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Ultrasonography is an important diagnostic imaging technique for visualization of tendons, which provides useful health diagnostic and fundamental information in neuromuscular studies of human motion systems. Conventional ultrasonic-based tendon studies, however, are highly dependent on subjective experience of operators due to various impairments of ultrasound images. Dynamic changes of muscle and tendon deformation in a sequence can hardly be manually processed. Consequently, there is an urgent need for automatic analysis of tendon behavior. This paper proposes an automatic ultrasonic tendon tracking algorithm to extract the shape deformation of central tendon of rectus femoris (CT-RF) from ultrasonic image sequences. The tracking problem is complicated by the highly deformable tendon, time-varying brightness, and the inconspicuousness of the target. To address this difficult tracking problem, we proposed a new intensity-compensated free-form deformation (IC-FFD)-based tracking algorithm with local shape refinement (LSR). Experimental results and comparison show that the proposed IC-FFD-LSR algorithm outperforms IC-FFD and conventional methods such as MI-FFD in CT-RF tracking.

In this work, we report the existence of spoof localized surface plasmons (spoof-LSPs) arising with closed high contrast gratings (HCGs) at deep subwavelength scales, another platform for field localization at microwave frequencies. The HCGs are in the form of a periodic array of radial dielectric blocks with high permittivity around a metal core supporting spoof-LSPs of transverse magnetic (TM) form. Simulation results validate the phenomenon and a metamaterial approach is also given to capture all the resonant features of this kind of spoof-LSPs. In addition, experimental verification of the existence of spoof-LSPs supported by a three dimensional (3D) HCGs resonance structure in the microwave regime is presented. This work expands the original spoof-LSPs theory and opens up a new avenue for obtaining resonance devices in the microwave frequencies.

Architecture of skeletal muscle can change significantly during body motion, which can be observed in vivo during contraction using ultrasonography noninvasively and in real-time. Yet gender differences are paid little attention to in most current studies on muscle architecture using ultrasonography. In this study, thickness of muscle and fat is compared for young male and female subjects using automatic processing method proposed previously. Significant differences are found, between results from male and female subjects, in thickness of tibialis anterior, lateral gastrocnemius or the fat layers in 7 pre-defined posture/motion. Even after rectified by the Body Fat Index, significant differences are also found, between male and female subjects, for muscle (P

Ultrasound imaging has been used frequently for the study of muscle contraction, including measurements of pennation angles and fascicle orientations. However, these measurements were traditionally conducted by manually drawing lines on the ultrasound images. In this study, we proposed a modified Hough transform (HT), aiming at automatically estimating orientations of straight line-shaped patterns, such as muscle fibers and muscle-bone interface in ultrasound images. The new method first located the global maximum in the HT accumulator matrix, which corresponded to the most dominant collinear feature points globally, using the standard HT; then the pixels close to the detected line were removed from the edge map, the HT accumulator matrix was calculated again, i.e., revoting, and a new line was detected. The iteration was repeated until the predefined termination conditions were satisfied. The performance of the algorithm was tested using computer-generated images with different levels of noises, as well as clinical ultrasound images, and compared with that of the conventional method. It was found that the orientation estimation results obtained by the new algorithm were well correlated (R2 = 0.965), with those obtained using the traditional method, i.e., drawing lines manually and reading the angles with the assistance of software. Further mean-difference plots revealed a difference of 0.18 +/- 2.41 degrees between the two methods at the 95% confidence level. Compared with the traditional method, the new algorithm was more capable of handling with highly noisy data and could avoid the aliasing problem, i.e., reporting multiple lines instead of single expected line. The results of this study suggested that the proposed revoting HT can be potentially used for the reliable and nonsubjective automatic estimation of the orientations of muscle fibers in musculoskeletal ultrasound images.

A new method is reported for monitoring respiratory activity using photoplethysmography (PPG) without the need of prior knowledge of the respiratory rate range. Two channels of transmission mode PPG signals were collected from the subject's index finger and analyzed using an independent component analysis (ICA) algorithm. The respiratory activity was separated from the heart‐related pulsation in PPG after the ICA analysis. The results demonstrated that the ICA analysis could successfully extract normal and simulated apnoea respiratory activities. The algorithm was applied for both simulated signals and those collected from 10 young normal adults. The reported technique may be potentially used for the simultaneous monitoring of the pulse rate and respiratory activity based on the hardware of current pulse oximetry devices. The structure and implementation of this preliminary respiratory activity monitoring system were presented. Possible further improvements for the system performance were also di...

