Volumetric analysis of the cranial and nasal cavity from micro-computed tomography scans in the rabbit

Background: The aim of the study was to estimate the volume values of the cranial cavity and nasal cavity structures and to compare the efficiency of manual segmentation of three-dimensional reconstruction and Cavalieri’s principle (CP) methodologies. Materials and methods: Volume values of the cranial cavity, maxillary sinus (MS), dorsal conchal sinus (DCS), dorsal nasal meatus (DNM), middle nasal meatus (MNM), ventral nasal meatus (VNM), ventral nasal concha (VNC), middle nasal concha (MNC) and nasal vestibule (NV) were estimated with manual segmentation and CP from micro-computed tomography images in 5 male New Zealand white rabbits. Volume measurements and elapsed time were compared with each other. Three-dimensional reconstruction models of nasal and cranial cavity structures were created. Results: There was a statistically significant difference between methods of the MS, DCS, DNM, MNM, VNM, VNC, and MNC volume measurements. Additionally, there was a statistically significant difference between the volumetric analysis time period of the methods and CP was found much shorter than manual segmentation. Conclusions: Realistic results were achieved in a short time with the CP among the stereology methods. It is thought that these image and quantitative data results can be used for modelling, toxicology and pathology studies such as acute and chronić rhinitis or rhino sinusitis as well as a good understanding of the relationship of the anatomical structures in the nasal cavity

Icex: Advances in the automatic extraction and volume calculation of cranial cavities

The use of non-destructive approaches for digital acquisition (e.g. computerised tomography-CT) allows detailed qualitative and quantitative study of internal structures of skeletal material. Here, we present a new R-based software tool, Icex, applicable to the study of the sizes and shapes of skeletal cavities and fossae in 3D digital images. Traditional methods of volume extraction involve the manual labelling (i.e. segmentation) of the areas of interest on each section of the image stack. This is time-consuming, error-prone and challenging to apply to complex cavities. Icex facilitates rapid quantification of such structures. We describe and detail its application to the isolation and calculation of volumes of various cranial cavities. The R tool is used here to automatically extract the orbital volumes, the paranasal sinuses, the nasal cavity and the upper oral volumes, based on the coordinates of 18 cranial anatomical points used to define their limits, from 3D cranial surface meshes obtained by segmenting CT scans. Icex includes an algorithm (Icv) for the calculation of volumes by defining a 3D convex hull of the extracted cavity. We demonstrate the use of Icex on an ontogenetic sample (0-19 years) of modern humans and on the fossil hominin crania Kabwe (Broken Hill) 1, Gibraltar (Forbes' Quarry) and Guattari 1. We also test the tool on three species of non-human primates. In the modern human subsample, Icex allowed us to perform a preliminary analysis on the absolute and relative expansion of cranial sinuses and pneumatisations during growth. The performance of Icex, applied to diverse crania, shows the potential for an extensive evaluation of the developmental and/or evolutionary significance of hollow cranial structures. Furthermore, being open source, Icex is a fully customisable tool, easily applicable to other taxa and skeletal regions

The paranasal sinuses: three-dimensional reconstruction, photo-realistic imaging, and virtual endoscopy

  Background: The purpose of the study was to create computer-aided design models of the paranasal sinuses (frontal, maxillary, and sphenoid) and to perform virtual endoscopy (VE) to them by using virtual reality modelling language technique. Materials and methods: The visible human dataset was used as the input imaging data. The Surfdriver software package was applied on these images to reconstruct the paranasal sinuses as 3-dimensional (3D) computer-aided design models. These models were post-processed in Cinema 4D to perform the photorealistic imaging and VE of the paranasal sinuses. Results: The volumes of the maxillary sinuses were 24747.89 mm3 on the right and 29008.78 mm3 on the left. As for sphenoidal sinuses, an enormous variation was seen between the right and left cavities. The sphenoidal sinuses were 1995.90 mm3 on the right and 10228.93 mm3 on the left while the frontal sinuses were 20805.67 mm3 on the right and 18048.85 mm3 on the left. The largest sinus was left maxillary sinus by volume. Right frontal sinus was the largest sinus by surface area. It was calculated as 6002.73 mm2. Our methodological outcomes proved that Surfdriver and Cinema 4D pair could be reliably used for 3D reconstructions, photo realistic imaging and creating 3D virtual environments from the serial sections of the anatomical structures. Conclusions: This technique allows students, researchers, and surgeons to perform noninvasive visualisation, simulation, and precise quantitative measurements of internal structures of the body. It was developed as a complementary tool for endoscopic surgery. It could be especially preferable for the patients who could not tolerate flexible or rigid endoscopy

