Femtosecond laser bone ablation with a high repetition rate fiber laser source

Femtosecond laser pulses can be used to perform very precise cutting of material, including biological samples from subcellular organelles to large areas of bone, through plasma-mediated ablation. The use of a kilohertz regenerative amplifier is usually needed to obtain the pulse energy required for ablation. This work investigates a 5 megahertz compact fiber laser for near-video rate imaging and ablation in bone. After optimization of ablation efficiency and reduction in autofluorescence, the system is demonstrated for the in vivo study of bone regeneration. Image-guided creation of a bone defect and longitudinal evaluation of cellular injury response in the defect provides insight into the bone regeneration process.OCIS codes: (170.1020) Ablation of tissue, (170.2520) Fluorescence microscopy, (060.4370) Nonlinear optics, fibers, (180.4315) Nonlinear microscopy     

Planning and simulation of microsurgical laser bone ablation

Purpose  

Laser ablation of hard tissue is not completely understood until now and not modeled for computer-assisted microsurgery. A precise planning and simulation is an essential step toward the usage of microsurgical laser bone ablation in the operating room.     

Hemodynamic assessment of critically ill patients using a miniaturized transesophageal echocardiography probe

Introduction

Hemodynamic management in intensive care patients guided by blood pressure and flow measurements often do not sufficiently reveal common hemodynamic problems. Trans-esophageal echocardiography (TEE) allows for direct measurement of cardiac volumes and function. A new miniaturized probe for TEE (mTEE) potentially provides a rapid and simplified approach to monitor cardiac function. The aim of the study was to assess the feasibility of hemodynamic monitoring using mTEE in critically ill patients after a brief operator training period.

Methods

In the context of the introduction of mTEE in a large ICU, 14 ICU staff specialists with no previous TEE experience received six hours of training as mTEE operators. The feasibility of mTEE and the quality of the obtained hemodynamic information were assessed. Three standard views were acquired in hemodynamically unstable patients: 1) for assessment of left ventricular function (LV) fractional area change (FAC) was obtained from a trans-gastric mid-esophageal short axis view, 2) right ventricular (RV) size was obtained from mid-esophageal four chamber view, and 3) superior vena cava collapsibility for detection of hypovolemia was assessed from mid-esophageal ascending aortic short axis view. Off-line blinded assessment by an expert cardiologist was considered as a reference. Inter-rater agreement was assessed using Chi-square tests or correlation analysis as appropriate.

Results

In 55 patients, 148 mTEE examinations were performed. Acquisition of loops in sufficient quality was possible in 110 examinations for trans-gastric mid-esophageal short axis, 118 examinations for mid-esophageal four chamber and 125 examinations for mid-esophageal ascending aortic short axis view. Inter-rater agreement (Kappa) between ICU mTEE operators and the reference was 0.62 for estimates of LV function, 0.65 for RV dilatation, 0.76 for hypovolemia and 0.77 for occurrence of pericardial effusion (all P < 0.0001). There was a significant correlation between the FAC measured by ICU operators and the reference (r = 0.794, P (one-tailed) < 0.0001).

Conclusions

Echocardiographic examinations using mTEE after brief bed-side training were feasible and of sufficient quality in a majority of examined ICU patients with good inter-rater reliability between mTEE operators and an expert cardiologist. Further studies are required to assess the impact of hemodynamic monitoring by mTEE on relevant patient outcomes.     

Fall of intradiscal pressure with laser ablation

In an experimental system where intradiscal pressure could be measured before and after laser ablation, we found that there was a significant fall of intradiscal pressure after 1000 J of Nd:YAG laser energy was delivered to fresh cadaver discs. That this was not due to fenestration was demonstrated by control experiments using an identical system, but without turning on the laser. Here, there was no significant fall of intradiscal pressure.     

Endovenous laser ablation for superficial venous insufficiency

Background: Endovenous laser ablation (EVLA) is a new minimally invasive alternative to conventional surgery for superficial venous insufficiency and varicose veins, where laser energy is used to ablate the incompetent veins. Discussion: Endovenous laser ablation avoids the need for surgical incisions, and the complications of surgical exploration of the groin or popliteal fossa, and stripping. The procedure is commonly performed under local anaesthesia, with immediate mobilisation and rapid return to normal activity. Severe varicosity of tributaries may require adjunctive procedures such as microphlebectomy or sclerotherapy. Conclusion: Early outcomes and cosmesis are superior, and long‐term data is accumulating that recurrence of EVLA rates may be lower.     

