Entwicklungen und Untersuchungen zur Bildgebung der Schilddrüse: 124Iod-PET/CT, 3D-Ultraschall und nuklearmedizinisch-sonographische Bildfusion

In der etablierten Schilddrüsenbildgebung existieren trotz des bereits hohen Standards begrenzende Faktoren. Methodische und technische Neuerungen erscheinen mithin sinnvoll und geboten. Die vorliegende Habilitationsschrift stellt die Entwicklung und Erprobung neuer Konzepte der Schilddrüsendiagnostik in drei Teilgebieten vor: *Durch die 124Iod-Niedrigaktivitäts-PET/Niedrigdosis-CT wird (i) die Ortsauflösung der herkömmlichen Szintigraphie übertroffen und die Detektierbarkeit kleinerer Strukturen sowie anatomischer Details verbessert. Durch den parallel akquirierten CT-Datensatz können (ii) zusätzliche Erkenntnisse zur Schilddrüse sowie deren Beziehung zu Nachbarorganen gewonnen werden. Darüber hinaus sind (iii) im Rahmen der Vorbereitung von Radiojodtherapien prätherapeutische Uptake-Messungen möglich. *Der 3D-US ermöglicht (i) den lückenlosen Scan der Schilddrüse und (ii) die vollständige digitale Archivierung des Untersuchungsvolumens im PACS. Dadurch ergeben sich auf Schnittbildworkstations die Vorteile (iii) des Second Readings, (iv) des Side-by-Side-Vergleichs mit vorangegangenen 3D-US-Studien und anderen Schnittbildverfahren. Darüber hinaus kann (v) eine nachträgliche Datenverarbeitung (Processing) erfolgen. *Die Einbeziehung des Ultraschalls in das Konzept der Fusions- bzw. Hybridbildgebung hat gezeigt, dass die räumliche Verknüpfung und bildliche Überlagerung der morphologisch-sonographischen Informationen mit den nuklearmedizinisch-funktionellen Bilddaten erfolgen kann. Aus dem klinischen Potential der Methoden einerseits, sowie den geschilderten Limitationen andererseits ergeben sich Implikationen für die Zukunft. Zunächst sind die apparativ-technische Weiterentwicklung der Verfahren sowie eine Optimierung der informationstechnischen Einbindung notwendig. Darüber hinaus muss eine Entwicklung hin zu einer zeitsparenden und einfachen Anwendbarkeit erfolgen, um einen rationellen klinischen Workflow zu ermöglichen und personelle Ressourcen zu schonen

Assessing the value of volume navigation during ultrasound-guided radiofrequency- and microwave-ablations of liver lesions

Purpose: The goal of our study was to determine the influence of ultrasound (US)-coupled volume navigation on the use of computed tomography (CT) during minimally-invasive radiofrequency and microwave ablation procedures of liver lesions.Method: Twenty-five patients with 40 liver lesions of different histological origin were retrospectively analysed. Lesions were ablated following standard protocol, using 1) conventional US-guidance, 2) manual registered volume navigation (mVNav), 3) automatic registered (alpha VNav) or 4) CT-guidance. In case of ultrasonographically inconspicuous lesions, conventional US-guidance was abandoned and mVNav was used. If mVNav was also unsuccessful, the procedure was either continued with alpha VNav or CT-guidance. The number, size and location of the lesions targeted using the different approaches were documented.Results: Of the 40 lesions, sixteen (40.0 %) could be targeted with conventional US-guidance only, sixteen (40.0 %) with mVNav, three (7.5 %) with aVNav and five (12.5 %) only through the use of CT-guidance. Of the three alternatives (mVNav, alpha VNav and CT only) the mean size of the lesions targeted using mVNav (9.1 +/- 4.6 mm) was significantly smaller from those targeted using US-guidance only (20.4 +/- 9.4 mm; p < 0.001). The location of the lesions did not influence the selection of the modality used to guide the ablation.Conclusions: In our cohort, mVNav allowed the ablation procedure to become less dependent on the use of CT. mVNav supported the ablation of lesions smaller than those that could be ablated with US only and doubled the application of minimally-invasive US-guided ablations.Cardiovascular Aspects of Radiolog

Engineering precision surgery: Design and implementation of surgical guidance technologies

