Implant-oriented navigation in orbital reconstruction part II: preclinical cadaver study

In orbital reconstruction, the acquired position of an orbital implant can be evaluated with the aid of intraoperative navigation. Feedback of the navigation system is only obtained after positioning of the implant: the implant’s position is not tracked in real time during positioning. The surgeon has to interpret the navigation feedback and translate it to desired adjustments of the implant’s position. In a previous study, a real-time implant-oriented navigation approach was introduced and the system’s accuracy was evaluated. In this study, this real-time navigation approach was compared to a marker-based navigation approach in a preclinical set-up. Ten cadavers (20 orbital defects) were reconstructed twice, by two surgeons (total: 80 reconstructions). Implant positioning was significantly improved in the real-time implant-oriented approach in terms of roll (2.0° vs. 3.2°, P = 0.03), yaw (2.2° vs. 3.4°, P = 0.01) and translation (1.3 mm vs. 1.8 mm, P = 0.005). Duration of the real-time navigation procedure was reduced (median 4.5 min vs. 7.5 min). Subjective appreciation of the navigation technique was higher for real-time implant-oriented navigation (mean 7.5 vs. 9.0). Real-time implant-oriented navigation feedback provides real-time, intuitive feedback to the surgeon, which leads to improved implant positioning and shortens duration of the navigation procedure.     

True accuracy of percutaneous pedicle screw placement in thoracic and lumbar spinal fixation with a CT-based navigation system: Intraoperative and postoperative assessment of 763 percutaneous pedicle screws

PurposeTo investigate intraoperative reinsertion of percutaneous pedicle screw (PPS) with intraoperative CT-based navigation and to evaluate the rate of deviation of PPS at postoperative radiographic examination.MethodsSeven hundred sixty-three screws were inserted in 138 patients. We investigated the rate of occurrence of intraoperative PPS reinsertion after the diagnosis of screw deviation by fluoroscopy and the causes of each screw deviation. The subsequent distribution of PPS deviation was evaluated by postoperative CT. We also assess the difference in variance between the group judged to be PPS misplaced intra-/postoperatively (IOD group/POD group) and appropriate PPS placement (ND group).ResultsAmong all the screws inserted, 10 (1.3%) were diagnosed as being deviated by fluoroscopy during surgery, and 74 (9.7%) screws were found to be deviated at postoperative CT evaluation. We found more pedicle screw mismatch in the POD group than in the ND group (52.7 vs 11.0%, P < 0.001). The distance between the screw and the reference was greater in the IOD group than that in the ND group (1.4 ± 1.2 vs 2.4 ± 1.1 vertebral levels, P = 0.016). In one patient in the IOD group, a motor function deficit was observed postoperatively.ConclusionPPS fixation under intraoperative CT-based navigation did not prevent screw deviation completely. It is necessary to consider errors that occur during surgery and to confirm placement with real-time assistance such as fluoroscopy even in a surgery performed under CT navigation assistance.     

Current status of diagnostic and therapeutic bronchoscopy in Japan: 2016 national survey of bronchoscopy

BackgroundThe safety management committee of the Japan Society for Respiratory Endoscopy (JSRE) conducted national surveys to clarify the state of diagnostic and therapeutic bronchoscopy in 2016.MethodsQuestionnaire forms were mailed to 532 JSRE-accredited facilities throughout Japan. We surveyed the actual condition of clinical practice and cases of bronchoscopy during 2016.ResultsFour hundred and thirty-three facilities responded giving a response rate of 81.4%; 67.6% held more than 400 beds. The average number of board accredited senior Fellows and Fellows per facility was 1.9 and 3.2, respectively. Diagnostic bronchoscopy was performed in a hospitalized setting in 74.6% of all facilities. The radial type ultrasound probe was operated in 51.7% of all facilities. The number of facilities has markedly increased compared with that reported in the 2010 survey (19.6%). The bronchoscopic navigation system had been in operation in 41.7% of all facilities. Antithrombotic drugs were adjusted before biopsy in 96.8% of all facilities. For intravenous sedation, midazolam was the first choice in 76.9% of all facilities. Endobronchial ultrasound guided transbronchial lymph node needle aspiration (EBUS-TBNA) has become popular over the decade (19.6% in 2010 to 68.1% in 2016).The mean number of the board accredited senior Fellows and board accredited Fellows increased in comparison with that in 2010. As a new technique, radial type ultrasound-guided peripheral approach has become popular.ConclusionsThrough this survey, the advanced safety of bronchoscopic examination has been secured in many facilities. A continuous monitoring of bronchoscopic practices with respect to safety management is recommended.     

