2,103 research outputs found
Advanced planning and intra-operative validation for robot-assisted keyhole neurosurgery in ROBOCAST
Medical image computing and computer-aided medical interventions applied to soft tissues. Work in progress in urology
Until recently, Computer-Aided Medical Interventions (CAMI) and Medical
Robotics have focused on rigid and non deformable anatomical structures.
Nowadays, special attention is paid to soft tissues, raising complex issues due
to their mobility and deformation. Mini-invasive digestive surgery was probably
one of the first fields where soft tissues were handled through the development
of simulators, tracking of anatomical structures and specific assistance
robots. However, other clinical domains, for instance urology, are concerned.
Indeed, laparoscopic surgery, new tumour destruction techniques (e.g. HIFU,
radiofrequency, or cryoablation), increasingly early detection of cancer, and
use of interventional and diagnostic imaging modalities, recently opened new
challenges to the urologist and scientists involved in CAMI. This resulted in
the last five years in a very significant increase of research and developments
of computer-aided urology systems. In this paper, we propose a description of
the main problems related to computer-aided diagnostic and therapy of soft
tissues and give a survey of the different types of assistance offered to the
urologist: robotization, image fusion, surgical navigation. Both research
projects and operational industrial systems are discussed
Three-dimensional reconstruction of intracoronary ultrasound images. Rationale, approaches, problems, and directions
Although intracoronary ultrasonography allows detailed tomographic imaging of the arterial wall, it fails to provide data on the structural architecture and longitudinal extent of arterial disease. This information is essential for decision making during therapeutic interventions. Three-dimensional reconstruction techniques offer visualization of the complex longitudinal architecture of atherosclerotic plaques in composite display. Progress in computer hardware and software technology have shortened the reconstruction process and reduced operator interaction considerably, generating three-dimensional images with delineation of mural anatomy and pathology. The indications for intravascular ultrasonography will grow as the technique offers the uni
Virtual and Augmented Reality Techniques for Minimally Invasive Cardiac Interventions: Concept, Design, Evaluation and Pre-clinical Implementation
While less invasive techniques have been employed for some procedures, most intracardiac interventions are still performed under cardiopulmonary bypass, on the drained, arrested heart. The progress toward off-pump intracardiac interventions has been hampered by the lack of adequate visualization inside the beating heart.
This thesis describes the development, assessment, and pre-clinical implementation of a mixed reality environment that integrates pre-operative imaging and modeling with surgical tracking technologies and real-time ultrasound imaging. The intra-operative echo images are augmented with pre-operative representations of the cardiac anatomy and virtual models of the delivery instruments tracked in real time using magnetic tracking technologies. As a result, the otherwise context-less images can now be interpreted within the anatomical context provided by the anatomical models. The virtual models assist the user with the tool-to-target navigation, while real-time ultrasound ensures accurate positioning of the tool on target, providing the surgeon with sufficient information to ``see\u27\u27 and manipulate instruments in absence of direct vision.
Several pre-clinical acute evaluation studies have been conducted in vivo on swine models to assess the feasibility of the proposed environment in a clinical context. Following direct access inside the beating heart using the UCI, the proposed mixed reality environment was used to provide the necessary visualization and navigation to position a prosthetic mitral valve on the the native annulus, or to place a repair patch on a created septal defect in vivo in porcine models.
Following further development and seamless integration into the clinical workflow, we hope that the proposed mixed reality guidance environment may become a significant milestone toward enabling minimally invasive therapy on the beating heart
Navigation system based in motion tracking sensor for percutaneous renal access
Tese de Doutoramento em Engenharia BiomédicaMinimally-invasive kidney interventions are daily performed to diagnose and treat several renal
diseases. Percutaneous renal access (PRA) is an essential but challenging stage for most of these
procedures, since its outcome is directly linked to the physician’s ability to precisely visualize and
reach the anatomical target.
Nowadays, PRA is always guided with medical imaging assistance, most frequently using X-ray
based imaging (e.g. fluoroscopy). Thus, radiation on the surgical theater represents a major risk to
the medical team, where its exclusion from PRA has a direct impact diminishing the dose exposure
on both patients and physicians.
To solve the referred problems this thesis aims to develop a new hardware/software framework
to intuitively and safely guide the surgeon during PRA planning and puncturing.
In terms of surgical planning, a set of methodologies were developed to increase the certainty of
reaching a specific target inside the kidney. The most relevant abdominal structures for PRA were
automatically clustered into different 3D volumes. For that, primitive volumes were merged as a local
optimization problem using the minimum description length principle and image statistical
properties. A multi-volume Ray Cast method was then used to highlight each segmented volume.
Results show that it is possible to detect all abdominal structures surrounding the kidney, with the
ability to correctly estimate a virtual trajectory.