In the quest for precision surgery, this thesis introduces several novel detection and navigation modalities for the localization of cancer-related tissues in the operating room. The engineering efforts have focused on image-guided surgery modalities that use the complementary tracer signatures of nuclear and fluorescence radiation. The first part of the thesis covers the use of “GPS-like” navigation concepts to navigate fluorescence cameras during surgery, based on SPECT images of the patient. The second part of the thesis introduces several new imaging modalities such as a hybrid 3D freehand Fluorescence and freehand SPECT imaging and navigation device. Furthermore, to improve the detection of radioactive tracer-emissions during robot-assisted laparoscopic surgery, a tethered DROP-IN gamma probe is introduced. The clinical indications that are used to evaluate the new technologies were all focused on sentinel lymph node procedures in urology (i.e. prostate and penile cancer). Nevertheless, all presented techniques are of such a nature, that they can be applied to different surgical indications, including sentinel lymph node and tumor-receptor-targeted procedures, localization the primary tumor and metastatic spread. This will hopefully contribute towards more precise, less invasive and more effective surgical procedures in the field of oncology. Crystal Photonics GmbH Eurorad S.A. Intuitive Surgical Inc. KARL STORZ Endoscopie Nederland B.V. MILabs B.V. PI Medical Diagnostic Equipment B.V. SurgicEye GmbH Verb Surgical Inc.LUMC / Geneeskund

Advancing radiology through informed leadership: summary of the proceedings of the Seventh Biannual Symposium of the International Society for Strategic Studies in Radiology (IS3R), 23–25 August 2007

The International Society for Strategic Studies in Radiology (IS3R) brings together thought leaders from academia and industry from around the world to share ideas, points of view and new knowledge. This article summarizes the main concepts presented at the 2007 IS3R symposium, providing a window onto trends shaping the future of radiology. Topics addressed include new opportunities and challenges in the field of interventional radiology; emerging techniques for evaluating and improving quality and safety in radiology; and factors impeding progress in molecular imaging and nanotechnology and possible ways to overcome them. Regulatory hurdles to technical innovation and drug development are also discussed more broadly, along with proposals for addressing regulators’ concerns and streamlining the regulatory process

Intraoperative Navigation Systems for Image-Guided Surgery

Recent technological advancements in medical imaging equipment have resulted in a dramatic improvement of image accuracy, now capable of providing useful information previously not available to clinicians. In the surgical context, intraoperative imaging provides a crucial value for the success of the operation. Many nontrivial scientific and technical problems need to be addressed in order to efficiently exploit the different information sources nowadays available in advanced operating rooms. In particular, it is necessary to provide: (i) accurate tracking of surgical instruments, (ii) real-time matching of images from different modalities, and (iii) reliable guidance toward the surgical target. Satisfying all of these requisites is needed to realize effective intraoperative navigation systems for image-guided surgery. Various solutions have been proposed and successfully tested in the field of image navigation systems in the last ten years; nevertheless several problems still arise in most of the applications regarding precision, usability and capabilities of the existing systems. Identifying and solving these issues represents an urgent scientific challenge. This thesis investigates the current state of the art in the field of intraoperative navigation systems, focusing in particular on the challenges related to efficient and effective usage of ultrasound imaging during surgery. The main contribution of this thesis to the state of the art are related to: Techniques for automatic motion compensation and therapy monitoring applied to a novel ultrasound-guided surgical robotic platform in the context of abdominal tumor thermoablation. Novel image-fusion based navigation systems for ultrasound-guided neurosurgery in the context of brain tumor resection, highlighting their applicability as off-line surgical training instruments. The proposed systems, which were designed and developed in the framework of two international research projects, have been tested in real or simulated surgical scenarios, showing promising results toward their application in clinical practice

How molecular imaging will enable robotic precision surgery: the role of artificial intelligence, augmented reality, and navigation

Molecular imaging is one of the pillars of precision surgery. Its applications range from early diagnostics to therapy planning, execution, and the accurate assessment of outcomes. In particular, molecular imaging solutions are in high demand in minimally invasive surgical strategies, such as the substantially increasing field of robotic surgery. This review aims at connecting the molecular imaging and nuclear medicine community to the rapidly expanding armory of surgical medical devices. Such devices entail technologies ranging from artificial intelligence and computer-aided visualization technologies (software) to innovative molecular imaging modalities and surgical navigation (hardware). We discuss technologies based on their role at different steps of the surgical workflow, i.e., from surgical decision and planning, over to target localization and excision guidance, all the way to (back table) surgical verification. This provides a glimpse of how innovations from the technology fields can realize an exciting future for the molecular imaging and surgery communities.Imaging- and therapeutic targets in neoplastic and musculoskeletal inflammatory diseas

