Objective measurement of motion in the orbit

The research described in the thesis had two major aims: to find methods for objective measurement of motion in the orbit, and to determine the clinical use of these methods in patients with orbital disorders. This implied that a number of research questions had to be answered in the fields of both image science and of ophthalmology and orbitology. The results have established that measurement of the two- and three-dimensional motion of tissues in the orbit is feasible in humans. It can be imaged in 2-D and 3-D with Magnetic Resonance Imaging (MRI) sequences. It can be calculated objectively from these sequences using optical flow methods. First order techniques were found to be superior for this purpose as they are less sensitive to noise, partial volume effects and aliasing. A new first-order 3-D optical flow algorithm was developed for robust and computationally efficient three-dimensional optical flow estimation. A number of techniques were developed to visualize 2- and 3-D motion combined with the anatomy in 3-D space, using color-coding. The results of two clinical studies have established the clinical use of objective measurement of motion in the orbit in a number of orbital and motion disorders. The studies have resulted in an explanation for the persistent pain that may occur after enucleation of the globe, based on motion measurements in patients after enucleation. They have also shown that orbital tumors can be differentiated using motion studies. The results have also shown that the position of the rectus muscle pulleys is the same in patients with Graves disease and in normals. After surgical decompression of the orbit, the muscles and their pulleys are usually not displaced, except in cases where specific muscle paths and pulleys are displaced in specific patterns, resulting in specific motility disturbances. Thus, a new explanation has been found for the motility disturbances that may occur in some patients after decompression surgery for Graves orbitopathy. These last findings have led to the notion central to this thesis, namely that the orbital tissues are an organ in their own right, the organ of gaze, and do not need their bony orbit to function normally

Inertial sensors signal processing methods for gait analysis of patients with impaired gait patterns

Analiza hoda je postala široko rasprostranjen klinički alat koji se koristi za objektivnu evaluaciju obrasca hoda, efekata hirurških intervencija, oporavka ili efekata terapije. Sve veći broj kliničara bira pogodne tretmane za lečenje pacijenata na osnovu informacija o kinematici i kinetici hoda. Procena i kvantifikacija parametara hoda je važan zahtev u oblasti ortopedije i rehabilitacije, ali takođe i u sportu, rekreaciji i posebno u razvoju tehnologija za ljude u procesu starenja. U cilju objektivne procene obrasca hoda, razvijen je bežični senzorski sistem čije su senzorske jedinice bežične, malih dimenzija i jednostavno se montiraju na segmente nogu subjekta čiji se hoda analizira. Senzorske jedinice podržavaju 3D inercijalne senzore (senzore ubrzanja i ugaonih brzina, tj. akcelerometre i žiroskope), kao i senzore sile. Osnovni cilj istraživanja je doprinos metodologiji za obradu podataka sa inercijalnih senzora i razvoj novih metoda obrade signala sa inercijalnih senzora u procesu određivanja kinematičkih veličina koje su uobičajene u analizi hoda (uglovi u zglobovima, brzina kretanja, dužina koraka). Ova metodologija je od posebne važnosti za objektivnu procenu nivoa motornog deficita, progresa bolesti i efikasnosti terapija, kao i efikasnosti primenjene motorne kontrole (prilikom funkcionalne električne stimulacije). U toku istraživanja razvijeno je nekoliko metoda za računanje uglova segmenata nogu ili zglobova, u zavisnosti od senzorske konfiguracije i složenosti algoritma. U disertaciji su odvojeno prikazani slučajevi u kojima je neophodno posmatrati kretanje u prostoru (3D analiza) i mnogo češći slučaj kad se kinematika može redukovati na sagitalnu ravan (2D analiza). Algoritmi uključuju i kalibraciju senzora, eliminaciju viii drifta, rekonstrukciju trajektorije i izračunavanje niza drugih relevantnih podataka koji karakterišu obrazac hoda. Dobijeni rezultati su poređeni sa postojećim sistemima za analizu hoda koji su validirani za kliničke primene. (sistemi sa kamerama, goniometri, enkoderi)...Gait analysis has become a widely used clinical tool which provides objective evaluation of the gait pattern, the effects of surgical interventions, recovery or therapy progress, and more and more clinicians are choosing therapy treatments based on gait kinematics and kinetics. Measuring gait parameters is an important requirement in the orthopedic and rehabilitation fields, but also in sports and fitness, and development of technologies for elderly population. In order to provide objective evaluation of the gait pattern, we have developed sensor system with light and small wireless sensor units, which can be easily mounted on body. These sensor units comprise 3-D inertial sensors (accelerometers and gyroscopes) and force sensing resistors, and our recommended setup includes one sensor unit per each segment of both legs. The main goal of this research is contribution to the methodology for processing of signals from inertial sensors (accelerometer pairs, or accelerometer and gyroscope sensor units). By using signal processing algorithms developed for this research, inertial sensors allow objective assessment of the quality of the gait pattern. This methodology is especially important for assessment of the motor deficit, progress of the disease and therapy effectiveness, and effectiveness of performed motor control (functional electrical stimulation). We have developed several methods for estimation of leg segment angles and joint angles, which differ in sensor configuration and algorithm complexity. Methods based only on accelerometers offer reliable angle estimations, which are limited to sagittal plane analysis, while the method using accelerometers and gyroscopes allows 3- D analysis. All this algorithms include sensor calibration, drift minimization, trajectory x reconstruction and calculation of numerous other parameters relevant to gait pattern analysis. The obtained results were compared with other commercial systems which are validated for clinical applications (camera systems, goniometers, encoders)..

