Laser-induced Interstitial Thermotherapy Research Articles

Hysteroscopic diode laser myolysis: from a case series to literature review of incisionless myolysis techniques for managing heavy menstrual bleeding in premenopausal women.

This case series examined the safety and effectiveness of hysteroscopic myolysis using laser-induced interstitial thermo-therapy (LITT) for treating heavy menstrual bleeding (HMB) in premenopausal women with FIGO type 1 or 2 uterine fibroids, not planning for future fertility. Additionally, a comprehensive review of innovative, minimally invasive, incisionless myolysis techniques was conducted. Women with HMB, sonographically diagnosed with a single FIGO type 1 or 2 fibroid, underwent hysteroscopic myolysis using the Leonardo® diode laser. Effectiveness was assessed via transvaginal ultrasound measurement of myoma size, volume and vascularization pre and post-procedure. Moreover, we also evaluated any improvements in symptoms using the Pictorial Blood Loss Assessment Chart (PBAC score) scores. The procedure resulted in significant HMB reductions and noticeable fibroid size, volume, and vascularization decrease in all three patients, with no reported complications. The literature review revealed both advantages and limitations of the minimally invasive, incisionless myolysis techniques. Hysteroscopic laser myolysis is a safe and effective therapeutic intervention for patients experiencing HMB, diagnosed with FIGO type 1 or 2 fibroids, and not planning for future fertility. The procedure resulted in significant reductions in menstrual blood loss and fibroid size. Despite the promising results, it is essential to note the limitations of this report, including its case series design, a small number of patients, and a short follow-up period. Further research is necessary to confirm these results.

Treatment Modelling of a 3D Tumour in Brain by Laser-Induced Interstitial Thermotherapy.

Introduction: There are some ways to examine heat transfer in tumor tissue, which is an important issue in bioengineering. One of these ways uses the bioheat equation, proposed by Pennes, in a continuous medium. Another one uses a porous medium to model heat transfer in living tissues. The objective of this paper was to study an approach to modelling the temperature distribution and tumour ablation in brain tissue and compare results to Pennes' approach. Methods: This approach presents and uses a porous medium as the tissue instead of a continuous medium. In addition, the two approaches (simulation in continuous and porous medium) are compared in terms of temperature simulation and amount of cell ablation. The density, heat conduction factor, and blood perfusion rate are considered functions of temperature. Results: In these approaches, after an 85-second treatment, the temperature increases to about 90°C. The temperature increase of the porous medium is relatively the same as that of the continuous medium and for this reason, the amount of cancerous cells that are ablated in a porous medium is approximately the same as that in a continuous medium. The volume of cell ablation is about 6500 mm3 for two ideas. In addition, the degree of damage, computed from the Arrhenius integral method, and the ablated volume of the tumour endorse equality at the end of treatment. According to the results, similar to the continuous approach, the porous approach predicts the temperature and amount of volume of damaged cells. Conclusion: Therefore, it is possible to use the porous approach instead of the Pennes approach for tumour treatment.

Outcomes of laser-induced thermotherapy for thyroid nodules at the West Vascular Center, Ukraine.

Thyroid nodules are common, occurring in 50-60% of healthy patients. Currently, there are no effective conservative treatment options for nodular goiter, and surgery can have limitations and potential complications. The purpose of this study was to evaluate the efficacy, tolerability, and long-term results of using sclerotherapy and laser-induced interstitial thermotherapy (LITT) to treat benign thyroid nodules. A retrospective analysis was conducted on 456 patients with benign nodular goiter who received LITT. The volume of the nodular goiter was measured at 1, 3, 6, and 12 months post-treatment, and a repeated fine needle aspiration (FNA) with the cytological examination was performed to verify the structure of the nodular goiter in the long term. The results showed that LITT was an effective method for treating nodular mass (nodules), as evidenced by a decrease in the volume of NG by 51-85% after 6-12 months. FNA results 2-3 years after LITT showed no thyrocytes, only connective tissue, indicating the efficacy of LITT for benign thyroid nodules. LITT is highly effective in most cases, often resulting in the disappearance or significant decrease in nodular formations.

