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1.
J Robot Surg ; 16(5): 1083-1090, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34837593

RESUMO

Excessive tissue-instrument interaction forces during robotic surgery have the potential for causing iatrogenic tissue damages. The current in vivo study seeks to assess whether tactile feedback could reduce intraoperative tissue-instrument interaction forces during robotic-assisted total mesorectal excision. Five subjects, including three experts and two novices, used the da Vinci robot to perform total mesorectum excision in four pigs. The grip force in the left arm, used for retraction, and the pushing force in the right arm, used for blunt pelvic dissection around the rectum, were recorded. Tissue-instrument interaction forces were compared between trials done with and without tactile feedback. The mean force exerted on the tissue was consistently higher in the retracting arm than the dissecting arm (3.72 ± 1.19 vs 0.32 ± 0.36 N, p < 0.01). Tactile feedback brought about significant reductions in average retraction forces (3.69 ± 1.08 N vs 4.16 ± 1.12 N, p = 0.02), but dissection forces appeared unaffected (0.43 ± 0.42 vs 0.37 ± 0.28 N, p = 0.71). No significant differences were found between retraction and dissection forces exerted by novice and expert robotic surgeons. This in vivo animal study demonstrated the efficacy of tactile feedback in reducing retraction forces during total mesorectal excision. Further research is required to quantify the clinical impact of such force reduction.


Assuntos
Neoplasias Retais , Procedimentos Cirúrgicos Robóticos , Robótica , Animais , Retroalimentação , Humanos , Neoplasias Retais/cirurgia , Reto/cirurgia , Procedimentos Cirúrgicos Robóticos/métodos , Suínos
2.
Lasers Med Sci ; 36(7): 1403-1410, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33106990

RESUMO

Bacterial biofilms are often found in chronically infected wounds. Biofilms protect bacteria from antibiotics and impair wound healing. Surgical debridement is often needed to remove the biofilm from an infected wound. Laser-generated shockwave (LGS) treatment is a novel tissue-sparing treatment for biofilm disruption. Previous studies have demonstrated that LGS is effective in disrupting biofilms in vitro. In this study, we aim to determine the safety threshold of the LGS technology in an in vivo rodent model. To understand the in vivo effects of LGS on healthy cutaneous tissue, the de-haired dorsal skin of Sprague-Dawley rats were treated with LGS at three different peak pressures (118, 296, 227 MPa). These pressures were generated using a 1064 nm Nd/YAG laser (pulse duration 5 ns and laser fluence of 777.9 mJ) with laser spot size diameters of 2.2, 3.0, and 4.2 mm, respectively. Following treatment, the animals were observed for 72 h, and a small subset was euthanized at 1-h, 24-h, and 72-h post-treatment and assessed for tissue injury or inflammation under histology. Each treatment group consisted of 9 rats (n = 3/time point for 1-h, 24-h, 72-h post-treatment). An additional 4 control (untreated) rats were included in the analysis, for a total of 31 animals. Gross injuries occurred in 21 (77%) animals and consisted of minor erythema, with prevalence positively correlated with peak pressure (p < 0.05). Of injuries under gross observation, 94% resolved within 24 h. Under histological analysis, the injuries and tissue inflammation were found to be localized to the epidermis and superficial dermis. LGS appears to be well tolerated by cutaneous tissue for the laser energy settings shown to be effective against bacterial biofilm in vitro. All injuries incurred, at even the highest peak pressures, were clinically mild and resolved within 1 day. This lends further support to the overall safety of LGS and serves to translate LGS towards in vivo efficacy studies.