The long-distance flight behavior of Drosophila supports an agent-based model for wind-assisted dispersal in insects

Despite the ecological importance of long-distance dispersal in insects, its mechanistic basis is poorly understood in genetic model species, in which advanced molecular tools are readily available. One critical question is how insects interact with the wind to detect attractive odor plumes and increase their travel distance as they disperse. To gain insight into dispersal, we conducted release-and-recapture experiments in the Mojave Desert using the fruit fly, Drosophila melanogaster. We deployed chemically baited traps in a 1 km radius ring around the release site, equipped with cameras that captured the arrival times of flies as they landed. In each experiment, we released between 30,000 and 200,000 flies. By repeating the experiments under a variety of conditions, we were able to quantify the influence of wind on flies’ dispersal behavior. Our results confirm that even tiny fruit flies could disperse ∼12 km in a single flight in still air and might travel many times that distance in a moderate wind. The dispersal behavior of the flies is well explained by an agent-based model in which animals maintain a fixed body orientation relative to celestial cues, actively regulate groundspeed along their body axis, and allow the wind to advect them sideways. The model accounts for the observation that flies actively fan out in all directions in still air but are increasingly advected downwind as winds intensify. Our results suggest that dispersing insects may strike a balance between the need to cover large distances while still maintaining the chance of intercepting odor plumes from upwind sources.

If asked to picture a migrating insect, the first image that comes to mind might be a large charismatic species such as the monarch butterfly, whose seasonal movements across North America have inspired naturalists for centuries. However, as pointed out by David and Elizabeth Lack (1), our impression of insect migration is strongly biased toward large animals; many species are so small that their geographic relocations escape our attention, especially if their population densities are not strongly concentrated by geological features such as narrow mountain passes. As research using high-altitude traps (2) and upward-looking radar (3, 4) indicates, long-distance migration may be more ubiquitous and ecologically important among both large and small insects than previously appreciated (5, 6). Long-distance dispersal (i.e., the noncyclic movement from one area to another) is even harder to observe and study in small insects, because the events are not generally predictable, and the animals are far too small to be captured on radar or outfitted with tracking devices. The dispersal of small insects across a landscape has often been modeled as stochastic processes governed by diffusion and advection (7), processes that may underestimate the ability of the animals to actively maintain constant trajectories over large spatial scales. Understanding long-distance migration and dispersal is quite important, because these phenomena are responsible for biomass relocation on both local and global scales (8, 9). Furthermore, as insect population densities decline due to environmental degradation and climate change (10–12), understanding the dispersal capacity of insects and the behavioral algorithms that underlie them will be crucial in predicting the ecological impact of population decline.Although not generally renowned for its capability to disperse over long distances, a series of release-and-recapture experiments over 40 y ago suggest that the fruit fly, Drosophila melanogaster, may be capable of movements on the order of 15 km in a single night, a distance equivalent to 6 million body lengths (13, 14). These experiments were conducted by releasing tens of thousands of fluorescently labeled flies in the evening and then censusing the contents of traps baited with yeast and banana placed at distant oases the next morning. Although these pioneering studies suggested that the dispersal capacity of Drosophila was much greater than previously estimated, they left open several critical questions. First, it was not clear whether individual flies dispersed in random directions or whether the population movement was biased by external conditions, such as the wind, geographical features, or celestial cues. Second, because the precise transit times of the flies were not known, it was impossible to estimate the actual groundspeeds used by the animals as they dispersed. To provide more clarity to these and other questions related to long-distance dispersal, we conducted a series of release-and-recapture experiments in the Mojave Desert. We equipped circular arrays of chemically baited traps with simple machine vision systems that captured the arrival times of flies as they landed and repeated the experiments under a variety of ambient wind conditions. The results provide key insight into the behavioral algorithms used by Drosophila while dispersing in the wild and serve as the basis for a general agent-based model of wind-assisted dispersal in insects.     

Implementation and performance evaluation of a drilling assistive device for distal locking of intramedullary nails

Intramedullary nailing is a common treatment for long bone fractures. The nail might deform during implantation because of the shape of medullary cavity. Thus, surgeons take many X‐ray images to position distal locking holes and check the drilling process. In this study, we developed a positioning algorithm with a passive or active (robot arm) assistive device for promptly positioning of distal locking holes and stably drilling guidance and support. Using the passive device, the surgeon could manually align the positioning probe with locking hole within 60 seconds based on 20 test cases. In 36 test cases, the active device aligned the positioning probe with locking hole automatically with average errors of 2.2 mm in position and 3.19° in direction. The passive device provides a reliable and low‐cost solution for distal locking of intramedullary nails, while the active device is easy and friendly to use.     

