A medical volume visualization system supporting head-tracked stereoscopic viewing and direct 3D interaction

We have developed an experimental medical volume visualization system supporting head-tracked stereoscopic viewing registered with direct 3D interaction. Our aim is to assess the suitability of these techniques for surgical planning tasks in real medical settings. In particular, vascular surgeons examining the distal site of the aneurysmatic sack are assisted by visualizing the artery aneurysm in depth. A better understanding of such complex spatial structures is achieved by incorporatingmotion parallax and stereoscopic cues to depth perception not available from static images. Our display when positioned as a surgical table provides theimpression of looking down at the patient in a naturalistic way. With simple head motions, good positions for observing the pathology are quickly established.1997-09Pisa, ItalyProceedings 15th International EuroPACS Meetin

Visualizzazione volumetrica diretta interattiva con effetti di illuminazione mediante Register Combiner OpenGL

In diversi ambiti scientifici e industriali, la sempre più frequente acquisizione di dati volumetrici fa crescere la domanda di potenti tool per la loro visualizzazione, analisi e manipolazione interattiva. In questo rapporto presentiamo una tecnica di visualizzazione volumetrica diretta che consente l’applicazione del modello di illuminazione di Phong in tempo reale. La tecnica implementa il modello ottico di assorbimento + emissione eseguendo in tempo reale campionamento, mapping e integrazione delle proprietà ottiche esclusivamente attraverso funzionalità base di OpenGL 1.2. L’implementazione del modello di Phong, basato sul calcolo del gradiente di opacità, e eseguito in tempo reale utilizzando i Register Combiner. I vincoli del real-time sono soddisfatti anche grazie alla applicazione di una tecnica di accelerazione multipass basata sulla copia rapida di informazioni dal framebuffer alla memoria di texture, offerta già dalla versione 1.1 di OpenGL

Recent results in rendering massive models on horizontal parallax-only light field displays

In this contribution, we report on specialized out-of-core multiresolution real-time rendering systems able to render massive surface and volume models on a special class of horizontal parallax-only light field displays. The displays are based on a specially arranged array of projectors emitting light beams onto a holographic screen, which then makes the necessary optical transformation to compose these beams into a continuous 3D view. The rendering methods employ state-of-the-art out-of-core multiresolution techniques able to correctly project geometries onto the display and to dynamically adapt model resolution by taking into account the particular spatial accuracy characteristics of the display. The programmability of latest generation graphics architectures is exploited to achieve interactive performance. As a result, multiple freely moving naked-eye viewers can inspect and manipulate virtual 3D objects that appear to them floating at fixed physical locations. The approach provides rapid visual understanding of complex multi-gigabyte surface models and volumetric data sets.304-30

Catheter insertion simulation with co-registered direct volume rendering and haptic feedback

We have developed an experimental catheter insertion simulation system supporting head-tracked stereoscopic viewing of volumetric anatomic reconstructions registered with direct haptic 3D interaction. The system takes as input data acquired with standard medical imaging modalities and regards it as a visual and haptic environment whose parameters are interactively defined using look-up tables. The system's display, positioned like a surgical table, provide a realistic impression of looking down at the patient. Measuring head motion via a six degrees-of-freedom head tracker, good positions to observe the anatomy and identify the catheter insertion point are quickly established with simple head motion. By generating appropriate stereoscopic images and co-registering physical and virtual spaces beforehand, volumes appear at fixed physical positions and it is possible to control catheter insertion via direct interaction with a PHANToM haptic device. During the insertion procedure, the system provides perception of the effort of penetration and deviation inside the traversed tissues. Semi-transparent volumetric rendering augment the sensory feedback with the visual indication of the inserted catheter position inside the body.96-9

Catheter insertion simulation with combined visual and haptic feedback

We have developed an experimental catheter insertion system supporting head-tracked stereoscopic viewing of volumetric reconstruction registered with direct haptic 3D interaction. The system takes as input patient data acquired with standard medical imaging modalities and regards it as a visual and haptic environment whose parameters are defined using look-up tables. By means of a mirror, the screen seems to be positioned like a surgical table providing the impression of looking down at the patient in a natural way. Co-registering physical and virtual spaces beforehand means that the patient appears at a fixed physical positionj on the surgical table and inside the workspace of the PHANToM device which controls catheter insertion. During the insertion procedure the system provides perception of the force of penetration and positional deviation of the inserted catheter

