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Is a thin diameter ureteroscope feasible for image guided intravascular procedures?

Is a thin diameter ureteroscope feasible for image guided intravascular procedures? DE GRUYTER Current Directions in Biomedical Engineering 2020;6(3): 20203151 Axel Boese*, and Michael Friebe Is a thin diameter ureteroscope feasible for image guided intravascular procedures? Abstract: Vascular endoscopic imaging is known for a long flushing with saline solution or contrast agent [1] to clear the time but has never made its way into clinical routine. Reasons field of view. for that are the complexity, lack of low-cost portable systems, Optical coherence tomography (OCT) is a different optical and the lack of suitable endoscopes providing high image imaging method used in the vascular system but suffers from quality with small dimensions. In addition, an interruption of the same problem of the blood opacity. For OCT the blood is the blood flow caused by the device and the opacity of blood removed shortly by a constant high-flow flush of saline are difficult to manage. In the past we have already developed solution or contrast agent during image acquisition. Thus, no ideas to overcome these difficulties and now we present a blockage of the artery is needed [3]. Recent research showed feasibility test of a thin diameter ureteroscope for observation the feasibility of a combination of OCT and angioscopy in one of vascular procedures. The imaging system was tested in a session. One flush is used for acquisition of structural and phantom where side branches were explored, a stent was surface information of the vessels [4], [5]. placed and a simulated aneurysm coiled. Another challenge for angioscopy is the selection of the appropriate endoscopy system. Conventional systems are Keywords: angioscopy, optical vascular imaging, expensive, bulky and are not easy to integrate into the endoscopy, stenting, coiling, vascular access workflow of vascular treatment procedures. A small and lightweight system would be required, that can acquire high https://doi.org/10.1515/cdbme-2020-3151 quality videos and can be connected to and displayed on the screens of the angiography suite [6]. Due to the small diameter and the tortuosity of most vessels, small dimensions and high 1 Introduction flexibility of the endoscopes are required. This is unfortunately contrary to the achievable image quality [7]. Mostly fibre Endoscopic imaging is used in several medical disciplines for endoscopes are applied for angioscopy. Image quality and diagnostic and treatment monitoring. It is intuitive, since the flexibility of these endoscopes are highly related to the number presented information is very close to the natural human of fibres inside the bundle. Miniaturisation of electronics will cognition. But vascular endoscopy (angioscopy) is rarely used possibly allow the use of chip on the tip cameras in the future in intra vascular procedures even though there are clear leading to better steerability of the endoscope tip and increased diagnostic benefits [1]. Angioscopy allows for example the image quality [8]. assessment of plaques, vessel wall dissections or implants. But Angioscopy is not only a tool for diagnostic. It can also be used the opacity of the blood itself prevents a free view to the for observation of treatment procedures. Compared to X-Ray structures of interest. There have been a few approaches to based fluoroscopic imaging it provides a realistic visualisation realize intra vascular endoscopy. One option is the use of a of the procedure and can reduce radiation exposure. Therefore, specific catheter with an optical image fiber inside a balloon. not only an endoscope is needed, but in addition, a second By inflating the balloon and pressing it onto the vessel wall the channel for tool access is necessary. This working channel can blood is shifted away allowing a clear view to the vessel wall. be integrated in the endoscope or can be created by a second This method is used for example to observe laser based catheter placed in parallel to it. ablation [2]. Another method to achieve clear view inside In this paper we show the feasibility test of a thin standard blood vessels is based on the blockage of the blood flow. The ureteroscope with integrated working channel for observation blood in front of an inflated balloon catheter is removed by of the placement of vascular implants. The integrated bending function of the endoscope is used to support access into bifurcations under direct optical image guidance. _____ *Corresponding author: Axel Boese: Otto-von-Guericke University Magdeburg, Medical Faculty, Leipziger Str. 44, Magdeburg, Germany, e-mail: axel.boese@ovgu.de Michael Friebe: Otto-von-Guericke University Magdeburg, Medical Faculty, Magdeburg, Germany Open Access. © 2020 Axel Boese et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 License. Axel Boese et al., Is a thin diameter ureteroscope feasible for image guided intravascular procedures? — 2 2 Materials 2.1 Creation of a test sample To test the approach of optical image guided intravascular procedures we first created an artificial test sample. Therefore, an inner core of the sample was produced out of tubes (Ø 4mm) and hot glue. One bifurcation and a simulated aneurysm (Ø 6mm, sidewall) were modeled. The core structure was pre- shaped using a 2 mm aluminum wire inside the tube. For Figure 2: Tip of the endoscope: a) image channel, b) light modelling the phantom, a two-component silicon rubber channel, c) working channel (GLOREX RTV, Switzerland) was used. At all three ends Table 1: Specifications of Olympus ureteroscope URF-P7 connection tubes for flushing and sealing were integrated. The Optical system Field of view 90° creation of the test sample can be seen in Figure 1. Direction of view Forward viewing Depth of field 2–50 mm Insertion tube Distal end outer 4.9 Fr EvolutionTip diameter Insertion tube outer 7.95 Fr (2.65 mm) diameter Working length 670 mm Instrument channel Inner channel diameter 3.6 Fr (1.2 mm) Bending section Angulation range Up 275°, Down 275° Total length 1050 mm Figure 1: Creation of the test sample a) inner core with bifurcation and aneurysm, b) pre-shaping of inner structure, c) modelling using silicon rubber, d) integration of connection tubes for flushing and access 2.2 Test setup A standard endoscopy system (EVIS EXERA III, Olympus, Germany) combined with a thin ureteroscope (URF-P7, Olympus, Germany) was used for image acquisition. This fiber endoscope offers optical, light and working channel and Figure 3: The test setup: a) endoscopic camera, b) light cable, a bending mechanism while having an outer diameter of only c) endoscope, d) dilatator, e) introducer sheet, f) test model, g) 2,65 mm. The diameter of the working channel of 1,2 mm syringe for flushing, h) catheter allows passage of standard microcatheters or other vascular For the tests standard vascular devices made for coronary or devices. It is used in combination with an introducer sheet that neurovascular procedures are used. An overview of these acts like a guide catheter. The specifications of the devices is given in Table 2. ureteroscope are shown in Table 1. Figure 2 shows a close up Table 2: Vascular test devices view of the bendable endoscope tip. Device Provider Type For the test setup the introducer sheet is placed inside the Guide Wire EV3 neurovascular SilverSpeed 14 proximal entry of the phantom. The ureteroscope is fed into Micro catheter EV3 neurovascular Rebar 18 2,4F the sheet. The phantom is filled with saline solution. Air Balloon expandable BBraun Coroflex Blue 2,75x13 bubbles are removed by flushing with a syringe on the distal stenting system ends of the phantom. The test setup is shown in Figure 3. Detachable coil EV3 neurovascular Morpheus 3D CSR system 8mm Axel Boese et al., Is a thin diameter ureteroscope feasible for image guided intravascular procedures? — 3 In a next step, the endoscope was fed deeper into the phantom 2.3 Testing to localize the aneurysm. Access of the aneurysm neck with a Four different tests were conducted under optical image micro catheter was recorded as the third maneuver. Finally, the guidance and supported by the bending function of the aneurysm was filled with a coil as a last maneuver. endoscope. The ureteroscope was placed in a distance of All procedures were recorded using a screen capture device on 10mm before a branch in the side wall. In the first test the endoscopic system. The time from beginning of the maneuver this side branch was accessed by a pre-shaped guide maneuver till successful placement was recorded for all wire and a balloon expandable catheter system. To support procedures. that, the ureteroscope tip was slightly bended into the direction 3. Results and discussion of the branching vessel. A balloon dilatation and stent placement including removal