Laser Ablation Of Tissue Research Articles

Infrared Laser Ablation and Capture of Formalin-Fixed Paraffin-Embedded Tissue.

Formalin-fixed paraffin-embedded (FFPE) tissue is a ubiquitous and invaluable resource for biomedical research and clinical applications. However, FFPE tissue proteomics is challenging due to protein cross-linking and chemical modification. Laser ablation sampling allows precise removal of material from tissue sections with high spatial control and reproducibility for offline proteomics by liquid chromatography coupled with tandem mass spectrometry. In this work, we used a pulsed mid-infrared laser for microsampling of rat liver tissue for subsequent identification and quantification of proteins. It was found that more proteins were identified by FFPE tissue laser ablation sampling compared to fresh frozen (FF) tissue laser ablation sampling and that more proteins were identified by laser ablation than by manual dissection of FFPE tissue. In contrast to previous studies, no loss of hydrophilic proteins due to residual cross-linking was observed. The efficient capture of proteins by laser ablation microsampling is attributed to efficient laser breakup of the tissue which facilitates downstream processing of the proteins.

A Multi-Institutional Study of Magnetic Resonance/Ultrasound Fusion-Guided Nanoparticle-Directed Focal Therapy for Prostate Ablation.

Focal therapy aims to provide a durable oncologic treatment option for men with prostate cancer (PCa), while preserving their quality of life. Most focal therapy modalities rely on the direct tissue effect, resulting in a possible nontargeted approach to ablation. Here, we report the results of the first human feasibility trial utilizing nanoparticle-directed focal photothermal ablation for PCa. A prospective, open-label, single-arm, multicenter study of men with localized PCa in Gleason Grade Group 1 to 3 was conducted. Men received a single infusion of gold nanoparticles (AuroShells), followed by magnetic resonance (MR)/ultrasound (US) fusion-guided laser excitation of the target tissue to induce photothermal ablation. MRI was used to assess the effectiveness of prostate tissue ablation at 48 to 96 hours, 3 months, and 12 months post treatment. At 3 months, a targeted fusion biopsy of the lesion(s) was conducted. At 12 months, a targeted fusion biopsy and standard templated biopsy were performed. Treatment success was determined based on a negative MR/US fusion biopsy outcome within the treated area. Forty-six men were enrolled in the study, and 44 men with 45 lesions completed nanoparticle infusion and laser treatment. The mean PSA level at baseline was 9.5 ng/mL, which decreased to 5.9 ng/mL at 3 months and to 4.7 ng/mL at 12 months (P < .0001). The oncologic success rates at 3 and 12 months resulted in 29 (66%) and 32 (73%) of 44 patients, respectively, being successfully treated, confirmed with negative MR/US fusion biopsies within the ablation zone. Among Gleason Grade Group, maximum lesion diameter on MRI, prostate volume, and Prostate Imaging Reporting and Data System scoring, the maximum lesion diameter was significantly associated with the odds of treatment failure at 12 months (P = .046). Nanoparticle-directed focal laser ablation of neoplastic prostate tissue resulted in 73% of patients with successful treatment at 12 months post treatment, confirmed by negative MR/US fusion biopsy of the treated lesion and a systematic biopsy. 02680535.

Laser interstitial thermal therapy for new and recurrent meningioma: a prospective and retrospective case series.

Meningiomas are the most common primary brain tumors in adults and a subset are aggressive lesions resistant to standard therapies. Laser interstitial thermal therapy (LITT) has been successfully applied to other brain tumors, and recent work aims to explore the safety and long-term outcome experiences of LITT for both new and recurrent meningiomas. The authors' objective was to report safety and outcomes data of the largest cohort of LITT-treated meningioma patients to date. Eight United States-based hospitals enrolled patients with meningioma in the Laser Ablation of Abnormal Neurological Tissue Using Robotic NeuroBlate System (LAANTERN) prospective multicenter registry and/or contributed additional retrospective enrollments for this cohort study. Demographic, procedural, safety, and outcomes data were collected and analyzed using standard statistical methods. Twenty adult patients (12 prospective and 8 retrospective) with LITT-targeted meningiomas were accrued. Patients underwent LITT for new (6 patients) and recurrent (14 patients) tumors (ranging from the 1st to 12th recurrence). The 30-day complication rate was 10%. Twenty percent of patients (4/20) had exhausted all other treatment options. Median length of follow-up was 1.3 years. One-third of new (2/6) and one-half of recurrent (7/14) meningiomas had disease progression during follow-up. One-year estimated local control (LC), progression-free survival, and overall survival rates were 55.3%, 48.4%, and 86.3%, respectively. In the 12 patients who had ≥ 91% ablative coverage, 1-year estimated LC was 61.4%. The complication rate was 10% (2/20), with 1 complication being transient and resolving postoperatively. This cohort study supports the safety of the procedure for this tumor type. LITT can offer a much-needed treatment option, especially for patients with multiply recurrent meningiomas who have limited remaining alternatives.

