Torbjörn Gustafsson

Real-time intraoperative visualization of myocardial circulation using augmented reality temperature display.

For direct visualization of myocardial ischemia during cardiac surgery, we tested the feasibility of presenting infrared (IR) tissue temperature maps in situ during surgery. A new augmented reality (AR) system, consisting of an IR camera and an integrated projector having identical optical axes, was used, with a high resolution IR camera as control. The hearts of five pigs were exposed and an elastic band placed around the middle of the left anterior descending coronary artery to induce ischemia. A proximally placed ultrasound Doppler probe confirmed reduction of flow. Two periods of complete ischemia and reperfusion were studied in each heart. There was a significant decrease in IR-measured temperature distal to the occlusion, with subsequent return to baseline temperatures after reperfusion (baseline 36.9xa0±xa00.60 (meanxa0±xa0SD) versus ischemia 34.1xa0±xa01.66 versus reperfusion 37.4xa0±xa00.48; pxa0<xa00.001), with no differences occurring in the non-occluded area. The AR presentation was clear and dynamic without delay, visualizing the temperature changes produced by manipulation of the coronary blood flow, and showed concentrically arranged penumbra zones during ischemia. Surface myocardial temperature changes could be assessed quantitatively and visualized in situ during ischemia and subsequent reperfusion. This method shows potential as a rapid and simple way of following myocardial perfusion during cardiac surgery. The dynamics in the penumbra zone could potentially be used for visualizing the effect of therapy on intraoperative ischemia during cardiac surgery.

Superficial vessel reconstruction with a multiview camera system

Abstract. We aim at reconstructing superficial vessels of the brain. Ultimately, they will serve to guide the deformation methods to compensate for the brain shift. A pipeline for three-dimensional (3-D) vessel reconstruction using three mono-complementary metal-oxide semiconductor cameras has been developed. Vessel centerlines are manually selected in the images. Using the properties of the Hessian matrix, the centerline points are assigned direction information. For correspondence matching, a combination of methods was used. The process starts with epipolar and spatial coherence constraints (geometrical constraints), followed by relaxation labeling and an iterative filtering where the 3-D points are compared to surfaces obtained using the thin-plate spline with decreasing relaxation parameter. Finally, the points are shifted to their local centroid position. Evaluation in virtual, phantom, and experimental images, including intraoperative data from patient experiments, shows that, with appropriate camera positions, the error estimates (root-mean square error and mean error) are ∼1u2009u2009mm.

Multi-view 3D vessel tracking using near-infrared cameras

Multi-view 3D vessel tracking using near-infrared cameras Filipe Marreiros, Sandro Rossitti, Torbjörn Gustafsson, Per Carleberg, Örjan Smedby Center for Medical Image Science and Visualization (CMIV), Linköping University, Sweden Department of Science and Technology (ITN) Media and Information Technology (MIT), Linköping University, Sweden Department of Medical and Health Sciences (IMH) – Radiology, Linköping University, Department of Radiology, County Council of Östergötland, Linköping, Sweden XM Reality Research AB, Linköping, Sweden Department of Neurosurgery, County Council of Östergötland, Linköping, Sweden

Erratum: Superficial vessel reconstruction with a Multiview camera system.

[This corrects the article DOI: 10.1117/1.JMI.3.1.015001.].

Real-time intraoperative visualization of myocardial circulation by augmented reality temperature display