An efficient image registration algorithm, the Inverse Compositional image alignment method based on minimization of Sum of Squared Differences of images, is applied in fundus blood vessel angiography under confocal scanning laser ophthalmoscope, to build image mosaics which have larger field of view without loss of resolution to assist diagnosis. Furthermore, based on similar technique, the angiography video stabilization algorithm is implemented for fundus documenting. The actual underlying models of motion between images and corresponding convergence criteria are also discussed. The experiment results in fundus images demonstrate the effectiveness of the registration scheme.

Currently, the evaluation of placental maturity has mainly focused on subjective measure, which highly depends on the observation and experiences of the clinicians and not reliable. This paper proposes a new method for grading placenta maturity in B-mod ultrasound (US) images automatically based on local intensity order pattern (LIOP) and fisher vector (FV). After extracting invariant LIOP feature from the affine covariant region, the feature is encoded by FV to improve the classification accuracy and reduce the processing time. Experimental results show the effectiveness of the proposed method with an accuracy of 0.9375, a sensitivity of 0.9804 and a specificity of 0.9375 for the placental maturity grading. Moreover, experimental results demonstrate that the LIOP feature outperforms the traditional SIFT feature for grading.

Muscle force output is an essential index in rehabilitation assessment or physical exams, and could provide considerable insights for various applications such as load monitoring and muscle assessment in sports science or rehabilitation therapy. Besides direct measurement of force output using a dynamometer, electromyography has earlier been used in several studies to quantify muscle force as an indirect means. However, its spatial resolution is easily compromised as a summation of the action potentials from neighboring motor units of electrode site. To explore an alternative method to indirectly estimate the muscle force output, and with better muscle specificity, we started with an investigation on the relationship between architecture dynamics and force output of triceps surae. The muscular architecture dynamics is captured in ultrasonography sequences and estimated using a previously reported motion estimation method. Then an indicator named as the dorsoventrally averaged motion profile (DAMP) is employed. The performance of force output is represented by an instantaneous version of the rate of force development (RFD), namely I-RFD. From experimental results on ten normal subjects, there were significant correlations between the I-RFD and DAMP for triceps surae, both normalized between 0 and 1, with the sum of squares error at 0.0516±0.0224, R-square at 0.7929±0.0931 and root mean squared error at 0.0159±0.0033. The statistical significance results were less than 0.01. The present study suggested that muscle architecture dynamics extracted from ultrasonography during contraction is well correlated to the I-RFD and it can be a promising option for indirect estimation of muscle force output.

As a direct determinant parameter to quantify muscle activity, the muscle thickness (MT) has been investigated in many aspects and for various purposes. Ultrasonography (US) is a promising modality to detect muscle morphological changes during contractions since it is portable, noninvasive, and real time. However, there are few reports on sensitive and efficient estimation of changes of MT in a cross-sectional plane. In this feasibility investigation, we proposed a coarse-to-fine method based on a compressive-tracking algorithm for estimation of MT changes during an example task of isometric knee extension using ultrasound images. The sensitivity and efficiency are evaluated with 1920 US images from quadriceps muscle (QM) in eight subjects. The detection results were compared with those obtained from both traditional manual measurement and the well known normalized cross-correlation method, and the effect of the size of tracking window on detection performance was evaluated as well. It is demonstrated that the proposed method agrees well with the manual measurement. Meanwhile, it is not only sensitive to relatively small changes of MT but also computationally efficient.

