Speckle reduction in ultrasound images using nonisotropic adaptive filtering

In this article, a speckle reduction approach for ultrasound imaging that preserves important features such as edges, corners and point targets is presented. Speckle reduction is an important problem in coherent imaging, such as ultrasound imaging or synthetic aperture radar, and many speckle reduction algorithms have been developed. Speckle is a non-additive and non-white process and the reduction of speckle without blurring sharp features is known to be difficult. The new speckle reduction algorithm presented in this article utilizes a nonhomogeneous filter that adapts to the proximity and direction of the nearest important features. To remove speckle without blurring important features, the location and direction of edges in the image are estimated. Then for each pixel in the image, the distance and angle to the nearest edge are efficiently computed by a two-pass algorithm and stored in distance and angle maps. Finally for each pixel, an adaptive directional filter aligned to the nearest edge is applied. The shape and orientation of the adaptive filter are determined from the distance and angle maps. The new speckle reduction algorithm is tested with both synthesized and real ultrasound images. The performance of the new algorithm is also compared with those of other speckle reduction approaches and it is shown that the new algorithm performs favorably in reducing speckle without blurring important features.     

Speckle noise reduction in ultrasound biomedical B-scan images using discrete topological derivative

Over three decades, several despeckling techniques have been developed by researchers to reduce the speckle noise inherently present in ultrasound B-scan images without losing the diagnostic information. The topological derivative (TD) is the recently adopted technique in the area of biomedical image processing. In this work, we computed the topological derivative for an appropriate function associated to the ultrasound B-scan image gradient by assigning a diffusion factor k, which indicates the cost endowed to that particular image. In this article, a novel image denoising approach, called discrete topological derivative (DTD) has been implemented. The algorithm has been developed in MATLAB7.1 and tested over 200 ultrasound B-scan images of several organs such as the liver, kidney, gall bladder and pancreas. Further, the performance of the DTD algorithm has been estimated by calculating important performance metrics. A comparative study was carried out between the DTD and the traditional despeckling techniques. The calculated peak signal-to-noise ratio (PSNR) (the ratio between the maximum possible power of a signal and the power of corrupting noise that affects the fidelity of its representation) value of the DTD despeckled liver image is found to be 28 which is comparable with the outperformed speckle reducing anisotropic diffusion (SRAD) filter. SRAD filter is an edge-sensitive diffusion method for speckled images of ultrasonic and radar imaging applications. Canny edge detection and visual inspection of DTD filtered images by the trained radiologist found that the DTD algorithm preserves the hypoechoic and hyperechoic regions resulting in improved diagnosis as well as tissue characterization.     

Unsupervised identification of white matter tracts in a mouse brain using a directional correlation-based region growing (DCRG) algorithm

The inner product of the major eigenvectors of adjacent pixels, known as the directional correlation (DC), has been used previously as a quantitative index to investigate directional similarity in white matter (WM) tracts. A high degree of directional similarity (i.e., high DC) among pixels within individual WM tracts was observed. Based on this observation, a region growing algorithm was employed to propagate an area from a seed point as a function of the DC threshold (DCt) to manually identify WM tracts in two-dimensional (2D) slices from diffusion tensor imaging (DTI). In the present study, an improved unsupervised DC based region growing (DCRG) method was implemented to reduce the operator-dependent variance and to improve the ease of use of the technique. By employing improved method, a multi-slice DTI data set of an in vivo mouse brain was used to identify the external capsule, visual pathway, and corpus callosum. The resultant WM tracts are computer rendered in three-dimensional (3D) images with anatomical images as structural references. In addition, three sets of ex vivo mouse brain data were used to examine the effects of different slice thickness and the signal-to-noise ratio (SNR) to the outcome of DCRG.     

Automated identification and reduction of artifacts in cine four-dimensional computed tomography (4DCT) images using respiratory motion model

Purpose

Four-dimensional computed tomography (4DCT) images are often marred by artifacts that substantially degrade image quality and confound image interpretation. Human observation remains the standard method of 4DCT artifact evaluation, which is time-consuming and subjective. We develop a method to automatically identify and reduce artifacts in cine 4DCT images.

Methods

We proposed an algorithm that consisted of two main stages: deformable image registration and respiratory motion simulation. Specifically, each 4DCT phase image was registered to the breath-holding CT image using the block-matching method, with erroneous spatial matches removed by the least median of squares filter and the full displacement vector field generated by the moving least squares interpolation. The lung’s respiratory motion trajectory was then recovered from the displacement vector field using the parameterized polynomial function, with fitting parameters estimated by combinatorial optimization. In this way, artifacts were located according to deviations between image points and their motion trajectories and further corrected based on position prediction.