Non-rigid medical image registration with extended free form deformations: modelling general tissue transitions

Image registration seeks pointwise correspondences between the same or analogous objects in different images. Conventional registration methods generally impose continuity and smoothness throughout the image. However, there are cases in which the deformations may involve discontinuities. In general, the discontinuities can be of different types, depending on the physical properties of the tissue transitions involved and boundary conditions. For instance, in the respiratory motion the lungs slide along the thoracic cage following the tangential direction of their interface. In the normal direction, however, the lungs and the thoracic cage are constrained to be always in contact but they have different material properties producing different compression or expansion rates. In the literature, there is no generic method, which handles different types of discontinuities and considers their directional dependence. The aim of this thesis is to develop a general registration framework that is able to correctly model different types of tissue transitions with a general formalism. This has led to the development of the eXtended Free Form Deformation (XFFD) registration method. XFFD borrows the concept of the interpolation method from the eXtended Finite Element method (XFEM) to incorporate discontinuities by enriching B-spline basis functions, coupled with extra degrees of freedom. XFFD can handle different types of discontinuities and encodes their directional-dependence without any additional constraints. XFFD has been evaluated on digital phantoms, publicly available 3D liver and lung CT images. The experiments show that XFFD improves on previous methods and that it is important to employ the correct model that corresponds to the discontinuity type involved at the tissue transition. The effect of using incorrect models is more evident in the strain, which measures mechanical properties of the tissues

Assessment of Foot Signature Using Wearable Sensors for Clinical Gait Analysis and Real-Time Activity Recognition