Assuntos
Biofilmes , Lasers de Estado Sólido , Roedores , Infecção da Ferida Cirúrgica , Animais , Bactérias , Ratos , Ratos Sprague-Dawley , Infecção da Ferida Cirúrgica/prevenção & controle
3.
Sci Rep ; 9(1): 5016, 2019 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-30899082

RESUMO

Minimally invasive robotic surgery allows for many advantages over traditional surgical procedures, but the loss of force feedback combined with a potential for strong grasping forces can result in excessive tissue damage. Single modality haptic feedback systems have been designed and tested in an attempt to diminish grasping forces, but the results still fall short of natural performance. A multi-modal pneumatic feedback system was designed to allow for tactile, kinesthetic, and vibrotactile feedback, with the aims of more closely imitating natural touch and further improving the effectiveness of HFS in robotic surgical applications and tasks such as tissue grasping and manipulation. Testing of the multi-modal system yielded very promising results with an average force reduction of nearly 50% between the no feedback and hybrid (tactile and kinesthetic) trials (p < 1.0E-16). The multi-modal system demonstrated an increased reduction over single modality feedback solutions and indicated that the system can help users achieve average grip forces closer to those normally possible with the human hand.


Assuntos
Fenômenos Mecânicos , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Procedimentos Cirúrgicos Robóticos/métodos , Robótica/métodos , Desenho de Equipamento , Retroalimentação Sensorial/fisiologia , Mãos/fisiologia , Força da Mão/fisiologia , Humanos , Procedimentos Cirúrgicos Minimamente Invasivos/efeitos adversos , Procedimentos de Cirurgia Plástica/métodos , Procedimentos Cirúrgicos Robóticos/efeitos adversos , Tato/fisiologia , Percepção do Tato/fisiologia
4.
Biomed Opt Express ; 10(1): 322-337, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30775103

RESUMO

A method to register THz and visible images of cutaneous burn wounds and to calibrate THz image data is presented. Images of partial and full thickness burn wounds in 9 rats were collected over 435 mins. = 7.25 hours following burn induction. A two-step process was developed to reference the unknown structure of THz imaging contrast to the known structure and the features present in visible images of the injury. This process enabled the demarcation of a wound center for each THz image, independent of THz contrast. Threshold based segmentation enabled the automated identification of air (0% reflectivity), brass (100% reflectivity), and abdomen regions within the registered THz images. Pixel populations, defined by the segmentations, informed unsupervised image calibration and contrast warping for display. The registered images revealed that the largest variation in THz tissue reflectivity occurred superior to the contact region at ~0.13%/min. Conversely the contact region showed demonstrated an ~6.5-fold decrease at ~0.02%/min. Exploration of occlusion effects suggests that window contact may affect the measured edematous response.

5.
IEEE Trans Biomed Eng ; 66(1): 14-22, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29993431

RESUMO

OBJECTIVE: This investigation was performed to evaluate the registration accuracy between magnetic resonance imaging (MRI) and pathology using three-dimensional (3-D) printed molds. METHODS: Tissue-mimicking prostate phantoms were manufactured with embedded fiducials. The fiducials were used to measure and compare target registration error (TRE) between phantoms that were sliced by hand versus phantoms that were sliced within 3-D-printed molds. Subsequently, ten radical prostatectomy specimens were placed inside molds, scanned with MRI, and then sliced. The ex vivo scan was used to assess the true location of whole mount (WM) slides relative to in vivo MRI. The TRE between WM and in vivo MRI was measured using anatomic landmarks. RESULTS: Manually sliced phantoms had a 4.1-mm mean TRE, whereas mold-sliced phantoms had a 1.9-mm mean TRE. Similarly, mold-assisted slicing reduced mean angular misalignment around the left-right (LR) anatomic axis from 10.7° to 4.5°. However, ex vivo MRI revealed that excised prostates were misaligned within molds, including a mean 14° rotation about the LR axis. The mean in-plane TRE was 3.3 mm using molds alone and 2.2 mm after registration was corrected with ex vivo MRI. CONCLUSION: Patient-specific molds improved accuracy relative to manual slicing techniques in a phantom model. However, the registration accuracy of surgically resected specimens was limited by their imperfect fit within molds. This limitation can be overcome with the addition of ex vivo imaging. SIGNIFICANCE: The accuracy of 3-D-printed molds was characterized, quantifying their utility for facilitating MRI-pathology registration.


