115 research outputs found
The Utility of Deformable Image Registration for Small Artery Visualisation in Contrast-Enhanced Whole Body MR Angiography
Purpose;
An investigation was carried out into the effect of three image registration techniques on the diagnostic image quality of contrast-enhanced magnetic resonance angiography (CE-MRA) images.
Methods Whole-body CE-MRA data from the lower legs of 27 patients recruited onto a study of asymptomatic atherosclerosis were processed using three deformable image registration algorithms. The resultant diagnostic image quality was evaluated qualitatively in a clinical evaluation by four expert observers, and quantitatively by measuring contrast-to-noise ratios and volumes of blood vessels, and assessing the techniquesâ ability to correct for varying degrees of motion.
Results The first registration algorithm (âAIRâ) introduced significant stenosis-mimicking artefacts into the blood vesselsâ appearance, observed both qualitatively (clinical evaluation) and quantitatively (vessel volume measurements). The other two algorithms (âSlicerâ and âSEMIâ) based on the normalised mutual information (NMI) concept and designed specifically to deal with variations in signal intensity as found in contrast-enhanced image data, did not suffer from this serious issue but were rather found to significantly improve the diagnostic image quality both qualitatively and quantitatively, and demonstrated a significantly improved ability to deal with the common problem of patient motion.
Conclusions This work highlights both the significant benefits to be gained through the use of suitable registration algorithms and the deleterious effects of an inappropriate choice of algorithm for contrast-enhanced MRI data. The maximum benefit was found in the lower legs, where the small arterial vessel diameters and propensity for leg movement during image acquisitions posed considerable problems in making accurate diagnoses from the un-registered images
3D nonrigid medical image registration using a new information theoretic measure.
International audienceThis work presents a novel method for the nonrigid registration of medical images based on the Arimoto entropy, a generalization of the Shannon entropy. The proposed method employed the Jensen-Arimoto divergence measure as a similarity metric to measure the statistical dependence between medical images. Free-form deformations were adopted as the transformation model and the Parzen window estimation was applied to compute the probability distributions. A penalty term is incorporated into the objective function to smooth the nonrigid transformation. The goal of registration is to optimize an objective function consisting of a dissimilarity term and a penalty term, which would be minimal when two deformed images are perfectly aligned using the limited memory BFGS optimization method, and thus to get the optimal geometric transformation. To validate the performance of the proposed method, experiments on both simulated 3D brain MR images and real 3D thoracic CT data sets were designed and performed on the open source elastix package. For the simulated experiments, the registration errors of 3D brain MR images with various magnitudes of known deformations and different levels of noise were measured. For the real data tests, four data sets of 4D thoracic CT from four patients were selected to assess the registration performance of the method, including ten 3D CT images for each 4D CT data covering an entire respiration cycle. These results were compared with the normalized cross correlation and the mutual information methods and show a slight but true improvement in registration accuracy