Validating a simulation model for laser-induced thermotherapy using MR thermometry

Objectives We want to investigate whether temperature measurements obtained from MR thermometry are accurate and reliable enough to aid the development and validation of simulation models for Laser-induced interstitial thermotherapy (LITT). Methods Laser-induced interstitial thermotherapy (LITT) is applied to ex-vivo porcine livers. An artificial blood vessel is used to study the cooling effect of large blood vessels in proximity to the ablation zone. The experimental setting is simulated using a model based on partial differential equations (PDEs) for temperature, radiation, and tissue damage. The simulated temperature distributions are compared to temperature data obtained from MR thermometry. Results The overall agreement between measurement and simulation is good for two of our four test cases, while for the remaining cases drift problems with the thermometry data have been an issue. At higher temperatures local deviations between simulation and measurement occur in close proximity to the laser applicator and the vessel. This suggests that certain aspects of the model may need some refinement. Conclusion Thermometry data is well-suited for aiding the development of simulations models since it shows where refinements are necessary and enables the validation of such models.

ИЗМЕНЕНИЯ ТЕМПЕРАТУРНЫХ ПОЛЕЙ И МИКРОЦИРКУЛЯЦИИ В СТЕНКАХ ПИЛОНИДАЛЬНЫХ КИСТ КОПЧИКОВОЙ ОБЛАСТИ ВО ВРЕМЯ И ПОСЛЕ ЛАЗЕРИНДУЦИРОВАННОЙ ТЕРМОТЕРАПИИ

Introduction. As of today, many options for conservative and surgical treatment of patients with pilonidal cysts have been developed. Our studies on the use of laser radiation in the treatment of epithelial coccygeal passage, which began in 2007, showed its positive clinical effect, which is expressed in a decrease in the number of complications and relapses. The principle of the method is the thermal ablation of the walls of the coccygeal passage with laser radiation. The aim. To study the effect of high-intensity laser radiation on the tissues of pilonidal cyst in patients with epithelial coccygeal passage, in order to improve the results of their treatment. Materials and methods. The study was conducted from 2018 to 2021. The patients were divided into 2 groups depending on the type of surgical treatment. The first group consisted of 124 patients who underwent cyst excision with primary sutures. The second group included 60 patients who underwent laser-induced interstitial thermotherapy. To study microcirculatory changes in the tissues of the pilonidal cyst while doing operational injury, SPECTROTEST (Spectro Analytical Instruments, Germany) spectrometer was used. Results. We have revealed changes in microcirculation and tissue saturation parameters depending on the type of surgical treatment. In the first group, a statistically significant microcirculatory and tissue saturation disorders were found in the walls of postoperative wounds. In the second group, microcirculatory disorders were less pro-nounced, and their normalization occurred much earlier. This indicates the absence of ischemia of the surrounding tissues around the treated area. Temperatures in the walls of pilonidal cysts at laser-induced interstitial thermom-etry vary from 56 to 65 °C, which are the temperatures of destruction of proteins that make up the structure of the cyst walls. On the surface and in the tissues surrounding the cyst, the maximum recorded temperature was 40 °C, and this does not cause protein destruction. Conclusions. High-intensity laser radiation leads to obliteration of the cystic cavity, the formation of scar tissue, the elimination of specific symptoms and the decrease in the risk of recurrence of pilonidal disease, which is confirmed by spectroscopy, thermometry and histological studies.

