Reuben Mezrich

Live augmented reality: a new visualization method for laparoscopic surgery using continuous volumetric computed tomography

BackgroundCurrent laparoscopic images are rich in surface detail but lack information on deeper structures. This report presents a novel method for highlighting these structures during laparoscopic surgery using continuous multislice computed tomography (CT). This has resulted in a more accurate augmented reality (AR) approach, termed “live AR,” which merges three-dimensional (3D) anatomy from live low-dose intraoperative CT with live images from the laparoscope.MethodsA series of procedures with swine was conducted in a CT room with a fully equipped laparoscopic surgical suite. A 64-slice CT scanner was used to image the surgical field approximately once per second. The procedures began with a contrast-enhanced, diagnostic-quality CT scan (initial CT) of the liver followed by continuous intraoperative CT and laparoscopic imaging with an optically tracked laparoscope. Intraoperative anatomic changes included user-applied deformations and those from breathing. Through deformable image registration, an intermediate image processing step, the initial CT was warped to align spatially with the low-dose intraoperative CT scans. The registered initial CT then was rendered and merged with laparoscopic images to create live AR.ResultsSuperior compensation for soft tissue deformations using the described method led to more accurate spatial registration between laparoscopic and rendered CT images with live AR than with conventional AR. Moreover, substitution of low-dose CT with registered initial CT helped with continuous visualization of the vasculature and offered the potential of at least an eightfold reduction in intraoperative X-ray dose.ConclusionsThe authors proposed and developed live AR, a new surgical visualization approach that merges rich surface detail from a laparoscope with instantaneous 3D anatomy from continuous CT scanning of the surgical field. Through innovative use of deformable image registration, they also demonstrated the feasibility of continuous visualization of the vasculature and considerable X-ray dose reduction. This study provides motivation for further investigation and development of live AR.

Radio Frequency Identification Systems Technology in the Surgical Setting

Radio frequency identification (RFID) is a technology that will have a profound impact on medicine and the operating room of the future. The purpose of this article is to provide an introduction to this exciting technology and a description of the problems in the perioperative environment that RFID might address to improve safety and increase productivity. Although RFID is still a nascent technology, applications are likely to become much more visible in patient care and treatment areas and will raise questions for practitioners. We also address both the current limitations and what appear to be reasonable near-future possibilities.

Informatics in Radiology: Automated Web-based Graphical Dashboard for Radiology Operational Business Intelligence

Radiology departments today are faced with many challenges to improve operational efficiency, performance, and quality. Many organizations rely on antiquated, paper-based methods to review their historical performance and understand their operations. With increased workloads, geographically dispersed image acquisition and reading sites, and rapidly changing technologies, this approach is increasingly untenable. A Web-based dashboard was constructed to automate the extraction, processing, and display of indicators and thereby provide useful and current data for twice-monthly departmental operational meetings. The feasibility of extracting specific metrics from clinical information systems was evaluated as part of a longer-term effort to build a radiology business intelligence architecture. Operational data were extracted from clinical information systems and stored in a centralized data warehouse. Higher-level analytics were performed on the centralized data, a process that generated indicators in a dynamic Web-based graphical environment that proved valuable in discussion and root cause analysis. Results aggregated over a 24-month period since implementation suggest that this operational business intelligence reporting system has provided significant data for driving more effective management decisions to improve productivity, performance, and quality of service in the department.

Sixteen-section multi-detector row CT scanners: this changes everything.

I don’t think it is much of an exaggeration to say that the new generation of multi–detector row computed tomographic (CT) scanners—the 16-section scanners—changes everything. It’s not just that they are fast; although speed may be important for obtaining high-quality images of the chest or abdomen, it doesn’t add much quality in imaging of the brain or spine or other body parts that don’t move much. It’s not that they provide high resolution, because in fact the axial resolution is no better than that provided by even the single-section CT scanners introduced quite a few years ago. What makes these new scanners so different is that for the first time the image voxels are isotropic; the image resolution can be as good in the sagittal and coronal planes as it is in the axial plane. Unlike the situation with single-section or even four-section multi–detector row scanners, with 16-section scanners there is no preferred plane for image reconstruction. The fact that the images may have been acquired in the axial plane is irrelevant. All planes have equal resolution, and the viewer can choose the plane that best shows the anatomy. One of the advantages of magnetic resonance imaging over CT was that it was possible to acquire images in arbitrary planes, but that advantage was realized only when one knew, a priori, which plane would be best. With the new 16-section multi–detector row CT scanners, one can decide after the fact which plane is optimal—axial, sagittal, coronal, or oblique—and vary it at will. This means that CT studies are no longer a collection of axial sections to be viewed one section at a time, but now are three-dimensional volumes that can be manipulated and displayed in whatever fashion best suits the diagnostic problem. The fact that these scanners perform at high speed is an enormous bonus. Artifacts due to respiratory and peristaltic motion are reduced or eliminated, while cardiac synchronization becomes simpler and more accurate. These features open up entirely new applications for CT, perhaps the most important of which are in cardiology. With submillimeter isotropic resolution, it should be possible to detect critical lesions even in the distal portions of the coronary arteries. With fewer artifacts due to volume averaging, it might even be possible to see “vulnerable plaques” (cholesterol-filled lesions in the walls of the coronary and carotid arteries that are thought to be the cause of most heart attacks and strokes) (1–5). With the ability to synchronize cardiac motion and to reformat volumes in any plane for viewing from any angle, it will be easy to display cine loops of two-, three-, and four-chamber views showing ventricular wall motion and cardiac function in exquisite detail and with precise accuracy. It will be possible, in short, to achieve the holy grail of cardiac imaging—the one-stop cardiac study that could change the way acute or chronic heart disease is diagnosed and followed up. One can imagine, for example, CT scanning being the first and perhaps the only test performed on the patient presenting at the emergency room with chest pain. At one swoop, acute myocardial infarction, pulmonary embolus, aortic dissection, pneumothorax, or even pneumonia can be diagnosed or excluded in a matter of minutes and the patient either sent home or on to treatment, with full confidence that appropriate and cost-effective care has been given. Along with these opportunities come many challenges, some technical and some social. Acquisition of high-quality images will require an understanding of the technology and physics behind CT operation that extends well beyond what was necessary for operating prior generaAcad Radiol 2003; 10:351–352

