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Yoed Rabin - One of the best experts on this subject based on the ideXlab platform.

  • computerized planning of prostate cryosurgery using variable Cryoprobe insertion depth
    Cryobiology, 2010
    Co-Authors: Michael R Rossi, Daigo Tanaka, Kenji Shimada, Yoed Rabin
    Abstract:

    The current study presents a computerized planning scheme for prostate cryosurgery using a variable insertion depth strategy. This study is a part of an ongoing effort to develop computerized tools for cryosurgery. Based on typical clinical practices, previous automated planning schemes have required that all Cryoprobes be aligned at a single insertion depth. The current study investigates the benefit of removing this constraint, in comparison with results based on uniform insertion depth planning as well as the so-called "pullback procedure". Planning is based on the so-called "bubble-packing method", and its quality is evaluated with bioheat transfer simulations. This study is based on five 3D prostate models, reconstructed from ultrasound imaging, and Cryoprobe active length in the range of 15-35 mm. The variable insertion depth technique is found to consistently provide superior results when compared to the other placement methods. Furthermore, it is shown that both the optimal active length and the optimal number of Cryoprobes vary among prostate models, based on the size and shape of the target region. Due to its low computational cost, the new scheme can be used to determine the optimal Cryoprobe layout for a given prostate model in real time.

  • computerized planning of cryosurgery using bubble packing an experimental validation on a phantom material
    International Journal of Heat and Mass Transfer, 2008
    Co-Authors: Michael R Rossi, Daigo Tanaka, Kenji Shimada, Yoed Rabin
    Abstract:

    The current study focuses on experimentally validating a planning scheme based on the so-called bubble-packing method. This study is a part of an ongoing effort to develop computerized planning tools for cryosurgery, where bubble packing has been previously developed as a means to find an initial, uniform distribution of Cryoprobes within a given domain; the so-called force-field analogy was then used to move Cryoprobes to their optimum layout. However, due to the high quality of the Cryoprobes' distribution, suggested by bubble packing and its low computational cost, it has been argued that a planning scheme based solely on bubble packing may be more clinically relevant. To test this argument, an experimental validation is performed on a simulated cross-section of the prostate, using gelatin solution as a phantom material, proprietary liquid-nitrogen based Cryoprobes, and a cryoheater to simulate urethral warming. Experimental results are compared with numerically simulated temperature histories resulting from planning. Results indicate an average disagreement of 0.8 mm in identifying the freezing front location, which is an acceptable level of uncertainty in the context of prostate cryosurgery imaging.

  • cryosurgery planning using bubble packing in 3d
    Computer Methods in Biomechanics and Biomedical Engineering, 2008
    Co-Authors: Daigo Tanaka, Michael R Rossi, Kenji Shimada, Yoed Rabin
    Abstract:

    As part of an ongoing project to develop automated tools for cryosurgery planning, the current study focuses on the development of a 3D bubble packing method. A proof-of-concept for the new method is demonstrated on five prostate models, reconstructed from ultrasound images. The new method is a modification of an established method in 2D. Ellipsoidal bubbles are packed in the volume of the prostate in the current study; such bubbles can be viewed as a first-order approximation of a frozen region around a single Cryoprobe. When all Cryoprobes are inserted to the same depth, optimum planning was found to occur at about 60% of the length of the prostate (measured from its apex), which leads to cooling of approximately 75% of the prostate volume below a specific temperature threshold of −22°C. Bubble packing has the potential to dramatically reduce the run time for automated planning.

  • computerized planning for multiprobe cryosurgery using a force field analogy
    Computer Methods in Biomechanics and Biomedical Engineering, 2004
    Co-Authors: David C Lung, Thomas F Stahovich, Yoed Rabin
    Abstract:

    Cryosurgery is the destruction of undesired biological tissues by freezing. For internal organs, multiple Cryoprobes are inserted into the tissue with the goal of maximizing cryoinjury within a predefined target region, while minimizing cryoinjury to the surrounding tissues. The objective of this study is to develop a computerized planning tool to determine the best locations to insert the Cryoprobes, based on bioheat transfer simulations. This tool is general and suitable for all available cooling techniques and hardware. The planning procedure employs a novel iterative optimization technique based on a force-field analogy. In each iteration, a single transient bioheat transfer simulation of the cryoprocedure is computed. At the end of the simulation, regions of tissue that would have undesired temperatures apply "forces" to the Cryoprobes directly moving them to better locations. This method is more efficient than traditional numerical optimization techniques, because it requires significantly fewer bioheat transfer simulations for each iteration of planning. For demonstration purposes, 2D examples on cross sections typical of prostate cryosurgery are given.