Results

The mean spatial error (standard deviation) was 1.00 (0.85) mm after registration as opposed to 6.96 (4.61) mm before registration. In addition, we took human observation conducted by medical experts as the gold standard. The average sensitivity, specificity, and accuracy of the proposed method in artifact identification were 0.97, 0.84, and 0.89, respectively.

Conclusions

The proposed method identified and reduced artifacts accurately and automatically, providing an alternative way to analyze 4DCT image quality and to correct problematic images for radiation therapy.

     

Classification of breast masses in ultrasonic B-mode images using a compounding technique in the Nakagami distribution domain

Classification of masses in ultrasonic B-mode images of the breast tissue using "normalized" parameters of the Nakagami distribution was recently investigated. The technique, however, did not yield performances that were comparable to those of an experienced radiologist, and utilized only a single image for tissue characterization. Because radiologists commonly use two to four images of a mass for characterization, a similar procedure is developed here. A simple summation of the normalized Nakagami parameters from two different images of a mass is utilized for classification as benign or malignant. The performance of the normalized Nakagami parameters before and after the summation has been carried out through a receiver operating characteristic (ROC) study. The bootstrap procedure has been utilized to compute the mean and SD of the ROC area, A(z), obtained for each parameter. It has been observed that combining normalized Nakagami parameters from two images of the mass may help to improve classification performance over that from utilizing the parameters of just a single image. The performance of this automated parameter-based approach appears to match that of a trained radiologist.     

腹腔镜保胆取石治疗小儿胆囊结石的初步报告

目的探讨腔镜下微创保胆取石治疗小儿胆囊结石的临床应用价值。方法回顾分析2008年6月至2011年1月采用腹腔镜联合尿道镜微创保胆取石术治疗小儿胆囊结石12例。胆囊多发结石7例,胆囊结石合并遗传性球形红细胞增多症2例。首先经脐部开放置入5 mm Trocar,建立气腹,压力8～12 mmHg,于右肋缘下腹直肌外缘处置入5mm Trocar,腹腔镜下将胆囊底部经右上腹Trocar孔提出腹外,切开胆囊底部约0.5cm,置小儿0°膀胱镜入胆囊,了解胆汁、胆囊黏膜、胆囊腔、胆囊颈、胆囊管和结石位置、数量、质地以及有无嵌顿等,发现结石后用电切环镜下依次取出,小结石可用吸引器吸出及生理盐水冲洗,胆道镜检查确认无结石残留。予36%泛影葡胺胆道造影,观察有无结石残留、胰胆管合流异常等。检查胆囊管开口见有胆汁流出,无出血,5-0PDS线缝合胆囊切口。观察无活动出血、胆漏等,缝合切口。结果 12例患儿中11例保胆取石获得成功,1例3岁患儿术中胆道造影提示胆总管稍扩张,胆囊开口与右肝管,中转行胆囊切除、肝管空肠Roux-Y吻合术,其余11例行腔镜保胆取石术(2例球形红细胞增多症患儿行腹腔镜脾切除)。手术时间30～70 min,平均50.45 min。术后24 h进食,3～7 d(平均4.27 d)出院。保胆成功的11例患儿获得随访3～30个月(平均16.6个月),期间复查B超检查未见结石复发,无特殊并发症。结论对于胆囊功能良好的小儿胆囊结石患儿采用腔镜下保胆取石手术,具有微创、可重复性强的特点,同时保留了胆道的完整性及胆囊功能,提高患儿的生存质量,对小儿的远期生长发育具有积极意义。手术操作简单,术后恢复快、并发症少,全可行。保胆取石是治疗小儿胆囊结石的可行性方法。     