Advanced Algorithms for 3D Medical Image Data Fusion in Specific Medical Problems
FĂșze obrazu je dnes jednou z nejbÄĆŸnÄjĆĄĂch avĆĄak stĂĄle velmi diskutovanou oblastĂ v lĂ©kaĆskĂ©m zobrazovĂĄnĂ a hraje dĆŻleĆŸitou roli ve vĆĄech oblastech lĂ©kaĆskĂ© pĂ©Äe jako je diagnĂłza, lĂ©Äba a chirurgie. V tĂ©to dizertaÄnĂ prĂĄci jsou pĆedstaveny tĆi projekty, kterĂ© jsou velmi Ășzce spojeny s oblastĂ fĂșze medicĂnskĂœch dat. PrvnĂ projekt pojednĂĄvĂĄ o 3D CT subtrakÄnĂ angiografii dolnĂch konÄetin. V prĂĄci je vyuĆŸito kombinace kontrastnĂch a nekontrastnĂch dat pro zĂskĂĄnĂ kompletnĂho cĂ©vnĂho stromu. DruhĂœ projekt se zabĂœvĂĄ fĂșzĂ DTI a T1 vĂĄhovanĂœch MRI dat mozku. CĂlem tohoto projektu je zkombinovat stukturĂĄlnĂ a funkÄnĂ informace, kterĂ© umoĆŸĆujĂ zlepĆĄit znalosti konektivity v mozkovĂ© tkĂĄni. TĆetĂ projekt se zabĂœvĂĄ metastĂĄzemi v CT ÄasovĂœch datech pĂĄteĆe. Tento projekt je zamÄĆen na studium vĂœvoje metastĂĄz uvnitĆ obratlĆŻ ve fĂșzovanĂ© ÄasovĂ© ĆadÄ snĂmkĆŻ. Tato dizertaÄnĂ prĂĄce pĆedstavuje novou metodologii pro klasifikaci tÄchto metastĂĄz. VĆĄechny projekty zmĂnÄnĂ© v tĂ©to dizertaÄnĂ prĂĄci byly ĆeĆĄeny v rĂĄmci pracovnĂ skupiny zabĂœvajĂcĂ se analĂœzou lĂ©kaĆskĂœch dat, kterou vedl pan Prof. JiĆĂ Jan. Tato dizertaÄnĂ prĂĄce obsahuje registraÄnĂ ÄĂĄst prvnĂho a klasifikaÄnĂ ÄĂĄst tĆetĂho projektu. DruhĂœ projekt je pĆedstaven kompletnÄ. DalĆĄĂ ÄĂĄst prvnĂho a tĆetĂho projektu, obsahujĂcĂ specifickĂ© pĆedzpracovĂĄnĂ dat, jsou obsaĆŸeny v disertaÄnĂ prĂĄci mĂ©ho kolegy Ing. Romana Petera.Image fusion is one of todayÂŽs most common and still challenging tasks in medical imaging and it plays crucial role in all areas of medical care such as diagnosis, treatment and surgery. Three projects crucially dependent on image fusion are introduced in this thesis. The first project deals with the 3D CT subtraction angiography of lower limbs. It combines pre-contrast and contrast enhanced data to extract the blood vessel tree. The second project fuses the DTI and T1-weighted MRI brain data. The aim of this project is to combine the brain structural and functional information that purvey improved knowledge about intrinsic brain connectivity. The third project deals with the time series of CT spine data where the metastases occur. In this project the progression of metastases within the vertebrae is studied based on fusion of the successive elements of the image series. This thesis introduces new methodology of classifying metastatic tissue. All the projects mentioned in this thesis have been solved by the medical image analysis group led by Prof. JiĆĂ Jan. This dissertation concerns primarily the registration part of the first project and the classification part of the third project. The second project is described completely. The other parts of the first and third project, including the specific preprocessing of the data, are introduced in detail in the dissertation thesis of my colleague Roman Peter, M.Sc.