of catheter and guidewire were performed as a second maneuver. Figure 4 shows some snap shots of the placement of the guide wire and catheter in a side branch. After endoscope placement catheter and guide wire were fed into the working channel until both appear in front of the endoscope tip. The guide wire with pre-shaped tip is rotated into the direction of the branch. Supported by the bending mechanism of the endoscope, the guide wire tip is pushed into the branch and then fed into it. The catheter easily follows the guide wire into the vessel. Tendencies of the guide wire to slip out can be recognized by the optical imaging and counteract by the bending mechanism of the endoscope. Figure 5: Dilatation and stenting of the side branch under Figure 4: Endoscopic view; workflow of guidewire and catheter optical observation placement in a side branch Axel Boese et al., Is a thin diameter ureteroscope feasible for image guided intravascular procedures? — 4 enough to be utilized in several vascular procedures. The maneuver of balloon dilatation and stenting is shown in Techniques of blockage and flushing to remove blood are Figure 5. The balloon is filled with saline solution and accepted for various applications. The image quality of the increases its diameter up to 3mm. At the same time the stent is system used is high but images will be blurrier in reality due expanded. After reduction of the balloon the catheter and guide to mixture of the flushing liquid with blood particles. Even wire were removed successively. though angioscopy adds more complexity to vascular The access to the aneurysm and coiling procedure is shown in procedures, it has a potential of providing better visual Figure 6. Coiling can be seen in distant and close up view. The feedback to perform interventions. Additionally, due to the bending mechanisms was used to support the coiling as well. intuitive presentation of the scene it has the potential to reduce procedure and radiation time. Author Statement Research funding: The author states no funding involved. Conflict of interest: Endoscope provided by Olympus. References [1] F. Ishibashi et al, „Update on Coronary Angioscopy: Review of a 20-Year Experience and Potential Application for Detection of Vulnerable Plaque“, Journal of Interventional Cardiology, Bd. 19, Nr. 1, S. 17–25, 2006, [2] S. R. Dukkipati u. a., „Visual Balloon-Guided Point-by-Point AblationClinical Perspective“, Circulation: Arrhythmia and Electrophysiology, Bd. 3, Nr. 3, S. 266–273, Juni 2010, doi: 10.1161/CIRCEP.109.933283. [3] T. Kume und S. Uemura, „Current clinical applications of coronary optical coherence tomography“, Cardiovasc Interv Ther, Bd. 33, Nr. 1, S. 1–10, Jan. 2018, [4] A. Boese, A. Sivankutty, und M. Friebe, „Optical endovascular imaging by combination of endoscopy and OCT“, in 53rd Annual Conference of the German Society for Biomedical Engineering, Frankfurt, Germany, 2019. [5] A. Boese, A. K. Sivankutty, und M. Friebe, „Optical endovascular imaging combining endoscopy, NBI and OCT, a feasibility study“, Current Directions in Biomed. Engineering, doi:10.1515/cdbme- 2019-0145. [6] A. Boese und M. Friebe, „SMARTSCOPE - portable, easy to use and cheap smartphone endoscopic system“, in Abstracts 51st Figure 6: The test setup: a) camera, b) filter box, c) laser, d) test sample annual conference of the German Society for Biomedical Engineering, Dresden, Germany, 2017, The recorded times for the described test maneuvers are fast [7] A. Boese, A. K. Sivankutty, und M. Friebe, „Evaluation and image compared to X-Ray guidance and are summarized in Table 3. quality comparison of ultra-thin fibre endoscopes for vascular Table 3: Times for the shown procedures endoscopy“, Current Directions in Biomedical Engineering, Bd. 3, Procedure Time Nr. 2, S. 231–233, 2017, doi: 10.1515/cdbme-2017-0048. Side branch access 28s [8] A. Boese, C. Arens, und M. Friebe, „Concept of a flexible Stenting 75s endoscope with swiveling camera tip“, in 54th Annual Conference Coiling access 22s of the German Society for Biomedical Engineering (BMT 2020), Coiling 124s Leipzig, Germany, Sep. 2020. 4. Conclusion Feasibility and potential of optical image guided intravascular procedures were shown in this paper. The endoscope is small http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Current Directions in Biomedical Engineering de Gruyter

Is a thin diameter ureteroscope feasible for image guided intravascular procedures?

