“Parenchyma transection-first”strategy is superior to“tunnel-first”strategy in robotic spleen-preserving distal pancreatectomy with conservation of splenic vessels

Background: Creating a tunnel between the pancreas and splenic vessels followed by pancreatic parenchyma transection(“tunnel-first” strategy) has long been used in spleen-preserving distal pancreatectomy(SPDP) with splenic vessel preservation(Kimura’s procedure). However, the operation space is limited in the tunnel, leading to the risks of bleeding and difficulties in suturing. We adopted the pancreatic “parenchyma transection-first” strategy to optimize Kimura’s procedure. Methods: The clinical data of consecutive patients who underwent robotic SPDP with Kimura’s procedure between January 2017 and September 2022 at our center were retrieved. The cohort was classified into a “parenchyma transection-first” strategy(P-F) group and a “tunnel-first” strategy(T-F) group and analyzed. Results: A total of 91 patients were enrolled in this cohort, with 49 in the T-F group and 42 in the P-F group. Compared with the T-F group, the P-F group had significantly shorter operative time(146.1 ± 39.2 min vs. 174.9 ± 46.6 min, P < 0.01) and lower estimated blood loss [40.0(20.0–55.0) m L vs. 50.0(20.0–100.0) m L, P = 0.03]. Failure of splenic vessel preservation occurred in 10.2% patients in the TF group and 2.4% in the P-F group( P = 0.14). The grade 3/4 complications were similar between the two groups( P = 0.57). No differences in postoperative pancreatic fistula, abdominal infection or hemorrhage were observed between the two groups. Conclusions: The pancreatic “parenchyma transection-first” strategy is safe and feasible compared with traditional “tunnel-first strategy” in SPDP with Kimura’s procedure.

Antidiastole Value of Three-dimensional Ultrasonography and Power Doppler between Uterine Parenchyma Lumps and Endometrial Cancer:A Retrospective Study

Sometimes endometrial polyps,submucosal myomas,and endometrial cancer show similar findings under ultrasonography.The aim of this study was to assess the antidiastole value of blood flow parameters using three-dimensional(3D)power Doppler ultrasonography angiography(PDA)between endometrial cancer and uterine parenchyma lumps.The data of the blood flow indices in 3D-PDA including the vascularization index(VI),flow index(FI),and vascularization flow index(VFI)in 40 patients with endometrial cancer and 41 patients with uterine parenchyma lumps(endometrial polyps and submucosal myomas)were retrospectively analysed and compared utilizing Virtual Organ Computer-aided AnaLysis(VOCAL)software.The results showed that all the blood flow parameters(VI,FI,VFI)were significantly higher in women with endometrial cancer than in those with uterine parenchyma lumps(P<0.001).The area under the curve of ROC of VI,FI,and VFI was 0.98,0.84,and 0.97,respectively.Thus,the best predictor of endometrial carcinoma was VI with a sensitivity of 97.0% and a specificity of 91.0%.The optimal cutoff value of VI was 4.06%.Our data demonstrated that all of the blood flow signal parameters(including VI,FI,and VFI)in 3D power Doppler ultrasonography had significant antidiastole values between endometrial cancer and uterine parenchyma lumps to assist clinicians in properly diagnosing patients.

Automatic Delineation of Lung Parenchyma Based on Multilevel Thresholding and Gaussian Mixture Modelling

Delineation of the lung parenchyma in the thoracic Computed Tomography(CT)is an important processing step for most of the pulmonary image analysis such as lung volume extraction,lung nodule detection and pulmonary vessel segmentation.An automatic method for accurate delineation of lung parenchyma in thoracic Computed Tomography images is presented in this paper.The proposed method involves a segmentation phase followed by a lung boundary correction technique.The tissues in the thoracic Computed Tomography can be represented by a number of Gaussians.We propose a histogram utilized Adaptive Multilevel Thresholding(AMT)for estimating the total number of Gaussians and their initial parameters.The parameters of Gaussian components are updated by Expectation Maximization(EM)algorithm.The segmented lung parenchyma from the Gaussian Mixture model(GMM)undergoes an Adaptive Morphological Filtering(AMF)to reduce the boundary errors.The proposed method has been tested on 70 diseased and 119 normal lung images from 28 cases obtained from Lung Image Database Consortium(LIDC).The performance of the proposed system has been validated.