Background Improvement in muscle strength is an important aim for the rehabilitation of hemiplegia patients. Presently, the rehabilitation prescription depends on the evaluation results of muscle strength, which are routinely estimated by experienced physicians and therefore not finely quantitative. Widely-used quantification methods for disability, such as Barthel Index (BI) and motor component of Functional Independent Measure (M-FIM), yet have limitations in their application, since both of them differentiated disability better in lower than higher disability, and they are subjective and recorded in wide scales. In this paper, to explore finely quantitative measures for evaluation of muscle strength level (MSL), we start with the study on quantified electromyography (EMG) and sonomyography (SMG) features of tibialis anterior (TA) muscles among hemiplegia patients. Methods 12 hemiplegia subjects volunteered to perform several sets of plantar-flexion movements in the study, and their EMG signals and SMG signals were recorded on TA independently to avoid interference. EMG data were filtered and then the root-mean-square (RMS) was computed. SMG signals, specifically speaking, the muscle thickness of TA, were manually measured by two experienced operators using ultrasonography. Reproducibility of the SMG assessment on TA between operators was evaluated by non-parametric test (independent sample T test). Possible relationship between muscle thickness changes (TC) of TA and muscle strength level of hemiplegia patients was estimated. Results Mean of EMG RMS between subjects is found linearly correlated with MSL (R2 = 0.903). And mean of TA muscle TC amplitudes is also linearly correlated with MSL among dysfunctional legs (R2 = 0.949). Moreover, rectified TC amplitudes (dysfunctional leg/ healthy leg, DLHL) and rectified EMG signals (DLHL) are found in linear correlation with MSL, with R2 = 0.756 and R2 = 0.676 respectively. Meanwhile, the preliminary results demonstrate that patients’ peak values of TC are generally proportional to their personal EMG peak values in 12 dysfunctional legs and 12 healthy legs (R2 = 0.521). Conclusions It’s concluded that SMG could be a promising option to quantitatively estimate MSL for hemiplegia patients during rehabilitation besides EMG. However, after this exploratory study, they should be further investigated on a larger number of subjects.

The quadriceps femoris is a large muscle group which is crucial in walking, running, jumping and squatting. Therefore, study on quadriceps muscle activity is of realistic significance. As one of architectural parameters, muscle thickness has been investigated in many aspects for various purposes. However, there are few studies on quantitating the relationship between quadriceps muscle thickness and torque output. In this study a coarse-to-fine method based on a compressive tracking algorithm is used for real-time estimation of muscle thickness during isometric contraction on ultrasound images. Ultrasonography is a convenient and widely-used technique to look into the muscle contraction as it is non-invasive and real-time. The relationship between quadriceps muscle thickness and torque output are investigated with data from 13 subjects. The experimental result showed that the change of muscle thickness in cross-sectional plane is similar to its torque during muscle contraction, but the relationship between them is nonlinear.

Muscle thickness is an important parameter related to musculoskeletal functions and has been studied in many ways and for various purposes. In recent years, ultrasound imaging has been widely used for measuring muscle properties of human muscles non-invasively, with the advantages of real time and low cost. The muscle thickness is usually measured manually, which is subjective and time consuming. In addition, there are few studies on automatic estimation of muscle thickness during dynamic contraction. In this study, an automatic estimation method based on compressive tracking algorithm is proposed to detect the thickness changes of tibialis anterior muscle during dynamic contraction on ultrasound images. The performance of the proposed method is compared to manual detection using clinical images from tibialis anterior muscles of ten patients. As a result, we found that the proposed method agrees well with the manual measurement, and it was able to provide an accurate and efficient approach for estimating muscle thickness during human motion.

Sclareol is a member of labdane type diterpenes mostly used as fragrance ingredient. To enable microbial production of sclareol, synthetic pathways were constructed by incorporating labdenediol diphosphate synthase (LPPS) and terpene synthase (TPS) of the plant Salvia sclarea into Saccharomyces cerevisiae. It was found that sclareol production could be benefited by overexpression of key enzyme for precursor biosynthesis, construction of fusion protein for substrate channeling, and removal of signal peptides from LPPS and TPS. Under optimal shake flask culture conditions, strain S6 produced 8.96 mg/L sclareol. These results provided useful information for development of heterologous hosts for production of terpenoids.

We built a Placido’s disc videokeratographic system intended for eye examination of small animals. To derive the corneal topology and other corneal biometric parameters we rely on precise extraction of Placido ring patterns. However, since the images from CCD are noisy, image enhancement is necessary as a pre-processing procedure in order to prevent further noise magnification during the corneal surface topography reconstruction. In this study, two popular image enhancement methods, namely Gabor Filtering (GF) and Multiscale Vessel Enhancement Filtering (MVEF), are quantitatively evaluated in the context of image enhancement before corneal reconstruction. The two methods were tested on 21 images of steel balls with different diameters. Both methods have been demonstrated to be useful for Placido ring extraction; however, the GF method showed better performance on images of steel balls with smaller diameter. Compared to the GF method, the MVEF method performed better on images of steel balls with larger diameter. The result of the present work implies that the two methods should be used cooperatively.