经皮肾镜气压弹道联合超声碎石术治疗肾结石的疗效研究

目的探讨经皮肾镜气压弹道超声碎石术联合超声碎石术治疗肾结石的临床疗效及安全性。方法2011年5月至2013年10月该院治疗的196例肾结石患者,分为观察组和对照组,各98例。对照组患者采用经皮肾镜气压弹道碎石术,观察组患者使用经皮肾镜气压弹道联合超声碎石术。比较2组患者的手术情况,Ⅰ、Ⅱ期结石清除率及术后并发症发生情况,并通过SF-36量表对2组患者手术安全性进行评价。结果 2组患者在手术时无严重并发症发生,观察组患者的手术时间、术中出血量及术后住院时间均少于对照组,差异有统计学意义(P0.05)。观察组患者的Ⅰ期结石清除率(79.6%)明显优于对照组(54.1%),差异有统计学意义(χ2=14.386,P0.05),且Ⅱ期结石清除率(95.0%)也明显高于对照组,差异有统计学意义(66.7%)(χ2=5.990,P0.05);观察组患者术后出现1例并发症(1.0%),明显少于对照组的7例(7.1%),差异有统计学意义(χ2=4.671,P0.05)。术前2组患者的SF-36量表评分差异无统计学意义(P0.05);术后对照组患者SF-36各项评分均低于观察组,差异有统计学意义(P0.05)。结论采用经皮肾镜气压弹道超声碎石术治疗肾结石疗效更好,操作简便安全,并发症较少,具有临床价值。     

Estimation of muscle fiber orientation in ultrasound images using revoting hough transform (RVHT)

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 (R(2) = 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. (E-mail: ypzheng@ieee.org).     

产前长骨弯曲合并多指(趾)畸形1例

患儿男,足月剖宫产后2 h,体质量3200g.术中医生发现患儿左小腿向外侧弯曲,外侧皮肤有1条小靥.右脚六趾,左手中、小指短缩畸形.X线检查:左侧胫腓骨向前外侧弯曲,左胫骨明显成角,右侧胫骨轻度弯曲,双侧胫骨内侧皮质较厚,髓腔变窄;右足第一趾内侧可见多余趾骨.     

Reducing amputation rates in patients with diabetes at a military medical center: the limb preservation service model

OBJECTIVE: To describe and evaluate the Limb Preservation Service (LPS), a multidisciplinary, state-of-the-art, foot care clinic for patients with diabetes at Madigan Army Medical Center (MAMC). Evaluation criteria include the overall incidence of lower-extremity amputation (LEA) and the distribution of the anatomic level of amputation between 1999 and 2003. RESEARCH DESIGN AND METHODS: This is a retrospective study of the incidence and types of LEAs performed in patients with diabetes at MAMC. Patients with diagnosed diabetes and LEA procedures were identified by ICD-9-Clinical Modification (CM) codes. Hospital and clinic characteristics that are integral to the success of the program are described. RESULTS: The number of patients at MAMC with diagnosed diabetes increased 48% from 1999 to 2003; however, the number of LEAs decreased 82% from 33 in 1999 to 9 in 2003. Amputations of the foot, ankle, and toe comprise 71% of amputations among patients with diabetes. CONCLUSIONS: The results of this study provide evidence of the value of a focused multidisciplinary foot care program for patients with diabetes. Associations between the creation of the LPS and LEA rates are discussed.     

The highly sensitive determination of serotonin by using gold nanoparticles (Au NPs) with a localized surface plasmon resonance (LSPR) absorption wavelength in the visible region

The development of improved methods for the synthesis of monodisperse gold nanoparticles (Au NPs) is of high priority because they can be used as substrates for surface-enhanced Raman scattering (SERS) applications relating to biological lipids. Herein, Au NPs have been successfully synthesized via a seed-mediated growth method. The LSPR peak is controlled via adjusting the gold nanoseed component, and different fabrication methods were studied to establish the effect of sonication time on NP size. The simple, facile, and room-temperature method is based on a conventional ultrasonic bath, which leads to ultrasonic energy effects on the size and morphology of the Au NPs. This research offers new opportunities for the production of highly monodispersed spherical Au NPs without the use of a magnetic stirrer method, as evidenced by ultraviolet-visible reflectance spectra and scanning electron microscopy (SEM) analysis. SEM images indicate that the spherical Au NP colloidal particles are stable and reliable, which paves the way for their use as a nanostructured biosensor platform that can be exploited for multiple applications, for example, in materials science, sensing, catalysis, medicine, food safety, biomedicine, etc. The highest enhancement factor that could be achieved in terms of the SERS enhancement activity of these Au NP arrays was determined using 10⁻⁹ M serotonin (5-hydroxytryptamine, 5-HT) as the Raman probe molecules.

The development of improved methods for the synthesis of monodisperse gold nanoparticles (Au NPs) is of high priority because they can be used as substrates for surface-enhanced Raman scattering (SERS) applications relating to biological lipids.     

Small calcification indicator in ultrasonography using correlation of echoes with a modified Wiener filter

Purpose

The purpose of this study is to improve the calcification depiction ability in ultrasonography using correlation of echoes with a modified Wiener filter.