Fusion and Analysis of Multidimensional Medical Image Data
AnalĂœza medicĂnskĂœch obrazĆŻ je pĆedmÄtem zĂĄkladnĂho vĂœzkumu jiĆŸ Ćadu let. Za tu dobu bylo v tĂ©to oblasti publikovĂĄno mnoho vĂœzkumnĂœch pracĂ zabĂœvajĂcĂch se dĂlÄĂmi ÄĂĄstmi jako je rekonstrukce obrazĆŻ, restaurace, segmentace, klasifikace, registrace (lĂcovĂĄnĂ) a fĂșze. KromÄ obecnĂ©ho Ășvodu, pojednĂĄvĂĄ tato disertaÄnĂ prĂĄce o dvou medicĂnsky orientovanĂœch tĂ©matech, jeĆŸ byla formulovĂĄna ve spoluprĂĄci s Philips Netherland BV, divizĂ Philips Healthcare. PrvnĂ tĂ©ma je zamÄĆeno na oblast zpracovĂĄnĂ obrazĆŻ subtrakÄnĂ angiografie dolnĂch konÄetin ÄlovÄka zĂskanĂœch pomocĂ vĂœpoÄetnĂ X-Ray tomografie (CT). SubtrakÄnĂ angiografie je obvykle vyuĆŸĂvanĂĄ pĆi podezĆenĂ na perifernĂ cĂ©vnĂ onemocnÄnĂ (PAOD) nebo pĆi akutnĂm poĆĄkozenĂ dolnĂch konÄetin jako jsou fraktury apod. SouÄasnĂ© komerÄnĂ metody nejsou dostateÄnÄ spolehlivĂ© uĆŸ v pĆedzpracovĂĄnĂ, jako je napĆĂklad odstranÄnĂ pacientskĂ©ho stolu, pokrĂœvky, dlahy, apod. Spolehlivost a pĆesnost identifikace cĂ©v v subtrahovanĂœch datech vedoucĂch v blĂzkosti kostĂ je v dĆŻsledku Partial Volume artefaktu rovnÄĆŸ nĂzkĂĄ. AutomatickĂ© odstranÄnĂ kalcifikacĂ nebo detekce malĂœch cĂ©v doplĆujĂcĂch nezbytnou informaci o nĂĄhradnĂm zĂĄsobenĂ dolnĂch konÄetin krvĂ v pĆĂpadÄ pĆeruĆĄenĂ hlavnĂch zĂĄsobujĂcĂch cĂ©v v souÄasnĂ© dobÄ rovnÄĆŸ nesplĆujĂ kritĂ©ria pro plnÄ automatickĂ© zpracovĂĄnĂ. Proto hlavnĂm cĂlem tĂœkajĂcĂ se tohoto tĂ©matu bylo vyvinout automatickĂœ systĂ©m, kterĂœ by mohl souÄasnĂ© nedostatky v CTSA vyĆĄetĆenĂ odstranit. DruhĂ© tĂ©ma je orientovĂĄno na identifikaci patologickĂœch zmÄn na pĂĄteĆi ÄlovÄka v CT obrazech se zamÄĆenĂm na osteolytickĂ© a osteoblastickĂ© lĂ©ze u jednotlivĂœch obratlĆŻ. Tyto zmÄny obvykle nastĂĄvajĂ v dĆŻsledkĆŻ postiĆŸenĂ metastazujĂcĂm procesem rakovinovĂ©ho onemocnÄnĂ. Pro detekci patologickĂœch zmÄn je pak potĆeba identifikace a segmentace jednotlivĂœch obratlĆŻ. PĆesnost analĂœzy jednotlivĂœch lĂ©zĂ vĆĄak zĂĄvisĂ rovnÄĆŸ na sprĂĄvnĂ© identifikaci tÄla a zadnĂch segmentĆŻ u jednotlivĂœch obratlĆŻ a na segmentaci trabekulĂĄrnĂho centra obratlĆŻ, tj. odstranÄnĂ kortikĂĄlnĂ kosti. BÄhem lĂ©Äby mohou bĂœt pacienti skenovĂĄni vĂcekrĂĄt, obvykle s nÄkolika-mesĂÄnĂm odstupem. HodnocenĂ pĆĂpadnĂ©ho vĂœvoje jiĆŸ detekovanĂœch patologickĂœch zmÄn pak logicky vychĂĄzĂ ze sprĂĄvnĂ© detekce patologiĂ v jednotlivĂœch obratlech korespondujĂcĂch si v jednotlivĂœch akvizicĂch. JelikoĆŸ jsou pĆĂsluĆĄnĂ© obratle v jednotlivĂœch akvizicĂch obvykle na rĆŻznĂ© pozici, jejich fĂșze, vedoucĂ k analĂœze ÄasovĂ©ho vĂœvoje detekovanĂœch patologiĂ, je komplikovanĂĄ. PoĆŸadovanĂœm vĂœsledkem v tomto tĂ©matu je vytvoĆenĂ komplexnĂho systĂ©mu pro detekci patologickĂœch zmÄn v pĂĄteĆi, pĆedevĆĄĂm osteoblastickĂœch a osteolytickĂœch lĂ©zĂ. TakovĂœ systĂ©m tedy musĂ umoĆŸnovat jak segmentaci jednotlivĂœch obratlĆŻ, jejich automatickĂ© rozdÄlenĂ na hlavnĂ ÄĂĄsti a odstranÄnĂ kortikĂĄlnĂ kosti, tak takĂ© detekci patologickĂœch zmÄn a jejich hodnocenĂ. AÄkoliv je tato disertaÄnĂ prĂĄce v obou vĂœĆĄe zmĂnÄnĂœch tĂ©matech primĂĄrnÄ zamÄĆena na experimentĂĄlnĂ ÄĂĄst zpracovĂĄnĂ medicĂnskĂœch obrazĆŻ, zabĂœvĂĄ se vĆĄemi nezbytnĂœmi kroky, jako je pĆedzpracovĂĄnĂ, registrace, dodateÄnĂ© zpracovĂĄnĂ a hodnocenĂ vĂœsledkĆŻ, vedoucĂmi k moĆŸnĂ© aplikovatelnosti obou systĂ©mu v klinickĂ© praxi. JelikoĆŸ oba systĂ©my byly ĆeĆĄeny v rĂĄmci tĂœmovĂ© spoluprĂĄce jako celek, u obou tĂ©mat jsou pro nÄkterĂ© konkrĂ©tnĂ kroky uvedeny odkazy na doktorskou prĂĄci MiloĆĄe MalĂnskĂ©ho.Analysis of medical images has been subject of basic research for many years. Many research papers have been published in the field related to image analysis and focused on partial aspects such as reconstruction, restoration, segmentation and classification, registration (spatial alignment) and fusion. Besides the introduction of related general concepts used in medical image processing, this thesis deals with two specific medical problems formulated in cooperation with Philips Netherland BV, Philips Healthcare division. The first topic is focused on subtraction angiography in patientsâ lower legs utilizing image data from X-Ray computed tomography (CT). CT subtraction angiography (CTSA) is typically used for indication of the Peripheral Artery Occlusive Disease (PAOD) and for examination of acute injuries of lower legs such as acute fractures, etc. Current methods in clinical praxis are not sufficient regarding the pre-processing such as masking of patient desk, cover, splint, etc. The subtraction of blood vessels adjacent to neighboring bones in lower legs is of low accuracy due to the Partial Volume artifact. Masking of calcifications and detection of tiny blood vessels complementing necessary information about the alternative blood supply in lower legs in case of obstruction in main arteries is also not reliable for fully automated process presently. Therefore, the main aim regarding this topic was to develop an automated framework that could overcome current shortcomings in CTSA examination. The second topic is oriented on the identification and evaluation of pathologic changes in human spine, focusing on osteolytic and osteoblastic lesions in individual vertebrae in CT images. Such changes occur typically as a consequence of metastasizing process of cancerous disease. For the detection of pathologic changes, an identification and segmentation of individual vertebrae is necessary. Moreover, the analysis of individual lesions in vertebrae depends also on correct identification of vertebral body and posterior segments of each vertebra, and on segmentation of their trabecular centers. Patients are typically examined more than once during their therapy. Then, the evaluation of possible tumorous progression is based on accurate detection of pathologies in individual vertebrae in the base-line and corresponding follow-up images. Since the corresponding vertebrae are in mutually different positions in the follow-up images, their fusion leading to the analysis of the lesion progression is complicated. The main aim regarding this topic is to develop a complex framework for detection of pathologic lesions on spine, with the main focus on osteoblastic and osteolystic lesions. Such system has to provide not only reliable segmentation of individual vertebrae and detection of their main regions but also the masking of their cortical bone, detection of their pathologic changes and their evaluation. Although this dissertation thesis is primarily oriented at the experimental part of medical image processing considering both the above mentioned topics, it deals with all necessary processing steps, i.e. preprocessing, image registration, post-processing and evaluation of results, leading to the future use of both frameworks in clinical practice. Since both frameworks were developed in a team, there are some chapters referring to the dissertation thesis of Milos Malinsky.