Лікування солідних вузлів щитоподібної залози з використанням лазеріндукованої термотерапії

Актуальність. Невирішеними питаннями застосування лазеріндукованої інтерстиціальної термотерапії (ЛІТТ) у лікуванні солідних вузлів щитоподібної залози (ЩЗ) на сьогодні є визначення показань і протипоказань, методики і технології її виконання, підвищення ефективності і покращання віддалених результатів. Мета дослідження: вивчити вплив ЛІТТ на навколовузлову тканину і функціональну здатність ЩЗ, визначити фактори, що впливають на терміни заміщення вузла сполучною тканиною та її об’єм, розробити показання до повторного застосування термотерапії. Матеріали та методи. З використанням ЛІТТ проліковані 272 хворі на вузловий зоб без ознак кістозної дегенерації. Усі пацієнти — жінки віком від 22 до 68 років. Об’єм вузлів був у межах від 0,8 до 5,0 см3. За ультразвуковими характеристиками, зокрема за ехогенністю, вузли були такими: 46 — гіпоехогенні, 189 — ізоехогенні та 37 — гіперехогенні. Використовували діодний лазер Лахта-Мілон. ЛІТТ проводили за таких параметрів: довжина хвилі 1060 нм, безперервний режим, потужність випромінювання у межах від 2,5 до 3,2 Вт. Перебіг ЛІТТ контролювали сонографічно. Зміни у вузлі, навколовузловій тканині та функцію залози після ЛІТТ визначали на другу добу, через 2 тижні, через 1, 3, 6, 9 та 12 місяців після маніпуляції. Результати. На другу добу після лазерної термотерапії у вузлах розвивається асептичне запалення, а розміри їх збільшуються на 25–30 %. У подальшому, у визначені терміни обстеження, розміри вузлів зменшувались, показники гормональної функції не змінювались. Через 6 місяців після ЛІТТ при розмірах вузлів до 2 см повне їх заміщення сполучною тканиною відмічалось у всіх випадках гіпо- й ізоехогених вузлів і в 71 % — гіперехогенних, а при розмірах від 2 до 5 см — у 75 % випадків вузлів гіпоехогенної структури, 18 % — ізоехогенної і не було позитивного ефекту у разі гіперехогенних вузлів. У випадках неефективного лікування знадобилося проведення повторної ЛІТТ, після якої у всіх пацієнтів настала повна редукція вузла. Висновки. У розроблених режимах ЛІТТ не викликає деструктивних змін у навколовузловій тканині і розладів гормональної функції залози. Тривалість регресу і заміщення вузла сполучною тканиною визначають його ехогенність і об’єм. Показаннями до повторного застосування термотерапії є залишкова тканина в ділянці вузла в межах більше 42 % від вихідного об’єму через півроку після проведеного лікування та наявність у ній тиреоїдного епітелію.

Treatment of the pilonidal sinus in children using laser radiation

The work carried out a comparative analysis of the results of surgical treatment of the epithelial-coccygeal course of ECC in 133 children aged 3 to 17 years, using laser-induced interstitial thermotherapy (LIT) and open excision. Comparative analysis was carried out according to the following criteria: duration of surgery, average time of hospital stay, duration of pain syndrome on a 10-point scale (VAS), the presence of complications in the early and late postoperative period. In the main group, the average time of hospital stay was 4.9 ± 0.3; the duration of surgical treatment was 17.2 ± 2.8 minutes. The duration of the pain syndrome was 5.3 ± 2.1 hours, and its severity was 2.7 ± 0.8 points. Average terms of epithelialization of fistulas are 3.1 ± 2.8 days. Recurrence of ECC was observed in 7 patients (11.7%), which required re-intervention. In 3 (5.0%) patients, LIT was used, and in 4 (6.7%), excision using plastics according to the Bascom method. In the comparison group, the duration of surgical treatment was 32.6 ± 5.4 minutes. The duration of inpatient treatment is 16.7 ± 1.4 days. Pain syndrome averaged 71.8 ± 11.9 hours, severity 6.5 ± 2.3 points. The number of relapses was 9 (12.3%), of which 5 (6.8%) children underwent laser treatment, and 4 (5.5%) repeated surgical excision with Bascom with recovery. This technique is an effective and minimally invasive method for treating ECC, which makes it possible to recommend this method for use in pediatric surgical practice.