Pulmonary vein isolation with a novel endoscopic ablation system using laser energy

Pulmonary vein isolation (PVI) is the basis of all ablation techniques for paroxysmal atrial fibrillation. Performing conventional radiofrequency ablation for PVI is time consuming and sometimes challenging when using point-by-point applications to create continuous lesions. Small electrically conducting gaps evolving in the ablation lines may cause recurrences of atrial fibrillation or regular atrial re-entry tachycardias. Development of novel anatomically designed ablation catheters for PVI aim to facilitate the ablation procedure, to produce continuous and durable lesions with a limited number of ablation impulses and to reduce the complication rate. The endoscopic laser balloon ablation system (HeartLight^® EAS, Cardiofocus Inc.) is the first system that allows direct visual guidance of energy delivery at the antral level of each pulmonary vein and uses a completely new energy source for ablation.     

Refractive surgery with excimer laser

Surgery to correct myopia, hypermetropia and astigmatism has become very popular over the past few years. Patients have been able to do away with their glasses or contact lenses are can carry out daily activities without having to worry about their vision. This happens by means of the LASIK technique (in situ "keratomyleusis" assisted by means of an "Excimer" laser). This method consists of the application of ultraviolet light on the cornea in order to modify its structure to offset the existing optical defect. This is the most effective and safest procedure available today. In spite of this, as with any surgical procedure, this procedure is not without its complications which may range from a small inflammation in the eye area to extreme cases which require a cornea transplant. A patient who desires to undergo this surgery should be fully aware of all these complications.     

川续断复合磷酸钙骨修复骨缺损

背景：复合磷酸钙骨植入材料的物理结构和无机成分与人体骨相似,具有良好的生物可吸收性和生物相容性。研究证实续断细粉能明显提高骨缺损修复速度。 目的：观察川续断复合磷酸钙骨复合植入材料修复骨缺损的效果。 方法：在新西兰大白兔双侧下颌骨体部制备长约1.0 cm、宽约0.5 cm、深约0.3 cm的骨缺损,右侧植入川续断复合磷酸钙材料作为实验组,左侧植入磷酸钙骨材料作为对照组。植入后4,8,12周取材,进行大体观察、CBCT检测、扫描电镜、组织学观察。 结果与结论：①大体观察：实验组成骨速度、材料降解率及硬度高于对照组。②CBCT 检测：实验组材料与周围组织结合紧密度强于对照组,且材料降解速度快于对照组。③扫描电镜：两组材料与周围正常骨组织间大多由纤维结缔组织充盈,实验组比对照组更为紧密,空隙更加微小,随着时间的增加,材料与周围正常骨组织的结合更为紧密。④组织学观察：实验组成骨速度及成骨活性优于对照组。表明川续断复合磷酸钙骨植入材料具有明显加速成骨的作用。     

A simple colorimetric and ratiometric fluoride ion probe with large color change

Two colorimetric and ratiometric fluoride ion probes SHJ-1 and SHJ-2 based on the acylhydrazone skeleton have been developed. Among the eight anions (F⁻, Cl⁻, Br⁻, I⁻, ClO₄⁻, H₂PO₄⁻, HSO₄⁻, CH₃COO⁻), the present probes showed high selectivity and sensitivity toward fluoride ion detection with obvious color change. Notably, the probe SHJ-1 exhibited a red shift of 145 nm upon fluoride sensing, which is the largest value among fluoride ion probes based on acylhydrazone derivates to date. ¹HNMR titration study and theoretical calculations suggested that the strong binding of the probe SHJ-1 to fluoride as well as the further deprotonation may facilitate the intramolecular charge transfer transition. These two probes are 1 : 1 complexed with fluoride ions, and the detection limits were calculated to be 1.24 μM for SHJ-1 and 15.73 μM for SHJ-2.

Two colorimetric and ratiometric fluoride ion probes SHJ-1 and SHJ-2 based on the acylhydrazone skeleton have been developed.     

New concepts in laser medicine: Towards a laser surgery with cellular precision

New concepts and instrumentation in laser medicine are driven by the progress in optical technology as well as by advances in the understanding of the interaction of optical irradiation with tissue, especially at a macromolecular scale, and by the changing needs in health care. Complexity and costs of laser sources will decrease due to the use of semiconductor and fiber lasers, and complex or non-linear mechanisms by which the radiation effects tissues are better understood, especially when ultra-short laser pulses are used.Especially femtosecond lasers and nanotechnology have the potential to treat diseases at a cellular level. Focused femtosecond irradiation was successfully used to manipulate tissues with subcellular precision. Laser-irradiated nanoparticles can selectively destroy individual cells.

