Efficacy and safety of near-infrared fluorescence identification of the thoracic duct during left lateral neck dissection.

BACKGROUND: Thoracic duct leaks occur in up to 5% of left lateral neck dissections. No one imaging modality is routinely used to identify the thoracic duct intraoperatively. The goal of our study was to evaluate the efficacy and safety of indocyanine green lymphangiography for intraoperative identification of the thoracic duct compared to traditional methods using ambient and evaluate the optimal timing of indocyanine green administration. METHODS: We enrolled all patients who underwent left lateral neck dissection at our institution from 2018 to 2022 in this prospective clinical trial. After indocyanine green injection into the dorsum of the foot, we performed intraoperative imaging was performed with a near-infrared fluorescence camera. We reported the data using descriptive statistics. RESULTS: Of the 42 patients we enrolled, 14 had prior neck surgery, and 3 had prior external beam radiation. We visualized the thoracic duct with ambient light in 48% of patients and with near-infrared fluorescence visualization in 64%. In 17% of patients, we could identify the thoracic duct only using near-infrared fluorescence visualization, which occurred within 3 minutes of injection, and were required to re-dose 5 patients. We visualized the thoracic duct with near-infrared fluorescence in all patients with prior neck radiation and 77% of patients with prior neck surgery. One adverse reaction occurred (hypotension), and 5 intraoperative thoracic duct injuries occurred that were ligated. There with no chylous fistulas postoperatively. CONCLUSION: This trial demonstrates that near-infrared fluorescence identification of the thoracic duct is feasible and safe with indocyanine green lymphangiography, even in patients with prior neck surgery or radiation.

LAPNet: Non-Rigid Registration Derived in k-Space for Magnetic Resonance Imaging.

Physiological motion, such as cardiac and respiratory motion, during Magnetic Resonance (MR) image acquisition can cause image artifacts. Motion correction techniques have been proposed to compensate for these types of motion during thoracic scans, relying on accurate motion estimation from undersampled motion-resolved reconstruction. A particular interest and challenge lie in the derivation of reliable non-rigid motion fields from the undersampled motion-resolved data. Motion estimation is usually formulated in image space via diffusion, parametric-spline, or optical flow methods. However, image-based registration can be impaired by remaining aliasing artifacts due to the undersampled motion-resolved reconstruction. In this work, we describe a formalism to perform non-rigid registration directly in the sampled Fourier space, i.e. k-space. We propose a deep-learning based approach to perform fast and accurate non-rigid registration from the undersampled k-space data. The basic working principle originates from the Local All-Pass (LAP) technique, a recently introduced optical flow-based registration. The proposed LAPNet is compared against traditional and deep learning image-based registrations and tested on fully-sampled and highly-accelerated (with two undersampling strategies) 3D respiratory motion-resolved MR images in a cohort of 40 patients with suspected liver or lung metastases and 25 healthy subjects. The proposed LAPNet provided consistent and superior performance to image-based approaches throughout different sampling trajectories and acceleration factors.

Oscillation and self-propulsion of Leidenfrost droplets enclosed in cylindrical cavities.

Leidenfrost droplets can be considered as soft engines capable of directly transforming heat into mechanical energy. Despite remarkable advancements in understanding the propulsion of Leidenfrost droplets on asymmetric structures, the complex dynamics of droplets in enclosed structures is not fully understood. To address this fundamental gap, we investigated the dynamics of Leidenfrost droplets restricted by metal disks. The disk alters the accumulation and release of the vapour generated by the droplet, and substantially changes its dynamic characteristics. Our experiments reveal the formation of oscillating multi-lobed structures when restricting the droplet within a disk. In comparison, patterning offset radial grooves on the surface of the disk rectifies the vapour flow and facilitates the self-propulsion of the droplet along the edge of the disk. Our work offers opportunities for developing soft and short-living actuators, which can operate at high temperatures.

Characteristics of scene trauma patients discharged within 24-hours of air medical transport.