Statistical Shape Modelling and Segmentation of the Respiratory Airway

The human respiratory airway consists of the upper (nasal cavity, pharynx) and the lower (trachea, bronchi) respiratory tracts. Accurate segmentation of these two airway tracts can lead to better diagnosis and interpretation of airway-specific diseases, and lead to improvement in the localization of abnormal metabolic or pathological sites found within and/or surrounding the respiratory regions. Due to the complexity and the variability displayed in the anatomical structure of the upper respiratory airway along with the challenges in distinguishing the nasal cavity from non-respiratory regions such as the paranasal sinuses, it is difficult for existing algorithms to accurately segment the upper airway without manual intervention. This thesis presents an implicit non-parametric framework for constructing a statistical shape model (SSM) of the upper and lower respiratory tract, capable of distinct shape generation and be adapted for segmentation. An SSM of the nasal cavity was successfully constructed using 50 nasal CT scans. The performance of the SSM was evaluated for compactness, specificity and generality. An averaged distance error of 1.47 mm was measured for the generality assessment. The constructed SSM was further adapted with a modified locally constrained random walk algorithm to segment the nasal cavity. The proposed algorithm was evaluated on 30 CT images and outperformed comparative state-of-the-art and conventional algorithms. For the lower airway, a separate algorithm was proposed to automatically segment the trachea and bronchi, and was designed to tolerate the image characteristics inherent in low-contrast CT images. The algorithm was evaluated on 20 clinical low-contrast CT from PET-CT patient studies and demonstrated better performance (87.1±2.8 DSC and distance error of 0.37±0.08 mm) in segmentation results against comparative state-of-the-art algorithms

ANALIZA CECH SEGMENTACJI GÓRNYCH DRÓG ODDECHOWYCH W CELU OKREŚLENIA PRZEWODNICTWA NOSOWEGO

The paper examines the features of segmentation of the upper respiratory tract to determine nasal air conduction. 2D and 3D illustrations of the segmentation process and the obtained results are given. When forming an analytical model of the aerodynamics of the nasal cavity, the main indicator that characterizes the configuration of the nasal canal is the equivalent diameter, which is determined at each intersection of the nasal cavity. It is calculated based on the area and perimeter of the corresponding section of the nasal canal. When segmenting the nasal cavity, it is first necessary to eliminate air structures that do not affect the aerodynamics of the upper respiratory tract - these are, first of all, intact spaces of the paranasal sinuses, in which diffuse air exchange prevails. In the automatic mode, this is possible by performing the elimination of unconnected isolated areas and finding the difference coefficients of the areas connected by confluences with the nasal canal in the next step. High coefficients of difference of sections between intersections will indicate the presence of separated areas and contribute to their elimination. The complex configuration and high individual variability of the structures of the nasal cavity does not allow segmentation to be fully automated, but this approach contributes to the absence of interactive correction in 80% of tomographic datasets. The proposed method, which takes into account the intensity of the image elements close to the contour ones, allows to reduce the averaging error from tomographic reconstruction up to 2 times due to artificial sub-resolution. The perspective of the work is the development of methods for fully automatic segmentation of the structures of the nasal cavity, taking into account the individual anatomical variability of the upper respiratory tract.W pracy przeanalizowano cechy segmentacji górnych dróg oddechowych w celu określenia powietrznego przewodnictwa nosowego. Przedstawiono zdjęcia 2D i 3D procesu segmentacji oraz uzyskanych wyników. Podczas formowania analitycznego modelu aerodynamiki jamy nosowej głównym wskaźnikiem charakteryzującym konfigurację kanału nosowego jest ekwiwalentna średnica, którą wyznacza się na każdym skrzyżowaniu jam nosowych. Jest ona obliczana na podstawie pola powierzchni i obwodu odpowiedniego odcinka kanału nosowego. Podczas segmentacji jamy nosowej w pierwszej kolejności należy wyeliminować struktury powietrzne, które nie wpływają na aerodynamikę górnych dróg oddechowych – są to przede wszystkim nienaruszone przestrzenie zatok przynosowych, w których dominuje rozproszona wymiana powietrza. W trybie automatycznym jest to możliwe dzięki eliminacji niepołączonych izolowanych obszarów i znalezieniu, w kolejnym kroku, współczynników różnicy obszarów połączonych konfluencjami z przewodem nosowym. Wysokie współczynniki różnic przekrojów pomiędzy skrzyżowaniami będą wskazywały na obecność wydzielonych obszarów i przyczynią się do ich eliminacji. Złożona konfiguracja i duża zmienność osobnicza struktur jamy nosowej nie pozwala na pełną automatyzację segmentacji, jednak takie podejście przyczynia się do braku konieczności interaktywnej korekcji w 80% zestawów danych tomograficznych. Zaproponowana metoda, uwzględniająca intensywność elementów obrazu znajdujących się blisko konturu, pozwala na nawet 2-krotne zmniejszenie błędu uśredniania z rekonstrukcji tomograficznej, wynikającego ze sztucznej subrozdzielczości. Perspektywą pracy jest opracowanie metod w pełni automatycznej segmentacji struktur jamy nosowej z uwzględnieniem indywidualnej zmienności anatomicznej górnych dróg oddechowych