In recent years, ultrasound imaging have been widely used to assess human muscle. Quantitative ultrasound can provide objective information about muscle architectures and changes of motion pattern during muscle contraction. However, there are few reports about the visualization of cross-sectional skeletal muscle motion using descriptive color coding strategy. In this study, ultrasound images were recorded from right quadriceps femoris muscle during isometric knee extension, and a motion estimation method based on a theory for warping was used to compute morphological changes of muscle during contraction. Then a novel color coding strategy, which agrees with the established directing rules in medical imaging, was applied to present the motion field. In comparison with the traditional color coding method, the new strategy was more capable of providing detailed information about the velocity and morphological changes in different region of muscle intuitively. The proposed approach has the potential to be applied for the functional understanding and segmentation of various muscle sections.

Background Muscle fiber orientation (MFO) is an important parameter related to musculoskeletal functions. The traditional manual method for MFO estimation in sonograms was labor-intensive. The automatic methods proposed in recent years also involved voting procedures which were computationally expensive. Methods In this paper, we proposed a new framework to efficiently estimate MFO in sonograms. We firstly employed Multi-scale Vessel Enhancement Filtering (MVEF) to enhance fascicles in the sonograms and then the enhanced images were binarized. Finally, line-shaped patterns in the binary map were detected one by one, according to their shape properties. Specifically speaking, for the long-and-thinner regions, the orientation of the targeted muscle fibre was directly computed, without voting procedures, as the orientation of the ellipse that had the same normalized second central moments as the region. For other cases, the Hough voting procedure might be employed for orientation estimation. The performance of the algorithm was evaluated using four various group of sonograms, which are a dataset used in previous reports, 33 sonograms of gastrocnemius from 11 young healthy subjects, one sonogram sequence including 200 frames from a subject and 256 frames from an aged subject with cerebral infarction respectively. Results It was demonstrated in the experiments that measurements of the proposed method agreed well with those of the manual method and achieved much more efficiency than the previous Re-voting Hough Transform (RVHT) algorithm. Conclusions Results of the experiments suggested that, without compromising the accuracy, in the proposed framework the previous orientation estimation algorithm was accelerated by reduction of its dependence on voting procedures.

Skeletal muscle is an important tissue of human body, and its contractions control and regulate body motions. Muscle contraction results in morphological changes of the related muscles. Ultrasound imaging is an effective tool for studying muscle architectures and monitoring the morphological changes of muscles. The latter process can be realized with a motion estimation algorithm. However, ultrasound images are usually corrupted by speckle noises and performance of motion estimation methods can be significantly affected by the noises. To get a better performance in motion analysis, in this paper, as a pre-processing step, an adaptive filter named adaptive guided image filtering (AGF) is suggested to reduce speckle noises. We first transformed the multiplicative noise model into an additive one by taking the logarithm of the original speckled data, then performed AGF to obtain the filtered image, and finally took the tackled image back into exponent. Experimental results showed that AGF had a better performance in terms of noise attenuation and edge preservation compared with other standard filters. In quantitative results, the filtered images also had the highest Peak-Signal-to-Noise Ratio (PSNR) using AGF. It's believed that AGF is a good choice for the pre-processing stage of muscle motion analysis.

Ultrasonography is a convenient and widely used technique to look into the longitudinal muscle motion as it is radiation-free and real-time. The motion of localized parts of the muscle, disclosed by ultrasonography, spatially reflects contraction activities of the corresponding muscles. However, little attention was paid to the estimation of longitudinal muscle motion, especially towards estimation of dense deformation field at different depths under the skin. Yet fewer studies on the visualization of such muscle motion or further clinical applications were reported in the literature. A primal–dual algorithm was used to estimate the motion of gastrocnemius muscle (GM) in longitudinal direction in this study. To provide insights into the rules of longitudinal muscle motion, we proposed a novel framework including motion estimation, visualization and quantitative analysis to interpret synchronous activities of collaborating muscles with spatial details. The proposed methods were evaluated on ultrasound image sequences, captured at a rate of 25 frames per second from eight healthy subjects. In order to estimate and visualize the GM motion in longitudinal direction, each subject was asked to perform isometric plantar flexion twice. Preliminary results show that the proposed visualization methods provide both spatial and temporal details and they are helpful to study muscle contractions. One of the proposed quantitative measures was also tested on a patient with unilateral limb dysfunction caused by cerebral infarction. The measure revealed distinct patterns between the normal and the dysfunctional lower limb. The proposed framework and its associated quantitative measures could potentially be used to complement electromyography (EMG) and torque signals in functional assessment of skeletal muscles.