Zusammenfassung

Neue Konzepte für die Lasermedizin: Der Weg zu Therapien mit zellulärer PräzisionNeue Konzepte und Geräte im Bereich der Lasermedizin werden durch die Fortschritte in den optischen Technologien, dem zunehmenden Verständnis der Wirkung von Licht auf Gewebe, besonders auch in makromolekularen Dimensionen, und den sich verändernden Anforderungen an die Medizin entstehen. Komplexität und Kosten von Lasergeräten werden sinken, vor allem auch durch die Fortschritte bei Halbleiterlasern und Lichtleitern. Das Verständnis komplexer, nichtlinearer Wirkungen von Licht auf Gewebe, speziell bei ultrakurzen Pulsen, wächst beständig.Zelluläre Therapien basierend auf Femtosekundenlaser und Nanotechnologie haben die Chance völlig neue diagnostische und therapeutische Verfahren auf zellulärer Ebene zu ermöglichen.     

Development and ex-vivo validation of 36G polyimide cannulas integrating a guiding miniaturized OCT probe for robotic assisted subretinal injections

We introduced and validated a method to encase guiding optical coherence tomography (OCT) probes into clinically relevant 36G polyimide subretinal injection (SI) cannulas. Modified SI cannulas presented consistent flow capacity and tolerated the typical mechanical stress encountered in clinical use without significant loss of sensitivity. We also developed an approach that uses a micromanipulator, modified SI cannulas, and an intuitive graphical user interface to enable precise SI. We tested the system using ex-vivo porcine eyes and we found a high SI success ratio 95.0% (95% CI: 83.1–99.4). We also found that 75% of the injected volume ends up at the subretinal space. Finally, we showed that this approach can be applied to transform commercial 40G SI cannulas to guided cannulas. The modified cannulas and guiding approach can enable precise and reproducible SI of novel gene and cell therapies targeting retinal diseases.     

Splenic thrombopoiesis after bone marrow ablation with radiostrontium: a murine model

Murine platelet production is normally supported by high-ploidy bone marrow megakaryocytes without significant contribution from splenic megakaryocytes with predominantly low-ploidy levels. We produced sustained bone marrow ablation using radiostrontium, and examined the processes by which splenic platelet production is initiated and maintained in the absence of bone marrow function. Bone marrow hematopoiesis, measured by total nucleated cell number and viability, megakaryocyte colony-forming cells, and granulocyte-macrophage colony-forming cells, was rapidly ablated in mice by using yttrium 90-free strontium 90. Platelet count declined from normal (1224 x 10(3)/microliters) to a nadir (98 x 10(3)/microliters) 11 days after 90Sr, and then rose to a stable level (705 x 10(3)/microliters) on days 20 through 115. Peripheral leukocyte concentration decreased rapidly and remained below 25% of normal in contrast to hemoglobin levels, which were minimally lowered. Mean spleen weight rose rapidly after 90Sr to 66% above normal. Splenic megakaryocyte frequency, measured by two-color fluorescence-activated flow cytometry, rose from basal levels (0.09% +/- 0.06%) to 0.15% +/- 0.07% (p less than 0.001), total spleen nucleated cells fell to 71% of normal, and the absolute number of spleen megakaryocytes was unchanged. Total spleen megakaryocyte colony-forming cells were not significantly increased above normal whereas total spleen granulocyte-macrophage colony-forming cells increased abruptly after day 13 to 10 times normal levels. Splenectomy after hematopoietic recovery from 90Sr bone marrow ablation resulted in a rapid decline of platelet levels, followed by death. Although the spleen became the sole site of platelet production, the splenic megakaryocyte ploidy distribution was only minimally changed from normal, and the modal ploidy class remained 2N. In contrast to experimental thrombocytopenia in mice with intact bone marrow, in which megakaryocyte ploidy is increased, thrombocytopenia associated with sustained bone marrow ablation does not result in upward regulation of splenic megakaryocyte ploidy as a compensatory mechanism.     