Assessment of a novel patient-specific 3D printed multi-material simulator for endoscopic sinus surgery

Background: Three-dimensional (3D) printing is an emerging tool in the creation of anatomical models for surgical training. Its use in endoscopic sinus surgery (ESS) has been limited because of the difficulty in replicating the anatomical details. Aim: To describe the development of a patient-specific 3D printed multi-material simulator for use in ESS, and to validate it as a training tool among a group of residents and experts in ear-nose-throat (ENT) surgery. Methods: Advanced material jetting 3D printing technology was used to produce both soft tissues and bony structures of the simulator to increase anatomical realism and tactile feedback of the model. A total of 3 ENT residents and 9 ENT specialists were recruited to perform both non-destructive tasks and ESS steps on the model. The anatomical fidelity and the usefulness of the simulator in ESS training were evaluated through specific questionnaires. Results: The tasks were accomplished by 100% of participants and the survey showed overall high scores both for anatomy fidelity and usefulness in training. Dacryocystorhinostomy, medial antrostomy, and turbinectomy were rated as accurately replicable on the simulator by 75% of participants. Positive scores were obtained also for ethmoidectomy and DRAF procedures, while the replication of sphenoidotomy received neutral ratings by half of the participants. Conclusion: This study demonstrates that a 3D printed multi-material model of the sino-nasal anatomy can be generated with a high level of anatomical accuracy and haptic response. This technology has the potential to be useful in surgical training as an alternative or complementary tool to cadaveric dissection

Anatomically Constrained Video-CT Registration via the V-IMLOP Algorithm

Functional endoscopic sinus surgery (FESS) is a surgical procedure used to treat acute cases of sinusitis and other sinus diseases. FESS is fast becoming the preferred choice of treatment due to its minimally invasive nature. However, due to the limited field of view of the endoscope, surgeons rely on navigation systems to guide them within the nasal cavity. State of the art navigation systems report registration accuracy of over 1mm, which is large compared to the size of the nasal airways. We present an anatomically constrained video-CT registration algorithm that incorporates multiple video features. Our algorithm is robust in the presence of outliers. We also test our algorithm on simulated and in-vivo data, and test its accuracy against degrading initializations.Comment: 8 pages, 4 figures, MICCA

Intensity modulated radiation therapy and arc therapy: validation and evolution as applied to tumours of the head and neck, abdominal and pelvic regions

Intensiteitsgemoduleerde radiotherapie (IMRT) laat een betere controle over de dosisdistributie (DD) toe dan meer conventionele bestralingstechnieken. Zo is het met IMRT mogelijk om concave DDs te bereiken en om de risico-organen conformeel uit te sparen. IMRT werd in het UZG klinisch toegepast voor een hele waaier van tumorlocalisaties. De toepassing van IMRT voor de bestraling van hoofd- en halstumoren (HHT) vormt het onderwerp van het eerste deel van deze thesis. De planningsstrategie voor herbestralingen en bestraling van HHT, uitgaande van de keel en de mondholte wordt beschreven, evenals de eerste klinische resultaten hiervan. IMRT voor tumoren van de neus(bij)holten leidt tot minstens even goede lokale controle (LC) en overleving als conventionele bestralingstechnieken, en dit zonder stralingsgeïnduceerde blindheid. IMRT leidt dus tot een gunstiger toxiciteitprofiel maar heeft nog geen bewijs kunnen leveren van een gunstig effect op LC of overleving. De meeste hervallen van HHT worden gezien in het gebied dat tot een hoge dosis bestraald werd, wat erop wijst dat deze “hoge dosis” niet volstaat om alle clonogene tumorcellen uit te schakelen. We startten een studie op, om de mogelijkheid van dosisescalatie op geleide van biologische beeldvorming uit te testen. Naast de toepassing en klinische validatie van IMRT bestond het werk in het kader van deze thesis ook uit de ontwikkeling en het klinisch opstarten van intensiteitgemoduleerde arc therapie (IMAT). IMAT is een rotationele vorm van IMRT (d.w.z. de gantry draait rond tijdens de bestraling), waarbij de modulatie van de intensiteit bereikt wordt door overlappende arcs. IMAT heeft enkele duidelijke voordelen ten opzichte van IMRT in bepaalde situaties. Als het doelvolume concaaf rond een risico-orgaan ligt met een grote diameter, biedt IMAT eigenlijk een oneindig aantal bundelrichtingen aan. Een planningsstrategie voor IMAT werd ontwikkeld, en type-oplossingen voor totaal abdominale bestraling en rectumbestraling werden onderzocht en klinisch toegepast

Modeling of the human upper airway from multimodal 3D dentofacial images

Ph.DDOCTOR OF PHILOSOPH