Background:xa0 Intraoperativexa0 ischemiaxa0xa0 duringxa0xa0 coronaryxa0xa0 surgeryxa0xa0 mayxa0xa0 havexa0xa0 severexa0xa0 consequencesxa0xa0 for the patient and may also pose a difficult diagnostic problemxa0 to thexa0 surgeon.xa0 Therexa0 is noxa0 clinically usedxa0directxa0 methodxa0 to evaluatexa0 thexa0 effect onxa0 thexa0 circulation of various therapeutic maneuversxa0 to the heart. Augmented (mixed)xa0 reality using projection xa0of color- codedxa0 infra-redxa0 (IR)xa0 images ontoxa0 the imagedxa0 tissues in realxa0 timexa0 mayxa0 give an xa0intuitivexa0 representation of the tissue surface temperature and thus,xa0 information aboutxa0 xa0myocardialxa0xa0 perfusionxa0xa0 onxa0 thexa0 surfacexa0 ofxa0 the organ itself.Purpose:xa0 To demonstrate in animal experiments the feasibility of presentingxa0 IR tissue temperature imagesxa0 reflectingxa0 myocardial xa0perfusion intoxa0 thexa0 surgicalxa0 fieldxa0 withxa0 augmented reality.Method: Wexa0 havexa0 constructed a xa0systemxa0 consisting of an IR cameraxa0 andxa0 a projectorxa0 integrated in such a way thatxa0 theyxa0 have xa0identicalxa0 opticalxa0 axes,xa0 solving thexa0 geometricalxa0 correspondence problemxa0 in an easy way. In 5 pigs (weight = 57.5 ± 7 kg), the thorax was openedxa0xa0xa0 byxa0xa0 medianxa0xa0xa0 sternotomy.xa0xa0 Afterxa0xa0 exposing thexa0 heart,xa0 anxa0 elasticxa0 vessel loopxa0 was placedxa0 around thexa0 middlexa0 ofxa0 thexa0 leftxa0 descending xa0coronaryxa0 artery. Axa0 2xa0 mmxa0xa0 ultrasoundxa0 probexa0xa0 wasxa0 insertedxa0xa0 distally around the LAD for flow velocity measurements. Subsequent ischemia-reperfusion periodsxa0 were induced using a fixed protocol.xa0Results:xa0 Thexa0 time course ofxa0 anxa0xa0 occlusionxa0xa0 wasxa0 clearlyxa0 seenxa0xa0 inxa0 quantitative curvesxa0 as well as inxa0 color-coded temperaturexa0 maps on the surface of the heart.xa0 Thexa0 difference in surface temperature between the three areas more or less affectedxa0 byxa0 thexa0 ischemiaxa0xa0 wasxa0 also xa0clearlyxa0 demon- strated.xa0 Duringxa0 ischemia,xa0 the surface of the myocardiumxa0 showed xa0concentricallyxa0 arrangedxa0 zonesxa0 of different temperatures (IR penumbra) potentially cor- responding to differentxa0 degreesxa0 of severity of ischemia.xa0Conclusion: Surfacexa0 temperature changesxa0 due to ischemia can be assessed quantitatively and visualizedxa0 in situ during occlusion of a coronaryxa0 artery andxa0xa0 subsequentxa0 reperfusion ofxa0 the myocardium. This method shows potentialxa0 asxa0 axa0 fastxa0 andxa0 simple way ofxa0 followingxa0 myocardialxa0 perfusion xa0during surgery. Thexa0 changexa0 of thexa0 extensionxa0 of thexa0 penumbra zonexa0 is a potential monitoring devicexa0 for thexa0 thera- pies usedxa0 in the salvage or prevention of ischemiaxa0 in experimental or clinical cardiac surgery and may introduce new practices in monitoringxa0 duringcardiacxa0 and vascular anesthesia.Abstracts of the 22 International Conference of the Society for Medical Innovation and Technology (SMIT), 2-4 September 2010, Trondheim, Norways of the 22 International Conference of the Society for Medical Innovation and Technology (SMIT), 2-4 September 2010, Trondheim, Norway Abstracts appear in alphabetical order according to title. An (O) or (P) after the titles appear in alphabetical order according to title. An (O) or (P) after the title indicate respectively whether the abstract was accepted for an oral or poster session. 1. 2D/3D Registration of Ultrasound and Fluoroscopy: is image preprocessing useful? (O) Pascal Fallavollita, School of Computing, Queen’s University, Canada Zahra KarimAghaloo, McGill University Clif Burdette, Acoustic MedSystems Inc. Danny Song, Johns Hopkins Hospital Purang Abolmaesumi, University of British Columbia Gabor Fichtinger, Queen’s University Motivation: In prostate brachytherapy, transrectal ultrasound (TRUS) is used to visualize the anatomy, while implanted seeds can be seen in C-arm fluoroscopy. Intra-operative dosimetry optimization requires reconstruction of the implanted seeds from multiple C-arm fluoroscopy images, which in turn requires estimation of the C-arm poses. We proposed to estimate the relative pose of C-arm images by the registration of the 2D fluoroscopy images to the 3D TRUS volume, and