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Abstract

DE GRUYTER Current Directions in Biomedical Engineering 2020;6(3): 20203151 Axel Boese*, and Michael Friebe Is a thin diameter ureteroscope feasible for image guided intravascular procedures? Abstract: Vascular endoscopic imaging is known for a long flushing with saline solution or contrast agent [1] to clear the time but has never made its way into clinical routine. Reasons field of view. for that are the complexity, lack of low-cost portable systems, Optical coherence tomography (OCT) is a different optical and the lack of suitable endoscopes providing high image imaging method used in the vascular system but suffers from quality with small dimensions. In addition, an interruption of the same problem of the blood opacity. For OCT the blood is the blood flow caused by the device and the opacity of blood removed shortly by a constant high-flow flush of saline are difficult to manage. In the past we have already developed solution or contrast agent during image acquisition. Thus, no ideas to overcome these difficulties and now we present a blockage of the artery is needed [3]. Recent research showed feasibility test of a thin diameter ureteroscope for observation the feasibility of a combination of OCT and angioscopy in one of vascular procedures. The imaging system was tested in a session. One flush is used for acquisition of structural and phantom where side branches were explored, a stent was surface information of the vessels [4], [5]. placed and a simulated aneurysm coiled. Another challenge for angioscopy is the selection of the appropriate endoscopy system. Conventional systems are Keywords: angioscopy, optical vascular imaging, expensive, bulky and are not easy to integrate into the endoscopy, stenting, coiling, vascular access workflow of vascular treatment procedures. A small and lightweight system would be required, that can acquire high https://doi.org/10.1515/cdbme-2020-3151 quality videos and can be connected to and displayed on the screens of the angiography suite [6]. Due to the small diameter and the tortuosity of most vessels, small dimensions and high 1 Introduction flexibility of the endoscopes are required. This is unfortunately contrary to the achievable image quality [7]. Mostly fibre Endoscopic imaging is used in several medical disciplines for endoscopes are applied for angioscopy. Image quality and diagnostic and treatment monitoring. It is intuitive, since the flexibility of these endoscopes are highly related to the number presented information is very close to the natural human of fibres inside the bundle. Miniaturisation of electronics will cognition. But vascular endoscopy (angioscopy) is rarely used possibly allow the use of chip on the tip cameras in the future in intra vascular procedures even though there are clear leading to better steerability of the endoscope tip and increased diagnostic benefits [1]. Angioscopy allows for example the image quality [8]. assessment of plaques, vessel wall dissections or implants. But Angioscopy is not only a tool for diagnostic. It can also be used the opacity of the blood itself prevents a free view to the for observation of treatment procedures. Compared to X-Ray structures of interest. There have been a few approaches to based fluoroscopic imaging it provides a realistic visualisation realize intra vascular endoscopy. One option is the use of a of the procedure and can reduce radiation exposure. Therefore, specific catheter with an optical image fiber inside a balloon. not only an endoscope is needed, but in addition, a second By inflating the balloon and pressing it onto the vessel wall the channel for tool access is necessary. This working channel can blood is shifted away allowing a clear view to the vessel wall. be integrated in the endoscope or can be created by a second This method is used for example to observe laser based catheter placed in parallel to it. ablation [2]. Another method to achieve clear view inside In this paper we show the feasibility test of a thin standard blood vessels is based on the blockage of the blood flow. The ureteroscope with integrated working channel for observation blood in front of an inflated balloon catheter is removed by of the placement of vascular implants. The integrated bending function of the endoscope is used to support access into bifurcations under direct optical image