Laser induced breakdown spectroscopy for bone and cartilage differentiation - ex vivo study as a prospect for a laser surgery feedback mechanism

Laser surgery enables for very accurate, fast and clean modeling of tissue. The specific and controlled cutting and ablation of tissue, however, remains a central challenge in the field of clinical laser applications. The lack of information on what kind of tissue is being ablated at the bottom of the cut may lead to iatrogenic damage of structures that were meant to be preserved. One such example is the shaping or removal of diseased cartilaginous and bone tissue in the temporomandibular joint (TMJ). Diseases of the TMJ can induce deformation and perforation of the cartilaginous discus articularis, as well as alterations to the cartilaginous surface of the condyle or even the bone itself. This may result in restrictions of movement and pain. The aim of a surgical intervention ranges from specific ablation and shaping of diseased cartilage, bone or synovial tissues to extensive removal of TMJ structures. One approach to differentiate between these tissues is to use Laser Induced Breakdown Spectroscopy (LIBS). The ultimate goal is a LIBS guided feedback control system for surgical laser systems that enables real-time tissue identification for tissue specific ablation. In the presented study, the authors focused on the LIBS based differentiation between cartilage tissue and cortical bone tissue using an ex-vivo pig model.OCIS codes: (170.1020) Ablation of tissue, (170.1470) Blood or tissue constituent monitoring, (170.6935) Tissue characterization, (300.6365) Spectroscopy, laser induced breakdown     

Optimizing deep bone ablation by means of a microsecond Er:YAG laser and a novel water microjet irrigation system

The microsecond Er:YAG pulsed laser with a wavelength of λ = 2.94 μm has been widely used in the medical field, particularly for ablating dental tissues. Since bone and dental tissues have similar compositions, consisting of mineralized and rigid structures, the Er:YAG laser represents a promising tool for laserosteotomy applications. In this study, we explored the use of the Er:YAG laser for deep bone ablation, in an attempt to optimize its performance and identify its limitations. Tissue irrigation and the laser settings were optimized independently. We propose an automated irrigation feedback system capable of recognizing the temperature of the tissue and delivering water accordingly. The irrigation system used consists of a thin 50 μm diameter water jet. The water jet was able to penetrate deep into the crater during ablation, with a laminar flow length of 15 cm, ensuring the irrigation of deeper layers unreachable by conventional spray systems. Once the irrigation was optimized, ablation was considered independently of the irrigation water. In this way, we could better understand and adjust the laser parameters to suit our needs. We obtained line cuts as deep as 21 mm without causing any visible thermal damage to the surrounding tissue. The automated experimental setup proposed here has the potential to support deeper and faster ablation in laserosteotomy applications.     

Deep learning with convolutional neural network for objective skill evaluation in robot-assisted surgery

Purpose

With the advent of robot-assisted surgery, the role of data-driven approaches to integrate statistics and machine learning is growing rapidly with prominent interests in objective surgical skill assessment. However, most existing work requires translating robot motion kinematics into intermediate features or gesture segments that are expensive to extract, lack efficiency, and require significant domain-specific knowledge.

Methods

We propose an analytical deep learning framework for skill assessment in surgical training. A deep convolutional neural network is implemented to map multivariate time series data of the motion kinematics to individual skill levels.

Results

We perform experiments on the public minimally invasive surgical robotic dataset, JHU-ISI Gesture and Skill Assessment Working Set (JIGSAWS). Our proposed learning model achieved competitive accuracies of 92.5%, 95.4%, and 91.3%, in the standard training tasks: Suturing, Needle-passing, and Knot-tying, respectively. Without the need of engineered features or carefully tuned gesture segmentation, our model can successfully decode skill information from raw motion profiles via end-to-end learning. Meanwhile, the proposed model is able to reliably interpret skills within a 1–3 second window, without needing an observation of entire training trial.

Conclusion

This study highlights the potential of deep architectures for efficient online skill assessment in modern surgical training.

     

腔内激光闭合术与传统剥脱手术治疗小隐静脉曲张的对比研究

目的:评估腔内激光闭合术(EVLA)治疗小隐静脉曲张的临床疗效。方法:通过与传统剥脱手术比较,采用非盲随机对照试验,将107例小隐静脉曲张患者分为51例EVLA组和56例传统手术组,分别进行EVLA术及高位结扎剥脱术,观察比较两组手术时间、住院时间、术后疼痛、术后并发症、症状改善情况、创口满意度及术后1年的复发率。结果:两组患者经治疗症状均得到明显改善;术后严重程度评分(VCSS)、生活质量评分(EQ-5D)差异无统计学意义。而EVLA组术后创口满意度较高(P0.05);手术时间、住院时间均低于传统手术组(P0.05)。EVLA组无创口感染及深静脉血栓发生。传统手术组发生神经损伤4例,EVLA组仅1例神经损伤。结论:腔内激光闭合术治疗小隐静脉曲张疗效与传统手术相当,但具有操作简便、术后恢复快、美容效果好等优势。