Toril Hernes - Academia.edu (original) (raw)
Papers by Toril Hernes
Acta Neurochirurgica, 2008
Objective The purpose of the study was to compare the ability of navigated 3D ultrasound to disti... more Objective The purpose of the study was to compare the ability of navigated 3D ultrasound to distinguish tumour and normal brain tissue at the tumour border zone in subsequent phases of resection. Materials and methods Biopsies were sampled in the tumour border zone as seen in the US images before and during surgery. After resection, biopsies were sampled in the resection cavity wall. Histopathology was compared with the surgeon's image findings. Results Before resection, the tumour border was delineated by ultrasound with high specificity and sensitivity (both 95%). During resection, ultrasound had acceptable sensi-tivity (87%), but poor specificity (42%), due to biopsies falsely classified as tumour by the surgeon. After resection, sensitivity was poor (26%), due to tumour or infiltrated tissue in several biopsies deemed normal by ultrasound, but the specificity was acceptable (88%). Conclusions Our study shows that although glioblastomas are well delineated prior to resection, there seem to be overestimation of tumour tissue during resection. After resection tumour remnants and infiltrated brain tissue in the resection cavity wall may be undetected. We believe that the benefits of intraoperative ultrasound outweigh the shortcomings, but users of intraoperative ultrasound should keep the limitations shown in our study in mind.
Acta Neurochirurgica, 2005
Background. The objective of the study was to test the ability of a 3D ultrasound (US) based intr... more Background. The objective of the study was to test the ability of a 3D ultrasound (US) based intraoperative imaging and navigation system to delineate gliomas and metastases in a clinical setting. The 3D US data is displayed as reformatted 2D image slices. The quality of the displayed 3D data is affected both by the resolution of the acquired data and the reformatting process. In order to investigate whether or not 3D US could be used for reliable guidance in tumour surgery, a study was initiated to compare interpretations of imaged biopsy sites with histopathology. The system also enabled concomitant comparison of navigated preoperative MR with histopathology.
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
Three-dimensional (3D) ultrasound (US) is increasingly being introduced in the clinic, both for d... more Three-dimensional (3D) ultrasound (US) is increasingly being introduced in the clinic, both for diagnostics and image guidance. Although dedicated 3D US probes exist, 3D US can also be acquired with the still frequently used two-dimensional (2D) US probes. Obtaining 3D volumes with 2D US probes is a two-step process.
Computer Aided Surgery, 2002
We have investigated the 3D navigation accuracy of a frameless ultrasound-based neuronavigation s... more We have investigated the 3D navigation accuracy of a frameless ultrasound-based neuronavigation system (SonoWand ) for surgical planning and intraoperative image guidance. In addition, we present a detailed description and review of the error sources associated with surgical neuronavigation based on preoperative MRI data and intraoperative ultrasound. A phantom with 27 precisely defined points was scanned with ultrasound by various translation and tilt movements of the ultrasound probe (180 3D scans in total), and the 27 image points in each volume were located using an automatic detection algorithm. These locations were compared to the physically measured locations of the same 27 points. The accuracy of the neuronavigation system and the effect of varying acquisition conditions were found through a thorough statistical analysis of the differences between the two point sets. The accuracy was found to be 1.40 ؎ 0.45 mm (arithmetic mean) for the ultrasound-based neuronavigation system in our laboratory setting. Improper probe calibration was the major contributor to this figure. Based on our extensive data set and thorough evaluation, the accuracy found in the laboratory setting is expected to be close to the overall clinical accuracy for ultrasound-based neuronavigation. Our analysis indicates that the overall clinical accuracy may be as low as 2 mm when using intraoperative imaging to compensate for brain shift. Comp