INTRODUCTION: Helicopters play an important role in trauma; however, this service comes with safety risks, high transport costs, and downstream care charges. OBJECTIVE: Our objective was to determine the characteristics of early discharged trauma patients (<24 h length of stay) in order to reduce overtriage. METHODOLOGY: Data were obtained from the trauma registries at one of two Level 1 trauma centers. Eligible patients included all scene trauma patients transported by helicopter to the Level 1 trauma centers from January 1, 2016, to December 31, 2017, who had a length of stay of 24 h or less. Patient factors such as age, gender, scene location, loaded miles, and transportation costs were collected. Trauma type, mechanism of injury, Abbreviated Injury Scale (AIS), Injury Severity Score, Revised Trauma Score, and prehospital vital signs were documented. Driving distances between the accident scene to local hospital, home of record to local hospital, and home of record to the Level I trauma center were also calculated for patients transported to Level 1 trauma center. RESULTS: Two hundred and twenty-six of 1042 total patients (21.7%) were discharged within 24 h of helicopter transport from the accident scene to trauma center. Less than 2% of patients were in the age group of 70 years or older. Only 2 (0.88%) patients discharged within 24 h had a prehospital systolic blood pressure <90 mmHg. For patients transported to Level 1 trauma center, the average loaded miles were 50.51 ± 14.99, with average transport charges being $27,921.19± $3536.61. Twenty-one percent of Level 1 trauma center patients were self-pay, and families typically drove 71.7 ± 123.23 miles to Level 1 trauma center versus 28.74 ± 40.62 to their local emergency department. CONCLUSIONS: A significant number of patients transported from the scene are discharged within 24 h of admission to a trauma center. These patients rarely have prehospital hypotension, do not receive significant volumes of crystalloid resuscitation, and are infrequently over 70 years of age. One in five patients has no third-party coverage and assumes $27,921.19 in average transport charges.

All-pass Parametric Image Registration.

Image registration is a required step in many practical applications that involve the acquisition of multiple related images. In this paper, we propose a methodology to deal with both the geometric and intensity transformations in the image registration problem. The main idea is to modify an accurate and fast elastic registration algorithm (Local All-Pass-LAP) so that it returns a parametric displacement field, and to estimate the intensity changes by fitting another parametric expression. Although we demonstrate the methodology using a low-order parametric model, our approach is highly flexible and easily allows substantially richer parametrisations, while requiring only limited extra computation cost. In addition, we propose two novel quantitative criteria to evaluate the accuracy of the alignment of two images ("salience correlation") and the number of degrees of freedom ("parsimony") of a displacement field, respectively. Experimental results on both synthetic and real images demonstrate the high accuracy and computational efficiency of our methodology. Furthermore, we demonstrate that the resulting displacement fields are more parsimonious than the ones obtained in other state-of-the-art image registration approaches.

Studying the Response of Aortic Endothelial Cells under Pulsatile Flow Using a Compact Microfluidic System.

We describe a piezoelectric pumping system for studying the mechanobiology of human aortic endothelial cells (HAECs) under pulsatile flow in microfluidic structures. The system takes advantage of commercially available components, including pumps, flow sensors, and microfluidic channels, which can be easily integrated, programmed, and operated by cellular biologists. Proof-of-concept experiments were performed to elucidate the complex mechanotransduction processes of endothelial cells to pulsatile flow. In particular, we investigated the effect of atheroprone and atheroprotective pulsatile shear stress on endothelial cytoskeleton remodeling and distribution of ß-catenin, as well as nuclear shape and size. The system is simple to operate, relatively inexpensive, portable, and controllable, providing opportunities for studying the mechanobiology of endothelial cells using microfluidic technologies.

Self-sufficient, low-cost microfluidic pumps utilising reinforced balloons.

Here, we introduce a simple method for increasing the inflation pressure of self-sufficient pressure pumps made of latex balloons. Our method involves reinforcing the latex balloon with elastane fibres to restrict the expansion of the balloon and increase its inflation pressure. This allowed us to increase the operational inflation pressure of a latex balloon from 2.5 to 25 kPa. Proof-of-concept experiments show the suitability of the reinforced balloon for inducing lateral forces and recirculating flows, which are employed for hydrodynamic capturing of large human monocytes. We also demonstrate the ability for the rapid exchange of solutions in repeated cycles upon manual squeezing of the reinforced balloons. We also show the suitability of the reinforced balloon for studying the mechanobiology of human aortic endothelial cells under various shear stress levels. The simplicity, portability, affordability, hyper-elasticity and scalability of the reinforced balloon pumps make them suitable for a wide range of microfluidic applications.

A Microfluidic System for Studying the Effects of Disturbed Flow on Endothelial Cells.