by doing so we estimate the poses of C-arm images in a coordinate system fixed to the prostate. This paper investigates whether preprocessing the TRUS images increases registration performance. Methodology: We implemented 7 different filters for the TRUS volume to investigate whether image pre-processing is a requirement. The baseline for comparison is no filtering (US-0). US-1 is a noise reduction filter based on two successive thresholdings. US-2 is a phase congruency filter. The beam profile filter (US-3) accounts for the finite thickness of the ultrasound beam and the focusing in the elevational and lateral directions. In US-4, we combine parallel noise reduction, phase congruency and beam profile filters in a Bayesian model. In US-5 noise reduction is followed by phase congruency. In US-6, noise reduction is followed by beam profile filtering. Finally, in US-7 we cascade noise reduction, phase congruency, and beam profile filtering. Experiments and Results: A commercial phantom was implanted with seeds and imaged with TRUS and CT. Ground-truth registration was established between the two modalities by fiducials. Synthetic ground-truth fluoro images were created from the CT volume and registered to the 3D TRUS using normalized correlation metric. The US-0 baseline provided best results for pose estimation: the average rotation and translation errors were 1.1 ± 1.2 and 1.1 ± 0.6 mm. The US-6 filter followed with average rotation and translation errors of 3.1 ± 3.9 and 3.2 ± 3.4 mm. In human patient data, the measured registration error compared to the manually selected seed locations by the clinician was 2.86 ± 1.26 mm when not filtering TRUS. Conclusion: Fully automated image-based C-arm pose estimation was demonstrated in prostate brachytherapy where accuracy and robustness was excellent on phantom andadequate in human patient data. We conclude that pre-processing of the TRUS images did not yield significant improvement in the process. 2. 3D needle guidance with cone-beam ct: results in 41 patients suspected of renal malignancy (O) Harm Van Melick, St. Antonius hospital, Nieuwegein, dept. of urology, the Netherlands Sicco Braak, St. Antonius hospital, Nieuwegein, dept. of radiology Mircea Onaca, St. Antonius hospital, Nieuwegein, dept. of urology Christiaan van Swol, St. Antonius hospital, Nieuwegein, dept. of clinical physics Marco van Strijen, St. Antonius hospital, Nieuwegein, dept. of radiology Background: The incidence of renal tumors is rising, mostly by the increase of abdominal imaging. Many of ISSN 1364-5706 print/ISSN 1365-2931 online 2010 Informa Healthcare DOI: 10.3109/13645706.2010.500867 M in im I nv as iv e T he r A lli ed T ec hn ol D ow nl oa de d fr om in fo rm ah ea lth ca re .c om b y T ec hn ic al U ni ve rs ity o f E in dh ov en o n 11 /0 1/ 10 Fo r pe rs on al u se o nl y. these tumors are small asymptomatic renal masses, less than 4 cm in diameter. Small tumors are less often malignant. This increases the indication for renal biopsies. The standard procedure for renal biopsies is image-guided biopsy with help of ultrasound or CT. These procedures possess several restrictions. Not all lesions are good visible on ultrasound and the use of CT is limited in some lesions. Purpose: XperGuide is a new real-time needle guidance technique that uses cone-beamCT and fluoroscopy in an angiosuite. This prospective study presents data of XperGuide biopsies in lesions suspected for renal carcinoma.Method: XperGuide uses a rotating flat panel detector (Philips Medical Systems) that creates a 3D CT image. A safe needle tract is determined within this reconstructed volume, avoiding essential anatomic structures. The information of the needle tract from the cone-beamCT is fused with real-time fluoroscopy. In this way accurate needle guidance is accomplished and coaxial 18 gauge biopsies are taken. XperGuide makes it easier to biopsy at sharper angles than in conventional CT-guided biopsies. Patients with an indication for renal biopsy because of suspected malignancy were selected for XperGuide biopsy if ultrasound-guided biopsy was technically not possible ornotsafe.Results:BetweenOctober2006andJanuary 2010 a total of 41 patients (average age 61.9 years) underwent 43 procedures. These 43 biopsies resulted