guidance. _____ *Corresponding author: Axel Boese: Otto-von-Guericke University Magdeburg, Medical Faculty, Leipziger Str. 44, Magdeburg, Germany, e-mail: axel.boese@ovgu.de Michael Friebe: Otto-von-Guericke University Magdeburg, Medical Faculty, Magdeburg, Germany Open Access. © 2020 Axel Boese et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 License. Axel Boese et al., Is a thin diameter ureteroscope feasible for image guided intravascular procedures? — 2 2 Materials 2.1 Creation of a test sample To test the approach of optical image guided intravascular procedures we first created an artificial test sample. Therefore, an inner core of the sample was produced out of tubes (Ø 4mm) and hot glue. One bifurcation and a simulated aneurysm (Ø 6mm, sidewall) were modeled. The core structure was pre- shaped using a 2 mm aluminum wire inside the tube. For Figure 2: Tip of the endoscope: a) image channel, b) light modelling the phantom, a two-component silicon rubber channel, c) working channel (GLOREX RTV, Switzerland) was used. At all three ends Table 1: Specifications of Olympus ureteroscope URF-P7 connection tubes for flushing and sealing were integrated. The Optical system Field of view 90° creation of the test sample can be seen in Figure 1. Direction of view Forward viewing Depth of field 2–50 mm Insertion tube Distal end outer 4.9 Fr EvolutionTip diameter Insertion tube outer 7.95 Fr (2.65 mm) diameter Working length 670 mm Instrument channel Inner channel diameter 3.6 Fr (1.2 mm) Bending section Angulation range Up 275°, Down 275° Total length 1050 mm Figure 1: Creation of the test sample a) inner core with bifurcation and aneurysm, b) pre-shaping of inner structure, c) modelling using silicon rubber, d) integration of connection tubes for flushing and access 2.2 Test setup A standard endoscopy system (EVIS EXERA III, Olympus, Germany) combined with a thin ureteroscope (URF-P7, Olympus, Germany) was used for image acquisition. This fiber endoscope offers optical, light and working channel and Figure 3: The test setup: a) endoscopic camera, b) light cable, a bending mechanism while having an outer diameter of only c) endoscope, d) dilatator, e) introducer sheet, f) test model, g) 2,65 mm. The diameter of the working channel of 1,2 mm syringe for flushing, h) catheter allows passage of standard microcatheters or other vascular For the tests standard vascular devices made for coronary or devices. It is used in combination with an introducer sheet that neurovascular procedures are used. An overview of these acts like a guide catheter. The specifications of the devices is given in Table 2. ureteroscope are shown in Table 1. Figure 2 shows a close up Table 2: Vascular test devices view of the bendable endoscope tip. Device Provider Type For the test setup the introducer sheet is placed inside the Guide Wire EV3 neurovascular SilverSpeed 14 proximal entry of the phantom. The ureteroscope is fed into Micro catheter EV3 neurovascular Rebar 18 2,4F the sheet. The phantom is filled with saline solution. Air Balloon expandable BBraun Coroflex Blue 2,75x13 bubbles are removed by flushing with a syringe on the distal stenting system ends of the phantom. The test setup is shown in Figure 3. Detachable coil EV3 neurovascular Morpheus 3D CSR system 8mm Axel Boese et al., Is a thin diameter ureteroscope feasible for image guided intravascular procedures? — 3 In a next step, the endoscope was fed deeper into the phantom 2.3 Testing to localize the aneurysm. Access of the aneurysm neck with a Four different tests were conducted under optical image micro catheter was recorded as the third maneuver. Finally, the guidance and supported by the bending function of the aneurysm was filled with a coil as a last maneuver. endoscope. The ureteroscope was placed in a distance of All procedures were recorded using a screen capture device on 10mm before a branch in the side wall. In the first test the endoscopic system. The time from beginning of the maneuver this side branch was accessed by a pre-shaped guide maneuver till successful placement was recorded for all wire and a balloon expandable catheter system. To support procedures. that, the ureteroscope tip was slightly bended into the direction 3. Results and discussion of the branching vessel. A balloon dilatation and stent placement including removal of catheter and guidewire were performed as a second maneuver. Figure 4 shows