Infrared Laser Ablation and Capture of Biological Tissue.

Sampling thin tissue sections with cellular precision can be accomplished using laser ablation microsampling for mass spectrometry analysis. In this work, the use of a pulsed mid-infrared (IR) laser for selecting small regions of interest (ROI) in tissue sections for offline liquid chromatography-tandem mass spectrometry (LC-MS/MS) is described. The laser is focused onto the tissue section, which is rastered as the laser is fired. The ablated tissue is captured in a microwell array and processed in situ through reduction, alkylation, and digestion with a low liquid volume workflow. The resulting peptides from areas as small as 0.01mm2 containing 5 ng of protein are analyzed for protein identification and quantification using offline LC-MS/MS.

A Novel Miniature Spring-Based Continuum Manipulator for Minimally Invasive Surgery: Design and Evaluation

Minimally invasive surgery is gaining wide-spread attention in the laboratory and the clinic due to its advantages of less trauma, less pain, and faster recovery. Miniature continuum instruments with a large central channel are needed for reducing damage to healthy tissue and delivering multiple surgical tools in microsurgery such as fetal surgery and maxillary sinus surgery. In this article, we proposed a novel miniature spring-based cable-driven continuum manipulator characterized by its offset neutral bending plane and its simple and clever structure. These features enable the manipulator to have several advantages such as easy miniaturization, bending stability and uniformity, a large central channel, smaller cable tension required, and low cost. A piecewise constant curvature model, with the offset neutral bending plane taken into account, is presented for the kinematic control of the proposed manipulator. To explore the relationship between the cable tension and manipulator bending angle, the statics model based on the equivalent model principle, is exhaustively discussed. The accuracy of kinematics and statics models, as well as the design superiority, was verified experimentally. Furthermore, teleoperation experiments of peg-transfer tasks and porcine tissue laser ablation are conducted to verify the feasibility and effectiveness of the proposed manipulator in different forms. Final, design variations are showcased to enrich manipulator design and functionality.

Thermal damage and the prognostic evaluation of laser ablation of bone tissue-a review.

In recent years, an increasing number of scientists have focused on conducting experiments on laser ablation of bone tissue. The purpose of this study was to summarize the prognosis of tissue and the extent of thermal damage in past hard tissue ablation experiments, and review the evidence for the feasibility of laser osteotomy in surgery. An electronic search of PubMed, China National Knowledge Infrastructure (CNKI), and Web of Science (WOS) for relevant English-language articles published through June 2023 was conducted. This review includes 48 literature reports on laser ablation of hard tissues from medical and biological perspectives. It summarizes previous studies in which the ideal ablation rate, depth of ablation, and minimal damage to bone tissue and surrounding soft tissues were achieved by changing the laser type, optimizing the laser parameter settings, or adding adjuvant devices. By observing their post-operative healing and inflammatory response, this review aims to provide a better understanding of pulsed laser ablation of hard tissues. Previous studies suggest that laser osteotomy has yielded encouraging results in bone resection procedures. We believe that low or even no thermal damage can be achieved by experimentally selecting a suitable laser type, optimizing laser parameters such as pulse duration and frequency, or adding additional auxiliary cooling devices. However, the lack of clinical studies makes it difficult to conclusively determine whether laser osteotomy is superior in clinical applications.