Assuntos
Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Próstata , Neoplasias da Próstata , Marcadores Fiduciais , Humanos , Masculino , Imagens de Fantasmas , Próstata/diagnóstico por imagem , Próstata/patologia , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/patologia
6.
Lasers Surg Med ; 51(4): 339-344, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30152534

RESUMO

Background and Objectives Laser generated shockwave (LGS) is a novel modality for minimally invasive disruption of bacterial biofilms. The objectives of this study are to determine the mechanisms behind LGS treatment and non-biofilm effects on bacterial disruption, including (1) comparing bacterial load with and without LGS in its planktonic form and (2) estimating bacterial cell permeability following LGS. Study Design/Materials and Methods For the first study, planktonic S. epidermidis were treated with gentamicin (0, 8, 16, 32, 64 µg/ml) with and without LGS (1064 nm Nd:YAG laser, 110.14 mJ/mm2 , pulse duration 9 ns, spot size 3 mm, n = 8/group), and absorbances at 600 nm compared. For the second study, four samples of planktonic S. epidermidis were treated with LGS (same settings). Propidium iodide (PI) uptake via flow cytometry as a measure of cell permeability was measured at 0, 10, and 20 minutes following LGS. RESULTS: In comparing corresponding gentamicin concentrations within both LGS-treated samples and controls at 0 hours, there were no differences in absorbance (P = 0.923 and P = 0.814, respectively). Flow cytometry found modest PI uptake (10.4 ± 2.5%) immediately following LGS treatment, with time-dependent increase and persistence of the signal at 20 minutes (R2 = 0.449, P = 0.048). CONCLUSION: Taken together, LGS does not appear to have direct bacteriocidal properties, but rather by allowing for biofilm disruption and bacterial cell membrane permeabilization, both of which likely increase topical antibiotic delivery to pathogenic organisms. Insight into the mechanisms of LGS will allow for improved clinical applications and facilitate safe and effective translation of this technology. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc.


Assuntos
Carga Bacteriana/efeitos da radiação , Biofilmes/efeitos da radiação , Membrana Celular/efeitos da radiação , Lasers de Estado Sólido , Staphylococcus epidermidis/efeitos da radiação , Antibacterianos/farmacologia , Carga Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Citometria de Fluxo , Gentamicinas/farmacologia , Permeabilidade/efeitos dos fármacos , Permeabilidade/efeitos da radiação , Plâncton/efeitos dos fármacos , Plâncton/efeitos da radiação , Staphylococcus epidermidis/efeitos dos fármacos
7.
J Mech Behav Biomed Mater ; 90: 591-603, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30500697

RESUMO

Realistic modeling of biologic material is required for optimizing fidelity in computer-aided surgical training and assistance systems. The modeling of liver tissue has remained challenging due to its nonlinear viscoelastic properties and high hysteresis of the stress-strain relation. While prior studies have described the behavior of liver tissue during the loading status (in elongation, compression, or indentation tests) or unloading status (in stress relaxation or creep tests), a hysteresis curve with both loading and unloading processes was incompletely defined. We seek to use a single material model to characterize the mechanical properties of liver tissue in a full indentation cycle ex vivo perfused and then sectioned. Based on measurements taken from ex-vivo perfused porcine livers, we converted force-displacement curves to stress-strain curves and developed a visco-hyperelastic constitutive model to characterize the liver's mechanical behavior at different locations under various rates of indentation (1, 2, 5, 10, and 20 mm/s). The proposed model is a mixed visco-hyperelastic model with up to 6 coefficients. The normalized root mean square standard deviations of fitted curves are less than 5% and 10% in low (<0.05) and high strain (>0.3) conditions respectively.


