基于深度学习的像素闪烁算法对高体质量指数患者低剂量腹部CT平扫图像质量的影响

目的 探讨基于深度学习的像素闪烁（PS）算法对体质量指数（BMI）≥ 25 kg/m²患者低剂量腹部CT平扫图像质量的影响。方法 选取59例接受腹部CT检查、BMI ≥ 25 kg/m²的患者,根据管电压分为A组（100 kVp,n=30）和B组（120 kVp,n=29）。根据不同重建算法和处理方式,将A组分为A1亚组（FBP）、A2亚组（FBP+PS）、A3亚组（50% ASiR-V）和A4亚组（50% ASiR-V+PS）;将B组分为B1亚组（FBP）和B2亚组（50% ASiR-V）。测量2组肝右叶、右侧竖脊肌CT值及SD值,计算肝脏SNR、CNR及容积CT剂量指数（CTDI_vol）,评价2名观察者间所测数值的一致性。结果 2名观察者所测数据的一致性良好（ICC值均> 0.80）。A组各亚组间肝脏及竖脊肌CT值差异无统计学意义（P > 0.05）;肝脏及竖脊肌SD值、肝脏SNR值差异有统计学意义（P均< 0.001）;两两比较SD_A4 < SD_A2 < SD_A3 < SD_A1,SNR_A4 > SNR_A2 > SNR_A3 > SNR_A1;A1与A3亚组间CNR值差异无统计学意义（P=0.078）,其余亚组间两两比较CNR_A4 > CNR_A2 > CNR_A3或CNR_A1（P均< 0.001）。A2亚组肝脏SD值较B1亚组、A4亚组较B2亚组明显降低,SNR及CNR值明显增高（P均< 0.001）。A组CTDI_vol明显低于B组（P均< 0.001）。结论 采用基于深度学习的PS算法可改善高BMI患者低剂量腹部CT平扫图像质量。     

A new method for quantitative analysis of dentinal tubules

Conventional methods to estimate the number of dentinal tubules cannot be considered reliable and repeatable, because results depends on the operator outlining of the tubules contours. In this study, we propose a totally automated computerized analysis technique to evaluate dentinal tubules and their surface area. The comparison test of these conventional with a semi-automatic methods shows that the automated analysis allowed a reliable identification and numbering of dentinal tubules, by means of high-quality images. No statistically significant difference exists in the number of tubules and the total tubule surface area between the control and test groups.     

Pixel compounding: resolution-enhanced ultrasound imaging for quantitative analysis

Accurate measurement of structural features represented in medical images is important in clinical trials and patient diagnosis. A key factor for precision is spatial resolution, which in ultrasonic imaging is limited by transducer array arrangements, transmitting frequency, and data acquisition firmware. In this paper, a variation of pixel compounding is proposed to enhance ultrasound resolution using acquired cine loops. The technique operates on a sequence of ultrasound B-scan images acquired with random motion. Subpixel registration is estimated and a maximum a posteriori (MAP) approach with the shift information is used to reconstruct a high-resolution single image. A nonhomogeneous anisotropic diffusion algorithm follows from the estimation process and is implemented to enhance the high-resolution edges. Preliminary tests using simulations and phantom studies show promising results. Pixel compounding can be a powerful preprocessing tool to assure accurate segmentation, measurement, and analysis of ultrasound images.     

Pixel激光治疗面部痤疮瘢痕

目的：观察Pixel激光治疗面部痤疮瘢痕的临床效果。方法：采用以色列飞顿2940nm像素激光对54例痤疮瘢痕的患者进行治疗,共治疗3～5次,每次间隔时间2～3周。除少教对疼痛敏感的患者治疗前外涂表面麻醉,其余不用任何处理。对比治疗前后的照片并进行疗效评价。结果：共治疗54例痤疮瘢痕患者,有效率75％～100％。Pixel同时可以有效改善4种不同类型痤疮,无一例色沉和瘢痕。结论：Pixel激光治疗痤疮凹陷性瘢痕疗效满意,对增生瘢痕疗效有限。是一种适合东方人痤疮瘢痕的安全,有效的治疗方法。     

The gray scale value of ear tissues undergoing volume-rendering high-resolution cone-beam computed tomography

Objective

When the thresholds for VR reconstruction from multi-slice CT images are changed, problems develop when assessing pathologies in the absence of standardized thresholds. The advantages of CBCT include lower radiation exposure compared with other techniques and better visualization of small ear structures. However, a disadvantage is that the scanner provides unstandardized gray scale values, thus not CT numbers (Hounsfield units, HU).