Laser thermotherapy or excision, what to offer to a patient with pilonidal disease?

Objective. To carry out a comparative analysis of the results of epithelial coccygeal course treatment using laser-induced interstitial thermotherapy LIT) under ultrasound control and traditional open excision. The high trauma rate of traditional operations in the epithelial coccygeal course ECC), the duration of hospital stay, pain syndrome force surgeons to search for new technologies in the treatment of this pathology.
 Materials and methods. A retrospective analysis of the treatment results of 369 patients with ECC who were admitted to the clinic for elective surgery in the period from 2009 to 2019 was carried out. There were 264 men 71.5 %) and 105 women 28.5 %). The mean age was 26.9 7.2 years. The patients were divided into 2 groups: 190 patients of the main group underwent surgery using a fiber-optic laser under ultrasound guidance, 179 patients of the comparison group underwent traditional radical excision of ECC with application of primary sutures or various types of plastic.
 Results. The severity of pain syndrome after surgery in patients of the main group was 1.7 0.6 points, in the comparison group 3.5 1.3 points by a five-point visual analogue scale VAS) for pain. The duration of inpatient treatment in the main group was 1.8 0.4 days, in the comparison group 11.5 1.7 days. Moreover, in 197 76.1 %) patients of the main group, the operation was performed on an outpatient basis. The restoration of working capacity in the main group occurred after 5.2 1.2 days, and in the comparison group after 17.4 2.8. After traditional operations, the relapse of the disease was noted in 11.7 %, and after laser treatment, slightly more than 12.1 %. Satisfaction with the results of treatment in the main group was noted in 95.1 %, and in the comparison group in 90 % of patients.
 Conclusions. The obtained results of treatment allow us to recommend the technique of interstitial laser obliteration of the coccygeal cyst under ultrasound navigation developed in the clinic for widespread use in practical work of surgeons.

A thermometry software tool for monitoring laser-induced interstitial thermotherapy.

The purpose of this study was to develop a thermometry software tool for temperature monitoring during laser-induced interstitial thermotherapy (LITT). C++ programming language and several libraries including DICOM Toolkit, Grassroots DICOM library, Insight Segmentation and Registration Toolkit, Visualization Toolkit and Quasar Toolkit were used. The software's graphical user interface creates windows displaying the temperature map and the coagulation extent in the tissue, determined by the magnetic resonance imaging (MRI) thermometry with the echo planar imaging sequence and a numerical simulation based on the radiation and heat transfer in biological tissues, respectively. The software was evaluated applying the MRI-guided LITT to ex vivo pig liver and simultaneously measuring the temperature through a fiber-optic thermometer as reference. Using the software, the temperature distribution determined by the MRI method was compared with the coagulation extent simulation. An agreement was shown between the MRI temperature map and the simulated coagulation extent. Furthermore, the MRI-based and simulated temperatures agreed with the measured one - a correlation coefficient of 0.9993 and 0.9996 was obtained, respectively. The precision of the MRI temperature amounted to 2.4°C. In conclusion, the software tool developed in the present study can be applied for monitoring and controlling the LITT procedure in ex vivo tissues.

Laser-Induced Interstitial Thermotherapy of Gliomas.

Laser-induced interstitial thermotherapy (LITT) is a modern minimally invasive treatment modality applied for management of a variety of diseases. Recent developments of techniques for precise targeting of the lesion, accurate delivery of the prescribed therapeutically effective thermal doses, and real-time visualization of the induced tissue damage during the procedure by means of intraoperative MR thermometry have stimulated a number of clinical studies testing LITT in cases of different brain pathologies, including gliomas. This modality is particularly attractive in patients with recurrent, deep-seated, and/or critically located neoplasms refractory to other treatments, where it can effectively demonstrate improvement of prognosis providing high quality of life and eliminating the risks of open tumor resection. Low morbidity rates associated with LITT and short hospital stay result in decreased cost of hospitalization. The effectiveness of thermal therapies, particularly after long-term follow-up, still needs evaluation in carefully planned randomized clinical trials, whereas elucidating the effects of laser treatment at the molecular, cellular, and organic levels will continue to expand the boundaries of its clinical applicability in neuro-oncology.

