Ipsilateral evaluation of the transverse sinus: Transcranial color-coded sonography approach in comparison with magnetic resonance venography

SummaryIntroductionThe ultrasound examination of intracranial venous structures by transcranial color-coded sonography (TCCS) is a validated and standardized application. Similarly some intracranial venous sinuses are known for their relatively low insonation rate, as straight sinus (SRS) and transverse sinus (TS), ranging from 35% to 73%. The relatively high frequency of hypoplasia of TS can partially take account for these data. The aim of this study is to evaluate the feasibility of this approach in a standard TCCS examination, in comparison with magnetic resonance (MR) findings by using the Virtual Navigator system.Patients and methodsThe standardized approach to the TS was a contralateral insonation, starting to the SRS plane and angulating downwards the probe. In this way it is possible to insonate the proximal segment of the contralateral TS. We proposed a new approach with an extreme downwards tilting and a slow opposite angulation of the probe for examining the ispilateral TS. Forty consecutive subjects were chosen among patients who underwent standard TCCS examinations at our lab and had a suitable temporal acoustic window, and a recently performed MR venography. The contralateral TS insonation rate was compared with the ipsilateral one.Results and discussionThe insonation rate was 61/80 (76.25%) for the contralateral TS and 75/80 (93.75%) for the ipsilateral approach. Two of 5 not detectable TS were aplasic in MR venography and the others were not identified by a poor acoustic window.ConclusionsThe ipsilateral approach could be associated to the contralateral standard study for insonating the TS

The role of accumulation of iron and other metals in the pathophysiology of neurodegenerative diseases

Vliv kumulace kovů v patofyziologii neurodegenerativních onemocnění je dlouhodobě diskutovaným tématem zejména kvůli možnosti ovlivnění pomocí chelátů. Ačkoliv mechanismy neurodegenerace jsou dobře prozkoumané, role kovů v nich je stále nejasná. Hlavním úskalím je omezená vyšetřitelnost koncentrace kovů v CNS in vivo. Nejdostupnější neinvazivní metodou je magnetická rezonance (MR). Naším cílem bylo posouzení možností užití transkraniální sonografie (TCS) v diagnostice neurodegenerativních onemocnění a bližší zkoumání podkladu echogenity. V první studii jsme pomocí fúze TCS se snímky MR ověřili přesnou lokalizaci běžně hodnocených struktur (zejména substantia nigra a nucleus lentiformis) a zaměřili se na přítomnost ložiskových strukturálních změn potenciálně ovlivňujících TCS nálezy u Wilsonovy nemocí (WN) a Parkinsonovy nemocí (PN). Získané snímky MR byly použity i k semikvantitativnímu porovnání s TCS. Ačkoliv se potvrdila vysoká přínosnost TCS v diferenciální diagnostice WN a měla by se stát běžným screeningovým vyšetřením extrapyramidových pacientů s atypickým obrazem, zjevnou vazbu na depozita kovů se nepodařilo prokázat. Druhá studie využila získaných výsledků fúze k navržení měření echogenity další mozkové struktury − inzulární oblasti − pro diferenciální diagnostiku WN. V poslední studii...The role of metal accumulation in the pathophysiology of neurodegenerative diseases has been a hot topic in recent years due to the possibility of its treatment by chelating agents. Although the mechanisms of neurodegeneration are well known, the role of metal accumulation is still unclear. The main limitation are unsatisfactory methods for in vivo metal imaging; the most widely used technique is magnetic resonance imaging (MRI). Our aim was to assess the possibility of using transcranial sonography (TCS) in differential diagnosis of neurodegenerative diseases and to further explore the underlying factors of echogenicity. In the first study, using TCS fusion with MRI, we focused on location verification of the commonly assessed structures (substantia nigra and nucleus lentiformis) and exclusion of possible focal structural changes affecting the echogenicity in WD and PD patients. Moreover, obtained MRI were used for semi-quantitative comparison with TCS images. Although TCS has been confirmed to be highly beneficial in differential diagnosis of Wilson's disease and it should be recommended as a screening method for extrapyramidal patients with atypical course of the disease, the direct relationship between TCS and metal deposits could not be proven. The obtained results from the ultrasound fusion...Neurologická klinika 1. LF UK a VFNDepartment of Neurology First Faculty of Medicine and General University Hospital1. lékařská fakultaFirst Faculty of Medicin

