Navigation problems are common in patients with acquired brain injury. These patients experience difficulty when travelling between places, frequently get lost and often experience spatial anxiety.... Show moreNavigation problems are common in patients with acquired brain injury. These patients experience difficulty when travelling between places, frequently get lost and often experience spatial anxiety. Navigation problems can have a profound impact on the daily lives of these patients. This doctoral research focuses on the development and validation of a rehabilitation therapy for patients with navigation problems. The goal was to develop a standardized therapy, suitable for patients with a variety of navigation impairments and various levels of cognitive functioning. A compensatory approach was taken: patients gain insight into their own navigational abilities and are trained to adopt a beneficial navigation strategy. The therapy encompasses psycho-education and the utilization of a serious game that patients can engage with in a home-based setting. In the game, patients are trained to use alternative navigation strategies in virtual environments. A series of studies was performed to develop the theoretical foundation of the therapy, ensure the usability and feasibility of the software and assess the acceptance of the therapy among healthcare providers. Finally, the effectiveness of the therapy was determined. Evidence is found that using the rehabilitation therapy leads to a reduction of navigation problems and the attainment of self-determined rehabilitation goals. Show less
Purpose Navigational strategies create a scenario whereby percutaneous needle-based interventions of the liver can be guided using both pre-interventional 3D imaging datasets and dynamic... Show morePurpose Navigational strategies create a scenario whereby percutaneous needle-based interventions of the liver can be guided using both pre-interventional 3D imaging datasets and dynamic interventional ultrasound (US). To score how such technologies impact the needle placement process, we performed kinematic analysis on different user groups. Methods Using a custom biopsy phantom, three consecutive exercises were performed by both novices and experts (n = 26). The exercise came in three options: (1) US-guidance, (2) US-guidance with pre-interventional image-registration (US + Reg) and (3) US-guidance with pre-interventional image-registration and needle-navigation (US + Reg + Nav). The traveled paths of the needle were digitized in 3D. Using custom software algorithms, kinematic metrics were extracted and related to dexterity, decision making indices to obtain overall performance scores (PS). Results Kinematic analysis helped quantifying the visual assessment of the needle trajectories. Compared to US-guidance, novices yielded most improvements using Reg (PSavg(US) = 0.43 vs. PSavg(US+Reg) = 0.57 vs. PSavg(US+Reg+Nav) = 0.51). Interestingly, the expert group yielded a reversed trend (PSavg(US) = 0.71 vs PSavg(US+Reg) = 0.58 vs PSavg(US+Reg+Nav) = 0.59). Conclusion Digitizing the movement trajectory allowed us to objectively assess the impact of needle-navigation strategies on percutaneous procedures. In particular, our findings suggest that these advanced technologies have a positive impact on the kinematics derived performance of novices. Show less
Meershoek, P.; Berg, N.S. van den; Lutjeboer, J.; Burgmans, M.C.; Meer, R.W. van der; Rijswijk, C.S.P. van; ... ; Leeuwen, F.W.B. van 2021
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... Show morePurpose: 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. Show less
Rietbergen, D.D.D.; Meershoek, P.; Oosterom, M.N. van; Roestenberg, M.; Erkel, A.R. van; Smit, F.; ... ; Leeuwen, F.W.B. van 2019
Purpose: To assess the feasibility of using freehand Single Photon Emission Computed Tomography (free-handSPECT) for the identification of technetium-99m-hydroxydiphosphonate (Tc-99m-HDP) positive... Show morePurpose: To assess the feasibility of using freehand Single Photon Emission Computed Tomography (free-handSPECT) for the identification of technetium-99m-hydroxydiphosphonate (Tc-99m-HDP) positive bone lesions and to evaluate the possibility of using these imaging data-sets for augmented- and virtual-reality based navigation approaches.Material and methods: In 20 consecutive patients referred for scintigraphy with Tc-99m-HDP, 21 three-dimensional freehandSPECT-images were generated using a handheld gamma camera. Concordance of the two different data sets was ranked. Furthermore, feasibility of segmenting the hotspot of tracer accumulation for navigation purposes was assessed.Results: In 86% of the cases freehandSPECT images showed good concordance with the corresponding part of the scintigraphic images. In lesions with a signal to background ratio (SBR) > 1.36, freehandSPECT provided an automatically segmented reference point for navigation purposes. In 14% of the cases (average SBR 1.82, range 1.0-3.4) freehandSPECT images showed intermediate concordance due to difficult anatomical area or negative bone scintigraphy and could not be used as navigation targets.Conclusion: In this pilot study, in 86% of the cases freehandSPECT demonstrated good concordance with traditional scintigraphy. A lesion with a SBR of 1.36 or more was suitable for navigation. These high quality freehandSPECT images supported the future exploration navigation strategies, e.g. guided needle biopsies. (C) 2019 Sociedad Espaiiola de Medicina Nuclear e Imagen Molecular. Published by Elsevier Espatia, S.L.U. All rights reserved. Show less