Pixel激光治疗黄褐斑的疗效和安全性分析

目的：评估Pixel激光治疗黄褐斑的疗效及安全性。方法：采用Pixel激光治疗黄褐斑患者72例,3～4周治疗1次,3～5次为一个疗程,每次复诊由医生和患者共同评定疗效和安全性。结果：72例患者中,痊愈17例（23.61%）,显效18例（25.0%）,有效率48.61%。轻度组：痊愈率45.45%（15例）,显效率36.36%（12例）,有效率81.81%;重度组：痊愈率5.13%（2例）,显效率15.38%（6例）,有效率20.51%;两组比较有显著性差异。病程小于2年者,有效率68.42%,疗效高于病程大于2年者。21例患者术后出现轻度色素沉着,均于术后3个月消退。结论：Pixel激光治疗黄褐斑安全有效,病程短、颜色浅者疗效更佳。     

计算机图像技术在糖尿病创面定量研究的应用

目的探讨计算机图像技术在糖尿病创面定量研究的应用价值。方法在糖尿病创面上放置标准网格模板,摄影后形成图片。使用计算机图像技术生成创面和肉芽的感兴趣区,获取像素值。与标准网格对比,算出创面和肉芽的面积等指标。结果第四周创面面积22.75cm^2,肉芽面积9.92cm^2,肉芽百分比43.60%,创面收缩率7.52%。肉芽百分比与创面收缩率的相关分析,Pearson相关系数r=0.900,P=0.037。结论计算机图像技术结合统计分析可为糖尿病创面提供客观、准确、动态的评价指标。     

Experimental correlation-based identification of X-ray CT point spread function. Part 2: simulation and design of input signal

The preferred signals for non-parametric correlation-based point spread function identification are white noise or pseudo-random binary sequences (PRBSs). Given the difficulty of building a phantom based on either of these signals, a new input is devised that corresponds to pseudo-randomly located holes. The positions of the holes correspond to zeros in a 2-D PRBS. To optimise the design of the phantom and to ensure proper imaging procedure, a number of simulations are conducted. The effects of the following parameters on identification quality are investigated: the size of the holes and their minimum separation, the period of the PRBS, input-output translational and rotational mis-registration, pixel size and the presence of cupping. The factors affecting identification quality the most are rotational alignment, hole size and separation, as well as sequence length. During simulations, a point spread function offering characteristics similar to the Philips Tomoscan CX is identified. Optimal results are obtained when the signal consists of 0·6 mm holes, separated by 0·9 mm, whose position is based on a 32×32 PRBS generated with a ten-stage shift-register. When adequate rotational alignment is provided, it is shown that the pseudo-randomly located holes signal is a good substitute for a purely white signal when identifying the PSF of a CT scanner.     

多层螺旋CT像素指数定量分析在新型冠状病毒肺炎评估中的应用价值研究

目的 探讨多层螺旋CT(MSCT)像素指数(PI)的定量分析在新型冠状病毒肺炎首次CT及病程评估中的临床应用价值.方法 回顾性收集2020年1月22日至2020年3月1日惠州市中心人民医院确诊的48例新型冠状病毒肺炎患者胸部MSCT数据,使用肺功能Thoracic VCAR软件分割肺叶,测量PI<-700Hu、-700...     

Quantitative assessment of mineralization in distraction osteogenesis

OBJECTIVES: The most important decision in distraction osteogenesis is the timing of fixator removal. Various methods have been tried, such as radiographic appearance of callus and bone mineral density (BMD) assessment, but none has acquired gold standard status. The purpose of this study was to develop another objective method of assessment of callus stiffness to help clinicians in taking the most important decision of when to remove the fixator. MATERIALS AND METHODS: We made a retrospective study of 70 patients to compare the BMD ratio and pixel value ratio. These ratios were calculated at the time of fixator removal, and Pearson's coefficient of correlation was used to show the comparability. Inter- and intra-observer variability of the new method was also tested. RESULTS: Good correlation was found between BMD ratio and pixel value ratio, with a Pearson's coefficient of correlation of 0.79. The interobserver variability was also low, with high intra-observer reproducibility, suggesting that this test was simple to perform. CONCLUSION: Pixel value ratio is a good method for assessing callus stiffness, and it can be used to judge the timing of fixator removal.