An Alternative Strategy to Obtain Cellulose Nanofibrils from Parenchyma Cellulose of Bagasse Pith and the Performance of Its Nanopaper

Cellulose nanofibrils(CNFs)were obtained through one-step mechano-partial dissolution by ball milling in N,N-dimethyl acetamide with a low concentration of LiCl from agricultural waste bagasse pith(BP).Compared with fibrous cellulose,parenchyma cellulose(PC)is less uniform in diameter and less aligned,causing PC to dissociate into CNFs during this process without pretreatment.The results showed that the CNFs prepared from PC of BP had a diameter of 30-200 nm and a length of several micrometers.The as-obtained CNFs,along with dissolved cellulose,formed a wet-stable and highly transparent nanopaper in a sorbitol aqueous solution bath,which exhibited a high strain of 101%and a low Young's modulus of 4.3 MPa owing to the addition of the plasticizer sorbitol.This type of nanopaper with favorable transparency,high tensile property,and low Young's modulus has great potential for use as electronic skin and medical dressing material.

Extrahepatic right portal vein ligation allows parenchyma-sparing en bloc resection of segments 7, 8 and 4a for liver tumors engaging the right and middle hepatic veins

Right trisectionectomy for posterior liver tumors engaging the right and middle hepatic veins may lead to post-hepatectomy liver failure if the anticipated liver remnant is small. In such patients we developed a parenchymasparing one-step approach, that includes extrahepatic right portal vein ligation accompanied by en bloc resection only of segments 7, 8 and 4a and resection of the right and middle hepatic veins. The technique was applied in 3 patients with normal liver function, where according to the preoperative computed tomography the volume of segments 1, 2 and 3 ranged between 17% and 20% of the total liver volume. In all patients liver biochemistry improved rapidly postoperatively and a doubling of volume of segments 1, 2 and 3 was achieved by the third postoperative week, as extrahepatic right portal vein ligation ameliorated reperfusion injury of the remaining segments 5 and 6 and induced hypertrophy of segments 1, 2, 3 and 4b. There was no mortality or long-term complications.Patients are alive and free of disease 74, 50 and 17 months after the operation, respectively. We propose that the term ＂extended upper right sectionectomy＂ may be considered for the en bloc resection of segments 7, 8 and 4a, in future revisions ofthe Brisbane 2000 terminology of hepatic anatomy and resections.

The Arrangement and Size of Cellulose Microfibril Aggregates in the Cell Walls of Sclerenchyma Fibers and Parenchyma Tissue in Bamboo

Understanding the assembly and spatial arrangement of bamboo cell wall components is crucial for its optimal utilization.Bamboo cell walls consist of aggregates of cellulose microfibrils and matrix.In the present study,the size and arrangement of cellulose microfibril aggregates in the cell walls of sclerenchyma fibers and parenchyma cells in moso bamboo were investigated with NMR and FE-SEM.The NMR measurement showed that the characteristic sizes of the microfibril aggregates of fibers and parenchyma cells were approximately 25.8 nm and 18.8 nm,respectively.Furthermore,high-resolution SEM showed the size of microfibril aggregates varied little across the cell wall of sclerenchyma fiber.However,there were significant size differences between the broad and narrow lamellae both in fiber and parenchyma cells,which is thought to be closely related to the orientation of microfibrils in these layers.The microfibril aggregates in the fibers mainly appear in a random arrangement,although occasionally in a radial or tangential arrangement in individual cell.Parenchyma cells have a relatively thinner cell wall layers,in which microfibril aggregates appear in a concentric lamellar arrangement.