Assessing Neuropsychology Testing Variation at Level IV Epilepsy Centers (P1-1.001)

<h3>Objective:</h3> To assess standard of care neuropsychology testing across multiple level IV epilepsy centers <h3>Background:</h3> Laser interstitial thermal therapy (LITT) is a minimally invasive epilepsy surgery option with increasing evidence regarding efficacy outcomes for seizure freedom and cognition. While post operative neuropsychology outcomes are long published for open resection, data are less available for LITT. The standard of care LAANTERN (Laser Ablation of Abnormal Neurological Tissue Using NeuroBlate System) Registry is an ongoing prospective multi-center study of LITT patients which did not include neuropsychological outcomes. Standard of care multicenter neuropsychology testing collection is complicated by differing testing protocols between centers. <h3>Design/Methods:</h3> Active epilepsy LITT sites within LAANTERN were identified. An electronic survey instrument that interrogated standard of care neuropsychological measures and timing of administration at each site was distributed to 17 LAANTERN sites. <h3>Results:</h3> Ten respondents (60% neuropsychologist, 20% epileptologist/neurologist, 20% epilepsy surgeon) at nine sites completed the survey instrument. All ten respondents regularly assess each cognitive domain. All sites perform comprehensive neuropsychology testing pre-LITT; however, no single neuropsychology test is performed across all centers. The Boston Naming, Digit Span, Grooved Pegboard, Trail Making Test A&amp;B, and Wechler’s Memory Scale were done by nine of ten respondents. Two thirds of tests are done by &gt;50% of respondents. Most (90%) repeat neuropsychology testing between six to 12 months following surgery. <h3>Conclusions:</h3> All responding LAANTERN sites perform comprehensive preoperative neuropsychological testing. Neuropsychological test selection ranges greatly between centers which can impact multicenter study design. Based on survey results, seven tests can be considered “preferred”, which include the above-mentioned tests as well as the Brief Visuospatial Memory Test-Revised and the Animal Naming Test. A multicenter study (NCT05075850) was initiated from these results to explore potential changes across cognitive domains and raw scores after LITT. <b>Disclosure:</b> Dr. Landazuri has nothing to disclose. Dr. Gess has nothing to disclose. David Denney has nothing to disclose. Bradley Folley has nothing to disclose. The institution of Dr. LoBue has received research support from NIA. The institution of Dr. LoBue has received research support from Alzheimer’s Association. The institution of Dr. LoBue has received research support from Department of Defense. The institution of Dr. LoBue has received research support from AWARE Organization. The institution of Dr. Sutcliffe has received research support from Rare Diseases Clinical Research Network. Dr. Abel has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Monteris Medical. Dr. Baumgartner has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for PMT Corporation. Dr. Neimat has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Monteris, Abbott. Dr. Palys has nothing to disclose. Dr. Pearson has received publishing royalties from a publication relating to health care.

Analytical solution of heat-transfer in central part of tibia bone tissue using non-Fourier heat equation with a laser heat source

Hyperbolic heat transfer equation considering a laser heat source is analytically investigated using Laplace transform method to study the temperature distribution in the central part of the tibia bone tissue. The target zone is the compact layer of tibia, and the laser irradiation in four near-surface points during 2 s is taken into account. Holmium–Yttrium–Aluminum-Garnet (Ho-YAG) laser is utilized in the simulations. Results indicate that there is a trilateral relationship among the temperature changes of various points in the tissue, the power used and the wavelength. While neglecting the effects of blood circulation upon laser interaction with the bone surface, the results reveal that the temperature of the points adjacent to the bone surface dramatically increases up to 85 °C. Meanwhile, the heat source is provided based on the Beer-Lambert law, and finally it demonstrates that the penetration depth exponentially reduces the intensity and causing considerable decrease in temperature. For the first time, the non-Fourier heat transfer equation was solved using the Laplace transform method for the tibia bone, and its results were compared with the numerical solution results using the Leap- Frog method. Knowing the temperature changes caused by laser inside the tissue is very crucial in Laser tissue welding, tissue ablation, photocoagulation and photo-thermal denaturation, angioplasty, treatment of granulation tissues, change and deformation of cartilage.

Surgical Excision of Hypertrophic Tissue and Retrieval of Orthodontic Mini-implant using Diode Laser- A Rare Case Report

Orthodontic mini-implants or transient anchorage devices can be used to shift difficult teeth. There is substantial evidence showing the effectiveness of Temporary Anchorage Devices (TAD) and their anchorage requirements. However, there are also reports of failures and complications like soft tissue inflammation, tissue overgrowth, peri-implantitis and mini-implant fracture. The present case report of 22 years old female patient, discusses a rare occurrence of tissue overgrowth over the mini-implant on right buccal mucosa in relation to 45, 46 regions. A 1.3×9 mm stainless steel mini-implant was used as an interim anchorage device. The tissue overgrowth was attributed to soft tissue inflammation around the mini-implant. Under adequate anaesthesia, the tissue was removed using a laser, and the mini-implant was retrieved using tissue forceps. After achieving hemostasis, simple interrupted sutures were placed. It is recommended to administer antibiotics, analgesics, and along with postoperative instructions. When used correctly, mini-screws are valuable tools that enhance the effectiveness of orthodontic treatment. However, there is a scarcity of case studies discussing the complications and side-effects of mini-implants. Clinicians should carefully evaluate both general and unique side-effects and complications at the insertion site. This case report demonstrates the successful removal of an orthodontic mini-implant following diode laser ablation of hyperplastic tissue.

