Bigrams and the richness of the stimulus.

Abstract Recent challenges to Chomsky's poverty of the stimulus thesis for language acquisition suggest that children's primary data may carry "indirect evidence" about linguistic constructions despite containing no instances of them. Indirect evidence is claimed to suffice for grammar acquisition, without need for innate knowledge. This article reports experiments based on those o

Preoperative Magnetic Resonance and Intraoperative Ultrasound Fusion Imaging for Real-Time Neuronavigation in Brain Tumor Surgery = Präoperative MRI- und intraoperative Ultraschallfusion für die Echtzeit-Neuronavigation in der Neurochirurgie von Hirntumoren

Purpose: Brain shift and tissue deformation during surgery for intracranial lesions are the main actual limitations of neuro-navigation (NN), which currently relies mainly on preoperative imaging. Ultrasound (US), being a real-time imaging modality, is becoming progressively more widespread during neurosurgical procedures, but most neurosurgeons, trained on axial computed tomography (CT) and magnetic resonance imaging (MRI) slices, lack specific US training and have difficulties recognizing anatomic structures with the same confidence as in preoperative imaging. Therefore real-time intraoperative fusion imaging (FI) between preoperative imaging and intraoperative ultrasound (ioUS) for virtual navigation (VN) is highly desirable. We describe our procedure for real-time navigation during surgery for different cerebral lesions. Materials and Methods: We performed fusion imaging with virtual navigation for patients undergoing surgery for brain lesion removal using an ultrasound-based real-time neuro-navigation system that fuses intraoperative cerebral ultrasound with preoperative MRI and simultaneously displays an MRI slice coplanar to an ioUS image. Results: 58 patients underwent surgery at our institution for intracranial lesion removal with image guidance using a US system equipped with fusion imaging for neuro-navigation. In all cases the initial (external) registration error obtained by the corresponding anatomical landmark procedure was below 2mm and the craniotomy was correctly placed. The transdural window gave satisfactory US image quality and the lesion was always detectable and measurable on both axes. Brain shift/deformation correction has been successfully employed in 42 cases to restore the co-registration during surgery. The accuracy of ioUS/MRI fusion/overlapping was confirmed intraoperatively under direct visualization of anatomic landmarks and the error was < \u30083mm in all cases (100%). Conclusion: Neuro-navigation using intraoperative US integrated with preoperative MRI is reliable, accurate and user-friendly. Moreover, the adjustments are very helpful in correcting brain shift and tissue distortion. This integrated system allows true real-time feedback during surgery and is less expensive and time-consuming than other intraoperative imaging techniques, offering high precision and orientation.Brain Shift und Gewebeverschiebung w\ue4hrend der chirurgischen Entfernung intrakranialer Raumforderungen sind die limitierenden Faktoren bei der Neuronavigation (NN), welche aktuell haupts\ue4chlich pr\ue4operative Bilder einsetzt. Ultraschall (US) als Echtzeit-Bildgebung wird bei neurochirurgischen Prozeduren zunehmend angewandt. Vielen Neurochirurgen fehlt aber die US Expertise, da schon in der Ausbildung standarisierte (typisch axiale) CT und MRT Schnittbilder f\ufcr die Navigation bevorzugt eingesetzt werden und somit die Sicherheit bei der sonografischen Identifikation anatomischer Strukturen fehlt. Daher ist eine intraoperative Echtzeitfusion zwischen pr\ue4operativen CT bzw. MRT Bildern und intraoperativem Ultraschall (ioUS) im Rahmen der virtuellen Navigation (VN) au ferordentlich w\ufcnschenswert. Wir pr\ue4sentieren hier die bei uns angewandte Methode f\ufcr dieEchtzeitnavigation bei der Entfernung verschiedener Hirntumoren. Material und Methoden: Wir wandten die Bildfusion mit virtueller Navigation bei der chirurgischen Entfernung von Hirntumoren an. Zum Einsatz kam ein Neuronavigationssystem, welches intraoperative Ultraschallbilder mit pr\ue4operativen MRT Bildern in Echtzeit \ufcberlagert und zu jedem US Bild simultan die dazu passende ko-planare MRTSchnittebene anzeigt. Ergebnisse: Die US-basierte Neuronavigation wurde bei der Operation von 58 Patienten mit Hirntumoren eingesetzt. In allen F\ue4llen war der Fehler der initialen (externen) Registrierung, welche anhand von anatomischen Landmarken erfolgte, unterhalb von 2mm und die Kraniotomie konnte korrekt angesetzt werden. Die Bildqualit\ue4t des transduralen Ultraschalls war gut und die L\ue4sion konnte bei allen Patienten detektiert und in allen Achsen vermessen werden. Die Korrektur von Brain Shift sowie Gewebeverschiebung gelang erfolgreich in 42 F\ue4llen zur Wiederherstel lung der intraoperativen Co-Registrierung. Die Genauigkeit der cberlagerung von ioUS und MRT wurde intraoperativ anhand der Visualisierung anatomischerLandmarken \ufcberpr\ufcft und der Fehler lag in allen F\ue4llen (100 %) unterhalb von 3mm. Schlussfolgerung: Neuronavigation mit Hilfe von in pr\ue4operative MRT Bilder integrierten intraoperativen US Bildern ist eine zuverl\ue4ssige, genaue und anwenderfreundliche neue Technologie. Brain Shift und Gewebeverlagerungen k\uf6nnen anhand verschiedener Einstellungsm\uf6glichkeiten am System erfolgreich intraoperativ korrigiert werden. Das integrierte System erm\uf6glicht eine intraoperative cberpr\ufcfung der Navigation in Echtzeit und ist dabei kosteng\ufcnstiger und weniger Zeit aufw\ue4ndig als andere intraoperative Bild-gebende Verfahren, trotzdem aber hoch pr\ue4zise

