Toril Hernes - Academia.edu (original) (raw)
Papers by Toril Hernes
Acta Neurochirurgica, 2008
Acta Neurochirurgica, 2005
International journal of computer assisted radiology and surgery, Jan 26, 2015
CustusX is an image-guided therapy (IGT) research platform dedicated to intraoperative navigation... more CustusX is an image-guided therapy (IGT) research platform dedicated to intraoperative navigation and ultrasound imaging. In this paper, we present CustusX as a robust, accurate, and extensible platform with full access to data and algorithms and show examples of application in technological and clinical IGT research. CustusX has been developed continuously for more than 15 years based on requirements from clinical and technological researchers within the framework of a well-defined software quality process. The platform was designed as a layered architecture with plugins based on the CTK/OSGi framework, a superbuild that manages dependencies and features supporting the IGT workflow. We describe the use of the system in several different clinical settings and characterize major aspects of the system such as accuracy, frame rate, and latency. The validation experiments show a navigation system accuracy of [Formula: see text]1.1 mm, a frame rate of 20 fps, and latency of 285 ms for a ...
Medical Imaging 2007: Physiology, Function, and Structure from Medical Images, 2007
The criterion for recommending treatment of an abdominal aortic aneurysm is that the diameter exc... more The criterion for recommending treatment of an abdominal aortic aneurysm is that the diameter exceeds 50-55 mm or shows a rapid increase. Our hypothesis is that a more accurate prediction of aneurysm rupture is obtained by estimating arterial wall strain from patient specific measurements. Measuring strain in specific parts of the aneurysm reveals differences in load or tissue properties. We
... Proceedings of SPIE Medical Imaging: Physiology, Function, and Structure from Medical Images,... more ... Proceedings of SPIE Medical Imaging: Physiology, Function, and Structure from Medical Images, 65111H, San Diego, CA, USA, February 18, 2007. ... Cantisani V, Ricci P, Grazhdani H, Napoli A, Fanelli F, Catalano C, Galati G, D'Andrea V, Biancari F, Passariello R. (2011). ...
Over the last decade, several ultrasound simulation methods have been developed specifically to b... more Over the last decade, several ultrasound simulation methods have been developed specifically to be used in training simulators for medical ultrasound imaging. However, the evaluation of these simulation methods has not been devoted a lot of attention in the literature. Here we present an experimental setup facilitating such evaluation. The setup produces true ultrasound images corresponding to the simulations, thus allowing an intuitive assessment of the simulation method by direct comparison of true and simulated ultrasound images.
Medical Imaging 2010: Ultrasonic Imaging, Tomography, and Therapy, 2010
ABSTRACT Ultrasound imaging is used within numerous medical disciplines. Extensive and repeated t... more ABSTRACT Ultrasound imaging is used within numerous medical disciplines. Extensive and repeated training is needed for efficient use of the technology. Simulator training has been proposed as a complement to other training methods. Advantages of simulator training include access to a large number of normal and rare cases without the need for suitable volunteers and available ultrasound equipment. The imaging of soft tissue can be simulated by considering the interaction between the tissue and the ultrasound field. The objective of this study is to include these effects in real-time simulators. One previous approach has been to simulate a three-dimensional (3D) ultrasound volume off line, and then cross-section the volume in real time. This approach, however, does not take into account the anisotropic resolution of ultrasound imaging. If we assume that the average acoustical properties of tissues are slowly varying and that the speckle pattern is independent of the tissue, we show that ultrasound images can be simulated by multiplying a pre-simulated speckle image by an any-plane cross section of a D representation of an anatomy. Thus anisotropic resolution can be simulated in real time. The simulated images were compared to true ultrasound images of soft tissue. Since the speckle was simulated independently of the tissue, the most realistic results were obtained for still images, but the method was also satisfactory for moving images when speckle tracking between views was not important. The method is well applicable to ultrasound training simulators on low cost platforms.
Physics in medicine and biology, Jan 9, 2015
Within the field of ultrasound-guided procedures, there are a number of methods for ultrasound pr... more Within the field of ultrasound-guided procedures, there are a number of methods for ultrasound probe calibration. While these methods are usually developed for a specific probe, they are in principle easily adapted to other probes. In practice, however, the adaptation often proves tedious and this is impractical in a research setting, where new probes are tested regularly. Therefore, we developed a method which can be applied to a large variety of probes without adaptation. The method used a robot arm to move a plastic sphere submerged in water through the ultrasound image plane, providing a slow and precise movement. The sphere was then segmented from the recorded ultrasound images using a MATLAB programme and the calibration matrix was computed based on this segmentation in combination with tracking information. The method was tested on three very different probes demonstrating both great versatility and high accuracy.