The effect of laser power, blood perfusion, thermal and optical properties of human liver tissue on thermal damage in LITT.

In this work, the finite-element method (FEM) was used to predict the temperature distribution, and the thermal damage volume in human liver tissue subjected to laser in laser-induced interstitial thermotherapy (LITT). The effect of laser power, blood perfusion, and thermal and optical properties on maximum temperature and thermal damage volume were predicted using the finite-element method. A computer program was written in visual basic language, which was verified by comparing its result with data published elsewhere. The bio-heat equation together with the effect of linear laser source were used to simulate heat transfer through tissue from which the temperature distributions, and the subsequent thermal damage, were obtained based on Arrhenius equation. In this mathematical model for LITT, it was found that increasing laser power, absorption, and scattering coefficient increased the damage zone while increasing tissue water content, perfusion rate, and tissue anisotropy factor decreased the damage zone. These findings are important aspects for doctors in the pre-estimation of the damage zone before starting the therapy so as to kill only the desired zone.

Real-time temperature monitoring with fiber Bragg grating sensor during diffuser-assisted laser-induced interstitial thermotherapy.

High-sensitivity temperature sensors have been used to validate real-time thermal responses in tissue during photothermal treatment. The objective of the current study was to evaluate the feasible application of a fiber Bragg grating (FBG) sensor for diffuser-assisted laser-induced interstitial thermotherapy (LITT) particularly to treat tubular tissue disease. A 600 - ? m core-diameter diffuser was employed to deliver 980-nm laser light for coagulation treatment. Both a thermocouple and a FBG were comparatively tested to evaluate temperature measurements in ex vivo liver tissue. The degree of tissue denaturation was estimated as a function of irradiation times and quantitatively compared with light distribution as well as temperature development. At the closer distance to a heat source, the thermocouple measured up to 41% higher maximum temperature than the FBG sensor did after 120-s irradiation (i.e., 98.7 ° C ± 6.1 ° C for FBG versus 131.0 ° C ± 5.1 ° C for thermocouple; p < 0.001 ). Ex vivo porcine urethra tests confirmed the real-time temperature measurements of the FBG sensor as well as consistently circumferential tissue denaturation after 72-s irradiation ( coagulation thickness = 2.2 ± 0.3 ?? mm ). The implementation of FBG can be a feasible sensing technique to instantaneously monitor the temperature developments during diffuser-assisted LITT for treatment of tubular tissue structure.

Choice of Thyroid Nodules Treatment

Introduction. Questions regarding indications and contraindications to the use of minimally invasive technologies in the treatment of various types of thyroid nodules remain still disputable. The objective of the research was to analyse the results of minimally invasive technologies use in the treatment of thyroid nodules and develop the indications for their use.Materials and methods. Results of treatment of 643 patients with thyroid nodules were analysed. Results. Indications to separate use of minimally invasive techniques and cases where they should be combined were determined. The absence of harmful effects of laser-induced interstitial thermotherapy and sclerotherapy with 70 % ethanol on paranodular tissue was proven. High efficiency of laser-induced interstitial thermotherapy in the treatment of functional autonomy of thyroid nodules with gradual achievement of clinical and laboratory stable euthyroidism was observed.Conclusions. When the indications to their use are observed, minimally invasive technologies result in the nodule replacement unit with the connective tissue in 98% of cases.