in24malignancies (56%),14benign lesions (33%)and 5 specimens (11%) could not be classified. Two of the latter lesions proofed to be renal cell carcinoma during follow-up. The 3 other unclassified lesions did not show significant increase in size during an average follow-up of 13 months. Average target diameter was 25.4 mm (range 10-68 mm) and the average number of biopsies taken per procedure was 3.6 (range 3-6). Radiation dose seams to be less than in similar CT-guided procedures. There were 2 minor bleeding complications that could be treated using absorbable haemostatic material. Conclusion: XperGuide is a safe and adequate technique to biopsy renal tumors. Biopsies can be taken in locations that were formerly hard to reach and in situations when ultrasound visibility is unsatisfactory. 3. 4D-Imaging of voluntary joint motion from bi-plane fluoroscopy images (O) Geert Streekstra, Remmet Jonges, Academic Medical Center, Amsterdam, The Netherlands Bart Carelsen, Philips Healthcare, Best, The Netherlands Kees Grimbergen, Simon Strackee, Academeic Medical Center, Amsterdam, The Netherlands Background: To understand the functioning of the wrist joint, the availability of dynamic 3D motion patterns (i.e. 4D-Imaging) of the carpal bones is essential. 3D motion patterns of carpal bones and dynamic joint space measurement during voluntary motion are potentially useful for patients with dynamic joint problems. Purpose: Current methods are capable of imaging 3D motion patterns of carpal bones by forced motion of the hand. A drawback of these methods is that a forced motion limits the freedom in choosing diagnostic motion protocols. Therefore we propose imaging of 3D dynamic motion patterns of carpal bones during voluntary motion of the hand based on bi-plane video fluoroscopy images. Method and materials: For acquisition of bi-plane video fluoroscopy images we used the Alura FD20/10 of Philips. During voluntary motion of the hand, video fluoroscopy time series of two flat panel detectors are simultaneously acquired. Additionally, a CT scan of the wrist is acquired from which radius, ulna and the carpal bones are segmented. By combination of the segmented CT scan and the biplane video fluoroscopy series, the three translation and three rotation parameters of each of the 15 bones are obtained. The feasibility of the method in vivo was evaluated by measuring joint space as a function of the pose of the hand during voluntary motion of the hand in healthy subjects and in a patient with SL dissociation. Results: Experiments on a cadaver specimen reveal that the precision is 0.05 mm for translations and 0.42 degrees for rotations. The in vivo experiments reveal that the 3D motion patterns differ substantially between healthy subjects and the SLpatient. Moreover, in healthy subjects the minimal joint space is virtually independent of the hand pose (1 mm) whereas the joint space varies substantially with the hand pose for the SL-patient (1-3 mm). Conclusion: Precise estimation of translations and rotation parameters of carpal bones as well as time dependent measurement of joint space can be achieved using dynamic bi-plane video fluoroscopy time series. 4. A field mapping technique for estimation of BOLD sensitivity in fmri (O) Anne-Lene Mathisen, University of Oslo, Physics Dept. and Interventional Centre, Oslo University Hospital, Oslo, Norway Atle Bjørnerud, University of Oslo, Physics Dept. and Interventional Centre, Oslo University Hospital, Oslo, Norway Frédéric Courivaud, Interventional Centre, Oslo University Hospital, Oslo, Norway 10 Abstracts M in im I nv as iv e T he r A lli ed T ec hn ol D ow nl oa de d fr om in fo rm ah ea lth ca re .c om b y T ec hn ic al U ni ve rs ity o f E in dh ov en o n 11 /0 1/ 10 Fo r pe rs on al u se o nl y. Background: Functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast is today a very useful tool in the field of neurological research. However, the presence of magnetic susceptibility difference in the brain, which creates local field inhomogeneity, can compromise the ability to detect the BOLD effect. These susceptibility differences arise typically near tissuesair interface or in the presence or surgical clips in the skull. Significant artefacts occurs in these regions when using Gradient E