidence and a poor prognosis. The majority of patients have their HCC diagnosed at an intermediate or advanced stage in theUSA or China. Curative therapy such as surgical resection or liver transplantation is not considered anoption of treatment at these stages.

Transarterial chemoembolization (TACE), the most widely used locoregional therapeutic approach, used to be the mainstay of treatment for cases with unresectable cancer entities. However, for those patients with hypovascular tumors or impaired liver function reserve, TACE is a suboptimal treatment option. For example, embolization does not result in complete coverage of a hypovascular tumor, and may rather promotes postoperative tumor recurrence, or leave residual tumor, in these TACE-resistance patients. In addition, TACE carries a higher risk of hepatic decompensation in patients with poor liver function or reserve.

Non-vascular interventional locoregional therapies for HCC include radiofrequency ablation (RFA), microwave ablation (MWA), high-intensity focused ultrasound (HIFU), laser-induced thermotherapy (LITT), cryosurgical ablation (CSA), irreversible Electroporation (IRE), percutaneous ethanol injection (PEI), and brachytherapy. Recent advancements in these techniques have significantly improved the treatment efficacy of HCC and expanded the population of patients who qualify for treatment. This review embraces the current status of imaging-guided locoregional non-intravascular interventional treatments for HCCs, with a primary focus on the clinical evaluation and assessment of the efficacy of combined therapies using these interventional techniques.

Laser Ablation Treatment of Recurrent Lymph Node Metastases from Papillary Thyroid Carcinoma

(1) Background: The incidence of papillary thyroid cancers is increasing. Papillary neoplasm metastasizes to the central and lateral lymph nodes of the neck. The recurrence rate is less than 30%. The gold standard of treatment for lymph node recurrences is surgery, but surgery is burdened by a high rate of complications. Therefore, laser ablation of recurrent lymph nodes has been recognized as an alternative treatment with minimal invasiveness, a low complication rate and a curative effect. (2) Methods: We analyzed 10 patients who underwent a total thyroidectomy and metabolic radiotherapy and who developed a lymph node recurrence in the laterocervical compartment in the following 12-18 months. (3) Results: Patients developed lymph node recurrence at IV and Vb levels in 70% and 30% of cases, respectively. All patients were treated with a single laser ablative session. Hydrodissection was performed in all patients. The energy delivered was 1120 ± 159.3 Joules and 3-4 Watts in 362 ± 45.7 s. No complications were reported. All patients underwent a 6-month follow-up. A volumetric reduction of 40.12 ± 2.2%, 49.1 ± 2.13% and 59.8 ± 3.05%, respectively at 1-, 3- and 6-months of follow-up was reported. (4) Conclusions: At 6 months, a fine needle aspiration was performed, which was negative for malignant cells and negative for a dosage of Thyroglobulin in eluate. The laser ablation is an effective alternative to surgical treatment.

A brief review of the essential role of nanovehicles for improving the therapeutic efficacy of pharmacological agents against tumours

Cancer is the leading cause of death globally. There are several differences between cancer cells and normal cells. From all the therapies, chemotherapy is the most prominent therapy to treat cancer. However, the conventional drug delivery that is used to deliver poorly aqueous soluble chemotherapeutic agents has several obstacles such as whole-body distribution, rapid excretion, degradation before reaching the infected site, side effects, etc. Nanoformulation of these aqueous insoluble agents is the emerging delivery system for targeted and increasing solubility. Among all the three methods (physical, chemical and biological) chemical and biological methods are mostly used for the synthesis of nanovehicles (NVs) of different sizes, shapes and dimensions. A passive targeting delivery system in which NVs supports the pharmacological agents (drugs/genes) is a good way for resolving the obstacles with a conventional delivery system. It enhances the therapeutic efficacy of pharmacological agents (drugs/genes). These NVs have several specific characters like small size, large surface area to volume ratio, surface functionalization, etc. However, this delivery is not able to deliver site-specific delivery of drugs. An active targeting delivery system in which pharmacological agents are loaded on NVs to attack directly on cancer cells and tissues is a superior way for delivering the pharmacological agents compared to a passive targeting delivery system. Various targeting ligands have been investigated and applied for targeting the delivery of drugs such as sugar, vitamin, antibodies, protein, peptides, etc. These targeted ligand supports to guide the NVs accumulated directly on the cancer cells with a higher level of cellular internalization compared to passive targeting and conventional delivery system.