some snap shots of the placement of the guide wire and catheter in a side branch. After endoscope placement catheter and guide wire were fed into the working channel until both appear in front of the endoscope tip. The guide wire with pre-shaped tip is rotated into the direction of the branch. Supported by the bending mechanism of the endoscope, the guide wire tip is pushed into the branch and then fed into it. The catheter easily follows the guide wire into the vessel. Tendencies of the guide wire to slip out can be recognized by the optical imaging and counteract by the bending mechanism of the endoscope. Figure 5: Dilatation and stenting of the side branch under Figure 4: Endoscopic view; workflow of guidewire and catheter optical observation placement in a side branch Axel Boese et al., Is a thin diameter ureteroscope feasible for image guided intravascular procedures? — 4 enough to be utilized in several vascular procedures. The maneuver of balloon dilatation and stenting is shown in Techniques of blockage and flushing to remove blood are Figure 5. The balloon is filled with saline solution and accepted for various applications. The image quality of the increases its diameter up to 3mm. At the same time the stent is system used is high but images will be blurrier in reality due expanded. After reduction of the balloon the catheter and guide to mixture of the flushing liquid with blood particles. Even wire were removed successively. though angioscopy adds more complexity to vascular The access to the aneurysm and coiling procedure is shown in procedures, it has a potential of providing better visual Figure 6. Coiling can be seen in distant and close up view. The feedback to perform interventions. Additionally, due to the bending mechanisms was used to support the coiling as well. intuitive presentation of the scene it has the potential to reduce procedure and radiation time. Author Statement Research funding: The author states no funding involved. Conflict of interest: Endoscope provided by Olympus. References [1] F. Ishibashi et al, „Update on Coronary Angioscopy: Review of a 20-Year Experience and Potential Application for Detection of Vulnerable Plaque“, Journal of Interventional Cardiology, Bd. 19, Nr. 1, S. 17–25, 2006, [2] S. R. Dukkipati u. a., „Visual Balloon-Guided Point-by-Point AblationClinical Perspective“, Circulation: Arrhythmia and Electrophysiology, Bd. 3, Nr. 3, S. 266–273, Juni 2010, doi: 10.1161/CIRCEP.109.933283. [3] T. Kume und S. Uemura, „Current clinical applications of coronary optical coherence tomography“, Cardiovasc Interv Ther, Bd. 33, Nr. 1, S. 1–10, Jan. 2018, [4] A. Boese, A. Sivankutty, und M. Friebe, „Optical endovascular imaging by combination of endoscopy and OCT“, in 53rd Annual Conference of the German Society for Biomedical Engineering, Frankfurt, Germany, 2019. [5] A. Boese, A. K. Sivankutty, und M. Friebe, „Optical endovascular imaging combining endoscopy, NBI and OCT, a feasibility study“, Current Directions in Biomed. Engineering, doi:10.1515/cdbme- 2019-0145. [6] A. Boese und M. Friebe, „SMARTSCOPE - portable, easy to use and cheap smartphone endoscopic system“, in Abstracts 51st Figure 6: The test setup: a) camera, b) filter box, c) laser, d) test sample annual conference of the German Society for Biomedical Engineering, Dresden, Germany, 2017, The recorded times for the described test maneuvers are fast [7] A. Boese, A. K. Sivankutty, und M. Friebe, „Evaluation and image compared to X-Ray guidance and are summarized in Table 3. quality comparison of ultra-thin fibre endoscopes for vascular Table 3: Times for the shown procedures endoscopy“, Current Directions in Biomedical Engineering, Bd. 3, Procedure Time Nr. 2, S. 231–233, 2017, doi: 10.1515/cdbme-2017-0048. Side branch access 28s [8] A. Boese, C. Arens, und M. Friebe, „Concept of a flexible Stenting 75s endoscope with swiveling camera tip“, in 54th Annual Conference Coiling access 22s of the German Society for Biomedical Engineering (BMT 2020), Coiling 124s Leipzig, Germany, Sep. 2020. 4. Conclusion Feasibility and potential of optical image guided intravascular procedures were shown in this paper. The endoscope is small

Journal

Current Directions in Biomedical Engineering – de Gruyter

Published: Sep 1, 2020

Keywords: angioscopy; optical vascular imaging; endoscopy; stenting; coiling; vascular access

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