Ultrasonography is a convenient and widely-used technique to look into the muscle contraction as it is non-invasive and real-time. Muscle thickness has been investigated in many aspects and for various purposes. However, there are few studies on automatic estimation of changes of muscle thickness in cross-sectional plane during contraction. In this study we proposed a coarse-to-fine method based on compressive tracking algorithm for real-time estimation of muscle thickness during isometric contraction on ultrasound images. The real-time performance and precision are investigated with data from quadriceps muscle in five subjects. The detection results were compared with those obtained from both cross-correlation algorithm and manual measurement. It is shown that the proposed method agrees well with the manual measurement and outperforms the cross-correlation method in the sense of both accuracy and computation cost.

Ultrasonography is a convenient and widely-used technique to view the longitudinal muscle motion as it is non-invasive and real-time. However, the estimation of longitudinal muscle motion, in sense of dense deformation field, was paid little attention to previously. In this report a primal-dual algorithm was used to estimate the motion of gastrocnemius muscle (GM) in longitudinal direction. Then a color encoding scheme and the mean velocities (mm/s) of frame-wise motion field were adopted to show the synchronous activities. The preliminary results, on 600 frames of ultrasound muscle images in motion, demonstrated that the proposed estimation method are helpful to study of the contraction of muscle in longitudinal direction, providing motion details both spatially and temporally.

In this paper, we applied the Adaptive Non-local Filtering to reduce the speckle noises and strengthen the meaningful features in musculoskeletal sonograms, then the structural features points were extracted after binarization, and finally we applied Re-voting Hough transform (RVHT) method proposed earlier to estimate the muscle fiber orientations. The results obtained by this new method was compared with those obtained using a previous method using the Sobel edge operator and RVHT only. 226 lines representing the orientation of muscle fibers or boundaries were manually selected by two operators from 45 muscular ultrasound images. These lines were also detected by the proposed automatic estimation methods. Using the results obtained manually as a reference, the differences of the new method and that using RVHT only were 0.40± 0.44 degrees and 0.70 ± 0.73 degrees, respectively. The results demonstrated that the performance of the orientation estimation method with the additional image processing approaches was fairly improved with few extra computation costs.

Background Muscle fascicle pennation angle (PA) is an important parameter related to musculoskeletal functions, and ultrasound imaging has been widely used for measuring PA, but manually and frame by frame in most cases. We have earlier reported an automatic method to estimate aponeurosis orientation based on Gabor transform and Revoting Hough Transform (RVHT). Methods In this paper, we proposed a method to estimate the overall orientation of muscle fascicles in a region of interest, in order to complete computing the orientation of the other side of the pennation angle, but the side found by RVHT. The measurements for orientations of both fascicles and aponeurosis were conducted in each frame of ultrasound images, and then the dynamic change of pennation angle during muscle contraction was obtained automatically. The method for fascicle orientation estimation was evaluated using synthetic images with different noise levels and later on 500 ultrasound images of human gastrocnemius muscles during isometric plantarflexion. Results The muscle fascicle orientations were also estimated manually by two operators. From the results it’s found that the proposed automatic method demonstrated a comparable performance to the manual method. Conclusions With the proposed methods, ultrasound measurement for muscle pennation angles can be more widely used for functional assessment of muscles.

Red yeasts hold great promise in the production of microbial lipids and carotenoids. Genetic study of red yeasts has attracted much attention; however, rapid amplification of genes from red yeast samples remains technically challenging. Here a highly efficient method for the preparation of genomic DNA (gDNA) template, which could be directly used for PCR, was developed. Cells from colonies or liquid cultures were collected and sequentially treated by microwave, plMAN5C, proteinase K and boiling (MMPB) in a single tube to give cell lysates that were qualified as PCR templates. Single-copied gDNA fragments o up to 2.8 kb were successfully amplified. We also demonstrated successful application of this method for species in the Ascomycetes and Basidiomycetes and identification of two leucine auxotroph mutants of Rhodotorula glutinis. This method could be widely employed for the screening and genetic engineering of various yeasts.