Methods

The waveform of an ultrasound pulse changes when it passes through the location of a calcification. Since the change in echo waveform caused by a calcification decreases the correlation of waveforms in adjacent scan lines, we have proposed a calcification depiction method using the decorrelation of echoes. However, the low signal-to-noise ratio of echoes also decreases the correlation of the echoes. In this study, we employ the correlation of echoes with a modified Wiener filter to suppress the effect of noise, as an indicator of a calcification.

Results

The proposed calcification indicator depicted copper cylindrical rods 0.2?mm in size at a depth of 2?cm with a sensitivity of 80% and a positive predictive value of 80%, despite being hardly depicted at all on B-mode ultrasound imaging.

Conclusion

This study suggests the potential of the proposed method to improve the performance of calcification depiction by ultrasound devices.     

Evaluation of Fe(iii)EDTA reduction with ascorbic acid in a wet denitrification system

The reduction of Fe(iii)EDTA to Fe(ii)EDTA is the core process in a wet flue gas system with simultaneous desulfurization and denitrification. Herein, at first, the reductant ascorbic acid (VC) was used for reducing Fe(iii)EDTA. The feasibility of Fe(iii)EDTA reduction with ascorbic acid was investigated at different Fe(iii)EDTA concentrations, various pH values, diverse temperatures, and different molar ratios of VC to Fe(iii)EDTA. The results showed that the Fe(ii)EDTA concentration increased with an increase in the initial Fe(iii)EDTA concentration. Furthermore, the reduction efficiency increased as the mole ratio of VC to Fe(iii)EDTA was increased, and all the Fe(iii)EDTA reduction efficiencies were close to 100% when the mole ratio was more than 0.5. On the other hand, an alkaline environment did not favor the conversion of Fe(iii)EDTA by VC. The Fe(iii)EDTA conversion slightly increased as the temperature was increased. Moreover, compared with other reduction systems, ascorbic acid (VC) was found to be more powerful in reducing Fe(iii)EDTA, especially in air. In addition, VC only exhibited powerful ability in the conversion of Fe(iii)EDTA to Fe(ii)EDTA and hardly reduced Fe(ii)EDTA–NO. Finally, the stoichiometry of Fe(iii)EDTA reduction by ascorbic acid was derived. Thus, our study would offer a bridge between foundational research and industrial denitration using the combination of Fe(ii)EDTA and VC.

Color change during Fe(iii)EDTA reduction by VC ((A) Fe(iii)EDTA color; (B) color of Fe(iii)EDTA solution after reduction by VC; (C) Fe(ii)EDTA-NO color; (D) color of Fe(ii)EDTA-NO solution after reduction by VC).     

Imaging the development of an ischemic core following photochemically induced cortical infarction in rats using Laser Speckle Contrast Analysis (LASCA)

Laser Speckle Contrast Analysis (LASCA) has been used to image the development of an ischemic core following photochemically induced infarction in rats up to 1 h post-lesion. Using LASCA, we have been able to image a central ischemic core which had little or no perfusion surrounded by a penumbral region with reduced perfusion. In addition, we have shown the existence of a surrounding region of hyperemic tissue. A potential feature of this imaging approach is its capability to track cerebral blood flow (CBF) changes in the region within and outside the ischemic core besides demonstrating the real-time progression of the ischemic core into the penumbral region. We have demonstrated the continuous disruption of CBF to the ischemic core that eventually affected the blood supply to the surrounding regions. The penumbral flow is shown to exhibit a sudden increase post-ischemic induction followed by a slow decline to the final baseline level. Interestingly, we observed an interaction (P < 0.03) between penumbral flow peak and the time effects of increase in pixel area from the infarct region to the surrounding penumbral region. Using a paired-sample t test, we observed that the mean pixel area was larger for the infarct region than for the penumbral region (P < 0.004) during the time interval between the induction of ischemia and the time point of peak flow in the penumbral region.     

Comparison of platelet loss during leukocyte reduction at 4, 24, and 48 hours postcollection using a closed system apheresis kit with integral filter

