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Pleural effusion is a pathologic symptom in which there is accumulation of body fluids around the lungs. A chest radiograph is a rapid examination technique and does not require complex setup for making a preliminary diagnosis of lung and heart diseases. In radiographic visualization, the symptom patterns appear as light or dark areas in the lung cavity. Computer-aided diagnosis is an automatic manner that can rapidly highlight the object region by preanalyzing medical images. It can improve the problems of manual inspection and allow diagnosis in remote medical facilities. Based on the ratios of lung anatomy, the automatic screening manner based on pattern recognition can be viewed as pixel value detection in the bilateral lung cavities. In this study, a fractional-order convolution (FOC) process is used to enhance the original image for an accurate extrapolation of the desired object in an image. The specific object image feature can be improved, and an accurate quantification of the pleural effusion region can be obtained using the suitable ranges of fractional-order parameters. Based on the boundaries of homogeneous regions, the pixel ratios of the lung anatomy between normal and abnormal conditions can be computed. The pleural effusion sizes and volumes can be rapidly estimated through the number of pixel changes. The experimental results reveal that the feature maps are similar and stable on image enhancement and segmentation with two fractional-order enhancement masks, as fractional-order v = 0.05 to 0.20 for mask 1# and v = 0.80 to 0.95 for mask 2#, respectively. The results also demonstrate the feasibility of the study on combining two-dimensional image FOC-process and bounding box pixel analysis to estimate the moderate and large effusion sizes from 500–2,000 mL. [ABSTRACT FROM AUTHOR]

Pulmonary valve diseases include the different degrees of aortic stenosis or congenital defects in children or adults. Valve repair or replacement surgery is commonly performed to relieve valvular dysfunction and improve the significant flow regurgitation in the aortic valve and the pulmonary valve. However, commercial valve stents and valved conduits are sometimes not available for children or patients with special conditions. The handmade trileaflet valve design has been used with different range of diameters for patch-valved conduit reconstruction. Thus, we propose a multiple regression model, as a generalized regression neural network (GRNN), to determine the optimal trileaflet parameters, including the width, length, and upper lower curved structure. Through computed tomography pulmonary angiography, while the diameter of the main pulmonary artery is determined, a leaflet template can be rapidly sketched and made. Using an experimental pulmonary circulation loop system, the efficacy of the valved conduit can be validated using the regurgitation fraction method. In contrast to commercial valve stents, experimental results indicate that the handmade trileaflet valve can also improve severe pulmonary regurgitations. [ABSTRACT FROM AUTHOR]

BACKGROUND: The increasing prevalence of end-stage renal disease (ESRD) imposes a substantial economic burden on public health-care systems. Hemodialysis (HD) is a pivotal treatment modality for patients with ESRD. However, prolonged use of HD vessels may result in stenosis, thrombosis, and occlusion due to repeated daily punctures. Thus, early detection and prevention of the dysfunction of dialysis routes are crucial. OBJECTIVE: In this study, we designed a wearable device for the early and accurate detection of arteriovenous access (AVA) stenosis in HD patients. METHODS: A personalized three-dimensional (3D) printed wearable device was designed by combining the phonoangiography (PAG) and photoplethysmography (PPG) techniques. The capability of this device to monitor AVA dysfunction before and after percutaneous transluminal angioplasty (PTA) was evaluated. RESULTS: After PTA, the amplitudes of both PAG and PPG signals increased in patients with arteriovenous fistulas and those with arteriovenous grafts; this might be due to increased blood flow. CONCLUSION: Our designed multi-sensor wearable medical device using PAG, PPG, and 3D printing appears suitable for early and accurate detection of AVA stenosis in HD patients. [ABSTRACT FROM AUTHOR]