  • cryoheater as a means of cryosurgery control
    Physics in Medicine and Biology, 2003
    Co-Authors: Yoed Rabin, Thomas F Stahovich
    Abstract:

    A new concept for cryosurgery control is presented in this paper, a concept which has the potential to dramatically change the outcome of cryosurgery. Unlike other cryosurgery control techniques, which are based on controlling the thermal performance of the Cryoprobe, this new concept is based on heating the treated tissue as a means of shaping the frozen region. The new controlling heater is termed a 'cryoheater'. The cryoheater is a complementary device to the Cryoprobe and can work with any cryosurgery cooling technique. In the current pilot study, the new cryoheater is demonstrated in a gelatin solution and, using heat transfer simulations, it is studied in simulated cases of prostate cryosurgery. It is suggested that cryosurgery planning tools and optimization techniques must be developed before the concept of the cryoheater can be applied in its full capacity.

Martin Hetzel - One of the best experts on this subject based on the ideXlab platform.

  • Cryoprobe biopsy increases the diagnostic yield in endobronchial tumor lesions
    The Journal of Thoracic and Cardiovascular Surgery, 2010
    Co-Authors: C Schumann, A Babiak, T Merk, T Wibmer, P M Lepper, Juergen Hetzel, Peter Moller, Martin Hetzel
    Abstract:

    Objective Forceps biopsy is the standard method to obtain specimens in endoscopically visible lesions. It is common to combine forceps biopsy with cytology methods to increase the diagnostic yield. Although the flexible Cryoprobe has been established for bronchoscopic interventions in malignant stenosis, the obtained biopsies, called "cryobiopsies," have not been investigated in a large cohort of patients. The aim of this feasibility study was to prospectively evaluate the diagnostic yield and safety of cryobiopsy and forceps biopsy. Methods During a 6-year period, 296 patients with visible endoluminal tumor lesions were included in the study at the bronchoscopy unit of a university hospital. In the first consecutively conducted 55 cases, both techniques, forceps biopsy and cryobiopsy, were applied simultaneously. Pathologic and quantitative image analyses were performed to evaluate the size and quality of the obtained specimens. We evaluated the safety and diagnostic yield to describe the feasibility of cryobiopsy. Results Comparative analysis of the first conducted and randomly assigned 55 cases revealed a significantly higher diagnostic yield for cryobiopsy compared with forceps biopsy (89.1% vs 65.5%, P P Conclusion Cryobiopsy is safe and increases the diagnostic yield in endobronchial tumor lesions. The method also is feasible under routine conditions.

  • endobronchial tumor debulking with a flexible Cryoprobe for immediate treatment of malignant stenosis
    The Journal of Thoracic and Cardiovascular Surgery, 2010
    Co-Authors: C Schumann, Martin Hetzel, A Babiak, J Hetzel, T Merk, T Wibmer, P M Lepper, Stefan Kruger
    Abstract:

    Objective In addition to use of a laser, argon plasma coagulation, electrocautery, or coring with a rigid bronchoscope, tumor debulking with a flexible Cryoprobe is used for therapeutic bronchoscopy with an immediate effect for endobronchial pathologies. We performed this analysis to determine the usefulness, efficacy, and safety of the flexible cryorecanalization in a large population under routine conditions. Methods We identified 225 bronchoscopic interventions that were done as cryorecanalization with a flexible Cryoprobe. All patients had symptomatic airway stenosis. We determined the endoscopic success rate and safety (bleeding and perforation) of the procedure. Results Successful cryorecanalization was achieved in 205 (91.1%) of 225 patients. The flexible Cryoprobe was used with all patients, in most patients in combination with flexible bronchoscopy and only in a minority (n = 31, 13.8%) in combination with a rigid bronchoscope. Additional interventional techniques used were endobronchial stents (n = 11, 4.9%) and argon plasma coagulation (n = 37, 16.4%). Mild bleeding (if ice-cold NaCl or epinephrine solution was necessary) occurred in 9 (4.0%) patients, moderate bleeding (if argon plasma coagulation or a bronchus blocker was required) occurred in 18 (8.0%) patients, and severe bleeding (events with hemodynamic instability) never occurred. Conclusions Cryorecanalization with the flexible Cryoprobe for treatment of symptomatic endobronchial tumor stenosis is a safe technique with a high success rate and immediate treatment effect.