Assuntos
Elasticidade , Fígado/citologia , Fígado/fisiologia , Teste de Materiais/métodos , Modelos Biológicos , Perfusão , Animais , Fenômenos Biomecânicos , Análise de Elementos Finitos , Teste de Materiais/instrumentação , Suínos , Viscosidade , Suporte de Carga
8.
IEEE Trans Biomed Eng ; 66(4): 1165-1171, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30207946

RESUMO

As robotic surgery has increased in popularity, the lack of haptic feedback has become a growing issue due to the application of excessive forces that may lead to clinical problems such as intraoperative and postoperative suture breakage. Previous suture breakage warning systems have largely depended on visual and/or auditory feedback modalities, which have been shown to increase cognitive load and reduce operator performance. This work catalogues a new sensing technology and haptic feedback system (HFS) that can reduce instances of suture failure without negatively impacting performance outcomes including knot quality. Suture breakage is common in knot-tying as the pulling motion introduces prominent shear forces. A shear sensor mountable on the da Vinci robotic surgical system's Cadiere grasper detects forces that correlate to the suture's internal tension. HFS then provides vibration feedback to the operator as forces near a particular material's failure load. To validate the system, subjects tightened a total of four knots, two with the Haptic Feedback System (HFS) and two without feedback. The number of suture breakages were recorded and knot fidelity was evaluated by measuring knot slippage. Results showed that instances of suture failure were significantly reduced when HFS was enabled (p = 0.0078). Notably, knots tied with HFS also showed improved quality compared to those tied without feedback (p = 0.010). The results highlight the value of HFS in improving robotic procedure outcomes by reducing instances of suture failures, producing better knots, and reducing the need for corrective measures.


Assuntos
Procedimentos Cirúrgicos Robóticos/instrumentação , Técnicas de Sutura/instrumentação , Suturas , Resistência à Tração , Desenho de Equipamento , Retroalimentação , Humanos , Teste de Materiais , Procedimentos Cirúrgicos Robóticos/métodos , Análise e Desempenho de Tarefas
9.
Surg Endosc ; 33(4): 1252-1259, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30187198

RESUMO

BACKGROUND: The loss of tactile feedback in minimally invasive robotic surgery remains a major challenge to the expanding field. With visual cue compensation alone, tissue characterization via palpation proves to be immensely difficult. This work evaluates a bimodal vibrotactile system as a means of conveying applied forces to simulate haptic feedback in two sets of studies simulating an artificial palpation task using the da Vinci surgical robot. METHODS: Subjects in the first study were tasked with localizing an embedded vessel in a soft tissue phantom using a single-sensor unit. In the second study, subjects localized tumor-like structures using a three-sensor array. In both sets of studies, subjects completed the task under three trial conditions: no feedback, normal force tactile feedback, and hybrid vibrotactile feedback. Recordings of correct localization, incorrect localization, and time-to-completion were used to evaluate performance outcomes. RESULTS: With the addition of vibrotactile and pneumatic feedback, significant improvements in the percentage of correct localization attempts were detected (p = 0.0001 and p = 0.0459, respectively) during the first experiment with phantom vessels. Similarly, significant improvements in correct localization were found with the addition of vibrotactile (p = 2.57E-5) and pneumatic significance (p = 8.54E-5) were observed in the second experiment involving tumor phantoms. CONCLUSIONS: This work demonstrates not only the superior benefits of a multi-modal feedback over traditional single-modality feedback, but also the effectiveness of vibration in providing haptic feedback to artificial palpation systems.


Assuntos
Retroalimentação Sensorial , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Palpação/métodos , Procedimentos Cirúrgicos Robóticos/métodos , Vasos Sanguíneos , Desenho de Equipamento , Humanos , Procedimentos Cirúrgicos Minimamente Invasivos/instrumentação , Modelos Anatômicos , Neoplasias , Palpação/instrumentação , Procedimentos Cirúrgicos Robóticos/instrumentação , Tato , Vibração
10.
Sci Rep ; 8(1): 17250, 2018 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-30467339