An arteriovenous graft (AVG) has a higher patency rate in stenosis progression at the venous anastomosis site, which causes coexisting inflow and outflow stenoses. This leads to increases in blood pressure, flow velocity, and flow resistance, resulting in hemodialysis (HD) vascular access dysfunction from early clots and thrombosis to the progression of coexisting stenoses. To prevent vascular access complications such as inflow or outflow stenoses, this study proposes a novel examination method in an experimental AVG system using a substitution-rate based screening model. In our practical measurements, we found that inflow and outflow channeled through a narrowed access indicated both pressure and resistance differences as the degree of stenosis (DOS) gradually increased. A substitution-rate matrix was conducted to replace bilateral pressure variations, while a transition probability matrix was calculated. Differences in transition probabilities were then used to distinguish between normal conditions and flow instabilities using the distance estimation method. The joint probability decayed from < 0.81 to 0.00 could be specified to identify the progression in stenosis levels from a DOS% = 50.0-95.0%. Average joint probabilities were found to be inversely related with the DOS using a non-linear regression (R>2 0.90). Hence, the joint probability could be specified as a critical threshold, < 0.81, to identify the severity stenosis level, DOS% ⩾ 70%, in the assessment of coexisting inflow and outflow stenoses. Experimental results suggest that the proposed model is superior to hemodynamic analysis and traditional intelligent method, and can be used for dysfunction screening during HD treatment. [ABSTRACT FROM AUTHOR]

Narrowed vessel accesses produce blood flow changes, and induce flow instability and vessel wall vibration, resulting in blood pressure, flow velocity, and flow resistance increases. The vessel wall vibrates and propagates the low axial blood flow, as representing the resistance (R) to blood flow. The compliance is a blood pressure-blood volume relation, representing the systole and diastole capacity of the blood vessel. These dynamic behaviors increase blood flow resistances and reduce blood vessel compliances. Vibration phenomena result on the elastic vessel walls and induce simple harmonic motion due to transverse vibration pressure (TVP). The rise time, amplitude, and pulse duration of transverse waves are determined by the flow resistances (R) and vessel compliances (C). Thus, a stenotic arteriovenous access has high resistance and low compliance, which can be expressed an astable multivibrator as an equivalent model consisting of a lumped resistor (R) and a lumped capacitor (C). TVP's oscillation frequency, rise time, and amplitude are determined by the flow resistances and vessel compliances. Hence, an astable multivibrator is used to model TVP parameters to estimate negative time constants, τ=(R× C), which are used to evaluate the flow instability and the dysfunction risk in in-vitro arteriovenous grafts (AVGs). Experimental results show the average negative time constants have the positive correlation as the degree of stenosis (DOS) increases (R2 = 0.8944), and their variations with the flow resistance and vessel compliance are also validated. Positive pole values, s=(-1/τ), are used to show that the force responses of the vessel walls grow in a finite time, 0.5415 ± 7.60 × 10-3 sec, and the equivalent model would be also unstable as DOS increases (R2 = 0.8802). By comparison with hemodynamic analysis, the finding of proposed model can be further carried out for screening AVG dysfunction risk during hemodialysis treatment. [ABSTRACT FROM AUTHOR]

Vascular access dysfunction commonly occurs in hemodialysis patients. Regularly monitoring and evaluating the vascular access condition is an important issue for these diseased patients. The objective of this study was to identify acoustic parameters and hemodynamics that related to changes in the stenosis of vascular access. In-vitro experimental circulation system offered pulsatile and physiological condition to simulate the arteriovenouse access in hemodialysis patient. We created the environments of various degrees of stenosis (DOS) inside the arteriovenouse access to simulate the stenotic conditions in patients. And we also used the computational fluid dynamics (CFD) to simulate the pressure distribution, primary axial velocity distribution, and secondary flow distribution in the same various DOS and boundary condition. There are two findings, one is recorded the bruit which caused by the fluctuation of fluid in different severe stenosis, the other is described the correlation between bruit and hemodynamic parameters. Experimental results show the time constants have linear regression with a positive correlation as the degree of stenosis (DOS) increases. Finally, in contrast to CFD computerized analysis and acoustic methods, the proposed parameter provides a feasibility index for evaluating the risk of AVG dysfunction in on-line/real time analysis. [ABSTRACT FROM AUTHOR]