Tilted Fiber Bragg Grating Measurements During Laser Ablation of Hepatic Tissues: Quasi-Distributed Temperature Reconstruction and Cladding Mode Resonances Analysis

In this work, we investigate the application of tilted fiber Bragg grating (TFBG) sensors during <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ex vivo</i> laser ablation of porcine hepatic tissues. Initially, TFBG’s ability to measure the surrounding refractive index (RI) for different sucrose concentrations and the possibility to measure the RI of the targeted tissue during laser ablation (LA) is analyzed. After, the temperature sensing modality of TFBG is investigated in detail. We have implemented an algorithm for quasi-distributed spatial temperature profile reconstruction along TFBG. The algorithm models the TFBG core mode spectrum as a chain of Bragg gratings (each Bragg grating is modeled <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">via</i> coupled mode theory), where each grating is sensitive to local temperature changes. After, the Gaussian-shape temperature profile along the TFBG is reconstructed using the iterative optimization technique. Temperature measurements have been compared with highly-dense FBG array measurements and with conventional TFBG point temperature measurements based on the core mode tracking techniques (maximum tracking, X-dB Bandwidth, centroid methods). Overall, the proposed reconstruction algorithm is able to provide a quasi-distributed temperature profile along TFBG, which is not possible to obtain using conventional point temperature measurements based on the TFBG’s core mode tracking. The resulted root-mean-square error in comparison to FBG array reference measurements is 7.8±1.7 °C. In general, the results show that the main reliable sensing modality of TFBG during LA is temperature monitoring, which can be significantly improved by the proposed algorithm.

MP01-06 OFFICE BASED TRANSPERINEAL LASER ABLATION FOR BENIGN PROSTATIC HYPERPLASIA: 3 &amp; 6 MONTHS OUTCOMES

You have accessJournal of UrologyCME1 May 2022MP01-06 OFFICE BASED TRANSPERINEAL LASER ABLATION FOR BENIGN PROSTATIC HYPERPLASIA: 3 & 6 MONTHS OUTCOMES Luna Eusebio, Luis Avila, Alberto Lopez-Prieto, Edward Gheiler, Ariel Kaufman, David Cohen, and Fernando Bianco Luna EusebioLuna Eusebio More articles by this author , Luis AvilaLuis Avila More articles by this author , Alberto Lopez-PrietoAlberto Lopez-Prieto More articles by this author , Edward GheilerEdward Gheiler More articles by this author , Ariel KaufmanAriel Kaufman More articles by this author , David CohenDavid Cohen More articles by this author , and Fernando BiancoFernando Bianco More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002513.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: BPH affects tens of millions of men across the world. Most procedures require either general or regional anesthesia or a transurethral approach. Herein, we present the 3 & 6 months results of NCT04760483 is a phase I prospective, single center, interventional pilot study evaluating transperineal laser ablation (TPLA) of BPH tissues, carried in Office setting under local anesthesia. A detailed step by step video depiction of this procedure is available at the AUA video library. The objectives call for safety, feasibility, and impact in pertinent outcomes measures, such as Uroflowmetry, IPSS, Hematuria, Erectile function, and ejaculation METHODS: The study contemplated accrual of 20 men between 50 and 80 years with prostate volumes between 30 and 120 cc, IPSS scores >9, peak flows between 5 and 15 cc/s and void residuals under <250 ml. Any patient neurological conditions, history of any surgical intervention or urinary retention were excluded. IPSS assessments, Flow studies and prostate volume measures were conducted at 3 months. Herein we present the results. Bayesian analysis for continuous measurements were performed and non-parametric differences were evaluated using chi2 tests. RESULTS: Patients enrolled between December 2020 and February of 2021. The median (IQR) for age and BMI was 68 (58,73) and 29 (27,31), respectively. These parameters for room time, ablation time, watts and total joules were 29 (23,32), 9 minutes (7,12), 6 (5,7) watts and 3,400 (2,600, 3600) joules, respectively. 8(40%) were discharged with a Foley due to elevated residuals. 16 patients had erections and ejaculations before and 3 months after TPLA. 17/20 (85%) had significant improvement in their urinary profile after TPLA (See TABLE for details). One of the initial responders suffered from COVID-19 infection and developed a CVA that hindered his urinary function. CONCLUSIONS: TPLA in the office setting is feasible and safe. Three month outcomes showed subjective and objective sustained improvement in over 80% of patients for at least 6 months. Furthermore, erections or ejaculations were not affected. This novel and promising approach demands further evaluation in phase II-III trials. Source of Funding: Urological Research Network Foundation © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e3 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Luna Eusebio More articles by this author Luis Avila More articles by this author Alberto Lopez-Prieto More articles by this author Edward Gheiler More articles by this author Ariel Kaufman More articles by this author David Cohen More articles by this author Fernando Bianco More articles by this author Expand All Advertisement PDF DownloadLoading ...