  • Experimental study on biopsy sampling using new flexible Cryoprobes: influence of activation time, probe size, tissue consistency, and contact pressure of the probe on the size of the biopsy specimen.
    Lung, 2009
    Co-Authors: Karl-josef Franke, Mara Szyrach, Martin Hetzel, Karl-heinz Ruehle, Georg Nilius, Jürgen Hetzel, Markus Enderle
    Abstract:

    Cryoextraction is a procedure for recanalization of obstructed airways caused by exophytic growing tumors. Biopsy samples obtained with this method can be used for histological diagnosis. The objective of this study was to evaluate the parameters influencing the size of cryobiopsies in an in vitro animal model. New flexible Cryoprobes with different diameters were used to extract biopsies from lung tissue. These biopsies were compared with forceps biopsy (gold standard) in terms of the biopsy size. Tissue dependency of the biopsy size was analyzed by comparing biopsies taken from the lung, the liver, and gastric mucosa. The effect of contact pressure exerted by the tip of the Cryoprobe on the tissue was analyzed on liver tissue separately. Biopsy size was estimated by measuring the weight and the diameter. Weight and diameter of cryobiopsies correlated positively with longer activation times and larger diameters of the Cryoprobe. The weight of the biopsies was tissue dependent: lung < liver < stomach. Only little tissue dependency was found for the biopsy diameter. The biopsy size increased when the probe was pressed on the tissue during cooling. Cryobiopsies can be taken from different tissue types with flexible Cryoprobes. The size of the samples depends on tissue type, probe diameter, application time, and pressure exerted by the probe on the tissue. Even the Cryoprobe with the smallest diameter can provide larger biopsies than a forceps biopsy in lung. It can be expected that the same parameters influence the sample size of biopsies in vivo.

Pauli Guido - One of the best experts on this subject based on the ideXlab platform.

C Schumann - One of the best experts on this subject based on the ideXlab platform.

  • Cryoprobe biopsy increases the diagnostic yield in endobronchial tumor lesions
    The Journal of Thoracic and Cardiovascular Surgery, 2010
    Co-Authors: C Schumann, A Babiak, T Merk, T Wibmer, P M Lepper, Juergen Hetzel, Peter Moller, Martin Hetzel
    Abstract:

    Objective Forceps biopsy is the standard method to obtain specimens in endoscopically visible lesions. It is common to combine forceps biopsy with cytology methods to increase the diagnostic yield. Although the flexible Cryoprobe has been established for bronchoscopic interventions in malignant stenosis, the obtained biopsies, called "cryobiopsies," have not been investigated in a large cohort of patients. The aim of this feasibility study was to prospectively evaluate the diagnostic yield and safety of cryobiopsy and forceps biopsy. Methods During a 6-year period, 296 patients with visible endoluminal tumor lesions were included in the study at the bronchoscopy unit of a university hospital. In the first consecutively conducted 55 cases, both techniques, forceps biopsy and cryobiopsy, were applied simultaneously. Pathologic and quantitative image analyses were performed to evaluate the size and quality of the obtained specimens. We evaluated the safety and diagnostic yield to describe the feasibility of cryobiopsy. Results Comparative analysis of the first conducted and randomly assigned 55 cases revealed a significantly higher diagnostic yield for cryobiopsy compared with forceps biopsy (89.1% vs 65.5%, P P Conclusion Cryobiopsy is safe and increases the diagnostic yield in endobronchial tumor lesions. The method also is feasible under routine conditions.

  • endobronchial tumor debulking with a flexible Cryoprobe for immediate treatment of malignant stenosis
    The Journal of Thoracic and Cardiovascular Surgery, 2010
    Co-Authors: C Schumann, Martin Hetzel, A Babiak, J Hetzel, T Merk, T Wibmer, P M Lepper, Stefan Kruger
    Abstract:

    Objective In addition to use of a laser, argon plasma coagulation, electrocautery, or coring with a rigid bronchoscope, tumor debulking with a flexible Cryoprobe is used for therapeutic bronchoscopy with an immediate effect for endobronchial pathologies. We performed this analysis to determine the usefulness, efficacy, and safety of the flexible cryorecanalization in a large population under routine conditions. Methods We identified 225 bronchoscopic interventions that were done as cryorecanalization with a flexible Cryoprobe. All patients had symptomatic airway stenosis. We determined the endoscopic success rate and safety (bleeding and perforation) of the procedure. Results Successful cryorecanalization was achieved in 205 (91.1%) of 225 patients. The flexible Cryoprobe was used with all patients, in most patients in combination with flexible bronchoscopy and only in a minority (n = 31, 13.8%) in combination with a rigid bronchoscope. Additional interventional techniques used were endobronchial stents (n = 11, 4.9%) and argon plasma coagulation (n = 37, 16.4%). Mild bleeding (if ice-cold NaCl or epinephrine solution was necessary) occurred in 9 (4.0%) patients, moderate bleeding (if argon plasma coagulation or a bronchus blocker was required) occurred in 18 (8.0%) patients, and severe bleeding (events with hemodynamic instability) never occurred. Conclusions Cryorecanalization with the flexible Cryoprobe for treatment of symptomatic endobronchial tumor stenosis is a safe technique with a high success rate and immediate treatment effect.