In this study, to complement our previously proposed method for estimating muscle fiber orientation, the Gabor filter bank (GF) technique was applied to sonograms of the biceps and forearm muscles to longitudinally enhance the coherently oriented and hyperechoic perimysiums regions. The method involved three steps: orientation field estimation, frequency map computation and Gabor filtering. The method was evaluated using a simulated image distorted with multiplicative speckle noises where the "muscles" were arranged in a bipennate fashion with an "aponeurosis" located in the middle. After enhancement using the GF approach, most of the original hyperechoic bands in the simulated image could be recovered. The proposed method was also tested using a group of biceps and forearm muscle sonograms collected from healthy adult subjects. Compared with the sonograms without enhancement, the enhanced images led to the detection of more linear patterns including muscle fascicles and smaller angle differences compared with the mean of manual results from two operators, therefore, were better prepared for the automatic estimation of muscle fiber orientation. The proposed method has the potential of assisting in the visualization of strongly oriented patterns in skeletal muscle sonograms as well as in the semi-automatic estimation of muscle fiber orientations.

Muscle fatigue is an exercise-induced reduction in the maximal capacity of muscle to produce force or power output. The continuous changes of brachialis pennation angles during the fatiguing isometric contraction was investigated in this study. The muscle torque, surface electromyography (SEMG) and ultrasound image of brachialis were continuously recorded during the process of isometric contraction. The mean brachialis pennation angles of four subjects increased from 19.75 ±± 2.57° of pre-fatigue to 23.10 ±± 2.85° of post-fatigue. The results demonstrated that the muscle fatigue would result in the dramatic increase of pennation angle during the submaximal sustained isometric contraction.

Ultrasound imaging has been widely used to investigate the morphological changes during skeletal muscle contraction. In this study, the ultrasound images were recorded from extensor muscle during finger flexion, and the optical flow algorithm was used to recognize the muscle deformation for different fingers' flexions. The preliminary results demonstrated that the directions of optical flow and deformation areas of muscle contraction at certain location were different for five fingers' flexions. The proposed approach has the potential to classify finger flexion with the feature extraction from optical flow field.

This experimental study sought to determine the repeatability of a Video Keratography System specially designed for animals with small eyes. From day 5, ten newly hatched White Leghorn chicks were reared with monocular hyperopic defocus using -5.0D (n = 3), -10.0D (n = 3), -15.0D(n = 4) spherical PMMA lenses on their right eyes; the left eyes served as controls. Two sets of corneal topographical measurements, each set separated by about 5 minutes apart, were collected from both eyes of each animal at the end of 2-wk treatment period (i. e., 19 days of age). Each set of measurements consisted of five consecutive readings of corneal astigmatism. Bland-Altman plots were used to evaluate the repeatability of 3, 4 or all 5 readings from each set of data. When all 5 consecutive readings were used, the mean difference (95% limits of agreement) for the right treated and left untreated eyes were, respectively, -0.09D (-0.81, 0.64) and -0.02D (-0.86, 0.82). There was a tendency that lesser readings from each set of data produced greater difference between the two sets of measurements, although the differences (-0.19D) were not clinically significant. The Video Keratography System specially designed for animals with small eyes produced repeatable measurements for both treated and untreated eyes in chickens. Further studies are needed to validate other biometric features associated with corneal changes during normal and abnormal eye growth.

In this study, the Gabor filter bank technique was applied to the biceps and gastrocnemius ultrasound images to longitudinally enhance the coherently oriented and hyperechoic perimysiums regions. The method involved three steps, orientation field estimation, frequency map computation and Gabor filtering. The method was evaluated using a simulated image distorted with multiplicative speckle noises, where the “muscles” were arranged in a bipennate fashion with a central “aponeurosis”. After the enhancement using the proposed method, most of the original hyperechoic bands in the simulated image could be recovered and the noises in other locations were greatly reduced. The proposed method was also tested on biceps sonograms collected from 4 healthy adult subjects. Based on the filtering results, the hyperechoic regions, especially the fibroadipose septas, could be enhanced in several aspects, such as the completion of broken but coherently oriented regions. It is believed that the proposed method have potentials in assisting the visualization of strongly oriented patterns in ultrasound images and especially the quantitative estimation of muscle thickness, muscle fiber pennation angle and fascicle length.