Arterial endothelium experience physical stress associated with blood flow and play a central role in maintaining vascular integrity and homeostasis in response to hemodynamic forces. Blood flow within vessels is generally laminar and streamlined. However, abrupt changes in the vessel geometry due to branching, sharp turns or stenosis can disturb the laminar blood flow, causing secondary flows in the form of vortices. Such disturbed flow patterns activate pro-inflammatory phenotypes in endothelial cells, damaging the endothelial layer and can lead to atherosclerosis and thrombosis. Here, we report a microfluidic system with integrated ridge-shaped obstacles for generating controllable disturbed flow patterns. This system is used to study the effect of disturbed flow on the cytoskeleton remodeling and nuclear shape and size of cultured human aortic endothelial cells. Our results demonstrate that the generated disturbed flow changes the orientation angle of actin stress fibers and reduces the nuclear size while increases the nuclear circularity.

Local All-Pass Geometric Deformations.

This paper deals with the estimation of a deformation that describes the geometric transformation between two images. To solve this problem, we propose a novel framework that relies upon the brightness consistency hypothesis-a pixel's intensity is maintained throughout the transformation. Instead of assuming small distortion and linearizing the problem (e.g. via Taylor Series expansion), we propose to interpret the brightness hypothesis as an all-pass filtering relation between the two images. The key advantages of this new interpretation are that no restrictions are placed on the amplitude of the deformation or on the spatial variations of the images. Moreover, by converting the all-pass filtering to a linear forward-backward filtering relation, our solution to the estimation problem equates to solving a linear system of equations, which leads to a highly efficient implementation. Using this framework, we develop a fast algorithm that relates one image to another, on a local level, using an all-pass filter and then extracts the deformation from the filter-hence the name "Local All-Pass" (LAP) algorithm. The effectiveness of this algorithm is demonstrated on a variety of synthetic and real deformations that are found in applications, such as image registration and motion estimation. In particular, when compared with a selection of image registration algorithms, the LAP obtains very accurate results for significantly reduced computation time and is very robust to noise corruption.

MR-based respiratory and cardiac motion correction for PET imaging.

PURPOSE: To develop a motion correction for Positron-Emission-Tomography (PET) using simultaneously acquired magnetic-resonance (MR) images within 90 s. METHODS: A 90 s MR acquisition allows the generation of a cardiac and respiratory motion model of the body trunk. Thereafter, further diagnostic MR sequences can be recorded during the PET examination without any limitation. To provide full PET scan time coverage, a sensor fusion approach maps external motion signals (respiratory belt, ECG-derived respiration signal) to a complete surrogate signal on which the retrospective data binning is performed. A joint Compressed Sensing reconstruction and motion estimation of the subsampled data provides motion-resolved MR images (respiratory + cardiac). A 1-POINT DIXON method is applied to these MR images to derive a motion-resolved attenuation map. The motion model and the attenuation map are fed to the Customizable and Advanced Software for Tomographic Reconstruction (CASToR) PET reconstruction system in which the motion correction is incorporated. All reconstruction steps are performed online on the scanner via Gadgetron to provide a clinically feasible setup for improved general applicability. The method was evaluated on 36 patients with suspected liver or lung metastasis in terms of lesion quantification (SUVmax, SNR, contrast), delineation (FWHM, slope steepness) and diagnostic confidence level (3-point Likert-scale). RESULTS: A motion correction could be conducted for all patients, however, only in 30 patients moving lesions could be observed. For the examined 134 malignant lesions, an average improvement in lesion quantification of 22%, delineation of 64% and diagnostic confidence level of 23% was achieved. CONCLUSION: The proposed method provides a clinically feasible setup for respiratory and cardiac motion correction of PET data by simultaneous short-term MRI. The acquisition sequence and all reconstruction steps are publicly available to foster multi-center studies and various motion correction scenarios.

On the Spectrum of the Plenoptic Function.

The plenoptic function is a powerful tool to analyze the properties of multi-view image data sets. In particular, the understanding of the spectral properties of the plenoptic function is essential in many computer vision applications, including image-based rendering. In this paper, we derive for the first time an exact closed-form expression of the plenoptic spectrum of a slanted plane with finite width and use this expression as the elementary building block to derive the plenoptic spectrum of more sophisticated scenes. This is achieved by approximating the geometry of the scene with a set of slanted planes and evaluating the closed-form expression for each plane in the set. We then use this closed-form expression to revisit uniform plenoptic sampling. In this context, we derive a new Nyquist rate for the plenoptic sampling of a slanted plane and a new reconstruction filter. Through numerical simulations, on both real and synthetic scenes, we show that the new filter outperforms alternative existing filters.