Concerning the percutaneous puncturing stage, either an electromagnetic or optical solution
were developed and tested in multiple in vitro, in vivo and ex vivo trials. The optical tracking solution
aids in establishing the desired puncture site and choosing the best virtual puncture trajectory.
However, this system required a line of sight to different optical markers placed at the needle base,
limiting the accuracy when tracking inside the human body. Results show that the needle tip can
deflect from its initial straight line trajectory with an error higher than 3 mm. Moreover, a complex
registration procedure and initial setup is needed.
On the other hand, a real-time electromagnetic tracking was developed. Hereto, a catheter
was inserted trans-urethrally towards the renal target. This catheter has a position and orientation
electromagnetic sensor on its tip that function as a real-time target locator. Then, a needle integrating a similar sensor is used. From the data provided by both sensors, one computes a virtual puncture
trajectory, which is displayed in a 3D visualization software. In vivo tests showed a median renal and
ureteral puncture times of 19 and 51 seconds, respectively (range 14 to 45 and 45 to 67 seconds).
Such results represent a puncture time improvement between 75% and 85% when comparing to
state of the art methods.
3D sound and vibrotactile feedback were also developed to provide additional information about
the needle orientation. By using these kind of feedback, it was verified that the surgeon tends to
follow a virtual puncture trajectory with a reduced amount of deviations from the ideal trajectory,
being able to anticipate any movement even without looking to a monitor. Best results show that 3D
sound sources were correctly identified 79.2 ± 8.1% of times with an average angulation error of
10.4º degrees. Vibration sources were accurately identified 91.1 ± 3.6% of times with an average
angulation error of 8.0º degrees.
Additionally to the EMT framework, three circular ultrasound transducers were built with a needle
working channel. One explored different manufacture fabrication setups in terms of the piezoelectric
materials, transducer construction, single vs. multi array configurations, backing and matching
material design. The A-scan signals retrieved from each transducer were filtered and processed to
automatically detect reflected echoes and to alert the surgeon when undesirable anatomical
structures are in between the puncture path. The transducers were mapped in a water tank and
tested in a study involving 45 phantoms. Results showed that the beam cross-sectional area
oscillates around the ceramics radius and it was possible to automatically detect echo signals in
phantoms with length higher than 80 mm.
Hereupon, it is expected that the introduction of the proposed system on the PRA procedure,
will allow to guide the surgeon through the optimal path towards the precise kidney target, increasing
surgeon’s confidence and reducing complications (e.g. organ perforation) during PRA. Moreover, the
developed framework has the potential to make the PRA free of radiation for both patient and surgeon
and to broad the use of PRA to less specialized surgeons.Intervenções renais minimamente invasivas são realizadas diariamente para o tratamento e
diagnóstico de várias doenças renais. O acesso renal percutâneo (ARP) é uma etapa essencial e
desafiante na maior parte destes procedimentos. O seu resultado encontra-se diretamente
relacionado com a capacidade do cirurgião visualizar e atingir com precisão o alvo anatómico.
Hoje em dia, o ARP é sempre guiado com recurso a sistemas imagiológicos, na maior parte
das vezes baseados em raios-X (p.e. a fluoroscopia). A radiação destes sistemas nas salas cirúrgicas
representa um grande risco para a equipa médica, aonde a sua remoção levará a um impacto direto
na diminuição da dose exposta aos pacientes e cirurgiões.
De modo a resolver os problemas existentes, esta tese tem como objetivo o desenvolvimento
de uma framework de hardware/software que permita, de forma intuitiva e segura, guiar o cirurgião
durante o planeamento e punção do ARP.
Em termos de planeamento, foi desenvolvido um conjunto de metodologias de modo a
aumentar a eficácia com que o alvo anatómico é alcançado. As estruturas abdominais mais
relevantes para o procedimento de ARP, foram automaticamente agrupadas em volumes 3D, através
de um problema de optimização global com base no princípio de “minimum description length” e
propriedades estatísticas da imagem. Por fim, um procedimento de Ray Cast, com múltiplas funções
de transferência, foi utilizado para enfatizar as estruturas segmentadas. Os resultados mostram que
é possível detetar todas as estruturas abdominais envolventes ao rim, com a capacidade para
estimar corretamente uma trajetória virtual.
No que diz respeito à fase de punção percutânea, foram testadas duas soluções de deteção
de movimento (ótica e eletromagnética) em múltiplos ensaios in vitro, in vivo e ex vivo. A solução
baseada em sensores óticos ajudou no cálculo do melhor ponto de punção e na definição da melhor
trajetória a seguir. Contudo, este sistema necessita de uma linha de visão com diferentes
marcadores óticos acoplados à base da agulha, limitando a precisão com que a agulha é detetada
no interior do corpo humano. Os resultados indicam que a agulha pode sofrer deflexões à medida
que vai sendo inserida, com erros superiores a 3 mm.