Development of continuous CT-guided minimally invasive surgery

Minimally invasive laparoscopic surgeries are known to lead to improved outcomes, less scarring, and significantly faster patient recovery as compared with conventional open invasive surgeries. Laparoscopes, used to visualize internal anatomy and guide laparoscopic surgeries, however, remain limited in visualization capability. Not only do they provide a relatively flat representation of the three-dimensional (3D) anatomy, they show only the exposed surfaces. A surgeon is thus unable to see inside a structure, which limits the precision of current-generation minimally invasive surgeries and is often a source of complications. To see inside a structure before dissecting it has been a long-standing need in minimally invasive laparoscopic surgeries, a need that laparoscopy is fundamentally limited in meeting. In this work we propose to use continuous computed tomography (CT) of the surgical field as a supplementary imaging tool to guide laparoscopic surgeries. The recent emergence of 64-slice CT and its continuing evolution make it an ideal candidate for four-dimensional (3D space + time) intraoperative imaging. We also propose a novel, elastic image registration-based technique to keep the net radiation dose within acceptable levels. We have successfully created 3D renderings from multislice CT corresponding to anatomy visible within the field of view of the laparoscope in a swine. These renderings show the underlying vasculature along with their latest intraoperative orientation. With additional developments, our research has the potential to help improve the precision of laparoscopic surgeries further, reduce complications, and expand the scope of minimally invasive surgeries.

Unbiased Review of Digital Diagnostic Images in Practice: Informatics Prototype and Pilot Study

RATIONALE AND OBJECTIVES Clinical and contextual information associated with images may influence how radiologists draw diagnostic inferences, highlighting the need to control multiple sources of bias in the methodologic design of investigations involving radiologic interpretation. In the past, manual control methods to mask review films presented in practice have been used to reduce potential interpretive bias associated with differences between viewing images for patient care and reviewing images for the purposes of research, education, and quality improvement. These manual precedents from the film era raise the question whether similar methods to reduce bias can be implemented in the modern digital environment. MATERIALS AND METHODS A prototype application, CreateAPatient, was built for masking review case presentations within one institutions production radiology information system and picture archiving and communication system. To test whether CreateAPatient could be used to mask review images presented in practice, six board-certified radiologists participated in a pilot study. During pilot testing, seven digital chest radiographs, known to contain lung nodules and associated with fictitious patient identifiers, were mixed into the routine workloads of the participating radiologists while they covered general evening call shifts. The aim was to test whether it was possible to mask the presentation of these review cases, both by probing the interpreting radiologists to report detection and by conducting a forced-choice experiment on a separate cohort of 20 radiologists and information technology professionals. RESULTS None of the participating radiologists reported awareness of review activity, and forced-choice detection was less than predicted at chance, suggesting that radiologists were effectively blinded. In addition, no evidence was identified of review reports unsafely propagating beyond their intended scope or otherwise interfering with patient care, despite integration of these records within production electronic work flow systems. CONCLUSIONS Information technology can facilitate the design of unbiased methods involving professional review of digital diagnostic images.

Ultrasonographic Detection of Airway Obstruction in a Model of Obstructive Sleep Apnea

Purpose Obstructive sleep apnea (OSA) is a common clinical disorder characterized by repetitive airway obstruction during sleep. The gold standard for diagnosis of OSA, polysomnogram (PSG), cannot anatomically localize obstruction. Precise identification of obstruction has potential to improve outcomes following surgery. Current diagnostic modalities that provide this information require anesthesia, involve ionizing radiation or disrupt sleep. To mitigate these problems, we conceived that ultrasound (US) technology may be adapted (i) to detect, quantify and localize airway obstruction and (ii) for translational application to home-based testing for OSA. Materials and Methods Segmental airway collapse was induced in 4 fresh cadavers by application of negative pressure. Following visualization of airway obstruction, a rotary US probe was used to acquire transcervical images of the airway before and after induction of obstruction. These images (n=800) were analyzed offline using image processing algorithms. Results Our results show that the non-obstructed airway consistently demonstrated the presence of a US air-tissue interface. Importantly, automated detection of the air-tissue interface strongly correlated with manual measurements. The algorithm correctly detected an air-tissue interface in 90% of the US images while incorrectly detecting it in 20% (area under the curve=0.91). Conclusion The non-invasive detection of airway obstruction using US represents a major step in expanding OSA diagnostics beyond PSG. The preliminary data obtained from our model could spur further research in non-invasive localization of obstruction. US offers the benefit of precise localization of the site of obstruction, with potential for improving outcomes in surgical management.

Should Post-Processing Be Performed by the Radiologist?

Post-processing of volumetric data sets lands in a fuzzy boundary between the technologist and the radiologist. Is this the role of the technologist as part of image preparation? Or is it the beginning of the diagnostic process by the radiologist? Technology advances in real-time server side rendering platforms is challenging the traditional role of expensive dedicated advanced visualizations workstations with dedicated personnel. Will this also challenge the role of a dedicated 3D post-processing technologist?