Prestorage leukocyte reduction of platelet concentrates may reduce adverse effects of transfusion while affording better quality control. Platelets and leukocytes may undergo activation during storage, which could affect the performance of leukocyte reduction filters. The purpose of this study was to evaluate the efficiency of leukocyte reduction and concomitant platelet loss with a new apheresis kit with an integral leukocyte reduction filter. Twelve donors underwent plateletpheresis on three occasions using the CS-3000 PLUS Blood Cell Separator with the Access™ Management System and the Access™ Closed System Apheresis Kit with Integral Sepacell® Leukocyte Reduction Filter and Double Return Line Needle (Baxter-Fenwal Division, Deerfield, IL). Of the three products from each donor, one each was filtered at 4, 24, and 48 hours completion of the plateletpheresis. Mean prefiltration platelet count was 4.43 × 10¹¹ and mean postfiltration platelet count was 3.56 × 10¹¹. Mean platelet recovery at 4, 24, and 48 hours filtration was 75%, 83%, and 84%, respectively. Analysis of variance (ANOVA) demonstrated that platelet recovery with filtration at four hours was significantly less than with filtration at 24 hours (P = 0.0236) and filtration at 48 hours (P = 0.0122). Platelet recovery with filtration at 24 hour did not differ significantly from filtration at 48 hours (P = 0.7684). Mean prefiltration WBC count was 0.93 × 10⁶ and mean postfiltration WBC count was 0.12 × 10⁶. Efficiency of leukocyte reduction was not significantly related to when filtration was performed. There was no significant variation from donor to donor in platelet recovery or in leukocyte reduction efficiency. This method of prestorage leukocyte reduction demonstrated slightly but statistically significantly better platelet recovery with filtration at 24 or 48 hours after platelet collection compared to four hours. All filtration times provided acceptable platelet yields with very low residual WBC. J. Clin. Apheresis 12:14–17, 1997 © 1997 Wiley-Liss, Inc.     

Catalytic filtration: efficient C-C cross-coupling using Pd(II)-salen complex-embedded cellulose filter paper as a portable catalyst

A new approach has been developed for environmentally friendly C-C cross-coupling reactions using bi-functional Pd(ii)-salen complex-embedded cellulose filter paper (FP@Si-Pd^II-Salen-[IM]OH). A Pd(ii)-salen complex bearing imidazolium [OH]⁻moieties was covalently embedded into a plain filter paper, then used as an efficient portable catalyst for the Heck, Suzuki, and Sonogashira cross-coupling reactions under environmentally friendly conditions via the filtration method. The catalytic filter paper properties were studied by EDX, XPS, TGA, ATR, XRD, and FESEM analyses. The reactions were catalyzed during reactants'' filtration over the catalytic filter paper. The modified filter paper was set up over a funnel and the reactants were passed through the catalytic filter paper several times. The effect of reaction parameters including loading of Pd(ii)-salen complex, temperature, solvent, and contact time were carefully studied and also the optimal model of conditions was presented by the design expert software. High to excellent yields were obtained for all C–C coupling types with 5 to 8 filtration times. Under optimal conditions, all coupling reactions showed high selectivity and efficiency. Another advantage of the modified filter paper was its stability and reusability for several times with preservation of catalytic activity and swellability.

A new platform has been developed for environmentally friendly C–C cross-coupling reactions via filtration of reactants through a portable Pd^(II)-salen complex-embedded filter paper.     

Identification of subclinical myocardial dysfunction by Speckle Tracking Imaging in patients with myocardial infarction with non-occlusive coronary arteries (MINOCA)

The International Journal of Cardiovascular Imaging - The objective of this study was to investigate subclinical left ventricular dysfunction in patients diagnosed with myocardial infarction with...     

腹腔镜联合硬性胆道镜保胆取石术的临床观察(附268例报告)

目的 探讨腹腔镜联合硬性胆道镜保胆取石的临床应用价值.方法 总结该院2006年12月～2009年8月,Olympus腹腔镜联合Wolf硬性胆道镜行保胆取石手术268例,采用气管插管全身麻醉,腹腔镜辅助下右肋缘下小切口提出胆囊,胆囊底丝线缝吊牵引,建立胆道镜通道,应用WoIf硬性胆道镜结合取石篮、取石钳及气压弹道碎石取出结石.4-0可吸收线缝扎胆囊底切口.结果 268例中263例保胆成功,5例胆囊管结石嵌顿改行LC术.平均手术时间55min,平均住院5d,均治愈出院,无并发症发生.结论 腹腔镜联合硬性胆道镜保胆取石术安全可靠,切实可行.     

内科急腹症的诊断体会(附220例报告)

报告内科急腹症220例。确诊217例,其中器质性疾病182例,功能性疾病35例。结果表明,两者的年龄分布存在显著性差异,(P<0.05)。呕吐的发生率,器质性疾病和功能性疾病分别为51.65%和14.29%,两者有显著性差异(P<0.01)。伴发热者,感染性疾病为76.85%,非感染性疾病为19.27%,两者有显著性差异(P<0.01)。提示这些症状有助于鉴别诊断。本文还介绍了内科急腹症的诊断思路和体会。