Designing and Testing a Closed-Loop Magnetically Actuated Laser Scanning System for Tissue Ablation

Abstract Biomedical robotic systems continue to hold unlimited potential for surgical procedures. Robotized laser endoscopic tools provide surgeons with increased accuracy in the laser ablation of tissue and tumors. The research here catalogs the design and implementation of a new laser endoscopic tool for tissue ablation. A novel feature of this new device is the inclusion of a feedback loop that measures the position of the laser beam via a photodetector sensor. The scale of this new device was governed by the dimensions of the photodetector sensor. The tip of the laser's fiber optic cable is controlled by the torque interaction between permanent magnet rings surrounding the fiber-optic and the custom-designed solenoid coils. Prior to building the physical test-bed, the system was modeled and simulated using comsol software. In preclinical trials, the physical experimental results showed that the designed prototype laser scanner system accurately tracks different ablation patterns and gives a consistent output position for the laser beam; however, the heat diffusion into the tissue around the desired line of the geometric shape would give wider ablation margins than was desirable.

Preliminary study on the osseointegration effects of contactless automated implant cavity preparation via femtosecond laser ablation.

Microrobots were used to control the femtosecond laser ablation of bone tissues to prepare implant cavities for dental implant surgery. The method was optimized through depth-of-cut experiments of ex vivo rabbit femurs, and the optimized method was used to prepare implant cavities on the left femurs of eight live rabbits. A power of 10 W and a scanning rate of 4000 mm/s were found to be optimal. After seven days of osteoinduction, the expression of collagen type I was significantly higher in the experimental group than in the control group (manually drilled implant cavities). The bone-implant contacts of the experimental group at 4 and 8 weeks were 9.65% and 23.08%, respectively.

Laser Ablation of Abnormal Neurological Tissue Using Robotic NeuroBlate System (LAANTERN): 12-Month Outcomes and Quality of Life After Brain Tumor Ablation

Laser Ablation of Abnormal Neurological Tissue Using Robotic NeuroBlate System (LAANTERN): 12-Month Outcomes and Quality of Life After Brain Tumor Ablation

Ablation of Bone Tissue by Femtosecond Laser: A Path to High-Resolution Bone Surgery.

Femtosecond lasers allow for high-precision, high-quality ablation of biological tissues thanks to their capability of minimizing the thermal loads into the irradiated material. Nevertheless, reported ablation rates remain still too limited to enable their exploitation on a clinical level. This study demonstrates the possibility to upscale the process of fs laser ablation of bone tissue by employing industrially available fs laser sources. A comprehensive parametric study is presented in order to optimize the bone tissue ablation rate while maintaining the tissue health by avoiding excessive thermal loads. Three different absorption regimes are investigated by employing fs laser sources at 1030 nm, 515 nm and 343 nm. The main differences in the three different wavelength regimes are discussed by comparing the evolution of the ablation rate and the calcination degree of the laser ablated tissue. The maximum of the ablation rate is obtained in the visible regime of absorption where a maximum value of 0.66 mm3/s is obtained on a non-calcined tissue for the lowest laser repetition rate and the lowest spatial overlap between successive laser pulses. In this regime, the hemoglobin present in the fresh bone tissue is the main chromophore involved in the absorption process. To the best of our knowledge, this is the highest ablation rate obtained on porcine femur upon fs laser ablation.

Lasers in endoscopic middle ear surgery: where do we stand today?