Intra-Operative Needle Tracking Using Optical Shape Sensing Technology

RÉSUMÉ Contexte : Les métastases hépatiques colorectales sont la principale cause de décès liée au cancer du foie dans le monde. Au cours de la dernière décennie, il a été démontré que l’ablation par radiofréquence (RFA, pour radiofrequency ablation) est une méthode de traitement percutané très efficace contre ce type de métastases. Cela dit, un positionnement précis de l’embout de l’aiguille utilisé en RFA est essentiel afin de se départir adéquatement de la totalité des cellules cancéreuses. Une technologie prometteuse pour obtenir la forme et la position de l’aiguille en temps réel est basée sur l’utilisation de réseaux de Bragg (FBG, pour fiber Bragg grating) à titre de senseur de contrainte. En effet, ce type de senseurs a une vitesse d’acquisition allant jusqu’à 20 kHz, ce qui est suffisamment rapide pour permettre des applications de guidage en temps réel. Méthode : Les travaux présentés au sein de ce mémoire décrivent le développement d’une technologie, compatible aux systèmes d’imageries par résonance magnétique (IRM), permettant d’effectuer le suivi de la forme de l’aiguille utilisée en RFA. Premièrement, trois fibres contenant une série de réseaux de Bragg ont été collées dans une géométrie spécifique et intégrées à l’intérieur d’une aiguille 20G-150 mm. Ensuite, un algorithme de reconstruction de forme tridimensionnelle a été développé, basé sur les mesures de translation spectrales des FBGs acquises en temps réel durant le guidage de l’aiguille. La position du bout de l’aiguille ainsi que la forme tridimensionnelle complète de celle-ci ont été représentées et comparées à la position de la zone ciblée à la suite d’une simple méthode de calibration. Finalement, nous avons validé notre système de navigation en effectuant une série d’expériences in vitro. La précision du système de reconstruction tridimensionnelle de la forme et de l’orientation de l’aiguille a été évaluée en utilisant deux caméras positionnées perpendiculairement de manière à connaitre la position de l’aiguille dans le système d’axes du laboratoire. L’évaluation de la précision au bout de l’aiguille a quant à elle été faite en utilisant des fantômes précisément conçus à cet effet. Finalement, des interventions guidées en IRM ont été testées et comparées au système de navigation électromagnétique NDI Aurora (EMTS, pour Electromagnétic tracking system) par le biais du FRE (fiducial registration error) et du TRE (target registration error). Résultats: Lors de nos premières expériences in vitro, la précision obtenue quant à la position du bout de l’aiguille était de 0,96 mm pour une déflexion allant jusqu’à ±10,68 mm. À titre comparatif, le système d’Aurora a une précision de 0.84 mm dans des circonstances similaires. Les résultats obtenus lors de nos seconds tests ont démontré que l’erreur entre la position réelle du bout de l’aiguille et la position fournie par notre système de reconstruction de forme est de 1,04 mm, alors qu’elle est de 0,82 mm pour le EMTS d’Aurora. Pour ce qui est de notre dispositif, cette erreur est proportionnelle à l’amplitude de déflexion de l’aiguille, contrairement à l’EMTS pour qui l’erreur demeure relativement constante. La dernière expérience a été effectuée à l’aide d’un fantôme en gélatine, pour laquelle nous avons obtenu un TRE de 1,19 mm pour notre système basé sur les FBG et de 1.06 mm pour le système de navigation par senseurs électromagnétiques (EMTS). Les résultats démontrent que l’évaluation du FRE est similaire pour les deux approches. De plus, l’information fournie par les caméras permet d’estimer la précision de notre dispositif en tout point le long de l’aiguille. Conclusion : En analysant et en interprétant les résultats obtenus lors de nos expériences in vitro, nous pouvons conclure que la précision de notre système de navigation basé sur les FBG est bien adaptée pour l’évaluation de la position du bout et la forme de l’aiguille lors d’interventions RFA des tumeurs du foie. La précision de notre système de navigation est fortement comparable avec celle du système basé sur des senseurs électromagnétiques commercialisé par Aurora. L’erreur obtenue par notre système est attribuable à un mauvais alignement des réseaux de Bragg par rapport au plan associé à la région sensorielle et aussi à la différence entre le diamètre des fibres et celui de la paroi interne de l’aiguille.----------ABSTRACT Background: Colorectal liver metastasis is the leading cause of liver cancer death in the world. In the past decade, radiofrequency ablation (RFA) has proven to be an effective percutaneous treatment modality for the treatment of metastatic hepatic cancer. Accurate needle tip placement is essential for RFA of liver tumors. A promising technology to obtain the real-time information of the shape of the needle is by using fiber Bragg grating (FBG) sensors at high frequencies (up to 20 kHz). Methods: In this thesis work, we developed an MR-compatible needle tracking technology designed for RFA procedures in liver cancer. At first, three fibers each containing a series of FBGs were glued together and integrated inside a 20G-150 mm needle. Then a three-dimensional needle shape reconstruction algorithm was developed, based on the FBG measurements collected in real-time during needle guidance. The tip position and shape of the reconstructed 3D needle model were represented with respect to the target defined in the image space by performing a fiducial-based registration. Finally, we validated our FBG-based needle navigation by doing a series of in-vitro experiments. The shape of the 3D reconstructed needle was compared to measurements obtained from camera images. In addition, the needle tip accuracy was assessed on the ground-truth phantoms. Finally, MRI guided intervention was tested and compared to an NDI Aurora EM tracking system (EMTS) in terms of fiducial registration error (FRE) and target registration error (TRE). Results: In our first in-vitro experiment, the tip tracking accuracy of our FBG tracking system was of 0.96 mm for the maximum tip deflection of up to ±10.68 mm, while the tip tracking accuracy of the Aurora system for the similar test was 0.84 mm. Results obtained from the second in-vitro experiment demonstrated tip tracking accuracy of 1.04 mm and 0.82 mm for our FBG tracking system and Aurora EMTS, respectively for the maximum tip deflection of up to ±16.83 mm. The tip tracking error in the developed FBG-based system reduced linearly with decreasing tip deflection, while the error was similar but randomly varying for the EMTS. The last experiment was done with a gel phantom, yielding a TRE of 1.19 mm and 1.06 mm for the FBG and EM tracking, respectively. Results showed that across all experiments, the computed FRE of both tracking systems was similar. Moreover, actual shape information obtained from the camera images ensured the shape accuracy of our FBG-based needle shape model. Conclusion: By analyzing and interpreting the results obtained from the in-vitro experiments, we conclude that the accuracy of our FBG-based tracking system is suitable for needle tip detection in RFA of liver tumors. The accuracy of our tracking system is nearly comparable to that of the Aurora EMTS. The error given by our tracking system is attributed to the misalignment of the FBG sensors in a single axial plane and also to the gap between the needle's inner wall and the fibers inside