Cost analysis of a patient navigation system to increase screening colonoscopy adherence among urban minorities

BACKGROUND:

Patient navigation (PN) is being used increasingly to help patients complete screening colonoscopy (SC) to prevent colorectal cancer. At their large, urban academic medical center with an open‐access endoscopy system, the authors previously demonstrated that PN programs produced a colonoscopy completion rate of 78.5% in a cohort of 503 patients (predominantly African Americans and Latinos with public health insurance). Very little is known about the direct costs of implementing PN programs. The objective of the current study was to perform a detailed cost analysis of PN programs at the authors' institution from an institutional perspective.

METHODS:

In 2 randomized controlled trials, average‐risk patients who were referred for SC by primary care providers were recruited for PN between May 2008 and May 2010. Patients were randomized to 1 of 4 PN groups. The cost of PN and net income to the institution were determined in a cost analysis.

RESULTS:

Among 395 patients who completed colonoscopy, 53.4% underwent SC alone, 30.1% underwent colonoscopy with biopsy, and 16.5% underwent snare polypectomy. Accounting for the average contribution margins of each procedure type, the total revenue was $95,266.00. The total cost of PN was $14,027.30. Net income was $81,238.70. In a model sample of 1000 patients, net incomes for the institutional completion rate (approximately 80%), the historic PN program (approximately 65%), and the national average (approximately 50%) were compared. The current PN program generated additional net incomes of $35,035.50 and $44,956.00, respectively.

CONCLUSIONS:

PN among minority patients with mostly public health insurance generated additional income to the institution, mainly because of increased colonoscopy completion rates. Cancer 2013. © 2012 American Cancer Society.     

Spatial coordinate transforms linking the allocentric hippocampal and egocentric parietal primate brain systems for memory,action in space,and navigation

A theory and model of spatial coordinate transforms in the dorsal visual system through the parietal cortex that enable an interface via posterior cingulate and related retrosplenial cortex to allocentric spatial representations in the primate hippocampus is described. First, a new approach to coordinate transform learning in the brain is proposed, in which the traditional gain modulation is complemented by temporal trace rule competitive network learning. It is shown in a computational model that the new approach works much more precisely than gain modulation alone, by enabling neurons to represent the different combinations of signal and gain modulator more accurately. This understanding may have application to many brain areas where coordinate transforms are learned. Second, a set of coordinate transforms is proposed for the dorsal visual system/parietal areas that enables a representation to be formed in allocentric spatial view coordinates. The input stimulus is merely a stimulus at a given position in retinal space, and the gain modulation signals needed are eye position, head direction, and place, all of which are present in the primate brain. Neurons that encode the bearing to a landmark are involved in the coordinate transforms. Part of the importance here is that the coordinates of the allocentric view produced in this model are the same as those of spatial view cells that respond to allocentric view recorded in the primate hippocampus and parahippocampal cortex. The result is that information from the dorsal visual system can be used to update the spatial input to the hippocampus in the appropriate allocentric coordinate frame, including providing for idiothetic update to allow for self‐motion. It is further shown how hippocampal spatial view cells could be useful for the transform from hippocampal allocentric coordinates to egocentric coordinates useful for actions in space and for navigation.     

Effective dose of radiation per screw in surgery of adolescent idiopathic scoliosis: matched pair analysis of 293 pedicle screws inserted using three different techniques

PurposeReports on heterogenous groups of patients have indicated that pedicle screw insertion guided by navigation (PIN) leads to, for the patient, higher doses of radiation compared with pedicle screw insertion guided by fluoroscopy (PIF). This would be a major concern, especially in paediatric deformity correction.MethodsAfter a power analysis (aiming at > 0.8) 293 pedicle screws which were inserted in patients with adolescent idiopathic scoliosis were analyzed by comparing effective dose and fluoroscopy time per screw for three different techniques. Groups 2 and 3 were matched to Group 1 by Lenke type of scoliosis. Group 1 were prospectively enrolled consecutive patients that have been operated on by PIN with image acquisition by preoperative CT scan (CTS). Group 2 were consecutive retrospectively matched patients who have been operated on by PIN with image acquisition by an intraoperative 3D scan (3DS). Group 3 were consecutive retrospectively matched patients who have been operated on by PIF.ResultsMean dose of radiation per screw was 1.0 mSv (sd 0.8) per screw in CTS patients, 0.025 mSv (sd 0.001) per screw in 3DS patients and 0.781 mSv (sd 0.12) per screw in PIF patients. The difference was significant (p < 0.0001).ConclusionWhen we compared different techniques of navigation, navigation by image acquisition with CTS showed a significantly higher (by 97.5%) dose of radiation per screw for the patient than navigation by image acquisition by a 3DS. Navigation by 3DS showed significantly lower effective dose per screw for the adolescent patients than the fluoroscopic technique.Level of Evidence:II