Temperature Monitoring in Hyperthermia Treatments of Bone Tumors: State-of-the-Art and Future Challenges

Bone metastases and osteoid osteoma (OO) have a high incidence in patients facing primary lesions in many organs. Radiotherapy has long been the standard choice for these patients, performed as stand-alone or in conjunction with surgery. However, the needs of these patients have never been fully met, especially in the ones with low life expectancy, where treatments devoted to pain reduction are pivotal. New techniques as hyperthermia treatments (HTs) are emerging to reduce the associated pain of bone metastases and OO. Temperature monitoring during HTs may significantly improve the clinical outcomes since the amount of thermal injury depends on the tissue temperature and the exposure time. This is particularly relevant in bone tumors due to the adjacent vulnerable structures (e.g., spinal cord and nerve roots). In this Review, we focus on the potential of temperature monitoring on HT of bone cancer. Preclinical and clinical studies have been proposed and are underway to investigate the use of different thermometric techniques in this scenario. We review these studies, the principle of work of the thermometric techniques used in HTs, their strengths, weaknesses, and pitfalls, as well as the strategies and the potential of improving the HTs outcomes.

Optical inactivation of a proprioceptor in an insect by non-genetic tools

BACKGROUND

The specific role of sensory organs in locomotor pattern generation is traditionally investigated by means of mechanical ablation in arthropods that currently do not allow genetic manipulation. Mechanical ablation is irreversible, and may lead to injury discharges and changes in the structural integrity of the cuticle.

NEW METHOD

Here, we present a new method to temporarily or permanently deprive parts of an insect nervous system of sensory feedback from leg proprioceptors by means of blue light application. We illuminated campaniform sensilla (CS) with a blue LED (420-480 nm) or a 473 nm laser at different light intensities to optically eliminate sensory and motor neuron responses to mechanical stimulation.

RESULTS

We were able to eliminate all stimulus-evoked responses of CS. Individual CS groups were precisely and selectively inactivated without affecting nearby proprioceptors, using an optical fiber (Ø 200 µm) to guide the light. Our results demonstrated that lower light intensities significantly increase the required exposure time, but also the chance for recovery, thus making the effect reversible.

COMPARISON WITH EXISTING METHODS

In contrast to mechanical ablation, optical inactivation of individual sensory organs is non-invasive and does not affect the behavioral state of the animal, nor does it induce escape behavior. This is especially relevant in non-model system experimental animals where optogenetic manipulation cannot be used, due to a lack of established methods of access.

CONCLUSION

Our results show that the proposed method is a reliable alternative to mechanical ablation and can be successfully applied to the CS, as it fulfills all requirements regarding selectivity, efficiency, and reproducibility.

Fiber optic probe with functional polymer composites for hyperthermia

We demonstrate a fiber optic probe incorporating functional polymer composites for controlled generation of photothermal effects. The probe combines carbon-based and rare-earth composites on the tip of standard multimode fibers, thus yielding a compact fiber optic photothermal probe (FOPP) whose temperature can be measured simultaneously through fluorescent thermometry. We evaluate the thermal features of the probe through experiments and numerical calculations showing that large thermal gradients are obtained within the vicinity of the heating zone. The temperatures achieved with the FOPP are within the ranges of interest for hyperthermia and can be attained using low optical powers (< 280 mW).

Advances in Cancer Therapeutics: Conventional Thermal Therapy to Nanotechnology-Based Photothermal Therapy

In this review, advancement in cancer therapy that shows a transition from conventional thermal therapies to laser-based photothermal therapies is discussed. Laser-based photothermal therapies are gaining popularity in cancer therapeutics due to their overall outcomes. In photothermal therapy, light is converted into heat to destruct the various types of cancerous growth. The role of nanoparticles as a photothermal agent is emphasized in this review article. Magnetic, as well as non-magnetic, nanoparticles have been effectively used in the photothermal-based cancer therapies. The discussion includes a critical appraisal of in vitro and in vivo, as well as the latest clinical studies completed in this area. Plausible evidence suggests that photothermal therapy is a promising avenue in the treatment of cancer.