A convenient nanoscale technique is reported for the fabrication of highly ordered hemispherical silver nanocap arrays templated by porous anodic alumina (PAA) membranes as robust and cost-efficient surface-enhanced Raman scattering (SERS) substrates. This geometry produces a high Raman signal due to its periodic hexagonal arrangements and control of the gap between the nanostructures in the sub-10-nm regime. The surface structure can be tuned further to optimize the enhancement factor according to optional PAA fabrication and silver deposition parameters. Finite-difference time-domain calculations indicate that the structure may possess excellent SERS characteristics due to the high density and abundance of hot spots.

A tunable incremental factor is introduced into the inverse compositional image alignment method in registration of fundus blood vessel angiograms under confocal scanning laser ophthalmoscope. The augmented version need less iteration to converge and hardly causes degradation to the registration precision, mainly due to the favorable convexity of the sum of squared differences (SSD) function between the angiograms around the correct registration. And as a compromise between the fidelity of diagnostic information and visual purpose, an adaptive blending strategy based on undecimated discrete sequence wavelet transform is presented in this paper to mosaic fundus angiograms. The effectiveness and efficiency of the tunable incremental factor algorithm is exemplified in the experimental results on clinical indocyanine green angiograms, and the convexity of the SSD function under ideal imaging condition is also illustrated in the paper.

In this paper, the traditional snake model and gradient vector flow (GVF) snake model are studied, which are believed to be quite slow due to the need to compute inverse matrix. Actually, the GVF in the latter snake model is formed by a biased linear diffusion procedure, and there would be oscillations around the edge of the object. Based on GVF generated through non-linear diffusion, we present a fast GVF (FGVF) snake model which is much faster than the traditional snake model and GVF snake model, and would cause no degradation of stability and flexibility, meanwhile, it could reduce the oscillations around the edges. The segmentation results using FGVF and error analysis on simulated images are presented. Finally, the demonstration of FGVF applied to Computed Tomography and Magnetic Resonance images are shown, the segmentation results are satisfactory visually with much less computation time in comparison with former snakes.

A tunable incremental factor is introduced to the inverse compositional image alignment method in registration of fundus blood vessel angiograms under confocal scanning laser ophthalmoscope, to build angiogram mosaics which have larger field of view without loss of resolution to assist diagnosis. The algorithm costs less iterations to converge usually and hardly causes degradation to the registration precision, mainly due to the favorable convexity of the normalized Sum of Squared Differences (SSD) function between the angiograms. The effectiveness and efficiency of the tunable incremental factor algorithm, as well as the convexity of the normalized SSD function, is exemplified in the experimental results on clinical indocyanine green angiograms.

Background Motion characteristics of CoP (Centre of Pressure, the point of application of the resultant ground reaction force acting on the plate) are useful for foot type characteristics detection. To date, only few studies have investigated the nonlinear characteristics of CoP velocity and acceleration during the stance phase. The aim of this study is to investigate whether CoP regularity is different among four foot types (normal foot, pes valgus, hallux valgus and pes cavus); this might be useful for classification and diagnosis of foot injuries and diseases. To meet this goal, sample entropy, a measure of time-series regularity, was used to quantify the CoP regularity of four foot types. Methods One hundred and sixty five subjects that had the same foot type bilaterally (48 subjects with healthy feet, 22 with pes valgus, 47 with hallux valgus, and 48 with pes cavus) were recruited for this study. A Footscan® system was used to collect CoP data when each subject walked at normal and steady speed. The velocity and acceleration in medial-lateral (ML) and anterior-posterior (AP) directions, and resultant velocity and acceleration were derived from CoP. The sample entropy is the negative natural logarithm of the conditional probability that a subseries of length m that matches pointwise within a tolerance r also matches at the next point. This was used to quantify variables of CoP velocity and acceleration of four foot types. The parameters r (the tolerance) and m (the matching length) for sample entropy calculation have been determined by an optimal method. Results It has been found that in order to analyze all CoP parameters of velocity and acceleration during the stance phase of walking gait, for each variable there is a different optimal r value. On the contrary, the value m=4 is optimal for all variables. Sample entropies of both velocity and acceleration in AP direction were highly correlated with their corresponding resultant variables for r>0.91. The sample entropy of the velocity in AP direction was moderately correlated with the one of the acceleration in the same direction (r≥0.673), as well as with the resultant acceleration (r≥0.660). The sample entropy of resultant velocity was moderately correlated with the one of the acceleration in AP direction, as well as with the resultant acceleration (for the both r≥0.689). Moderate correlations were found between variables for the left foot and their corresponding variables for the right foot. Sample entropies of AP velocity, resultant velocity, AP acceleration, and resultant acceleration of the right foot as well as AP velocity and resultant velocity of the left foot were, respectively, significantly different among the four foot types. Conclusions It can be concluded that the sample entropy of AP velocity (or the resultant velocity) of the left foot, ML velocity, resultant velocity, ML acceleration and resultant acceleration could serve for evaluation of foot types or selection of appropriate footwear.