To provide an overview of the current status regarding the parallel use of the endoscope and the laser in middle ear surgery. Comprehensive Pubmed search from 1975 to 2020 including clinical articles, of any type, reporting the combined use of a laser and an endoscope. Purely experimental and non-human studies were excluded. Reports on the application of the laser in pediatric and adult endoscopic middle ear surgery (EES) are increasing since 2013. Laser-assisted EES is performed for cholesteatoma, non-squamous chronic otitis media, ossicular fixation, otosclerosis and tympanic paraganglioma. The improved haemostasis and the non-contact ablation of tissue around the ossicles and inaccessible areas, represent unique advantages. In stapes surgery, the resection of stapes superstructure with minimal force and the non-contact footplate fenestration are potential advantages. Proper use of the laser, i.e. direction away from the facial nerve and the open labyrinth and safe energy settings have resulted in minimal complications. Based on the increasing number of publications, endoscopic ear surgeons show an interest in using a laser for specific operative tasks. The configuration of a hand-held laser probe does not differ significantly from other otological instruments and therefore is easy to use alongside the endoscope, even in children. The 'handicap' of single-handed surgery can be partially offset by the bloodless and non-contact laser ablation of tissue.

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).

Methodology for the Implementation of Internal Standard to Laser-Induced Breakdown Spectroscopy Analysis of Soft Tissues.

The improving performance of the laser-induced breakdown spectroscopy (LIBS) triggered its utilization in the challenging topic of soft tissue analysis. Alterations of elemental content within soft tissues are commonly assessed and provide further insights in biological research. However, the laser ablation of soft tissues is a complex issue and demands a priori optimization, which is not straightforward in respect to a typical LIBS experiment. Here, we focus on implementing an internal standard into the LIBS elemental analysis of soft tissue samples. We achieve this by extending routine methodology for optimization of soft tissues analysis with a standard spiking method. This step enables a robust optimization procedure of LIBS experimental settings. Considering the implementation of LIBS analysis to the histological routine, we avoid further alterations of the tissue structure. Therefore, we propose a unique methodology of sample preparation, analysis, and subsequent data treatment, which enables the comparison of signal response from heterogenous matrix for different LIBS parameters. Additionally, a brief step-by-step process of optimization to achieve the highest signal-to-noise ratio (SNR) is described. The quality of laser–tissue interaction is investigated on the basis of the zinc signal response, while selected experimental parameters (e.g., defocus, gate delay, laser energy, and ambient atmosphere) are systematically modified.

PID Controlling Approach Based on FBG Array Measurements for Laser Ablation of Pancreatic Tissues

In this article, we propose a temperature-based proportional–integral–derivative (PID) controlling algorithm using highly dense fiber Bragg grating (FBG) arrays for laser ablation (LA) of ex vivo pancreatic tissues. Custom-made highly dense FBG arrays with a spatial resolution of 1.2 mm were fabricated with the femtosecond point-by-point writing technology and optimized for LA applications. In order to obtain proper PID gain values, finite element method-based iterative simulation of different PID gains was performed. Then, the proposed algorithm, with numerically derived PID gains, was experimentally validated. In the experiments, the point temperature was controlled at different distances from the laser fiber tip (6.0, 7.2, 8.4, and 10.8 mm). The obtained results report robust controlling and correlation between controlled distance and the resulting area of ablation. The results of the work encourage further investigation of FBG array application for LA control.

Dynamics of picosecond laser ablation for surgical treatment of colorectal cancer

Endoluminal surgery for the treatment of colorectal neoplasia is typically carried out using electrocautery tools which imply limited precision and the risk of harm through collateral thermal damage to the adjacent healthy tissue. As a potential alternative, we present the successful colonic epithelial laser ablation by means of picosecond laser pulses. Laser ablation studies performed in ex-vivo colon tissue result in cavities with comparable thickness to early stage colorectal cancers. The corresponding histology sections exhibit only minimal collateral damage to the surrounding tissue and the depth of the ablation can be controlled precisely by means of the pulse energy. High-speed imaging has been used for the first time to visualize picosecond laser ablation of cancerous tissue in a clinically relevant model. This information was correlated with histopathology and optical surface profilometry revealing the dynamic nature of the laser tissue interaction and the need for temporal or spatial separation of pulses for optimum efficacy with regards to tissue removal. Overall, the application of picosecond laser pulses to ablate endoluminal bowel lesions demonstrates significantly improved precision and reduced thermal damage to the adjacent tissue in comparison to conventional procedures and hence will enable more precise surgical treatment of cancers.