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
The objective of the study was to investigate tissue motion and strain imposed by cardiovascular ... more The objective of the study was to investigate tissue motion and strain imposed by cardiovascular pulsation in pathologic and normal brain parenchyma, as quantified from in vivo ultrasound data. Ultrasound acquired during surgery of 16 patients with glial tumors was retrospectively processed and analyzed. The tissue velocity was quantified at depths of 1 cm, 2 cm and 3 cm from brain cortex to investigate spatial dependency with depth. Comparison of strain and velocity in tumor and adjacent normal parenchyma was performed by selecting two regions-of-interest in the hyperechoic tumor and two regions in the low-echogenic areas interpreted as mainly normal tissue with some degree of tumor cell infiltration. The absolute maximum tissue velocity is seen to increase with increasing depths in 14 of 16 cases (87.5%). The maximum tissue velocities in the four regions close to the ultrasound visible tumor border are not statistically different (p 5 0.163 to p 5 0.975). The strain magnitudes are significantly higher in the regions with expected normal brain parenchyma than in regions with expected glial tumor tissue, both for the two regions being closest to the tumor border (p 5 0.0004) and for the two regions further away from the tumor border (p 5 0.0009). We conclude that the velocity of the brain parenchyma imposed by arterial pulsation during a cardiac cycle is generally increasing with increasing depth from cortex. The maximum velocity appears to be similar in regions with expected normal brain and tumor tissue, thus, does not seem to be affected by pathology. Strain magnitude is, however, a suitable parameter for discrimination of glial tumor and normal brain parenchyma. (E-mail: Tormod.Selbekk@sintef.no) Ó
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.
Ultrasonics, 2011
Freehand 3D ultrasound is increasingly being introduced in the clinic for diagnostics and image-a... more Freehand 3D ultrasound is increasingly being introduced in the clinic for diagnostics and image-assisted interventions. Various algorithms exist for combining 2D images of regular ultrasound probes to 3D volumes, being either voxel-, pixel-or function-based. Previously, the most commonly used input to 3D ultrasound reconstruction has been digitized analog video. However, recent scanners that offer access to digital image frames exist, either as processed or unprocessed data. To our knowledge, no comparison has been performed to determine which data source gives the best reconstruction quality. In the present study we compared both reconstruction algorithms and data sources using novel comparison methods for detecting potential differences in image quality of the reconstructed volumes. The ultrasound scanner used in this study was the Sonix RP from Ultrasonix Medical Corp (Richmond, Canada), a scanner that allow third party access to unprocessed and processed digital data. The ultrasound probe used was the L14-5/38 linear probe. The assessment is based on a number of image criteria: detectability of wire targets, spatial resolution, detectability of small barely visible structures, subjective tissue image quality, and volume geometry. In addition we have also performed the more ''traditional'' comparison of reconstructed volumes by removing a percentage of the input data. By using these evaluation methods and data from the specific scanner, the results showed that the processed video performed better than the digital scan-line data, digital video being better than analog video. Furthermore, the results showed that the choice of video source was more important than the choice of tested reconstruction algorithms.