Optical fiber solutions for laser ablation of tissue and immunostimulating interstitial laser thermotherapy – Product development in the network of developers, industry and users

Abstract: Clinical Laserthermia Systems AB (CLS) has developed a treatment protocol named immunostimulating interstitial laser thermotherapy (imILTCLS) which is intended to improve current treatment regimens for metastatic cancer diseases. It aims at a controlled local tumor ablation with a subsequent release of tumor specific antigens resulting in a systemic immune activation against the remaining cancer cells. The approach has its origins in the laser-induced interstitial thermotherapy procedure and is based on a proprietary and patented technique to optimize the immunological effect. CLS has gained know-how through long experience both in clinical and pre-clinical studies of the application, laser technology, thermometry, and expertise in regulatory affairs. However, CLS does not have the in-house expertise required for fiber development and production. Therefore the company has actively searched for industrial partners to collaborate with on the design and development of a fiber delivery system tailored to imILTCLS. The aim of this collaboration is to design an application-specific laser fiber that allows the treatment of a wider range of tumors with a single treatment and overcomes the limitations of currently available laser fibers, such as the limited achievable lesion sizes due the maximum power that can be used without carbonizing tissue. The present contribution gives a short overview about the current development steps within the network of developers, industry and users.

Laser-induced interstitial thermotherapy via a single-needle delivery system: Optimal conditions of ablation, pathological and ultrasonic changes.

This study aimed to examine the optimal conditions of laser-induced interstitial thermotherapy (LITT) via a single-needle delivery system, and the ablation-related pathological and ultrasonic changes. Ultrasound (US)-guided LITT (EchoLaser system) was performed at the output power of 2-4 Wattage (W) for 1-10 min in ex vivo bovine liver. Based on the results of the ex vivo study, the output power of 3 and 4 W with different durations was applied to in vivo rabbit livers (n=24), and VX2 tumors implanted in the hind limbs of rabbits (n=24). The ablation area was histologically determined by hematoxylin-eosin (HE) staining. Traditional US and contrast enhanced ultrasound (CEUS) were used to evaluate the treatment outcomes. The results showed: (1) In the bovine liver, ablation disruption was grossly seen, including a strip-like ablation crater, a carbonization zone anteriorly along the fiber tip, and a surrounding gray-white coagulation zone. The coagulation area, 1.2 cm in length and 1.0 cm in width, was formed in the bovine liver subjected to the ablation at 3 W for 5 min and 4 W for 4 min, and it extended slightly with the ablation time. (2) In the rabbit liver, after LITT at 3 W for 3 min and more, the coagulation area with length greater than or equal to 1.2 cm, and width greater than or equal to 1.0 cm, was found. Similar coagulation area was seen in the implanted VX2 carcinoma at 3 W for 5 min. (3) Gross examination of the liver and carcinoma showed three distinct regions: ablation crater/carbonization, coagulation and congestion distributed from the center outwards. (4) Microscopy revealed four zones after LITT, including ablation crater/carbonization, coagulation, edema and congestion from the center outwards. A large area with coagulative necrosis was observed around a vessel in the peripheral area with edema and hyperemia. (5) The size of coagulation was consistent well to the CEUS findings. It was concluded that EchoLaser system at low power can produce a coagulation area larger than 1.0 cm×1.0 cm during a short time period. The real-time US imaging can be used to effectively guide and assess the treatment.

Лечение узлового эутиреоидного зоба лазериндуцированной интерстициальной термотерапией

Лечение узлового эутиреоидного зоба лазериндуцированной интерстициальной термотерапией

Comparison of percutaneous ablation technologies in the treatment of malignant liver tumors.

Tumor ablation is a minimally invasive technique used to deliver chemical, thermal, electrical, or ultrasonic damage to a specific focal tumor in an attempt to achieve substantial tumor destruction or complete eradication. As the technology continues to advance, several image-guided tumor ablations have emerged to effectively manage primary and secondary malignancies in the liver. Percutaneous chemical ablation is one of the oldest and most established techniques for treating small hepatocellular carcinomas. However, this technique has been largely replaced by newer modalities including radiofrequency ablation, microwave ablation, laser-induced interstitial thermotherapy, cryoablation, high-intensity-focused ultrasound ablation, and irreversible electroporation. Because there exist significant differences in underlying technological bases, understanding each mechanism of action is essential for achieving desirable outcomes. In this article, the authors review the current state of each ablation method including technological and clinical considerations.