A convenient strategy is demonstrated for placing C60 nanoclusters in hot spots between neighbouring arms of silver nano-dendrites leading to intense surface-enhanced Raman scattering (SERS) enhancement. The finite difference time domain calculations indicate that the dendrite-like model pattern may demonstrate a high quality SERS property owing to the 'metal/nanoclusters/metal' hot geometries. Further calculations provide useful guidelines for the synthesis of hot dendritic geometries and further increasing the enhancement factor of the SERS.

This study aimed to characterize corneal accommodation in alert chicks with and without experimentally-induced astigmatism. Refraction and corneal biometry were measured in 16 chicks with experimentally-induced astigmatism (1.00 D) and 6 age-matched control chicks (astigmatism ⩽ 1.00 D). Corneal accommodation was detected using a Placido-ring based videokeratography system, by measuring changes in corneal curvature from a series of consecutive images acquired from alert chicks. The correlation between the magnitudes of corneal accommodation and astigmatism was analyzed by including data from all 22 chicks. Data from all eyes showed obvious bi-directional changes in corneal accommodation. There was no significant difference in corneal accommodative changes between the fellow eyes of the treated birds, and the right and left eyes of control birds. However, positive accommodation (PA) and maximum magnitude of PA (MPA) were significantly higher in the astigmatic vs. the fellow eyes of treated chicks (mean ± SE: PA=+2.24 ± 0.44 D vs. +1.26 ± 0.20 D; MPA=+7.53 ± 0.81 D vs. +4.38 ± 0.53 D, both p0.05). This was not the case for negative accommodation (NA) or maximum magnitude of NA (MNA) (NA=-0.46 ± 0.15 D vs. -0.33 ± 0.04 D; MNA=-0.92 ± 0.23 D vs. -0.73 ± 0.12D, respectively, p0.05). Furthermore, higher PA and MPA were found to be correlated with higher refractive astigmatism (both r=0.34, p0.05). These results suggest that the presence of astigmatism may interfere with accommodative function in chicks.

Background Ultrasonography is a convenient technique to investigate muscle properties and has been widely used to look into muscle functions since it is non-invasive and real-time. Muscle thickness, a quantification which can effectively reflect the muscle activities during muscle contraction, is an important measure for musculoskeletal studies using ultrasonography. The traditional manual operation to read muscle thickness is subjective and time-consuming, therefore a number of studies have focused on the automatic estimation of muscle fascicle orientation and muscle thickness, to which the speckle noises in ultrasound images could be the major obstacle. There have been two popular methods proposed to enhance the hyperechoic regions over the speckles in ultrasonography, namely Gabor Filtering and Multiscale Vessel Enhancement Filtering (MVEF). Methods A study on gastrocnemius muscle is conducted to quantitatively evaluate whether and how these two methods could help the automatic estimation of the muscle thickness based on Revoting Hough Transform (RVHT). The muscle thickness results obtained from each of the two methods are compared with the results from manual measurement, respectively. Data from an aged subject with cerebral infarction is also studied. Results It’s shown in the experiments that, Gabor Filtering and MVEF can both enable RVHT to generate comparable results of muscle thickness to those by manual drawing (mean ± SD, 1.45 ± 0.48 and 1.38 ± 0.56 mm respectively). However, the MVEF method requires much less computation than Gabor Filtering. Conclusions Both methods, as preprocessing procedure can enable RVHT the automatic estimation of muscle thickness and MVEF is believed to be a better choice for real-time applications.