Minerva chirurgica, 2005
The main drawback with laparoscopic surgery is that the surgeon is unable to palpate vessels, tum... more The main drawback with laparoscopic surgery is that the surgeon is unable to palpate vessels, tumours and organs during surgery. Further-more, the laparoscope only provides a surface view of organs. There is a need for more advanced visualizations techniques that can enhance the display presented to the surgeon so that important information below the surface of the organs is included when planning the procedure as well as for guidance and control during treatment. In this paper, we present a review of the literature and the state of art within image-guided laparoscopic surgery. We describe our own experience using a prototype navigation system for advanced visualizations and guidance during laparoscopic procedures in the retroperitoneum. Furthermore, we show sample images from the Future Operating Room for laparoscopic surgery in Trondheim, where this technology is being further developed and tested in clinical studies. Our system is based on three-dimensional navigation technology,...
Computer aided surgery : official journal of the International Society for Computer Aided Surgery, 2003
We have investigated alternative ways to integrate intraoperative 3D ultrasound images and preope... more We have investigated alternative ways to integrate intraoperative 3D ultrasound images and preoperative MR images in the same 3D scene for visualizing brain shift and improving overview and interpretation in ultrasound-based neuronavigation. A Multi-Modal Volume Visualizer (MMVV) was developed that can read data exported from the SonoWand neuronavigation system and reconstruct the spatial relationship between the volumes available at any given time during an operation, thus enabling the exploration of new ways to fuse pre- and intraoperative data for planning, guidance and therapy control. In addition, the mismatch between MRI volumes registered to the patient and intraoperative ultrasound acquired from the dura was qualified. The results show that image fusion of intraoperative ultrasound images in combination with preoperative MRI will make perception of available information easier by providing updated (real-time) image information and an extended overview of the operating field ...
Tidsskrift for den Norske lægeforening : tidsskrift for praktisk medicin, ny række, Jan 4, 2004
The main drawback with the laparoscopic approach is that the surgeon lacks the possibility to pal... more The main drawback with the laparoscopic approach is that the surgeon lacks the possibility to palpate vessels, tumours and organs during surgery. Furthermore, the laparoscope only provides a surface view of organs. There is a need for more advanced visualization that enhances the view to include information below the surface of the organs when the procedure is planned and for control and guidance during treatment. We propose 3-D navigation technology based on preoperatively acquired MR or CT data used in combination with a laparoscopic navigation pointer. The pointer has an attached position tracker which enables the surgeon to interactively control the display of images prior to and during surgery. We have used this technology during treatment of four patients with adrenal tumours. Preoperative registration of images of the patients was performed within two minutes with an average accuracy of 7.1 mm. 2-D and 3-D visualizations interactively controlled by the pointer were used both ...
Ultrasound in Medicine & Biology, 2007
Computer Aided Surgery, 2002
Minimally Invasive Therapy & Allied Technologies, 2014
Surgical navigation based on preoperative images partly overcomes some of the drawbacks of minima... more Surgical navigation based on preoperative images partly overcomes some of the drawbacks of minimally invasive interventions - reduction of free sight, lack of dexterity and tactile feedback. The usefulness of preoperative images is limited in laparoscopic liver surgery, as the liver shifts due to respiration, induction of pneumoperitoneum and surgical manipulation. In this study, we evaluated the shift and deformation in an animal liver caused by respiration and pneumopertioneum using intraoperative cone beam CT. 3D cone beam CT scans were acquired with arterial contrast. The centerlines of the segmented vessels were extracted from the images taken at different respiration and pressure settings. A non-rigid registration method was used to measure the shift and deformation. The mean Euclidean distance between the annotated landmarks was used for evaluation. A shift and deformation of 44.6 mm on average was introduced due to the combined effect of respiration and pneumoperitoneum. On average 91% of the deformations caused by the respiration and pneumoperitoneum were recovered. The results can contribute to the use of intraoperative imaging to correct for anatomic shift so that preoperative data can be used with greater confidence and accuracy during guidance of laparoscopic liver procedures.
Ultrasound in Medicine & Biology, 2010
Ultrasound in Medicine & Biology, 2012
The purpose of this study was to develop a simulation model for evaluating methods for ultrasound... more The purpose of this study was to develop a simulation model for evaluating methods for ultrasound strain estimation in abdominal aortic aneurysms. Wall geometry was obtained from a real ultrasound image and wall motion was simulated applying realistic blood pressures to a nonlinear viscoelastic wall model. The ultrasound simulation included speckle, absorption and angle dependent reflection. Gaussian white noise was added to simulate various noise levels. Despite not fully replicating real ultrasound images, the model simulated realistic circumferential variations in intensity and realistic speckle patterns and has potential for initial evaluation of strain estimation methods.