Acoustically Detonated Microbubbles Coupled with Low Frequency Insonation: Multiparameter Evaluation of Low Energy Mechanical Ablation

Noninvasive ultrasound surgery can be achieved using focused ultrasound to locally affect the targeted site without damaging intervening tissues. Mechanical ablation and histotripsy use short and intense acoustic pulses to destroy the tissue via a purely mechanical effect. Here, we show that coupled with low-frequency excitation, targeted microbubbles can serve as mechanical therapeutic warheads that trigger potent mechanical effects in tumors using focused ultrasound. Upon low frequency excitation (250 kHz and below), high amplitude microbubble oscillations occur at substantially lower pressures as compared to higher MHz ultrasonic frequencies. For example, inertial cavitation was initiated at a pressure of 75 kPa for a center frequency of 80 kHz. Low frequency insonation of targeted microbubbles was then used to achieve low energy tumor cell fractionation at pressures below a mechanical index of 1.9, and in accordance with the Food and Drug Administration guidelines. We demonstrate these capabilities in vitro and in vivo. In cell cultures, cell viability was reduced to 16% at a peak negative pressure of 800 kPa at the 250 kHz frequency (mechanical index of 1.6) and to 10% at a peak negative pressure of 250 kPa at a frequency of 80 kHz (mechanical index of 0.9). Following an intratumoral injection of targeted microbubbles into tumor-bearing mice, and coupled with low frequency ultrasound application, significant tumor debulking and cancer cell death was observed. Our findings suggest that reducing the center frequency enhances microbubble-mediated mechanical ablation; thus, this technology provides a unique theranostic platform for safe low energy tumor fractionation, while reducing off-target effects.

Thermomechanical Modeling of Laser Ablation Therapy of Tumors: Sensitivity Analysis and Optimization of Influential Variables

In cancer treatment, laser ablation is a promising technique used to induce localized thermal damage. Different variables influence the temperature distribution in the tissue and the resulting therapy efficacy; thus, the optimal therapy settings are required for obtaining the desired clinical outcome. In this work, thermomechanical modeling of contactless laser ablation was implemented to analyze the sensitivity of independent variables on the optimal treatment conditions. The Finite Element Method was utilized to solve the governing equations, i.e., the bioheat, mechanical deformation, and the Navier-Stokes equations. Validation of the model was evaluated by comparing experimental and simulated temperatures, which indicated high accuracy for estimating temperature. In particular, the results showed that the model is capable of estimating temperature with a good correlation factor (R=0.98) and low Mean Absolute Error (3.9 C). A sensitivity analysis based on laser irradiation time, power, beam distribution, and the blood vessel depth on temperature distribution and fraction of necrotic tissue was performed. Based on the most significant variables i.e., laser irradiation time and power, an optimization process was performed. This resulted into an indication of the optimal therapy settings for achieving maximum procedure efficiency i.e., the required fraction of necrotic tissue within the target volume, constituted by tumor and safety margins around it.

Quasi-distributed fiber optic sensor-based control system for interstitial laser ablation of tissue: theoretical and experimental investigations

This work proposes the quasi-distributed real-time monitoring and control of laser ablation (LA) of liver tissue. To confine the thermal damage, a pre-planning stage of the control strategy based on numerical simulations of the bioheat-transfer was developed to design the control parameters, then experimentally assessed. Fiber Bragg grating (FBG) sensors were employed to design the automatic thermometry system used for temperature feedback control for interstitial LA. The tissue temperature was maintained at a pre-set value, and the influence of different sensor locations (on the direction of the beam propagation and backward) on the thermal outcome was evaluated in comparison with the uncontrolled case. Results show that the implemented computational model was able to properly describe the temperature evolution of the irradiated tissue. Furthermore, the realized control strategy allowed for the accurate confinement of the laser-induced temperature increase, especially when the temperature control was actuated by sensors located in the direction of the beam propagation, as confirmed by the calculated fractions of necrotic tissues (e.g., 23 mm³ and 53 mm³ for the controlled and uncontrolled LA, respectively).