Medical Image Analysis: Progress over two decades and the challenges ahead
International audienceThe analysis of medical images has been woven into the fabric of the pattern analysis and machine intelligence (PAMI) community since the earliest days of these Transactions. Initially, the efforts in this area were seen as applying pattern analysis and computer vision techniques to another interesting dataset. However, over the last two to three decades, the unique nature of the problems presented within this area of study have led to the development of a new discipline in its own right. Examples of these include: the types of image information that are acquired, the fully three-dimensional image data, the nonrigid nature of object motion and deformation, and the statistical variation of both the underlying normal and abnormal ground truth. In this paper, we look at progress in the field over the last 20 years and suggest some of the challenges that remain for the years to come
Automatic Spatiotemporal Analysis of Cardiac Image Series
RĂSUMĂ
Ă ce jour, les maladies cardiovasculaires demeurent au premier rang des principales causes de
dĂ©cĂšs en AmĂ©rique du Nord. Chez lâadulte et au sein de populations de plus en plus jeunes,
la soi-disant Ă©pidĂ©mie dâobĂ©sitĂ© entraĂźnĂ©e par certaines habitudes de vie tels que la mauvaise
alimentation, le manque dâexercice et le tabagisme est lourde de consĂ©quences pour les personnes
affectées, mais aussi sur le systÚme de santé. La principale cause de morbidité et de
mortalitĂ© chez ces patients est lâathĂ©rosclĂ©rose, une accumulation de plaque Ă lâintĂ©rieur des
vaisseaux sanguins à hautes pressions telles que les artÚres coronaires. Les lésions athérosclérotiques
peuvent entraĂźner lâischĂ©mie en bloquant la circulation sanguine et/ou en provoquant
une thrombose. Cela mĂšne souvent Ă de graves consĂ©quences telles quâun infarctus. Outre les
problÚmes liés à la sténose, les parois artérielles des régions criblées de plaque augmentent la
rigidité des parois vasculaires, ce qui peut aggraver la condition du patient. Dans la population
pédiatrique, la pathologie cardiovasculaire acquise la plus fréquente est la maladie de
Kawasaki. Il sâagit dâune vasculite aigĂŒe pouvant affecter lâintĂ©gritĂ© structurale des parois des
artĂšres coronaires et mener Ă la formation dâanĂ©vrismes. Dans certains cas, ceux-ci entravent
lâhĂ©modynamie artĂ©rielle en engendrant une perfusion myocardique insuffisante et en activant
la formation de thromboses.
Le diagnostic de ces deux maladies coronariennes sont traditionnellement effectuĂ©s Ă lâaide
dâangiographies par fluoroscopie. Pendant ces examens paracliniques, plusieurs centaines de
projections radiographiques sont acquises en sĂ©ries suite Ă lâinfusion artĂ©rielle dâun agent de
contraste. Ces images révÚlent la lumiÚre des vaisseaux sanguins et la présence de lésions
potentiellement pathologiques, sâil y a lieu. Parce que les sĂ©ries acquises contiennent de lâinformation
trĂšs dynamique en termes de mouvement du patient volontaire et involontaire (ex.