Por outro lado, foi desenvolvida e testada uma solução com base em sensores
eletromagnéticos. Para tal, um cateter que integra um sensor de posição e orientação na sua ponta, foi colocado por via trans-uretral junto do alvo renal. De seguida, uma agulha, integrando um sensor
semelhante, é utilizada para a punção percutânea. A partir da diferença espacial de ambos os
sensores, é possível gerar uma trajetória de punção virtual. A mediana do tempo necessário para
puncionar o rim e ureter, segundo esta trajetória, foi de 19 e 51 segundos, respetivamente
(variações de 14 a 45 e 45 a 67 segundos). Estes resultados representam uma melhoria do tempo
de punção entre 75% e 85%, quando comparados com o estado da arte dos métodos atuais.
Além do feedback visual, som 3D e feedback vibratório foram explorados de modo a fornecer
informações complementares da posição da agulha. Verificou-se que com este tipo de feedback, o
cirurgião tende a seguir uma trajetória de punção com desvios mínimos, sendo igualmente capaz
de antecipar qualquer movimento, mesmo sem olhar para o monitor. Fontes de som e vibração
podem ser corretamente detetadas em 79,2 ± 8,1% e 91,1 ± 3,6%, com erros médios de angulação
de 10.4º e 8.0 graus, respetivamente.
Adicionalmente ao sistema de navegação, foram também produzidos três transdutores de
ultrassom circulares com um canal de trabalho para a agulha. Para tal, foram exploradas diferentes
configurações de fabricação em termos de materiais piezoelétricos, transdutores multi-array ou
singulares e espessura/material de layers de suporte. Os sinais originados em cada transdutor
foram filtrados e processados de modo a detetar de forma automática os ecos refletidos, e assim,
alertar o cirurgião quando existem variações anatómicas ao longo do caminho de punção. Os
transdutores foram mapeados num tanque de água e testados em 45 phantoms. Os resultados
mostraram que o feixe de área em corte transversal oscila em torno do raio de cerâmica, e que os
ecos refletidos são detetados em phantoms com comprimentos superiores a 80 mm.
Desta forma, é expectável que a introdução deste novo sistema a nível do ARP permitirá
conduzir o cirurgião ao longo do caminho de punção ideal, aumentado a confiança do cirurgião e
reduzindo possíveis complicações (p.e. a perfuração dos órgãos). Além disso, de realçar que este
sistema apresenta o potencial de tornar o ARP livre de radiação e alarga-lo a cirurgiões menos
especializados.The present work was only possible thanks to the support by the Portuguese Science and
Technology Foundation through the PhD grant with reference SFRH/BD/74276/2010 funded by
FCT/MEC (PIDDAC) and by Fundo Europeu de Desenvolvimento Regional (FEDER), Programa
COMPETE - Programa Operacional Factores de Competitividade (POFC) do QREN
Robot-Assisted Image-Guided Interventions
Image guidance is a common methodology of minimally invasive procedures. Depending
on the type of intervention, various imaging modalities are available. Common imaging
modalities are computed tomography, magnetic resonance tomography, and ultrasound.
Robotic systems have been developed to enable and improve the procedures using these
imaging techniques. Spatial and technological constraints limit the development of
versatile robotic systems. This paper offers a brief overview of the developments of
robotic systems for image-guided interventions since 2015 and includes samples of our
current research in this field
Robot-Assisted Image-Guided Interventions
Image guidance is a common methodology of minimally invasive procedures. Depending on the type of intervention, various imaging modalities are available. Common imaging modalities are computed tomography, magnetic resonance tomography, and ultrasound. Robotic systems have been developed to enable and improve the procedures using these imaging techniques. Spatial and technological constraints limit the development of versatile robotic systems. This paper offers a brief overview of the developments of robotic systems for image-guided interventions since 2015 and includes samples of our current research in this field
Arterial anatomy and arteriographic diagnosis of arteriogenic impotence
One hundred twenty-six bilateral selective arteriographic examinations of the iliopudendal vascular tree were performed after comprehensive multidisciplinary evaluation in patients with chronic erectile dysfunction. Best imaging results were obtained by performing the arteriography under epidural anesthesia after intracavernous injection of a vasoactive drug combination. The arteriography is mandatory prior to revascularization procedures. It is further indicated in primary erectile dysfunction and posttraumatic erectile failure. The importance of cavernosography and selective arteriography in primary erectile dysfunction is stressed. Increasing knowledge about the influence of vasoactive drugs on penile hemodynamics has led to its application in diagnosis and therapy of erectile dysfunction. Pharmacocovernosography, Doppler-ultrasound of penile arteries after intracavernous injection of a vasoactive drug combination, and pharmacoarteriography are refined techniques to prove a vascular etiology of erectile dysfunction. The results of the morphologic studies of the vascular system are correlated with functional testing of erectile capacity by intracavernous application of a papaverinephentolamine drug combination
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