Clinical therapies and nano drug delivery systems for urinary bladder cancer

Bladder cancer is the 10^th most commonly occurring malignancy worldwide with a 75% of 5-year survival rate, while it ranks 13^th among the deaths occurring due to cancer. The majority of bladder cancer cases are diagnosed at an early stage and 70% are of non-invasive grade. However, 70% of these cases develop chemoresistance and progress to the muscle invasive stage. Conventional chemotherapy treatments are unsuccessful in curbing chemoresistance, bladder cancer progression while having an adverse side effect, which is mainly due to off-target drug distribution. Therefore, new drug delivery strategies, new therapeutics and therapies or their combination are being explored to develop better treatments. In this regard, nanotechnology has shown promise in the targeted delivery of therapeutics to bladder cancer cells. This review discusses the recent discovery of new therapeutics (chemotherapeutics, immunotherapeutic, and gene therapies), recent developments in the delivery of therapeutics using nano drug delivery systems, and the combination treatments with FDA-approved therapies, i.e., hyperthermia and photodynamic therapy. We also discussed the potential of other novel drug delivery systems that are minimally explored in bladder cancer. Lastly, we discussed the clinical status of therapeutics and therapies for bladder cancer. Overall, this review can provide a summary of available treatments for bladder cancer, and also provide opportunities for further development of drug delivery systems for better management of bladder cancer.

Laser-induced optothermal response of gold nanoparticles: From a physical viewpoint to cancer treatment application

Gold nanoparticles (GNPs)-based photothermal therapy (PTT) is a promising minimally invasive thermal therapy for the treatment of focal malignancies. Although GNPs-based PTT has been known for over two decades and GNPs possess unique properties as therapeutic agents, the delivery of a safe and effective therapy is still an open question. This review aims at providing relevant and recent information on the usage of GNPs in combination with the laser to treat cancers, pointing out the practical aspects that bear on the therapy outcome. Emphasis is given to the assessment of the GNPs' properties and the physical mechanisms underlying the laser-induced heat generation in GNPs-loaded tissues. The main techniques available for temperature measurement and the current theoretical simulation approaches predicting the therapeutic outcome are reviewed. Topical challenges in delivering safe thermal dosage are also presented with the aim to discuss the state-of-the-art and the future perspective in the field of GNPs-mediated PTT.

New approach of controlling the area affected in brain tumour treatment by LITT

There are some techniques to ablate tumours of brain, breast and liver. One of them is laser irradiation. The most important problem of this technique is to injure noncancerous tissues. It is a challenging work to control the domain of laser effects. In other words, it is hard to ablate cancerous tissue without ablating noncancerous. To gain this goal, some researchers have been proposed some ways, such as using two or three applicators or moving applicator. The objective of this paper is to present an approach to control the temperature distribution and heat affected zone in brain tumours when irradiated by shielded laser beam, 1064 nm ND-YAG. The effects of laser beam, resulting in tissue temperature increasing, follows the border of tumour by defining of a dual intensity distribution. This is included two distinct intensity distributions of laser on the applicator by shielding. Treatment of an arbitrary topology of tumour will be simulated irradiation of laser by two different distributions through numerical method. Results show when dual distribution on the tumour border is used, the pattern of photon distribution is coincident by the tumour and the affected zone and temperature increasing follows the borderline of tumour, qualitatively. It shows that the ablated volume of tumour will be 53% more than when the unique distribution is used and the treatment time is shorter, resultantly.

Targeted Single-Walled Carbon Nanotubes for Photothermal Therapy Combined with Immune Checkpoint Inhibition for the Treatment of Metastatic Breast Cancer