Patient Specific Systems for Computer Assisted Robotic Surgery Simulation, Planning, and Navigation

The evolving scenario of surgery: starting from modern surgery, to the birth of medical imaging and the introduction of minimally invasive techniques, has seen in these last years the advent of surgical robotics. These systems, making possible to get through the difficulties of endoscopic surgery, allow an improved surgical performance and a better quality of the intervention. Information technology contributed to this evolution since the beginning of the digital revolution: providing innovative medical imaging devices and computer assisted surgical systems. Afterwards, the progresses in computer graphics brought innovative visualization modalities for medical datasets, and later the birth virtual reality has paved the way for virtual surgery. Although many surgical simulators already exist, there are no patient specific solutions. This thesis presents the development of patient specific software systems for preoperative planning, simulation and intraoperative assistance, designed for robotic surgery: in particular for bimanual robots that are becoming the future of single port interventions. The first software application is a virtual reality simulator for this kind of surgical robots. The system has been designed to validate the initial port placement and the operative workspace for the potential application of this surgical device. Given a bimanual robot with its own geometry and kinematics, and a patient specific 3D virtual anatomy, the surgical simulator allows the surgeon to choose the optimal positioning of the robot and the access port in the abdominal wall. Additionally, it makes possible to evaluate in a virtual environment if a dexterous movability of the robot is achievable, avoiding unwanted collisions with the surrounding anatomy to prevent potential damages in the real surgical procedure. Even if the software has been designed for a specific bimanual surgical robot, it supports any open kinematic chain structure: as far as it can be described in our custom format. The robot capabilities to accomplish specific tasks can be virtually tested using the deformable models: interacting directly with the target virtual organs, trying to avoid unwanted collisions with the surrounding anatomy not involved in the intervention. Moreover, the surgical simulator has been enhanced with algorithms and data structures to integrate biomechanical parameters into virtual deformable models (based on mass-spring-damper network) of target solid organs, in order to properly reproduce the physical behaviour of the patient anatomy during the interactions. The main biomechanical parameters (Young's modulus and density) have been integrated, allowing the automatic tuning of some model network elements, such as: the node mass and the spring stiffness. The spring damping coefficient has been modeled using the Rayleigh approach. Furthermore, the developed method automatically detect the external layer, allowing the usage of both the surface and internal Young's moduli, in order to model the main parts of dense organs: the stroma and the parenchyma. Finally the model can be manually tuned to represent lesion with specific biomechanical properties. Additionally, some software modules of the simulator have been properly extended to be integrated in a patient specific computer guidance system for intraoperative navigation and assistance in robotic single port interventions. This application provides guidance functionalities working in three different modalities: passive as a surgical navigator, assistive as a guide for the single port placement and active as a tutor preventing unwanted collision during the intervention. The simulation system has beed tested by five surgeons: simulating the robot access port placemen, and evaluating the robot movability and workspace inside the patient abdomen. The tested functionalities, rated by expert surgeons, have shown good quality and performance of the simulation. Moreover, the integration of biomechanical parameters into deformable models has beed tested with various material samples. The results have shown a good visual realism ensuring the performance required by an interactive simulation. Finally, the intraoperative navigator has been tested performing a cholecystectomy on a synthetic patient mannequin, in order to evaluate: the intraoperative navigation accuracy, the network communications latency and the overall usability of the system. The tests performed demonstrated the effectiveness and the usability of the software systems developed: encouraging the introduction of the proposed solution in the clinical practice, and the implementation of further improvements. Surgical robotics will be enhanced by an advanced integration of medical images into software systems: allowing the detailed planning of surgical interventions by means of virtual surgery simulation based on patient specific biomechanical parameters. Furthermore, the advanced functionalities offered by these systems, enable surgical robots to improve the intraoperative surgical assistance: benefitting of the knowledge of the virtual patient anatomy