RESUMO

The ability to reversibly and non-invasively modulate region-specific brain activity in vivo suggests Low Intensity Focused Ultrasound (LIFU) as potential therapeutics for neurological dysfunctions such as epilepsy and Parkinson's disease. While in vivo studies provide evidence of the bioeffects of LIFU on neuronal activity, they merely hint at potential mechanisms but do not fully explain how this technology achieves these effects. One potential hypothesis is that LIFU produces local membrane depolarization by mechanically perturbing the neuronal cell membrane, or activating channels or other proteins embedded in the membrane. Proteins that sense mechanical perturbations of the membrane, such as those gated by membrane tension, are prime candidates for activating in response to LIFU and thus leading to the neurological responses that have been measured. Here we use the bacterial mechanosensitive channel MscL, which has been purified and reconstituted in liposomes, to determine how LIFU may affect the activation of this membrane-tension gated channel. Two bacterial voltage-gated channels, KvAP and NaK2K F92A channels were also studied. Surprisingly, the results suggest that ultrasound modulation and membrane perturbation does not induce channel gating, but rather induces pore formation at the membrane protein-lipid interface. However, in vesicles with high MscL mechanosensitive channel concentrations, apparent decreases in pore formation are observed, suggesting that this membrane-tension-sensitive protein may serve to increase the elasticity of the membrane, presumably because of expansion of the channel in the plane of the membrane independent of channel gating.


Assuntos
Membrana Celular/fisiologia , Canais Iônicos/metabolismo , Lipossomos/metabolismo , Ativação do Canal Iônico , Mecanotransdução Celular , Modelos Biológicos , Ondas Ultrassônicas
11.
Yale J Biol Med ; 91(3): 215-223, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30258308

RESUMO

Oral and head and neck squamous cell carcinoma (OSCC) is the sixth most common cancer worldwide. The primary management of OSCC relies on complete surgical resection of the tumor. Margin-free resection, however, is difficult given the devastating effects of aggressive surgery. Currently, surgeons determine where cuts are made by palpating edges of the tumor. Accuracy varies based on the surgeon's experience, the location and type of tumor, and the risk of damage to adjacent structures limiting resection margins. To fulfill this surgical need, we contrast tissue regions by identifying disparities in viscoelasticity by mixing two ultrasonic beams to produce a beat frequency, a technique termed vibroacoustography (VA). In our system, an extended focal length of the acoustic stress field yields surgeons' high resolution to detect focal lesions in deep tissue. VA offers 3D imaging by focusing its imaging plane at multiple axial cross-sections within tissue. Our efforts culminate in production of a mobile VA system generating image contrast between normal and abnormal tissue in minutes. We model the spatial direction of the generated acoustic field and generate images from tissue-mimicking phantoms and ex vivo specimens with squamous cell carcinoma of the tongue to qualitatively demonstrate the functionality of our system. These preliminary results warrant additional validation as we continue clinical trials of ex vivo tissue. This tool may prove especially useful for finding tumors that are deep within tissue and often missed by surgeons. The complete primary resection of tumors may reduce recurrence and ultimately improve patient outcomes.


Assuntos
Carcinoma de Células Escamosas/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Cinetocardiografia/métodos , Humanos , Imageamento Tridimensional
12.
Int J Med Robot ; 14(6): e1949, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30152081

RESUMO

BACKGROUND: With the development of laser-assisted platforms, the outcomes of cataract surgery have been improved by automating several procedures. The cataract-extraction step continues to be manually performed, but due to deficiencies in sensing capabilities, surgical complications such as posterior capsule rupture and incomplete cataract removal remain. METHODS: An optical coherence tomography (OCT) system is integrated into our intraocular robotic interventional surgical system (IRISS) robot. The OCT images are used for preoperative planning and intraoperative intervention in a series of automated procedures. Real-time intervention allows surgeons to evaluate the progress and override the operation. RESULTS: The developed system was validated by performing lens extraction on 30 postmortem pig eyes. Complete lens extraction was achieved on 25 eyes, and "almost complete" extraction was achieved on the remainder due to an inability to image small lens particles behind the iris. No capsule rupture was found. CONCLUSION: The IRISS successfully demonstrated semiautomated OCT-guided lens removal with real-time supervision and intervention.