The greatest contributors to cancer mortality are metastasis and the consequences of its treatment. Here, we present a novel treatment of metastatic breast cancer that combines photothermal therapy with targeted single-walled carbon nanotubes (SWCNTs) and immunostimulation with a checkpoint inhibitor. We find that the selective near-infrared photothermal ablation of primary orthotopic EMT6 breast tumors in syngeneic BALB/cJ mice using an annexin A5 (ANXA5) functionalized SWCNT bioconjugate synergistically enhances an anti-cytotoxic T-lymphocyte-associated protein 4 (anti-CTLA-4)-dependent abscopal response, resulting in an increased survival (55%) at 100 days after tumor inoculation. In comparison, there was no survival at 100 days for either photothermal therapy by itself or immunostimulation by itself. Prior to photothermal therapy, the SWCNT-ANXA5 bioconjugate was administered systemically at a relatively low dose of 1.2 mg/kg, where it then accumulated in tumor vasculature via ANXA5-dependent binding. During photothermal therapy, the average maximum temperature in the tumor reached 54 °C (duration 175 s). The mechanism of prolonged survival resulting from combinatorial photothermal ablation and immune stimulation was evaluated by flow cytometric quantification of splenic antitumoral immune effector cells and serum cytokine quantification.

Effect of optical energy modulation on the thermal response of biological tissue: computational and experimental validations

This study develops an energy modulation technique to attain a constant interstitial tissue temperature and to induce the predetermined thermal coagulation without carbonization in tissue. An optical diffuser was employed to deliver 1064 nm light to the biological tissue. The combined mode maintained the interstitial temperature at 70 °C for longer durations compared to the continuous wave mode. Coagulation volumes increased linearly with the time and met the predetermined treatment volume range (0.32-0.52 cm³) after the combined treatment for 100 s. The combined modulation can be a feasible modality to induce the predetermined extent of thermal coagulation for treating papillary thyroid microcarcinoma.

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.

Closed-Loop Temperature Control Based on Fiber Bragg Grating Sensors for Laser Ablation of Hepatic Tissue

Laser ablation (LA) of cancer is a minimally invasive technique based on targeted heat release. Controlling tissue temperature during LA is crucial to achieve the desired therapeutic effect in the organs while preserving the healthy tissue around. Here, we report the design and implementation of a real-time monitoring system performing closed-loop temperature control, based on fiber Bragg grating (FBG) spatial measurements. Highly dense FBG arrays (1.19 mm length, 0.01 mm edge-to-edge distance) were inscribed in polyimide-coated fibers using the femtosecond point-by-point writing technology to obtain the spatial resolution needed for accurate reconstruction of high-gradient temperature profiles during LA. The zone control strategy was implemented such that the temperature in the laser-irradiated area was maintained at specific set values (43 and 55 °C), in correspondence to specific radii (2 and 6 mm) of the targeted zone. The developed control system was assessed in terms of measured temperature maps during an ex vivo liver LA. Results suggest that the temperature-feedback system provides several advantages, including controlling the margins of the ablated zone and keeping the maximum temperature below the critical values. Our strategy and resulting analysis go beyond the state-of-the-art LA regulation techniques, encouraging further investigation in the identification of the optimal control-loop.

Microfocusing sapphire capillary needle for laser surgery and therapy: Fabrication and characterization

A sapphire shaped capillary needle designed for collimating and focusing of laser radiation was proposed and fabricated by the edge-defined film-fed growth technique. It features an as-grown surface quality, high transparency for visible and near-infrared radiation, high thermal and chemical resistance and the complex shape of the tip, which protects silica fibers. The needle's geometrical parameters can be adjusted for use in various situations, such as type of tissue, modality of therapy and treatment protocol. The focusing effect was demonstrated numerically and observed experimentally during coagulation of the ex vivo porcine liver samples. This needle in combination with 0.22NA optical fiber allows intensive and uniform coagulation of 150 mm³ volume interstitially and 30 mm³ superficially by laser exposure with 280 J without tissue carbonization and fiber damaging along with delicate treatment of small areas. The demonstrated results reveal the perspectives of the proposed sapphire microfocusing needle for laser surgery and therapy.

Distributed 2D temperature sensing during nanoparticles assisted laser ablation by means of high-scattering fiber sensors

The high demand in effective and minimally invasive cancer treatments, namely thermal ablation, leads to the demand for real-time multi-dimensional thermometry to evaluate the treatment effectiveness, which can be also assisted by the use of nanoparticles. We report the results of 20-nm gold and magnetic iron oxide nanoparticles-assisted laser ablation on a porcine liver phantom. The experimental set-up consisting of high-scattering nanoparticle-doped fibers was operated by means of a scattering-level multiplexing arrangement and interrogated via optical backscattered reflectometry, together with a solid-state laser diode operating at 980 nm. The multiplexed 2-dimensional fiber arrangement based on nanoparticle-doped fibers allowed an accurate superficial thermal map detected in real-time.