  • cryorecanalization a new approach for the immediate management of acute airway obstruction
    The Journal of Thoracic and Cardiovascular Surgery, 2004
    Co-Authors: M Hetzel, C Schumann, Juergen Hetzel, Nikolaus Marx, A Babiak
    Abstract:

    Abstract Objectives Endobronchial cryotherapy is an established recanalization method for stenoses of the respiratory tract. However, previous applications of cryotherapy have not been immediately effective, requiring a second clean-up procedure several days later to finally obtain sufficient recanalization. In this study we demonstrate a newly developed Cryoprobe allowing recanalization of tumor stenoses during a single intervention. Methods In this prospective study flexible bronchoscopy was used for cryorecanalization of 60 patients with high-grade stenoses of the respiratory tract from exophytic tumors. Tumor tissue was frozen on the tip of the probe and subsequently removed from the surrounding respiratory tract tissue through retraction of the probe. Procedures were carried out on sedated, spontaneously breathing, intubated patients. Results Fifty (83%) of 60 patients were successfully or partially successfully treated. Tumor bleeding occurred in 6 patients but was stopped with argon plasma coagulator treatment in all patients not requiring rigid bronchoscopy. Conclusion Cryorecanalization with the newly developed Cryoprobe permits effective, safe, and inexpensive therapy of endobronchial stenoses of the respiratory tract.

David Fellerkopman - One of the best experts on this subject based on the ideXlab platform.

  • a randomized controlled trial of a novel sheath Cryoprobe for bronchoscopic lung biopsy in a porcine model
    Chest, 2016
    Co-Authors: Lonny Yarmus, Peter B Illei, David Fellerkopman, Roy Semaan, Sixto Arias, Ricardo Ortiz, Hans Bosmuller, Bernice Frimpong, Karen Oakjonesburgess, Hans J Lee
    Abstract:

    Background Transbronchial forceps biopsy (FBx) has been the preferred method for obtaining bronchoscopic lung biopsy specimens. Cryoprobe biopsy (CBx) has been shown to obtain larger and higher quality samples, but is limited by its inability to retrieve the sample through the working channel of the bronchoscope, requiring the bronchoscope to leave the airway for sample retrieval. Objective We evaluated a novel device using a sheath cryobiopsy (SCBx). This method allows for specimen retrieval through the working channel of the bronchoscope, with the scope remaining inside the airway. Methods This prospective, randomized controlled, single-blinded porcine study compared a 1.1-mm SCBx probe, a 1.9-mm CBx probe, and 2.0-mm FBx forceps. Assessment of histologic accessibility, sample quantity and quality, number of attempts to acquire and retrieve samples, Cryoprobe activation time, fluoroscopy activation time, technical feasibility, and complications were compared. Results Samples adequate for standard pathologic processing were retrieved with 82.1% of the SCBx specimens, 82.9%% of the CBx specimens, and 30% of the FBx specimens. The histologic accessibility of both SCBx ( P  = .0002) and CBx ( P  = .0003) was superior to FBx. Procedure time for FBx was faster than for both SCBx and CBx, but SCBx was significantly faster than CBx ( P Conclusions SCBx is a feasible technique providing a higher quality lung biopsy specimen compared with FBx and can successfully be retrieved through the working channel. Human studies are needed to further assess this technique with additional safety data.

  • Cryoprobe transbronchial lung biopsy in patients after lung transplantation a pilot safety study
    Chest, 2013
    Co-Authors: Lonny Yarmus, Jason Akulian, Christopher R Gilbert, Peter B Illei, P Shah, Christian A Merlo, Jon Orens, David Fellerkopman
    Abstract:

    Background Transbronchial biopsies using standard forceps (FTBBxs) are often limited by crush artifact and their small size. To date, there have been no studies aimed at assessing the safety and efficacy of Cryoprobe biopsies (CPBxs) in the population of patients who have undergone lung transplants. We present the safety profile and biopsy results from the first 21 procedures in a pilot study comparing CPBx to FTBBx in patients after lung transplantation. Methods Patients who had undergone lung transplant and who were scheduled for bronchoscopy were sequentially enrolled between November 2011 and September 2012. Inclusion criteria included age > 18 years and bilateral, orthotopic lung transplant. Exclusion criteria were coagulopathy, FEV1 O 2 O 2 Results Twenty-one procedures in 17 patients (median age: 52 years; 12 male patients) were performed. Specimen area and percent open alveoli were significantly greater using CPBx compared with FTBBx (P Conclusions The use of the Cryoprobe is a safe, alternative technique to FTBBx during post-lung transplant bronchoscopy. Further studies are needed to determine if larger samples obtained with CPBx translate to an increased diagnostic yield. Trial registry ClinicalTrials.gov ; No.: NA_00052081; URL: clinicaltrials.gov