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.

Science to Practice: What Light through Yonder Tumor Breaks: Noninvasive Staging of Cancer--Shining a Light on Disease.

Photoacoustic imaging imparts the ability to distinguish materials according to their differences in optical absorption (ie, their color) with the high spatial and temporal resolution of ultrasonography (US). Experiments in rats show the advantages this approach would have in the clinically important noninvasive determination of the presence of tumor in the lymph nodes draining a tumor, providing the ability to achieve the results of total axillary lymph node dissection without the risks of surgery or even percutaneous sentinel node biopsy. The coupling of this technique to a conventional US imaging system gives the promise of rapid translation to clinical use.

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 institution's 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.

Science to practice: Son et Lumiere--understanding tumor heterogeneity.

Treatment of cancer is often confounded by tumor heterogeneity.Variations in perfusion inhibit drug delivery to all parts of the tumor (1). Differences in oxygen tension (Po2)cause variations in response to radiation therapy (2).Understanding this tumor heterogeneity, which is caused by the interplay between the cancer cell's gene makeup and the tumor's environment (eg, stromal matrix, tissue vascularity),will likely enable improved treatment strategies.Whole-mount studies, in which the excised tumor is fixed or frozen and then sliced into thin sections - with subsequent staining and microscopic examination of the multiple sections­provide much information about tumor heterogeneity but cannot provide information about dynamic events, perfusion, metabolism, or those processes that exist in the tumor in vivo (including Po2). Intravital microscopy(3), in which a tumor or organ is exteriorized or viewed through a window cut in overlying tissue, can provide information on such dynamic processes; however, those studies are limited by scattering and diffusion of light as it penetrates tissue and so can only enable differentiation of surface structures and events.

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?

Science to practice: photoacoustic imaging--can it let us see color and function deep inside the body?

Photoacoustic imaging imparts the ability to distinguish materials according to their differences in optical absorption (ie, their colors) with the high spatial and temporal resolution of ultrasonography (US). Experiments in rats demonstrate the advantages this approach would have in the clinically important application of percutaneous sentinel node biopsy. The incorporation of the technique in a conventional US imaging system gives promise of rapid translation to clinical use.

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

BACKGROUND: Current 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. METHODS: A 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. RESULTS: Superior 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. CONCLUSIONS: The 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.

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.

The academic RVU: a system for measuring academic productivity.

Despite the importance of teaching, research, and related activities to the mission of academic medical departments, no useful and widely agreed-on metrics exist with which to assess the value of individual faculty members' contributions in these areas. Taking the concept of the clinical relative value unit (RVU) as a model, the authors describe the development of an academic RVU (aRVU) system that assigns weights to and creates formulas for assessing productivity in publications, teaching, administrative and community service, and research. The resulting aRVU schema was implemented on a Web-based system that incorporates a number of novel tools, including a curriculum vitae manager that automatically maintains and calculates total aRVU scores and breaks out component elements for each individual and for the department as a whole. The benefits and limitations of this system are discussed, as well as the potential advantages in sharing this approach with other radiology departments and other medical disciplines. Wide acceptance and implementation would make the aRVU the appropriate counterpoint to the clinical work RVU in academic medicine.

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.