Surgical Neurology, 2006
Background: Avoiding damage to blood vessels is often the concern of the neurosurgeon during tumo... more Background: Avoiding damage to blood vessels is often the concern of the neurosurgeon during tumor surgery. Using angiographic image data in neuronavigation may be useful in cases where vascular anatomy is of special interest. Since 2003, we have routinely used 3D ultrasound angiography in tumor surgery, and between January 2003 and May 2005, 62 patients with different tumors have been operated using intraoperative 3D ultrasound angiography in neuronavigation. Methods: An ultrasound-based neuronavigation system was used. In addition to 3D ultrasound tissue image data, 3D ultrasound angiography (power Doppler) image data were acquired at different stages of the operation. The value and role of navigated 3D ultrasound angiography as judged by the surgeon were recorded. Results: We found that intraoperative ultrasound angiography was easy to acquire and interpret, and that image quality was sufficient for neuronavigation. In 26 of 62 cases, ultrasound angiography was found to be helpful by visualizing hidden vessels adjacent to and inside the tumor, facilitating tailored approaches and safe biopsy sampling. Conclusions: Intraoperative 3D ultrasound angiography is straightforward to use, image quality is sufficient for image guidance, and it adds valuable information about hidden vessels, increasing safety and facilitating tailored approaches. Furthermore, with updated 3D ultrasound angiography imaging, accuracy of neuronavigation may be maintained in cases of brain shift. D
Surgical Endoscopy, 2004
Background: The main drawback with the laparoscopic approach is that the surgeon is unable to pal... more Background: The main drawback with the laparoscopic approach is that the surgeon is unable to palpate vessels, tumors, and organs during surgery. Furthermore, the laparoscope provides only surface view of organs. There is a need for more advanced visualizations that can enhance the view to include information below the surface of the organs for planning of the procedure and for control and guidance during treatment. Methods: We propose three-dimensional (3D) navigation technology based on preoperatively acquired magnetic resonance or computed tomography data used in combination with a laparoscopic navigation pointer (LNP). The LNP has an attached position tracker that allows the surgeon to control the display of images interactively before and during surgery. This study evaluated the patient registration accuracy, the feasibility of image-based navigation and, qualitatively, the navigation precision in the retroperitoneum during laparoscopic surgery. Results: This technology was used during the treatment of six patients (involving adrenalectomies and a neuroma protruding into the pelvis). An average patient registration accuracy of 6.90 mm was achieved. The precision during navigation in the retroperitoneum was, in some cases, better than the patient registration accuracy suggested. The technology helped the surgeons to understand better the anatomy and to locate blood vessels. Conclusions: In the reported cases, the LNP was a useful tool for image guidance in laparoscopic surgery, both for planning the surgical approach in detail and for guidance. The authors believe that adominal 3D image guidance using an LNP has a large potential for improving laparoscopic surgery, especially when vessels and anatomic relations may be difficult to identify using only a laparoscope. Accordingly, they believe this new technology could increase safety and make it easier for the surgeon to perform successful laparoscopic surgery.
Acta Neurochirurgica, 2008
Objective The purpose of the study was to compare the ability of navigated 3D ultrasound to disti... more Objective The purpose of the study was to compare the ability of navigated 3D ultrasound to distinguish tumour and normal brain tissue at the tumour border zone in subsequent phases of resection. Materials and methods Biopsies were sampled in the tumour border zone as seen in the US images before and during surgery. After resection, biopsies were sampled in the resection cavity wall. Histopathology was compared with the surgeon's image findings. Results Before resection, the tumour border was delineated by ultrasound with high specificity and sensitivity (both 95%). During resection, ultrasound had acceptable sensi-tivity (87%), but poor specificity (42%), due to biopsies falsely classified as tumour by the surgeon. After resection, sensitivity was poor (26%), due to tumour or infiltrated tissue in several biopsies deemed normal by ultrasound, but the specificity was acceptable (88%). Conclusions Our study shows that although glioblastomas are well delineated prior to resection, there seem to be overestimation of tumour tissue during resection. After resection tumour remnants and infiltrated brain tissue in the resection cavity wall may be undetected. We believe that the benefits of intraoperative ultrasound outweigh the shortcomings, but users of intraoperative ultrasound should keep the limitations shown in our study in mind.
Acta Neurochirurgica, 2005
Background. The objective of the study was to test the ability of a 3D ultrasound (US) based intr... more Background. The objective of the study was to test the ability of a 3D ultrasound (US) based intraoperative imaging and navigation system to delineate gliomas and metastases in a clinical setting. The 3D US data is displayed as reformatted 2D image slices. The quality of the displayed 3D data is affected both by the resolution of the acquired data and the reformatting process. In order to investigate whether or not 3D US could be used for reliable guidance in tumour surgery, a study was initiated to compare interpretations of imaged biopsy sites with histopathology. The system also enabled concomitant comparison of navigated preoperative MR with histopathology.