One of the tasks of the Royal Netherlands Navy in Tydeman's lifetime was the hydrographic survey of the seas at home and in the colonial waters. The hydrographic expertise of naval officers could... Show moreOne of the tasks of the Royal Netherlands Navy in Tydeman's lifetime was the hydrographic survey of the seas at home and in the colonial waters. The hydrographic expertise of naval officers could also be applied to other endeavours like scientific expeditions.In the second half of the nineteenth century private scientific societies took the initiative to engage in maritime research. Contact between scientists and the Navy resulted in naval assintance in scientific research. The Navy took part in polar expeditions and in scientific explorations in the tropics. As a junior officer Gustaaf Tydeman was involved in hydrographic surveij in the East Indies and in Dutch coastal waters. Tydeman was commanding officer of H. Neth. MS Siboga during the oceanographic expedition in the East Indian Archipelago in 1899-1900. He continued his years in the Navy as commanding officer of the Royal Naval College, of large ships and of a squadron of ships in teh East Indies. He was promoted to flagofficer in his command of the Naval establishment in Amsterdam. His achievements as hydrographer and commanding officer of a ship on a scientific expedition and author of several publications made his naval career exceptional. Show less
There is little evidence of the routes connecting Amerindian communities in the Caribbean prior to and just after 1492. Uncovering possible canoe routes between these communities can help to... Show moreThere is little evidence of the routes connecting Amerindian communities in the Caribbean prior to and just after 1492. Uncovering possible canoe routes between these communities can help to explain the structure, capabilities, and limitations of the physical links in their social and material networks. This book evaluates how routes connecting islands indicate the structure of past inter-island networks, by using computer modeling. Computer modeling and least-cost pathway analysis is a popular approach for analyzing the physical connection between sites in archaeology. Over the past three decades researchers have explored several theories and methods to analyze least-cost pathways on landscapes. Land-based least-cost efforts have outpaced the number of works evaluating optimal travel routes across the sea’s surface. Perhaps as a result, no community standard for using computer- and GIS-based methods to model canoe or sailing routes exists. Although methods used in previous research often focus on determining the time-cost and success of specific routes, these measures have been calculated or judged in different ways. One way this book adds to the discussion of seascape modeling is by focusing on inter-island voyaging, or the process of maintained connections between island sites, a technique rarely explored in sea-based least-cost pathways analysis. Show less
In mijn proefschrift heb ik onderzocht wat de invloed is van het gebruik van navigatie bij het plaatsen van een knieprothese. Hiervoor zijn drie onderzoeksvragen opgesteld en beantwoord. Allereerst... Show moreIn mijn proefschrift heb ik onderzocht wat de invloed is van het gebruik van navigatie bij het plaatsen van een knieprothese. Hiervoor zijn drie onderzoeksvragen opgesteld en beantwoord. Allereerst: leidt CAOS tot het nauwkeuriger plaatsen van een TKP? Op basis van de door mij gedane studies en analyse van de huidige literatuur concludeer ik dat juiste registratie tijdens CAOS essentieel is voor het bereiken van een goede stand van de TKP. Zolang hier nog onnauwkeurigheden in zitten leidt CAOS (nog) niet tot het nauwkeuriger plaatsen van de TKP, met name wat betreft de rotatie van de femurcomponent. Daarnaast heb ik onderzocht of CAOS leidt tot een juiste maatvoering van de TKP en patella tracking. Ik kom tot de conclusie dat men uit moet kijken voor het plaatsen van met name een te grote femurcomponent. De data die verkregen zijn middels het gebruik van de patella tracking module worden significant be_nvloed door de snelheid van bewegen van de knie en de zichtbaarheid van een markertree. Tot slot is bekeken wat de klinische en radiologische uitkomst is van een TKP geplaatst met CAOS. Hoewel er aanwijzingen zijn dat het aantal outliers wat betreft het alignment van de TKP met CAOS afneemt, kan er geen relatie aangetoond worden met de klinische uitkomst van de prothese. Momenteel is CAOS een bruikbare techniek voor onderzoeksdoeleinden, zoals de chirurgische techniek en kinematische analyse, en als onderwijsinstrument. Verder onderzoek is nodig om de exacte plaats van CAOS bij het plaatsen van TKP te bepalen. Tot die tijd moet men kritisch blijven wat betreft de toepassing van nieuwe technieken in de Orthopaedische Chirurgie, deze gefaseerd invoeren en de vraag stellen of iets een __tool__ of een __toy__ is. Show less
