An autonomous X-ray image acquisition and interpretation system for assisting percutaneous pelvic fracture fixation.

PURPOSE: Percutaneous fracture fixation involves multiple X-ray acquisitions to determine adequate tool trajectories in bony anatomy. In order to reduce time spent adjusting the X-ray imager's gantry, avoid excess acquisitions, and anticipate inadequate trajectories before penetrating bone, we propose an autonomous system for intra-operative feedback that combines robotic X-ray imaging and machine learning for automated image acquisition and interpretation, respectively. METHODS: Our approach reconstructs an appropriate trajectory in a two-image sequence, where the optimal second viewpoint is determined based on analysis of the first image. A deep neural network is responsible for detecting the tool and corridor, here a K-wire and the superior pubic ramus, respectively, in these radiographs. The reconstructed corridor and K-wire pose are compared to determine likelihood of cortical breach, and both are visualized for the clinician in a mixed reality environment that is spatially registered to the patient and delivered by an optical see-through head-mounted display. RESULTS: We assess the upper bounds on system performance through in silico evaluation across 11 CTs with fractures present, in which the corridor and K-wire are adequately reconstructed. In post hoc analysis of radiographs across 3 cadaveric specimens, our system determines the appropriate trajectory to within 2.8 ± 1.3 mm and 2.7 ± 1.8[Formula: see text]. CONCLUSION: An expert user study with an anthropomorphic phantom demonstrates how our autonomous, integrated system requires fewer images and lower movement to guide and confirm adequate placement compared to current clinical practice. Code and data are available.

From diversity to complexity: Microbial networks in soils.

Network analysis has been used for many years in ecological research to analyze organismal associations, for example in food webs, plant-plant or plant-animal interactions. Although network analysis is widely applied in microbial ecology, only recently has it entered the realms of soil microbial ecology, shown by a rapid rise in studies applying co-occurrence analysis to soil microbial communities. While this application offers great potential for deeper insights into the ecological structure of soil microbial ecosystems, it also brings new challenges related to the specific characteristics of soil datasets and the type of ecological questions that can be addressed. In this Perspectives Paper we assess the challenges of applying network analysis to soil microbial ecology due to the small-scale heterogeneity of the soil environment and the nature of soil microbial datasets. We review the different approaches of network construction that are commonly applied to soil microbial datasets and discuss their features and limitations. Using a test dataset of microbial communities from two depths of a forest soil, we demonstrate how different experimental designs and network constructing algorithms affect the structure of the resulting networks, and how this in turn may influence ecological conclusions. We will also reveal how assumptions of the construction method, methods of preparing the dataset, and definitions of thresholds affect the network structure. Finally, we discuss the particular questions in soil microbial ecology that can be approached by analyzing and interpreting specific network properties. Targeting these network properties in a meaningful way will allow applying this technique not in merely descriptive, but in hypothesis-driven research. Analysing microbial networks in soils opens a window to a better understanding of the complexity of microbial communities. However, this approach is unfortunately often used to draw conclusions which are far beyond the scientific evidence it can provide, which has damaged its reputation for soil microbial analysis. In this Perspectives Paper, we would like to sharpen the view for the real potential of microbial co-occurrence analysis in soils, and at the same time raise awareness regarding its limitations and the many ways how it can be misused or misinterpreted.

Psychedelics as Novel Therapeutics in Alzheimer's Disease: Rationale and Potential Mechanisms.

Serotonin 2A receptor (5-HT2AR) agonist "classic psychedelics" are drawing increasing interest as potential mental health treatments. Recent work suggests psychedelics can exert persisting anxiolytic and antidepressant effects lasting up to several months after a single administration. Data indicate acute subjective drug effects as important psychological factors involved in observed therapeutic benefits. Additionally, animal models have shown an important role for 5-HT2AR agonists in modulating learning and memory function with relevance for Alzheimer's Disease (AD) and related dementias. A number of biological mechanisms of action are under investigation to elucidate 5-HT2AR agonists' therapeutic potential, including enhanced neuroplasticity, anti-inflammatory effects, and alterations in brain functional connectivity. These diverse lines of research are reviewed here along with a discussion of AD pathophysiology and neuropsychiatric symptoms to highlight classic psychedelics as potential novel pharmacotherapies for patients with AD. Human clinical research suggests a possible role for high-dose psychedelic administration in symptomatic treatment of depressed mood and anxiety in early-stage AD. Preclinical data indicate a potential for low- or high-dose psychedelic treatment regimens to slow or reverse brain atrophy, enhance cognitive function, and slow progression of AD. In conclusion, rationale and potential approaches for preliminary research with psychedelics in patients with AD are presented, and ramifications of this line of investigation for development of novel AD treatments are discussed.

Single-lumen and multi-lumen poly(ethylene glycol) nerve conduits fabricated by stereolithography for peripheral nerve regeneration in vivo.