Locomotion is one of the most important abilities of humans. Actually, gait locomotion provides mobility, and symbolizes freedom and independence. However, gait can be affected by several pathologies, due to aging, neurodegenerative disease, or trauma. The evaluation and treatment of mobility diseases thus requires clinical gait assessment, which is commonly done by using either qualitative analysis based on subjective observations and questionnaires, or expensive analysis established in complex motion laboratories settings. This thesis presents a new wearable system and algorithmic methods for gait assessment in natural conditions, addressing the limitations of existing methods. The proposed system provides quantitative assessment of gait performance through simple and precise outcome measures. The system includes wireless inertial sensors worn on the foot, that record data unobtrusively over long periods of time without interfering with subject's walking. Signal processing algorithms are presented for the automatic calibration and online virtual alignment of sensor signals, the detection of temporal parameters and gait phases, and the estimation of 3D foot kinematics during gait based on fusion methods and biomechanical assumptions. The resulting 3D foot trajectory during one gait cycle is defined as Foot Signature, by analogy with hand-written signature. Spatio-temporal parameters of interest in clinical assessment are derived from foot signature, including commonly parameters, such as stride velocity and gait cycle time, as well as original parameters describing inner-stance phases of gait, foot clearance, and turning. Algorithms based on expert and machine learning methods have been also adapted and implemented in real-time to provide input features to recognize locomotion activities including level walking, stairs, and ramp locomotion. Technical validation of the presented methods against gold standard systems was carried out using experimental protocols on subjects with normal and abnormal gait. Temporal aspects and quantitative estimation of foot-flat were evaluated against pressure insoles in subjects with ankle treatments during long-term gait. Furthermore, spatial parameters and foot clearance were compared in young and elderly persons to data obtained from an optical motion capture system during forward gait trials at various speeds. Finally, turning was evaluated in children with cerebral palsy and people with Parkinson's disease against optical motion capture data captured during timed up and go and figure-of-8 tests. Overall, the results demonstrated that the presently proposed system and methods were precise and accurate, and showed agreement with reference systems as well as with clinical evaluations of subjects' mobility disease using classical scores. Currently, no other methods based on wearable sensors have been validated with such precision to measure foot signature and subsequent parameters during unconstrained walking. Finally, we have used the proposed system in a large-scale clinical application involving more than 1800 subjects from age 7 to 77. This analysis provides reference data of common and original gait parameters, as well as their relationship with walking speed, and allows comparisons between different groups of subjects with normal and abnormal gait. Since the presented methods can be used with any foot-worn inertial sensors, or even combined with other systems, we believe our work to open the door to objective and quantitative routine gait evaluations in clinical settings for supporting diagnosis. Furthermore, the present studies have high potential for further research related to rehabilitation based on real-time devices, the investigation of new parameters' significance and their association with various mobility diseases, as well as for the evaluation of clinical interventions

Proceedings SIAMOC 2019

Il congresso annuale della Società Italiana di Analisi del Movimento in Clinica, giunto quest'anno alla sua ventesima edizione, ritorna a Bologna, che già ospitò il terzo congresso nazionale nel 2002. Il legame tra Bologna e l'analisi del movimento è forte e radicato, e trova ampia linfa sia nel contesto accademico che nel ricco panorama di centri clinici d'eccellenza. Il congresso SIAMOC, come ogni anno, è l’occasione per tutti i professionisti dell’ambito clinico, metodologico ed industriale di incontrarsi, presentare le proprie ricerche e rimanere aggiornati sulle più recenti innovazioni nell’ambito dell’applicazione clinica dei metodi di analisi del movimento. Questo ha contribuito, in questi venti anni, a fare avanzare sensibilmente la ricerca italiana nel settore, conferendole un respiro ed un impatto internazionale, e a diffonderne l'applicazione clinica per migliorare la valutazione dei disordini motori, aumentare l'efficacia dei trattamenti attraverso l'analisi quantitativa dei dati e una più focalizzata pianificazione dei trattamenti, ed inoltre per quantificare i risultati delle terapie correnti

Proceedings SIAMOC 2019

Il congresso annuale della Società Italiana di Analisi del Movimento in Clinica, giunto quest'anno alla sua ventesima edizione, ritorna a Bologna, che già ospitò il terzo congresso nazionale nel 2002. Il legame tra Bologna e l'analisi del movimento è forte e radicato, e trova ampia linfa sia nel contesto accademico che nel ricco panorama di centri clinici d'eccellenza. Il congresso SIAMOC, come ogni anno, è l’occasione per tutti i professionisti dell’ambito clinico, metodologico ed industriale di incontrarsi, presentare le proprie ricerche e rimanere aggiornati sulle più recenti innovazioni nell’ambito dell’applicazione clinica dei metodi di analisi del movimento. Questo ha contribuito, in questi venti anni, a fare avanzare sensibilmente la ricerca italiana nel settore, conferendole un respiro ed un impatto internazionale, e a diffonderne l'applicazione clinica per migliorare la valutazione dei disordini motori, aumentare l'efficacia dei trattamenti attraverso l'analisi quantitativa dei dati e una più focalizzata pianificazione dei trattamenti, ed inoltre per quantificare i risultati delle terapie correnti