Advances in massive model visualization in the CYBERSAR project

We provide a survey of the major results obtained within the CYBERSAR project in the area of massive data visualization. Despite the impressive improvements in graphics and computational hardware performance, interactive visualization of massive models still remains a challenging problem. To address this problem, we developed methods that exploit the programmability of latest generation graphics hardware, and combine coarse-grained multiresolution models, chunk-based data management with compression, incremental view-dependent level-of-detail selection, and visibility culling. The models that can be interactively rendered with our methods range from multi-gigabyte-sized datasets for general 3D meshes or scalar volumes, to terabyte-sized datasets in the restricted 2.5D case of digital terrain models. Such a performance enables novel ways of exploring massive datasets. In particular, we have demonstrated the capability of driving innovative light field displays able of giving multiple freely moving naked-eye viewers the illusion of seeing and manipulating massive 3D objects with continuous viewer-independent parallax.233-23

Un sistema multiprocessore per la simulazione della chirurgia sull'osso temporale

Nel presente articolo si presenta un simulatore per l’addestramento alla chirurgia dell’osso temporale. Il sistema si basa su modelli volumetrici direttamente derivati da dati 3D di TAC e MR. Il ritorno di sensazioni in tempo reale viene fornito all’utente per mezzo di tecniche di rendering volumetrico e di modellazione di sensazioni aptiche. I vincoli nelle prestazioni imposti dal sistema percettivo umano sono soddisfatti sfruttando il parallelismo attraverso il disaccoppiamento della simulazione su una piattaforma di PC multi-processore. In quest’articolo, vengono descritti in dettaglio i componenti del sistema e lo stato attuale dell’integrazione dei medesimi

Mastoidectomy simulation with combined visual and haptic feedback

Mastoidectomy is one of the most common surgical procedures relating to the petrous bone. In this paper we describe our preliminary results in the realization of a virtual reality mastoidectomy simulator. Our system is designed to work on patient-specific volumetric object models directly derived from 3D CT and MRI images. The paper summarizes the detailed task analysis performed in order to define the system requirements, introduces the architecture of the prototype simulator, and discusses the initial feedback received from selected end users.17-2

Towards a psychophysical evaluation of a surgical simulator for bone-burring

The CRS4 experimental bone-burr simulator implements visual and haptic effects through the incorporation of a physics-based contact model and patient-specific data. Psychophysical tests demonstrate that, despite its simplified model and its inherent technological constraints, the simulator can articulate material differences, and that its users can learn to associate virtual bone with real bone material. Tests addressed both surface probing and interior drilling task. We also explore a haptic contrast sensitivity function based on the model s two main parameters: an elastic constant and an erosion factor. Both parameters manifest power-law-like sensitivity with respective exponents of around two and three. Further tests may reveal how well simulator users perceive fine differences in bone material, like those encountered while drilling through real volume boundaries.139-14

Anastomosis configuration and technique following ileocaecal resection for Crohn's disease: a multicentre study

A limited ileocaecal resection is the most frequently performed procedure for ileocaecal CD and different anastomotic configurations and techniques have been described. This manuscript audited the different anastomotic techniques used in a national study and evaluated their influence on postoperative outcomes following ileocaecal resection for primary CD. This is a retrospective, multicentre, observational study promoted by the Italian Society of Colorectal Surgery (SICCR), including all adults undergoing elective ileocaecal resection for primary CD from June 2018 May 2019. Postoperative morbidity within 30 days of surgery was the primary endpoint. Postoperative length of hospital stay (LOS) and anastomotic leak rate were the secondary outcomes. 427 patients were included. The side to side anastomosis was the chosen configuration in 380 patients (89%). The stapled anastomotic (n = 286; 67%), techniques were preferred to hand-sewn (n = 141; 33%). Postoperative morbidity was 20.3% and anastomotic leak 3.7%. Anastomotic leak was independent of the type of anastomosis performed, while was associated with an ASA grade ≥ 3, presence of perianal disease and ileocolonic localization of disease. Four predictors of LOS were identified after multivariate analysis. The laparoscopic approach was the only associated with a reduced LOS (p = 0.017), while age, ASA grade ≥ 3 or administration of preoperative TPN were associated with increased LOS. The side to side was the most commonly used anastomotic configuration for ileocolic reconstruction following primary CD resection. There was no difference in postoperative morbidity according to anastomotic technique and configuration. Anastomotic leak was associated with ASA grade ≥ 3, a penetrating phenotype of disease and ileo-colonic distribution of CD