Augmented navigation

Spinal fixation procedures have the inherent risk of causing damage to vulnerable anatomical structures such as the spinal cord, nerve roots, and blood vessels. To prevent complications, several technological aids have been introduced. Surgical navigation is the most widely used, and guides the surgeon by providing the position of the surgical instruments and implants in relation to the patient anatomy based on radiographic images. Navigation can be extended by the addition of a robotic arm to replace the surgeon’s hand to increase accuracy. Another line of surgical aids is tissue sensing equipment, that recognizes different tissue types and provides a warning system built into surgical instruments. All these technologies are under continuous development and the optimal solution is yet to be found. The aim of this thesis was to study the use of Augmented Reality (AR), Virtual Reality (VR), Artificial Intelligence (AI), and tissue sensing technology in spinal navigation to improve precision and prevent surgical errors. The aim of Paper I was to develop and validate an algorithm for automatizing the intraoperative planning of pedicle screws. An AI algorithm for automatic segmentation of the spine, and screw path suggestion was developed and evaluated. In a clinical study of advanced deformity cases, the algorithm could provide correct suggestions for 86% of all pedicles—or 95%, when cases with extremely altered anatomy were excluded. Paper II evaluated the accuracy of pedicle screw placement using a novel augmented reality surgical navigation (ARSN) system, harboring the above-developed algorithm. Twenty consecutively enrolled patients, eligible for deformity correction surgery in the thoracolumbar region, were operated on using the ARSN system. In this cohort, we found a pedicle screw placement accuracy of 94%, as measured according to the Gertzbein grading scale. The primary goal of Paper III was to validate an extension of the ARSN system for placing pedicle screws using instrument tracking and VR. In a porcine cadaver model, it was demonstrated that VR instrument tracking could successfully be integrated with the ARSN system, resulting in pedicle devices placed within 1.7 ± 1.0 mm of the planed path. Paper IV examined the feasibility of a robot-guided system for semi-automated, minimally invasive, pedicle screw placement in a cadaveric model. Using the robotic arm, pedicle devices were placed within 0.94 ± 0.59 mm of the planned path. The use of a semi-automated surgical robot was feasible, providing a higher technical accuracy compared to non-robotic solutions. Paper V investigated the use of a tissue sensing technology, diffuse reflectance spectroscopy (DRS), for detecting the cortical bone boundary in vertebrae during pedicle screw insertions. The technology could accurately differentiate between cancellous and cortical bone and warn the surgeon before a cortical breach. Using machine learning models, the technology demonstrated a sensitivity of 98% [range: 94-100%] and a specificity of 98% [range: 91-100%]. In conclusion, several technological aids can be used to improve accuracy during spinal fixation procedures. In this thesis, the advantages of adding AR, VR, AI and tissue sensing technology to conventional navigation solutions were studied