Urs Eisenmann

Semantic Focusing Allows Fully Automated Single-Layer Slide Scanning of Cervical Cytology Slides

Liquid-based cytology (LBC) in conjunction with Whole-Slide Imaging (WSI) enables the objective and sensitive and quantitative evaluation of biomarkers in cytology. However, the complex three-dimensional distribution of cells on LBC slides requires manual focusing, long scanning-times, and multi-layer scanning. Here, we present a solution that overcomes these limitations in two steps: first, we make sure that focus points are only set on cells. Secondly, we check the total slide focus quality. From a first analysis we detected that superficial dust can be separated from the cell layer (thin layer of cells on the glass slide) itself. Then we analyzed 2,295 individual focus points from 51 LBC slides stained for p16 and Ki67. Using the number of edges in a focus point image, specific color values and size-inclusion filters, focus points detecting cells could be distinguished from focus points on artifacts (accuracy 98.6%). Sharpness as total focus quality of a virtual LBC slide is computed from 5 sharpness features. We trained a multi-parameter SVM classifier on 1,600 images. On an independent validation set of 3,232 cell images we achieved an accuracy of 94.8% for classifying images as focused. Our results show that single-layer scanning of LBC slides is possible and how it can be achieved. We assembled focus point analysis and sharpness classification into a fully automatic, iterative workflow, free of user intervention, which performs repetitive slide scanning as necessary. On 400 LBC slides we achieved a scanning-time of 13.9±10.1 min with 29.1±15.5 focus points. In summary, the integration of semantic focus information into whole-slide imaging allows automatic high-quality imaging of LBC slides and subsequent biomarker analysis.

Approach to intraoperative electromagnetic navigation in orthognathic surgery: A phantom skull based trial.

INTRODUCTION Intraoperative guidance using electromagnetic navigation is an upcoming method in maxillofacial surgery. However, due to their unwieldy structures, especially the line-of-sight problem, optical navigation devices are not used for daily orthognathic surgery. Therefore, orthognathic surgery was simulated on study phantom skulls, evaluating the accuracy and handling of a new electromagnetic tracking system. MATERIAL AND METHODS Le-Fort I osteotomies were performed on 10 plastic skulls. Orthognathic surgical planning was done in the conventional way using plaster models. Accuracy of the gold standard, splint-based model surgery versus an electromagnetic tracking system was evaluated by measuring the actual maxillary deviation using bimaxillary splints and preoperative and postoperative cone beam computer tomography imaging. The distance of five anatomical marker points were compared pre- and postoperatively. RESULTS The electromagnetic tracking system was significantly more accurate in all measured parameters compared with the gold standard using bimaxillary splints (p < 0.01). The data shows a discrepancy between the model surgical plans and the actual correction of the upper jaw of 0.8 mm. Using the electromagnetic tracking, we could reduce the discrepancy of the maxillary transposition between the planned and actual orthognathic surgery to 0.3 mm on average. DISCUSSION The data of this preliminary study shows a high level of accuracy in surgical orthognathic performance using electromagnetic navigation, and may offer greater precision than the conventional plaster model surgery with bimaxillary splints. CONCLUSION This preliminary work shows great potential for the establishment of an intraoperative electromagnetic navigation system for maxillofacial surgery.

Electromagnetic navigated condylar positioning after high oblique sagittal split osteotomy of the mandible: a guided method to attain pristine temporomandibular joint conditions?

OBJECTIVES Reproduction of the exact preoperative proximal-mandible position after osteotomy in orthognathic surgery is difficult to achieve. This clinical pilot study evaluated an electromagnetic (EM) navigation system for condylar positioning after high-oblique sagittal split osteotomy (HSSO). STUDY DESIGN After HSSO as part of 2-jaw surgery, the position of 10 condyles was intraoperatively guided by an EM navigation system. As controls, 10 proximal segments were positioned by standard manual replacement. Accuracy was measured by pre- and postoperative cone beam computed tomography imaging. RESULTS Overall, EM condyle repositioning was equally accurate compared with manual repositioning (P > .05). Subdivided into 3 axes, significant differences could be identified (P < .05). Nevertheless, no significantly and clinically relevant dislocations of the proximal segment of either the EM or the manual repositioning method could be shown (P > .05). CONCLUSIONS This pilot study introduces a guided method for proximal segment positioning after HSSO by applying the intraoperative EM system. The data demonstrate the high accuracy of EM navigation, although manual replacement of the condyles could not be surpassed. However, EM navigation can avoid clinically hidden, severe malpositioning of the condyles.

Volume Rendering for Planning and Performing Neurosurgical Interventions

Volume rendering is widely accepted as a method for generating high quality visualizations for different medical purposes. Due to the rapid development of graphics hardware, volume rendering techniques nowadays can be used to interactively render morphological CT or MR data. Therefore these methods are getting more and more interesting for planning and performing surgical interventions.

Integrated Software for Fusion of CT- and Rotational Angiography for Image Guided Neurosurgery on Cerebral Aneurysms

Aneurysms of intracerebral arteries may be a source of often life-thraetening subarachnoid bleedings (SAB) that require an immediate course of action. Therefore fast and accurate diagnostics and planning of interventions is crucial. For the case of neurosurgical clipping of the aneurysm we presented a framework for optimised fusion of the routinely available imaging modalities CT- and conventional Rotational Angiography (CTA and RA) and integration with a commercial navigation system. To gain access to these benefits, however, the surgeon had to rely on a number of people providing him with the data and operating the various software tools.

Tracking und Visualisierung von Elektrodengrids für kortikale Ableitungen in der Neurochirurgie

Bei neurochirurgischen Eingriffen spielen Elektrodengrids zur Messung kortikaler Ableitungen eine wichtige Rolle. Um die erhaltenen Ergebnisse bewerten zu konnen ist es wichtig die genaue Position jeder einzelnen Elektrode zu kennen. In diesem Artikel wird ein Verfahren zur Positionsbestimmung von Elektrodengrids vorgestellt. Mittels eines Trackingsystems werden die Positionen weniger charakterisierender Elektroden ermittelt. Die Positionen der restlichen Elektroden werden durch ein Interpolationsverfahren berechnet. Der Trackingvorgang sowie die Visualisierung der Elektrodengrids wurde in das Operationsplanungsystem MOPS 3D (Multimodales Operations-Planungs-System) integriert[1]. In diesem System konnen den einzelnen Elektroden abhangig von der jeweiligen Aktivitat Farbkodierungen zugeordnet werden.