Acta Neurochirurgica, 2008
Acta Neurochirurgica, 2005
International journal of computer assisted radiology and surgery, Jan 26, 2015
CustusX is an image-guided therapy (IGT) research platform dedicated to intraoperative navigation... more CustusX is an image-guided therapy (IGT) research platform dedicated to intraoperative navigation and ultrasound imaging. In this paper, we present CustusX as a robust, accurate, and extensible platform with full access to data and algorithms and show examples of application in technological and clinical IGT research. CustusX has been developed continuously for more than 15 years based on requirements from clinical and technological researchers within the framework of a well-defined software quality process. The platform was designed as a layered architecture with plugins based on the CTK/OSGi framework, a superbuild that manages dependencies and features supporting the IGT workflow. We describe the use of the system in several different clinical settings and characterize major aspects of the system such as accuracy, frame rate, and latency. The validation experiments show a navigation system accuracy of [Formula: see text]1.1 mm, a frame rate of 20 fps, and latency of 285 ms for a ...
Medical Imaging 2007: Physiology, Function, and Structure from Medical Images, 2007
The criterion for recommending treatment of an abdominal aortic aneurysm is that the diameter exc... more The criterion for recommending treatment of an abdominal aortic aneurysm is that the diameter exceeds 50-55 mm or shows a rapid increase. Our hypothesis is that a more accurate prediction of aneurysm rupture is obtained by estimating arterial wall strain from patient specific measurements. Measuring strain in specific parts of the aneurysm reveals differences in load or tissue properties. We
... Proceedings of SPIE Medical Imaging: Physiology, Function, and Structure from Medical Images,... more ... Proceedings of SPIE Medical Imaging: Physiology, Function, and Structure from Medical Images, 65111H, San Diego, CA, USA, February 18, 2007. ... Cantisani V, Ricci P, Grazhdani H, Napoli A, Fanelli F, Catalano C, Galati G, D'Andrea V, Biancari F, Passariello R. (2011). ...
Over the last decade, several ultrasound simulation methods have been developed specifically to b... more Over the last decade, several ultrasound simulation methods have been developed specifically to be used in training simulators for medical ultrasound imaging. However, the evaluation of these simulation methods has not been devoted a lot of attention in the literature. Here we present an experimental setup facilitating such evaluation. The setup produces true ultrasound images corresponding to the simulations, thus allowing an intuitive assessment of the simulation method by direct comparison of true and simulated ultrasound images.
Medical Imaging 2010: Ultrasonic Imaging, Tomography, and Therapy, 2010
ABSTRACT Ultrasound imaging is used within numerous medical disciplines. Extensive and repeated t... more ABSTRACT Ultrasound imaging is used within numerous medical disciplines. Extensive and repeated training is needed for efficient use of the technology. Simulator training has been proposed as a complement to other training methods. Advantages of simulator training include access to a large number of normal and rare cases without the need for suitable volunteers and available ultrasound equipment. The imaging of soft tissue can be simulated by considering the interaction between the tissue and the ultrasound field. The objective of this study is to include these effects in real-time simulators. One previous approach has been to simulate a three-dimensional (3D) ultrasound volume off line, and then cross-section the volume in real time. This approach, however, does not take into account the anisotropic resolution of ultrasound imaging. If we assume that the average acoustical properties of tissues are slowly varying and that the speckle pattern is independent of the tissue, we show that ultrasound images can be simulated by multiplying a pre-simulated speckle image by an any-plane cross section of a D representation of an anatomy. Thus anisotropic resolution can be simulated in real time. The simulated images were compared to true ultrasound images of soft tissue. Since the speckle was simulated independently of the tissue, the most realistic results were obtained for still images, but the method was also satisfactory for moving images when speckle tracking between views was not important. The method is well applicable to ultrasound training simulators on low cost platforms.
Physics in medicine and biology, Jan 9, 2015
Within the field of ultrasound-guided procedures, there are a number of methods for ultrasound pr... more Within the field of ultrasound-guided procedures, there are a number of methods for ultrasound probe calibration. While these methods are usually developed for a specific probe, they are in principle easily adapted to other probes. In practice, however, the adaptation often proves tedious and this is impractical in a research setting, where new probes are tested regularly. Therefore, we developed a method which can be applied to a large variety of probes without adaptation. The method used a robot arm to move a plastic sphere submerged in water through the ultrasound image plane, providing a slow and precise movement. The sphere was then segmented from the recorded ultrasound images using a MATLAB programme and the calibration matrix was computed based on this segmentation in combination with tracking information. The method was tested on three very different probes demonstrating both great versatility and high accuracy.