BACKGROUND: The use of nerve conduits to facilitate nerve regrowth after peripheral nerve injury is limited to defects less than 3 cm. The purpose of this study is to determine the capability of novel single and multi-lumen poly(ethylene glycol) (PEG) conduits manufactured by stereolithography to promote peripheral nerve regeneration. MATERIALS AND METHODS: Eight Sprague Dawley rats with sharp transection injuries of the sciatic nerve were randomly assigned to receive single-lumen or multi-lumen PEG conduits to bridge a 10-mm gap. Sciatic nerve and conduit samples were harvested after 5 weeks, and axon number, myelin thickness, fiber diameter, and g-ratio were analyzed. The contralateral intact nerve was also harvested for comparison. RESULTS: Partial nerve regeneration was observed in three out of four single-lumen conduits and one out of four multi-lumen conduits. Axon number in the single-lumen regenerated nerve approached that of the contralateral intact nerve at 4,492 ± 2,810.0 and 6,080 ± 627.9 fibers/mm(2), respectively. The percentage of small fibers was greater in the single-lumen conduit compared with the intact nerve, whereas myelin thickness and g-ratio were consistently greater in the autologous nerve. Axon regrowth through the multi-lumen conduits was severely limited. CONCLUSION: Single-lumen stereolithography-manufactured PEG nerve conduits promote nerve regeneration, with regenerating axon numbers approaching that of normal nerve. Multi-lumen conduits demonstrated significantly less nerve regeneration, possibly due to physical properties of the conduit inhibiting growth. Further studies are necessary to compare the efficacy of the two conduits for functional recovery and to elucidate the reasons underlying their differences in nerve regeneration potential.

Extracranial internal carotid artery mycotic aneurysm: case report and review.

Mycotic aneurysms of the internal carotid artery (ICA) are rare and often difficult to diagnose. They can have nonspecific signs and symptoms, an unclear etiology, and can lead to severe morbidity and mortality if left untreated. We present a case of a 47-year-old woman with an apparent mycotic aneurysm of the extracranial ICA associated with Klebsiella pneumonia. We discuss the various clinical findings and radiographic imaging that lead to this unusual diagnosis and the details of our surgical treatment, which included excision of the mycotic aneurysm and reconstruction with a greater saphenous vein interposition graft. We also review the literature on mycotic aneurysms of the ICA, including the radiologic modalities available to diagnose this condition, epidemiology, pathophysiology, and treatment options.

Magnetic resonance imaging characterization of orbital changes with age and associated contributions to lower eyelid prominence.

BACKGROUND: Multiple orbital aging models have been suggested to explain the progressive development of lower eyelid prominence. Objective data to support these theories are limited, however. METHODS: Orbital anatomy was measured with high-resolution orbital magnetic resonance imaging in the quasi-sagittal plane parallel to the long axis of the orbit passing through the globe center. The association between measurements and age was analyzed by stratifying subjects into predetermined age groups and as a continuous variable. RESULTS: Forty subjects (17 men and 23 women) were imaged and are reported by age group: 12 to 29 years, 30 to 54 years, and 55 to 80 years. Inferior periocular soft-tissue area anterior to the anteroposterior globe axis increased with age: 99, 103, and 131 mm (p = 0.008), respectively. The largest contributor to this size increase was fat expansion: 28, 31, and 43 mm (p = 0.009), respectively. Total orbital fat also increased with age: 335, 377, and 398 mm, respectively (p = 0.035). The globe position relative to the inferior orbit in both the anteroposterior and the superoinferior planes remained unchanged. CONCLUSIONS: The authors' measurements suggest that with aging there is a significant increase in anterior inferior periocular soft-tissue volume, and that fat expansion is the main contributor to this volume increase. These observations provide supporting evidence that orbital fat expansion occurs with age and is the primary age-associated contributor to lower eyelid prominence, rather than globe descent or fat repositioning caused by weakening of the orbital septum. We believe these data suggest that fat excision should be a component of treatment for lower eyelid prominence.

Evolution of fine needle aspiration cytology in the accurate diagnosis of pancreatic neoplasms.

In the era of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA), a minimally invasive, safe, and accurate cytologic examination of a variety of intra-abdominal neoplasms has become possible. To assess the efficacy of EUS-FNA for diagnosis of primary pancreatic tumors, a 10-year retrospective review of a consecutive series of patients diagnosed between 1996 and 2005 was undertaken. Comparisons were made between early (1996-2000) and late (2001-2005) periods regarding diagnostic modalities used and the concordance of EUS-FNA cytology with macroscopic tissue histology. Although macroscopic biopsy diagnostic yield did not change over time, yield from EUS-FNA increased from 40 per cent to 95 per cent (P = 0.001). Because of improved accuracy of FNA cytology, only six per cent of tumors required additional macroscopic tissue histology in the late period versus 35 per cent in the early period (P = 0.001). There was 100 per cent concordance between the cytologic and histologic diagnoses in the late period versus only 33 per cent in the early period (P = 0.032). We conclude that (1) the frequency of pathologically diagnosed pancreatic tumors doubled over 10 years, (2) utilization of EUS-FNA significantly increased the accuracy of cytologic diagnosis, and (3) as a result, the need for macroscopic tissue biopsy for diagnosis of pancreatic neoplasms has been obviated.