Radiation dose reduction in computer assisted navigation for functional endoscopic sinus surgery--cadaver head experiments and clinical implementation

Computed tomography based navigation for endoscopic sinus surgery is inflationary used despite of major public concern about iatrogenic radiation induced cancer risk. Studies on dose reduction for CAS-CT are almost nonexistent. We validate the use of radiation dose reduced CAS-CT for clinically applied surface registration.

Comparison of three optical tracking systems in a complex navigation scenario

Three-dimensional rotational X-ray imaging with the SIREMOBIL Iso-C3D (Siemens AG, Medical Solutions, Erlangen, Germany) has become a well-established intra-operative imaging modality. In combination with a tracking system, the Iso-C3D provides inherently registered image volumes ready for direct navigation. This is achieved by means of a pre-calibration procedure. The aim of this study was to investigate the influence of the tracking system used on the overall navigation accuracy of direct Iso-C3D navigation. Three models of tracking system were used in the study: Two Optotrak 3020s, a Polaris P4 and a Polaris Spectra system, with both Polaris systems being in the passive operation mode. The evaluation was carried out at two different sites using two Iso-C3D devices. To measure the navigation accuracy, a number of phantom experiments were conducted using an acrylic phantom equipped with titanium spheres. After scanning, a special pointer was used to pinpoint these markers. The difference between the digitized and navigated positions served as the accuracy measure. Up to 20 phantom scans were performed for each tracking system. The average accuracy measured was 0.86 mm and 0.96 mm for the two Optotrak 3020 systems, 1.15 mm for the Polaris P4, and 1.04 mm for the Polaris Spectra system. For the Polaris systems a higher maximal error was found, but all three systems yielded similar minimal errors. On average, all tracking systems used in this study could deliver similar navigation accuracy. The passive Polaris system showed ? as expected ? higher maximal errors; however, depending on the application constraints, this might be negligible.

Identification of venous variants in the pineal region with three-dimensional preoperative magnetic resonance imaging navigation in patients harbouring tumors in this area: significance for surgical approach to the lesion

The purpose of this study was to identify the anatomy of pineal region venous complex using neuronavigation software when distorted by the presence of a space-occupying lesion and to describe the anatomical relationship between lesion and veins. Moreover we discuss its influence on the choice of the surgical strategy.

Can handheld micropower impulse radar technology be used to detect pneumothorax? Initial experience in a European trauma centre

BACKGROUND: Pneumothoraces are a common injury pattern in emergency medicine. Rapid and safe identification can reduce morbidity and mortality. A new handheld, battery powered device, the Pneumoscan (CE 561036, PneumoSonics Inc., Cleveland, OH, USA), using micropower impulse radar (MIR) technology, has recently been introduced in Europe for the rapid and reliable detection of PTX. However, this technology has not yet been tested in trauma patients. This is the first quality control evaluation to report on emergency room performance of a new device used in the trauma setting. MATERIAL AND METHODS: This study was performed at a Level I trauma centre in Switzerland. All patients with thoracic trauma and undergoing chest X-ray and CT-scan were eligible for the study. Readings were performed before the chest X-ray and CT scan. The patients had eight lung fields tested (four on each side). All readings with the Pneumoscan were performed by two junior residents in our department who had previously received an instructional tutorial of 15min. The qualitative MIR results were blinded, and stored on the device. We then compared the results of the MIR to those of the clinical examination, chest X-ray and CT-scan. RESULTS: 50 patients were included, with a mean age of 46 (SD 17) years. Seven patients presented with PTX diagnosed by CT; six of these were detected by Pneumoscan, leading to an overall sensitivity of 85.7 (95% confidence interval 42.1-99.6)%. Only two of seven PTX were found during clinical examination and on chest X-ray (sensitivity 28.6 (95% CI 3.7-71.0)%). Of the remaining 43 of 50 patients without PTX, one false-positive PTX was found by the Pneumoscan, resulting in a specificity of 97.7 (95% CI 87.7-99.9)%. DISCUSSION: The Pneumoscan is an easy to use handheld technology with reliable results. In this series, the sensitivity to detect a PTX by the Pneumoscan was higher than by clinical examination and chest X-ray. Further studies with higher case numbers and a prospective study design are needed to confirm our findings.

Depiction of small veins draining into the vein of galen using preoperative 3-dimensional navigation in living patients

OBJECTIVE: The purpose of this study was to delineate the anatomy of the precentral cerebellar vein, superior vermian vein, and internal occipital vein using reconstructions of computed tomographic and magnetic resonance imaging scans with navigation software. These data were compared with previous anatomic and angiographic findings to show the resolution and accuracy of the system. METHODS: We retrospectively reviewed 100 patients with intracranial pathologies (50 computed tomographic scans with contrast and 50 magnetic resonance imaging scans with gadolinium) using a neuronavigation workstation for 3-dimensional reconstruction. Particular attention was paid to depiction of the precentral cerebellar vein, superior vermian vein, and internal occipital vein. The data were reviewed and analyzed. RESULTS: The precentral cerebellar vein, superior vermian vein, and its tributary, the supraculminate vein, were depicted in 52 (52%) patients. The internal occipital vein was delineated on 99 (49.5%) sides and joined the basal vein and vein of Galen in 39 (39.4%) and 60 (60.6%) hemispheres, respectively. Comparing these results with previous angiographic studies, the ability of the neuronavigation system for depicting these vessels is similar to that of digital subtraction angiography. CONCLUSION: This study illustrates the possibility of depicting the small vessels draining into the pineal region venous complex using 3-dimensional neuronavigation with an accuracy comparable to that of digital subtraction angiography. This tool provides important information for both surgical planning and intraoperative orientation.

Supporting Task-oriented Navigation in IDEs with Configurable HeatMaps

Mainstream IDEs generally rely on the static structure of a software project to support browsing and navigation. We propose HeatMaps, a simple but highly configurable technique to enrich the way an IDE displays the static structure of a software system with additional kinds of information. A heatmap highlights software artifacts according to various metric values, such as bright red or pale blue, to indicate their potential degree of interest. We present a prototype system that implements heatmaps, and we describe an initial study that assesses the degree to which different heatmaps effectively guide developers in navigating software.