Minerva chirurgica, 2005
The main drawback with laparoscopic surgery is that the surgeon is unable to palpate vessels, tum... more The main drawback with laparoscopic surgery is that the surgeon is unable to palpate vessels, tumours and organs during surgery. Further-more, the laparoscope only provides a surface view of organs. There is a need for more advanced visualizations techniques that can enhance the display presented to the surgeon so that important information below the surface of the organs is included when planning the procedure as well as for guidance and control during treatment. In this paper, we present a review of the literature and the state of art within image-guided laparoscopic surgery. We describe our own experience using a prototype navigation system for advanced visualizations and guidance during laparoscopic procedures in the retroperitoneum. Furthermore, we show sample images from the Future Operating Room for laparoscopic surgery in Trondheim, where this technology is being further developed and tested in clinical studies. Our system is based on three-dimensional navigation technology,...
Computer aided surgery : official journal of the International Society for Computer Aided Surgery, 2003
We have investigated alternative ways to integrate intraoperative 3D ultrasound images and preope... more We have investigated alternative ways to integrate intraoperative 3D ultrasound images and preoperative MR images in the same 3D scene for visualizing brain shift and improving overview and interpretation in ultrasound-based neuronavigation. A Multi-Modal Volume Visualizer (MMVV) was developed that can read data exported from the SonoWand neuronavigation system and reconstruct the spatial relationship between the volumes available at any given time during an operation, thus enabling the exploration of new ways to fuse pre- and intraoperative data for planning, guidance and therapy control. In addition, the mismatch between MRI volumes registered to the patient and intraoperative ultrasound acquired from the dura was qualified. The results show that image fusion of intraoperative ultrasound images in combination with preoperative MRI will make perception of available information easier by providing updated (real-time) image information and an extended overview of the operating field ...
Tidsskrift for den Norske lægeforening : tidsskrift for praktisk medicin, ny række, Jan 4, 2004
The main drawback with the laparoscopic approach is that the surgeon lacks the possibility to pal... more The main drawback with the laparoscopic approach is that the surgeon lacks the possibility to palpate vessels, tumours and organs during surgery. Furthermore, the laparoscope only provides a surface view of organs. There is a need for more advanced visualization that enhances the view to include information below the surface of the organs when the procedure is planned and for control and guidance during treatment. We propose 3-D navigation technology based on preoperatively acquired MR or CT data used in combination with a laparoscopic navigation pointer. The pointer has an attached position tracker which enables the surgeon to interactively control the display of images prior to and during surgery. We have used this technology during treatment of four patients with adrenal tumours. Preoperative registration of images of the patients was performed within two minutes with an average accuracy of 7.1 mm. 2-D and 3-D visualizations interactively controlled by the pointer were used both ...
Ultrasound in Medicine & Biology, 2007
Computer Aided Surgery, 2002
Minimally Invasive Therapy & Allied Technologies, 2014
Surgical navigation based on preoperative images partly overcomes some of the drawbacks of minima... more Surgical navigation based on preoperative images partly overcomes some of the drawbacks of minimally invasive interventions - reduction of free sight, lack of dexterity and tactile feedback. The usefulness of preoperative images is limited in laparoscopic liver surgery, as the liver shifts due to respiration, induction of pneumoperitoneum and surgical manipulation. In this study, we evaluated the shift and deformation in an animal liver caused by respiration and pneumopertioneum using intraoperative cone beam CT. 3D cone beam CT scans were acquired with arterial contrast. The centerlines of the segmented vessels were extracted from the images taken at different respiration and pressure settings. A non-rigid registration method was used to measure the shift and deformation. The mean Euclidean distance between the annotated landmarks was used for evaluation. A shift and deformation of 44.6 mm on average was introduced due to the combined effect of respiration and pneumoperitoneum. On average 91% of the deformations caused by the respiration and pneumoperitoneum were recovered. The results can contribute to the use of intraoperative imaging to correct for anatomic shift so that preoperative data can be used with greater confidence and accuracy during guidance of laparoscopic liver procedures.
Ultrasound in Medicine & Biology, 2010
Ultrasound in Medicine & Biology, 2012
The purpose of this study was to develop a simulation model for evaluating methods for ultrasound... more The purpose of this study was to develop a simulation model for evaluating methods for ultrasound strain estimation in abdominal aortic aneurysms. Wall geometry was obtained from a real ultrasound image and wall motion was simulated applying realistic blood pressures to a nonlinear viscoelastic wall model. The ultrasound simulation included speckle, absorption and angle dependent reflection. Gaussian white noise was added to simulate various noise levels. Despite not fully replicating real ultrasound images, the model simulated realistic circumferential variations in intensity and realistic speckle patterns and has potential for initial evaluation of strain estimation methods.