Contrast-enhanced MR Imaging versus Contrast-enhanced US: A Comparison in Glioblastoma Surgery by Using Intraoperative Fusion Imaging

Purpose To compare contrast material enhancement of glioblastoma multiforme (GBM) with intraoperative contrast-enhanced ultrasonography (US) versus that with preoperative gadolinium-enhanced T1-weighted magnetic resonance (MR) imaging by using real-time fusion imaging. Materials and Methods Ten patients with GBM were retrospectively identified by using routinely collected, anonymized data. Navigated contrast-enhanced US was performed after intravenous administration of contrast material before tumor resection. All patients underwent tumor excision with navigated intraoperative US guidance with use of fusion imaging between real-time intraoperative US and preoperative MR imaging. With use of fusion imaging, glioblastoma contrast enhancement at contrast-enhanced US (regarding location, morphologic features, margins, dimensions, and pattern) was compared with that at gadolinium-enhanced T1-weighted MR imaging. Results Fusion imaging for virtual navigation enabled matching of real-time contrast-enhanced US scans to corresponding coplanar preoperative gadolinium-enhanced T1-weighted MR images in all cases, with a positional discrepancy of less than 2 mm. Contrast enhancement of gadolinium-enhanced T1-weighted MR imaging and contrast-enhanced US was superimposable in all cases with regard to location, margins, dimensions, and morphologic features. The qualitative analysis of contrast enhancement pattern demonstrated a similar distribution in contrast-enhanced US and gadolinium-enhanced T1-weighted MR imaging in nine patients: Seven lesions showed peripheral inhomogeneous ring enhancement, and two lesions showed a prevalent nodular pattern. In one patient, the contrast enhancement pattern differed between the two modalities: Contrast-enhanced US showed enhancement of the entire bulk of the tumor, whereas gadolinium-enhanced T1-weighted MR imaging demonstrated peripheral contrast enhancement. Conclusion Glioblastoma contrast enhancement with contrast-enhanced US is superimposable on that provided with preoperative gadolinium-enhanced T1-weighted MR imaging regarding location, margins, morphologic features, and dimensions, with a similar enhancement pattern in most cases. Thus, contrast-enhanced US is of potential use in the surgical management of GBM

Compensating control participants when the intervention is of significant value: experience in Guatemala, India, Peru and Rwanda

The Household Air Pollution Intervention Network (HAPIN) trial is a randomised controlled trial in Guatemala, India, Peru and Rwanda to assess the health impact of a clean cooking intervention in households using solid biomass for cooking. The HAPIN intervention—a liquefied petroleum gas (LPG) stove and 18-month supply of LPG—has significant value in these communities, irrespective of potential health benefits. For control households, it was necessary to develop a compensation strategy that would be comparable across four settings and would address concerns about differential loss to follow-up, fairness and potential effects on household economics. Each site developed slightly different, contextually appropriate compensation packages by combining a set of uniform principles with local community input. In Guatemala, control compensation consists of coupons equivalent to the LPG stove’s value that can be redeemed for the participant’s choice of household items, which could include an LPG stove. In Peru, control households receive several small items during the trial, plus the intervention stove and 1 month of fuel at the trial’s conclusion. Rwandan participants are given small items during the trial and a choice of a solar kit, LPG stove and four fuel refills, or cash equivalent at the end. India is the only setting in which control participants receive the intervention (LPG stove and 18 months of fuel) at the trial’s end while also being compensated for their time during the trial, in accordance with local ethics committee requirements. The approaches presented here could inform compensation strategy development in future multi-country trials

Registration of 3D U/S and CT images of the Prostate

Radiotherapy is a rapidly growing cancer treatment technique. In brachytherapy -- one radiotherapy treatment technique -- pre- and post-planning is usually carried out using CT imaging. As CT scanners cannot easily be moved from one operation room to an other and as CT does not have real-time imaging capability, alternative imaging modalities are needed to realize the vision of image guided surgery. Ultrasound (U/S) is such an alternative imaging modality. For the comparison of U/S and CT image fusion is very useful

3-D Visualization of MRA Data

After analyzing several possible illumination methods, we selected the maximum intensity projection as the method giving the most accurate results. In order to visualize small structures (thin veins), we apply the principles of the sampling theory in order to supply a gapless covering of the vein volume and to avoid sampling errors, while in the same time minimizing the computational effort. Line-oriented filtering is used to enhance the vein contrast. Visual cues like stereo, depth-of-field, depth cueing, prespective, rotation & parallex are employed to significantly increase the depth perception. As an alternative, the usual slice-oriented presentation of the dataset can be presented on the workstation screen, if desired by the physician. Last not least, our approach is fast enough to provide volumetric images of high quality within a few seconds of computation on a commercial modern workstation

Unterstützung der Krebstherapie

Das weltweit zugelassene Simulationsverfahren EXOMIO erhöht die Präzision und Qualität einer Strahlentherapie und gestaltet den Behandlungsprozess schonend für den Patienten und flexibel für den Arzt