Investigation of LED-based photodynamic therapy efficiency on breast cancer cells

Photodynamic therapy (PDT) is based on special light source, photosensitizer (PS), and in the presence of oxygen. Different light sources have been used for PDT applications. Recent studies have focused on LED light sources for PDT applications due to reducing the cost of laser-based PDT and providing easy access for research laboratory or clinic facilities. LED-mediated PDT applications have shown promising results for the treatment of different types of disease. However, few studies have determined the effects of LED-based PDT on cancer cells. For the first time, the aim of this study was to explore the therapeutic effects of 5-aminolevulinic acid (5-ALA)-mediated PDT after LED irradiation on two sub-types (a poorly aggressive MCF-7 and a highly aggressive MDA-MB-231) of breast cancer cell lines. The effectiveness of 5-ALA PDT treatment was evaluated by WST-1, annexin V, and acridine orange staining with different energy levels. The LED system was specially developed with optical power and wavelength stability techniques. The system consists of user interface and embedded LED controller with real-time optic power output calibration by photodiode feedback. Our results demonstrated that the cell viability of breast cancer cells was considerably decreased a LED dose-dependent manner (P < 0.05). Additionally, a significant increase in the percentage of apoptotic cells was detected in breast cancer cells after irradiation with LED at a density of 18 and 30 J/cm² energy. Consequently, the LED system could be effectively used for irradiation of 5-ALA in the treatment of breast cancer cells.

In vivo optoacoustic monitoring of percutaneous laser ablation of tumors in a murine breast cancer model

Laser ablation (LA) is a promising approach for minimally invasive cancer treatments. Its in vivo applicability is often impeded by the lack of efficient monitoring tools that can help to minimize collateral tissue damage and aid in determining the optimal treatment end-points. We have devised a new, to the best of our knowledge, hybrid LA approach combining simultaneous volumetric optoacoustic (OA) imaging to monitor the lesion progression accurately in real time and 3D. Time-lapse imaging of laser ablation of solid tumors was performed in a murine breast cancer model in vivo by irradiation of subcutaneous tumors with a 100 mJ short-pulsed (${\sim}{5}\;{\rm ns}$∼5ns) laser operating at 1064 nm and 100 Hz pulse repetition frequency. Local changes in the OA signal intensity ascribed to structural alterations in the tumor vasculature were clearly observed, while the OA volumetric projections recorded in vivo appeared to correlate with cross sections of the excised tumors.

Thermal ablation of biological tissues in disease treatment: A review of computational models and future directions

Percutaneous thermal ablation has proven to be an effective modality for treating both benign and malignant tumours in various tissues. Among these modalities, radiofrequency ablation (RFA) is the most promising and widely adopted approach that has been extensively studied in the past decades. Microwave ablation (MWA) is a newly emerging modality that is gaining rapid momentum due to its capability of inducing rapid heating and attaining larger ablation volumes, and its lesser susceptibility to the heat sink effects as compared to RFA. Although the goal of both these therapies is to attain cell death in the target tissue by virtue of heating above 50°C, their underlying mechanism of action and principles greatly differs. Computational modelling is a powerful tool for studying the effect of electromagnetic interactions within the biological tissues and predicting the treatment outcomes during thermal ablative therapies. Such a priori estimation can assist the clinical practitioners during treatment planning with the goal of attaining successful tumour destruction and preservation of the surrounding healthy tissue and critical structures. This review provides current state-of-the-art developments and associated challenges in the computational modelling of thermal ablative techniques, viz., RFA and MWA, as well as touch upon several promising avenues in the modelling of laser ablation, nanoparticles assisted magnetic hyperthermia and non-invasive RFA. The application of RFA in pain relief has been extensively reviewed from modelling point of view. Additionally, future directions have also been provided to improve these models for their successful translation and integration into the hospital work flow.