battements cardiaques, respiration et dĂ©placement dâorganes), le clinicien base gĂ©nĂ©ralement
son interprĂ©tation sur une seule image angiographique oĂč des mesures gĂ©omĂ©triques sont effectuĂ©es
manuellement ou semi-automatiquement par un technicien en radiologie. Bien que
lâangiographie par fluoroscopie soit frĂ©quemment utilisĂ© partout dans le monde et souvent
considĂ©rĂ© comme lâoutil de diagnostic âgold-standardâ pour de nombreuses maladies vasculaires,
la nature bidimensionnelle de cette modalitĂ© dâimagerie est malheureusement trĂšs
limitante en termes de spécification géométrique des différentes régions pathologiques. En effet,
la structure tridimensionnelle des stĂ©noses et des anĂ©vrismes ne peut pas ĂȘtre pleinement
appréciée en 2D car les caractéristiques observées varient selon la configuration angulaire de
lâimageur. De plus, la prĂ©sence de lĂ©sions affectant les artĂšres coronaires peut ne pas reflĂ©ter
la véritable santé du myocarde, car des mécanismes compensatoires naturels (ex. vaisseaux----------ABSTRACT
Cardiovascular disease continues to be the leading cause of death in North America. In adult
and, alarmingly, ever younger populations, the so-called obesity epidemic largely driven by
lifestyle factors that include poor diet, lack of exercise and smoking, incurs enormous stresses
on the healthcare system. The primary cause of serious morbidity and mortality for these
patients is atherosclerosis, the build up of plaque inside high pressure vessels like the coronary
arteries. These lesions can lead to ischemic disease and may progress to precarious blood
flow blockage or thrombosis, often with infarction or other severe consequences. Besides
the stenosis-related outcomes, the arterial walls of plaque-ridden regions manifest increased
stiffness, which may exacerbate negative patient prognosis. In pediatric populations, the
most prevalent acquired cardiovascular pathology is Kawasaki disease. This acute vasculitis
may affect the structural integrity of coronary artery walls and progress to aneurysmal lesions.
These can hinder the blood flowâs hemodynamics, leading to inadequate downstream
perfusion, and may activate thrombus formation which may lead to precarious prognosis.
Diagnosing these two prominent coronary artery diseases is traditionally performed using
fluoroscopic angiography. Several hundred serial x-ray projections are acquired during selective
arterial infusion of a radiodense contrast agent, which reveals the vesselsâ luminal
area and possible pathological lesions. The acquired series contain highly dynamic information
on voluntary and involuntary patient movement: respiration, organ displacement and
heartbeat, for example. Current clinical analysis is largely limited to a single angiographic
image where geometrical measures will be performed manually or semi-automatically by a
radiological technician. Although widely used around the world and generally considered
the gold-standard diagnosis tool for many vascular diseases, the two-dimensional nature of
this imaging modality is limiting in terms of specifying the geometry of various pathological
regions. Indeed, the 3D structures of stenotic or aneurysmal lesions may not be fully appreciated
in 2D because their observable features are dependent on the angular configuration of
the imaging gantry. Furthermore, the presence of lesions in the coronary arteries may not
reflect the true health of the myocardium, as natural compensatory mechanisms may obviate
the need for further intervention. In light of this, cardiac magnetic resonance perfusion
imaging is increasingly gaining attention and clinical implementation, as it offers a direct
assessment of myocardial tissue viability following infarction or suspected coronary artery
disease. This type of modality is plagued, however, by motion similar to that present in fluoroscopic
imaging. This issue predisposes clinicians to laborious manual intervention in order
to align anatomical structures in sequential perfusion frames, thus hindering automation o
Respiratory organ motion in interventional MRI : tracking, guiding and modeling
Respiratory organ motion is one of the major challenges in interventional MRI, particularly in interventions with therapeutic ultrasound in the abdominal region. High-intensity focused ultrasound found an application in interventional MRI for noninvasive treatments of different abnormalities. In order to guide surgical and treatment interventions, organ motion imaging and modeling is commonly required before a treatment start. Accurate tracking of organ motion during various interventional MRI procedures is prerequisite for a successful outcome and safe therapy.