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
Three-dimensional (3D) ultrasound (US) is increasingly being introduced in the clinic, both for d... more Three-dimensional (3D) ultrasound (US) is increasingly being introduced in the clinic, both for diagnostics and image guidance. Although dedicated 3D US probes exist, 3D US can also be acquired with the still frequently used two-dimensional (2D) US probes. Obtaining 3D volumes with 2D US probes is a two-step process.
Computer Aided Surgery, 2002
We have investigated the 3D navigation accuracy of a frameless ultrasound-based neuronavigation s... more We have investigated the 3D navigation accuracy of a frameless ultrasound-based neuronavigation system (SonoWand ) for surgical planning and intraoperative image guidance. In addition, we present a detailed description and review of the error sources associated with surgical neuronavigation based on preoperative MRI data and intraoperative ultrasound. A phantom with 27 precisely defined points was scanned with ultrasound by various translation and tilt movements of the ultrasound probe (180 3D scans in total), and the 27 image points in each volume were located using an automatic detection algorithm. These locations were compared to the physically measured locations of the same 27 points. The accuracy of the neuronavigation system and the effect of varying acquisition conditions were found through a thorough statistical analysis of the differences between the two point sets. The accuracy was found to be 1.40 ؎ 0.45 mm (arithmetic mean) for the ultrasound-based neuronavigation system in our laboratory setting. Improper probe calibration was the major contributor to this figure. Based on our extensive data set and thorough evaluation, the accuracy found in the laboratory setting is expected to be close to the overall clinical accuracy for ultrasound-based neuronavigation. Our analysis indicates that the overall clinical accuracy may be as low as 2 mm when using intraoperative imaging to compensate for brain shift. Comp
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
The objective of the study was to investigate tissue motion and strain imposed by cardiovascular ... more The objective of the study was to investigate tissue motion and strain imposed by cardiovascular pulsation in pathologic and normal brain parenchyma, as quantified from in vivo ultrasound data. Ultrasound acquired during surgery of 16 patients with glial tumors was retrospectively processed and analyzed. The tissue velocity was quantified at depths of 1 cm, 2 cm and 3 cm from brain cortex to investigate spatial dependency with depth. Comparison of strain and velocity in tumor and adjacent normal parenchyma was performed by selecting two regions-of-interest in the hyperechoic tumor and two regions in the low-echogenic areas interpreted as mainly normal tissue with some degree of tumor cell infiltration. The absolute maximum tissue velocity is seen to increase with increasing depths in 14 of 16 cases (87.5%). The maximum tissue velocities in the four regions close to the ultrasound visible tumor border are not statistically different (p 5 0.163 to p 5 0.975). The strain magnitudes are significantly higher in the regions with expected normal brain parenchyma than in regions with expected glial tumor tissue, both for the two regions being closest to the tumor border (p 5 0.0004) and for the two regions further away from the tumor border (p 5 0.0009). We conclude that the velocity of the brain parenchyma imposed by arterial pulsation during a cardiac cycle is generally increasing with increasing depth from cortex. The maximum velocity appears to be similar in regions with expected normal brain and tumor tissue, thus, does not seem to be affected by pathology. Strain magnitude is, however, a suitable parameter for discrimination of glial tumor and normal brain parenchyma. (E-mail: Tormod.Selbekk@sintef.no) Ó
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.