Assuntos
Extração de Catarata/instrumentação , Catarata , Tomografia de Coerência Óptica/instrumentação , Animais , Automação , Extração de Catarata/métodos , Desenho de Equipamento , Humanos , Procedimentos Cirúrgicos Robóticos , Software , Suínos , Tomografia de Coerência Óptica/métodos
13.
Curr Opin Otolaryngol Head Neck Surg ; 26(2): 102-107, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29517537

RESUMO

PURPOSE OF REVIEW: The quantity of tissue removed during an oncologic surgical procedure is not standardized and there are numerous reports of local recurrence despite histologically adequate resection margins. The oral cavity is one of the sites in the head and neck with high chances of recurrence following negative margins. To address this need, this article reviews the recent applications of Dynamic Optical Contrast Imaging (DOCI) towards both oral screening and the intraoperative evaluation of tumor margins in head and neck surgery. RECENT FINDINGS: Human ex-vivo and in-vivo trials suggest DOCI is well tolerated, low-cost, and sensitive for differentiating cancerous from normal tissues throughout the head and neck, in addition to the oral cavity. Ex-vivo imaging of OSCC specimens generated histologically verified image contrast. Furthermore, in-vivo intraoperative results demonstrate significant potential for image-guided detection and resection of oral cavity squamous cell carcinoma (OSCC). SUMMARY: DOCI augments tissue contrast and may enable surgeons to clinically screen patients for oral cancer, make histologic evaluations in vivo with fewer unnecessary biopsies, delineate clinical margins for tumor resection, provide guidance in the choice of biopsy sites, and preserve healthy tissue to increase the postoperative functionality and quality of life of the patient.


Assuntos
Carcinoma de Células Escamosas/patologia , Carcinoma de Células Escamosas/cirurgia , Margens de Excisão , Neoplasias Bucais/diagnóstico por imagem , Imagem Óptica/métodos , Intensificação de Imagem Radiográfica/métodos , Carcinoma de Células Escamosas/mortalidade , Meios de Contraste , Detecção Precoce de Câncer , Feminino , Humanos , Masculino , Neoplasias Bucais/patologia , Neoplasias Bucais/cirurgia , Invasividade Neoplásica/patologia , Estadiamento de Neoplasias , Análise de Sobrevida , Resultado do Tratamento
14.
IEEE Trans Terahertz Sci Technol ; 8(1): 27-37, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29430335

RESUMO

Terahertz (THz) imaging of corneal tissue water content (CTWC) is a proposed method for early, accurate detection and study of corneal diseases. Despite promising results from ex vivo and in vivo cornea studies, interpretation of the reflectivity data is confounded by the contact between corneal tissue and rigid dielectric window used to flatten the imaging field. This work develops a novel imaging system and image reconstruction methods specifically for nearly spherical targets such as human cornea. A prototype system was constructed using a 650 GHz multiplier source and Schottky diode detector. Resolution and imaging field strength measurement from characterization targets correlate well with those predicted by the quasioptical theory and physical optics analysis. Imaging experiments with corneal phantoms and ex vivo corneas demonstrate the hydration sensitivity of the imaging system and reliable measurement of CTWC. We present successful acquisition of non-contact THz images of in vivo human cornea, and discuss strategies for optimizing the imaging system design for clinical use.

15.
IEEE Trans Terahertz Sci Technol ; 8(1): 1-12, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29450106

RESUMO

Reflection mode Terahertz (THz) imaging of corneal tissue water content (CTWC) is a proposed method for early, accurate detection and study of corneal diseases. Despite promising results from ex vivo and in vivo cornea studies, interpretation of the reflectivity data is confounded by the contact between corneal tissue and dielectric windows used to flatten the imaging field. Herein, we present an optical design for non-contact THz imaging of cornea. A beam scanning methodology performs angular, normal incidence sweeps of a focused beam over the corneal surface while keeping the source, detector, and patient stationary. A quasioptical analysis method is developed to analyze the theoretical resolution and imaging field intensity profile. These results are compared to the electric field distribution computed with a physical optics analysis code. Imaging experiments validate the optical theories behind the design and suggest that quasioptical methods are sufficient for designing of THz corneal imaging systems. Successful imaging operations support the feasibility of non-contact in vivo imaging. We believe that this optical system design will enable the first, clinically relevant, in vivo exploration of CTWC using THz technology.