Numerical simulations on conformable laser-induced interstitial thermotherapy through combined use of multi-beam heating and biodegradable nanoparticles

Clinically, precisely heating and thus completely ablating diseased tumor tissue through laser beam is still facing many technical challenges. In this study, numerical simulation of a conformal heating modality based on multi-beam laser along with biodegradable magnesium nanoparticles (Mg-NPs) was put forward to treat liver tumor with large size or irregular shape. Further, a Gaussian-like distribution was proposed to investigate the influence of Mg-NP deposition on the nanoenhanced laser-induced interstitial thermotherapy (LITT). A temperature feedback system was adopted to control the temperature range to avoid overheating. To preliminarily validate the heating enhancement induced by the applied multi-beam laser and Mg-NPs, a conceptual experiment was performed. Both theoretical simulation and experimental measurements demonstrated that multi-beam laser with Mg-NPs could improve efficiency in the conformal heating of tumors with irregular shape or large size. In addition, the distribution and content of Mg-NPs produced significant impact on thermotherapy: (1) The adjustable parameter σ in the Gaussian-like distribution could reflect various practical situations and diffusivities of Mg-NPs; (2) under the premise of the same concentration of Mg-NPs and short time to heat a small-sized target, the whole liver tumor containing Mg-NPs could not improve the efficiency as the nanoparticles limited the photons to be absorbed only around the fibers, while liver tumor partially containing Mg-NPs could improve the thermotherapy efficiency up to 20 %; and (3) the addition of Mg-NPs was rather beneficial for realizing a conformal heating as the residual thermal energy was much less than that without Mg-NPs. This study suggests a feasible and promising modality for planning a high-performance LITT in future clinics.

MR‐guided laser‐induced thermotherapy (LITT) in patients with liver metastases of uveal melanoma

Evaluation of the local tumour control rate and survival data for magnetic resonance (MR) imaging-guided laser ablation of uveal malignant melanoma liver metastases by using laser-induced interstitial thermotherapy (LITT). The LITT was performed in 18 patients with liver metastases (n = 44) from uveal malignant melanoma. All patients tolerated this intervention well. With the Kaplan-Meier method, the survival rates were calculated. Indications for the procedure were defined for patients with no more than five metastases, none of which were larger than 5 cm in diameter: The Indication for LITT treatment were recurrent liver metastases after partial liver resection (22%), locally non-resectable tumours (17%) or metastases in both liver lobes (61%). The mean survival rate for all treated patients was 3.6 years (95% CI: 2.19, 5.06). We started the calculation on the date of diagnosis of the metastases treated with LITT. The median survival was 1.83 years; 1-year survival, 88%; 3-year survival 47%, 5-year survival 17%. Calculated after the first LITT treatment the median survival was 2.8 years (95% CI: 1.0, 5.0). 10 patients were treated by transarterial chemoembolization before LITT. MR-guided LITT treatment shows a high local tumour control and survival rates in patients with liver metastases of uveal malignant melanoma.

Change in refractive index of muscle tissue during laser-induced interstitial thermotherapy

This paper presents a long-period fiber-grating (LPG) based Michelson interferometric refractometry to monitor the change in refractive index of porcine muscle during laser-induced interstitial thermotherapy (LITT). As the wavelength of RI interferometer alters with the change in refractive index around the probe, the LPG based refractometry is combined with LITT system to measure the change in refractive index of porcine muscle when irradiated by laser. The experimental results show the denaturation of tissue alters the refractive index significantly and the LPG sensor can be applied to monitor the tissue state during the LITT.