Ultrasonics, 2011
Freehand 3D ultrasound is increasingly being introduced in the clinic for diagnostics and image-a... more Freehand 3D ultrasound is increasingly being introduced in the clinic for diagnostics and image-assisted interventions. Various algorithms exist for combining 2D images of regular ultrasound probes to 3D volumes, being either voxel-, pixel-or function-based. Previously, the most commonly used input to 3D ultrasound reconstruction has been digitized analog video. However, recent scanners that offer access to digital image frames exist, either as processed or unprocessed data. To our knowledge, no comparison has been performed to determine which data source gives the best reconstruction quality. In the present study we compared both reconstruction algorithms and data sources using novel comparison methods for detecting potential differences in image quality of the reconstructed volumes. The ultrasound scanner used in this study was the Sonix RP from Ultrasonix Medical Corp (Richmond, Canada), a scanner that allow third party access to unprocessed and processed digital data. The ultrasound probe used was the L14-5/38 linear probe. The assessment is based on a number of image criteria: detectability of wire targets, spatial resolution, detectability of small barely visible structures, subjective tissue image quality, and volume geometry. In addition we have also performed the more ''traditional'' comparison of reconstructed volumes by removing a percentage of the input data. By using these evaluation methods and data from the specific scanner, the results showed that the processed video performed better than the digital scan-line data, digital video being better than analog video. Furthermore, the results showed that the choice of video source was more important than the choice of tested reconstruction algorithms.
Surgical Neurology, 2006
Background: Avoiding damage to blood vessels is often the concern of the neurosurgeon during tumo... more Background: Avoiding damage to blood vessels is often the concern of the neurosurgeon during tumor surgery. Using angiographic image data in neuronavigation may be useful in cases where vascular anatomy is of special interest. Since 2003, we have routinely used 3D ultrasound angiography in tumor surgery, and between January 2003 and May 2005, 62 patients with different tumors have been operated using intraoperative 3D ultrasound angiography in neuronavigation. Methods: An ultrasound-based neuronavigation system was used. In addition to 3D ultrasound tissue image data, 3D ultrasound angiography (power Doppler) image data were acquired at different stages of the operation. The value and role of navigated 3D ultrasound angiography as judged by the surgeon were recorded. Results: We found that intraoperative ultrasound angiography was easy to acquire and interpret, and that image quality was sufficient for neuronavigation. In 26 of 62 cases, ultrasound angiography was found to be helpful by visualizing hidden vessels adjacent to and inside the tumor, facilitating tailored approaches and safe biopsy sampling. Conclusions: Intraoperative 3D ultrasound angiography is straightforward to use, image quality is sufficient for image guidance, and it adds valuable information about hidden vessels, increasing safety and facilitating tailored approaches. Furthermore, with updated 3D ultrasound angiography imaging, accuracy of neuronavigation may be maintained in cases of brain shift. D
Surgical Endoscopy, 2004
Background: The main drawback with the laparoscopic approach is that the surgeon is unable to pal... more Background: The main drawback with the laparoscopic approach is that the surgeon is unable to palpate vessels, tumors, and organs during surgery. Furthermore, the laparoscope provides only surface view of organs. There is a need for more advanced visualizations that can enhance the view to include information below the surface of the organs for planning of the procedure and for control and guidance during treatment. Methods: We propose three-dimensional (3D) navigation technology based on preoperatively acquired magnetic resonance or computed tomography data used in combination with a laparoscopic navigation pointer (LNP). The LNP has an attached position tracker that allows the surgeon to control the display of images interactively before and during surgery. This study evaluated the patient registration accuracy, the feasibility of image-based navigation and, qualitatively, the navigation precision in the retroperitoneum during laparoscopic surgery. Results: This technology was used during the treatment of six patients (involving adrenalectomies and a neuroma protruding into the pelvis). An average patient registration accuracy of 6.90 mm was achieved. The precision during navigation in the retroperitoneum was, in some cases, better than the patient registration accuracy suggested. The technology helped the surgeons to understand better the anatomy and to locate blood vessels. Conclusions: In the reported cases, the LNP was a useful tool for image guidance in laparoscopic surgery, both for planning the surgical approach in detail and for guidance. The authors believe that adominal 3D image guidance using an LNP has a large potential for improving laparoscopic surgery, especially when vessels and anatomic relations may be difficult to identify using only a laparoscope. Accordingly, they believe this new technology could increase safety and make it easier for the surgeon to perform successful laparoscopic surgery.