16.
PLoS One ; 13(1): e0191919, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29373598

RESUMO

Viscoelasticity of soft tissue is often related to pathology, and therefore, has become an important diagnostic indicator in the clinical assessment of suspect tissue. Surgeons, particularly within head and neck subsites, typically use palpation techniques for intra-operative tumor detection. This detection method, however, is highly subjective and often fails to detect small or deep abnormalities. Vibroacoustography (VA) and similar methods have previously been used to distinguish tissue with high-contrast, but a firm understanding of the main contrast mechanism has yet to be verified. The contributions of tissue mechanical properties in VA images have been difficult to verify given the limited literature on viscoelastic properties of various normal and diseased tissue. This paper aims to investigate viscoelasticity theory and present a detailed description of viscoelastic experimental results obtained in tissue-mimicking phantoms (TMPs) and ex vivo tissues to verify the main contrast mechanism in VA and similar imaging modalities. A spherical-tip micro-indentation technique was employed with the Hertzian model to acquire absolute, quantitative, point measurements of the elastic modulus (E), long term shear modulus (η), and time constant (τ) in homogeneous TMPs and ex vivo tissue in rat liver and porcine liver and gallbladder. Viscoelastic differences observed between porcine liver and gallbladder tissue suggest that imaging modalities which utilize the mechanical properties of tissue as a primary contrast mechanism can potentially be used to quantitatively differentiate between proximate organs in a clinical setting. These results may facilitate more accurate tissue modeling and add information not currently available to the field of systems characterization and biomedical research.


Assuntos
Elasticidade , Modelos Animais , Imagens de Fantasmas , Viscosidade , Animais , Masculino , Ratos Sprague-Dawley , Suínos
17.
Annu Int Conf IEEE Eng Med Biol Soc ; 2017: 3936-3939, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29060758

RESUMO

This paper describes the design, microfabrication, and characterization of a miniature force sensor for providing tactile feedback in robotic surgical systems. We demonstrate for the first time a microfabricated sensor that can provide triaxial sensing (normal, x-shear, y-shear) in a single sensor element that can be integrated with commercial robotic surgical graspers. Features of this capacitive force sensor include differential sensing in the shear directions as well as a design where all electrical connections are on one side, leaving the backside pristine as the sensing face. The sensor readout is performed by a custom-designed printed circuit board with 24-bit resolution. Experimental results of sensor performance show normal force resolution of 0.055 N, x-shear resolution of 0.25 N, and y-shear resolution of 1.45 N, all of which fall in a range of clinically relevant forces.


Assuntos
Procedimentos Cirúrgicos Robóticos , Desenho de Equipamento , Procedimentos Cirúrgicos Minimamente Invasivos , Tato
19.
J Urol ; 198(4): 839-847, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28396184

RESUMO

PURPOSE: Focal laser ablation is a potential treatment in some men with prostate cancer. Currently focal laser ablation is performed by radiologists in a magnetic resonance imaging unit (in bore). We evaluated the safety and feasibility of performing focal laser ablation in a urology clinic (out of bore) using magnetic resonance imaging-ultrasound fusion for guidance. MATERIALS AND METHODS: A total of 11 men with intermediate risk prostate cancer were enrolled in this prospective, institutional review board approved pilot study. Magnetic resonance imaging-ultrasound fusion was used to guide laser fibers transrectally into regions of interest harboring intermediate risk prostate cancer. Thermal probes were inserted for real-time monitoring of intraprostatic temperatures during laser activation. Multiparametric magnetic resonance imaging (3 Tesla) was done immediately after treatment and at 6 months along with comprehensive fusion biopsy. RESULTS: Ten of 11 patients were successfully treated while under local anesthesia. Mean procedure time was 95 minutes (range 71 to 105). Posttreatment magnetic resonance imaging revealed a confined zone of nonperfusion in all 10 men. Mean zone volume was 4.3 cc (range 2.1 to 6.0). No CTCAE grade 3 or greater adverse events developed and no changes were observed in urinary or sexual function. At 6 months magnetic resonance imaging-ultrasound fusion biopsy of the treatment site showed no cancer in 3 patients, microfocal Gleason 3 + 3 in another 3 and persistent intermediate risk prostate cancer in 4. CONCLUSIONS: Focal laser ablation of prostate cancer appears safe and feasible with the patient under local anesthesia in a urology clinic using magnetic resonance imaging-ultrasound fusion for guidance and thermal probes for monitoring. Further development is necessary to refine out of bore focal laser ablation and additional studies are needed to determine appropriate treatment margins and oncologic efficacy.