In this thesis, an attempt has been made to develop approaches using focused ultrasound which could be used in future clinically for the treatment of abdominal organs, such as the liver and the kidney. Two distinct methods have been presented with its ex vivo and in vivo treatment results. In the first method, an MR-based pencil-beam navigator has been used to track organ motion and provide the motion information for acoustic focal point steering, while in the second approach a hybrid imaging using both ultrasound and magnetic resonance imaging was combined for advanced guiding capabilities.
Organ motion modeling and four-dimensional imaging of organ motion is increasingly required before the surgical interventions. However, due to the current safety limitations and hardware restrictions, the MR acquisition of a time-resolved sequence of volumetric images is not possible with high temporal and spatial resolution. A novel multislice acquisition scheme that is based on a two-dimensional navigator, instead of a commonly used pencil-beam navigator, was devised to acquire the data slices and the corresponding navigator simultaneously using a CAIPIRINHA parallel imaging method. The acquisition duration for four-dimensional dataset sampling is reduced compared to the existing approaches, while the image contrast and quality are improved as well.
Tracking respiratory organ motion is required in interventional procedures and during MR imaging of moving organs. An MR-based navigator is commonly used, however, it is usually associated with image artifacts, such as signal voids. Spectrally selective navigators can come in handy in cases where the imaging organ is surrounding with an adipose tissue, because it can provide an indirect measure of organ motion. A novel spectrally selective navigator based on a crossed-pair navigator has been developed. Experiments show the advantages of the application of this novel navigator for the volumetric imaging of the liver in vivo, where this navigator was used to gate the gradient-recalled echo sequence
Practical application of contrast-enhanced magnetic resonance mammography [CE-MRM] by an algorithm combining morphological and enhancement patterns
The purpose of this article is to report our practical utilization of dynamic contrast-enhanced magnetic resonance mammography [DCE-MRM] in the diagnosis of breast lesions. In many European centers, was preferred a high-temporal acquisition of both breasts simultaneously in a large FOV. We preferred to scan single breasts, with the aim to combine the analysis of the contrast intake and washout with the morphological evaluation of breast lesions. We followed an interpretation model, based upon a diagnostic algorithm, which combined contrast enhancement with morphological evaluation, in order to increase our confidence in diagnosis. DCE-MRM with our diagnostic algorithm has identified 179 malignant and 41 benign lesions; final outcome has identified 178 malignant and 42 benign lesions, 3 false positives and 2 false negatives. Sensitivity of CE-MRM was 98.3%; specificity, 95.1%; positive predictive value 98.9%; negative predictive,. value, 92.8% and accuracy, 97.7%. (C) 2008 Elsevier Ltd. All rights reserve
Continuous roadmapping in liver TACE procedures using 2Dâ3D catheter-based registration
PURPOSE: Fusion of pre/perioperative images and intra-operative images may add relevant information during image-guided procedures. In abdominal procedures, respiratory motion changes the position of organs, and thus accurate image guidance requires a continuous update of the spatial alignment of the (pre/perioperative) information with the organ position during the intervention. METHODS: In this paper, we propose a method to register in real time perioperative 3D rotational angiography images (3DRA) to intra-operative single-plane 2D fluoroscopic images for improved guidance in TACE interventions. The method uses the shape of 3D vessels extracted from the 3DRA and the 2D catheter shape extracted from fluoroscopy. First, the appropriate 3D vessel is selected from the complete vascular tree using a shape similarity metric. Subsequently, the catheter is registered to this vessel, and the 3DRA is visualized based on the registration results. The method is evaluated on simulated data and clinical data. RESULTS: The first selected vessel, ranked with the shape similarity metric, is used more than 39Â % in the final registration and the second more than 21Â %. The median of the closest corresponding points distance between 2D angiography vessels and projected 3D vessels is 4.7â5.4Â mm when using the brute force optimizer and 5.2â6.6Â mm when using the Powell optimizer. CONCLUSION: We present a catheter-based registration method to continuously fuse a 3DRA roadmap arterial tree onto 2D fluoroscopic images with an efficient shape similarity
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