Assuntos
Terapia a Laser/métodos , Imagem por Ressonância Magnética Intervencionista/métodos , Neoplasias da Próstata/cirurgia , Ultrassonografia de Intervenção/métodos , Idoso , Estudos de Viabilidade , Humanos , Biópsia Guiada por Imagem/métodos , Terapia a Laser/efeitos adversos , Imagem por Ressonância Magnética Intervencionista/efeitos adversos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Estudos Prospectivos , Próstata/patologia , Próstata/cirurgia , Neoplasias da Próstata/patologia , Ultrassonografia de Intervenção/efeitos adversos
20.
Lasers Surg Med ; 49(5): 539-547, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28333393

RESUMO

BACKGROUND AND OBJECTIVES: Bacterial biofilm formation within chronic wound beds, which provides an effective barrier against antibiotics, is a known cause of recalcitrant infections and a significant healthcare burden, often requiring repeated surgical debridements. Laser-generated shockwaves (LGS) is a novel, minimally invasive, and nonthermal modality for biofilm mechanical debridement which utilizes compressive stress waves, generated by photonic absorption in thin titanium films to mechanically disrupt the biofilm. Prior studies have demonstrated LGS monotherapy to be selectively efficacious for biofilm disruption and safe for host tissues. In this study, we sought to determine if LGS can enhance the antimicrobial activity and biofilm disruption capability of topical antibiotic therapy. STUDY DESIGN/MATERIALS AND METHODS: Staphylococcus epidermidis biofilms grown in vitro on glass were treated with topical gentamicin (31, 62, and 124 µg/ml) with and without LGS (n = 3-11/treatment group). Mechanical shockwaves were generated with a 1,064 nm Nd:YAG laser (laser fluence 110.14 mJ/mm2 , pulse duration 5 ns, spot size 3 mm). Following a 24-hour incubation period, bacterial viability was assessed by determining the number of colony-forming units (CFU) via the Miles and Misra method. Residual biofilm bioburden was analyzed using the crystal violet biofilm assay. RESULTS: With gentamicin monotherapy, CFU density (CFU/mm2 ) at 31, 62, and 124 µg/ml were (282 ± 84) × 104 , (185 ± 34) × 104 , and (113 ± 9) × 104 , respectively. With LGS and gentamicin therapy, CFU density decreased to (170 ± 44) × 104 , (89 ± 24) × 104 , and (43 ± 3) × 104 , respectively (P = 0.1704, 0.0302, and 0.0004 when compared with gentamicin alone). Biofilm burden as measured by the assay in the gentamicin 31, 62, and 124 µg/ml groups was reduced by 80%, 95%, and 98% when LGS was added (P = 0.0102, >0.0001, and 0.0001 for all groups when compared with gentamicin alone). Furthermore, samples treated with LGS saw an increase in susceptibility to gentamicin, in terms of reduced biofilm bioburden and CFU densities. CONCLUSION: LGS enhances the efficacy of topical antibiotics in an in vitro model. This has significant implications for clinical applications in the management of chronic soft tissue infections and recalcitrant chronic rhinosinusitis. Lasers Surg. Med. 49:539-547, 2017. © 2017 Wiley Periodicals, Inc.


Assuntos
Antibacterianos/uso terapêutico , Biofilmes/efeitos da radiação , Gentamicinas/uso terapêutico , Ondas de Choque de Alta Energia , Lasers de Estado Sólido/uso terapêutico , Staphylococcus epidermidis/efeitos da radiação , Carga Bacteriana/efeitos dos fármacos , Carga Bacteriana/efeitos da radiação , Biofilmes/crescimento & desenvolvimento , Staphylococcus epidermidis/efeitos dos fármacos , Staphylococcus epidermidis/fisiologia
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