Study on Preparation of Lignin-Containing Nanocellulose from Bamboo Parenchyma

Bamboo vascular bundle fiber and parenchyma(BP)are separated by high-temperature treatment with saturated steam.Bamboo vascular bundle fiber is widely used in the market,but how to develop and utilize parenchyma tissue is a difficult problem.The sulfated cellulose nanofibers(ANFs)were obtained by sulfating BP with a deep eutectic solvent(DES),which provided a theoretical basis for the value-added utilization of BP.Using DES as the reaction medium and reagent,the BP was grafted with a sulfonic acid group to form a gel substance in water,ANFs and nanocellulose gel were obtained by ultrasonic cell crusher.The highest yield of ANFS was 75%.The width of the ANFs was about 3 nm,and a small number of nanofiber aggregates existed at the same time.A high aspect ratio of ANFs,due to their high viscosity,has potential applications as enhancers at low concen-trations.Lewis acid(ZnCl 2)added based on binary(DES)greatly improved the thermal stability of the ANFs and maintained the crystal form of cellulose I.

Sickle renal parenchyma incision for the removal of complex staghorn renal stone

Objective To evaluate the sickle renal parenchyma incision for the removal of complex staghorn renal calculi. Methods Sickle parenchyma incision was used to remove stones in 37 patients with complex staghorn renal calculi. The procedure was as follows; the kidney was disected free and the pelvis within sinus renalis was isolated. Two of botton style sutures were made on the renal parenchyma with 2-0 plain catgut along mid-lower 1 /3 of the dorsal surface of kidney free of vessels (Brodie’ s line) from the renal posterior lib to the plane of lower major calyx. The renal parenchyma was opened. Then, the incision was developed from the plane of lower major calyx through the middle major calyx to the plane of upper major calyx. The shape of this incision appeared like a sickle. The renal parenchyma and each calyx along this incision were opened and so was all the stones could then be easily removed. The calyces could well be observed. Results The calculi were completely removed in all the 37 cases. 21

Limited influences of chemotherapy on healthy and metastatic liver parenchyma

AIM: To examine the expression of E-cadherin, β-catenin,γ-catenin, VEGF, and p53 in 39 patients with hepatic metastasis from colorectal cancer immunohistochemically.METHODS: The patients were divided into two groups:those (n = 16) who had no chemotherapy for at least 6 mo before the liver resections and those (n = 23)who were treated with chemotherapy before liver resections. A score from 0 to 3 was given for the number of positive cells and from 0 to 3 for the intensity of staining in these cells, in both healthy and metastatic liver parenchyma.RESULTS: No significant differences in the expression of E-cadherin, β- and γ-catenin, VEGF and p53, could be observed between patients who received and did not receive chemotherapy, in both normal and metastatic liver parenchyma.CONCLUSION: Despite the assumption that chemotherapy had an effect on liver metastasis, no influences were noticed immunohistochemically.

锦绣杜鹃花药发育及散粉孔形成的形态与解剖学研究

被子植物中部分类群的花药开裂方式为孔裂,人们对此类花药的发育与散粉孔的形成及散粉机制了解甚少。杜鹃属(Rhododendron)植物的花药普遍为顶孔开裂,为探究其花药的发育和散粉孔的形成及散粉机制,该研究对锦绣杜鹃(Rhododendron×pulchrum)进行了解剖观察和石蜡切片。结果表明:(1)锦绣杜鹃花药顶端成孔区与花药主体具有不同的组织构成,成孔区由薄壁组织构成,起源于雄蕊原基顶端的分生组织,花粉成熟时薄壁细胞分解成为散粉孔;花药的主体由孢原细胞发育而来,孢原细胞经多次分裂分化成为具多层花药壁的花粉囊。(2)锦绣杜鹃的花药壁在小孢子母细胞至小孢子四分体时期发育完全,有6~7层细胞,包括1层表皮、2~3层药室内壁、1~2层中层和1层绒毡层,中层在小孢子四分体形成后即分解,绒毡层在花粉完全成熟前分解消失,花药壁在花粉成熟时有表皮和2~3层药室内壁。(3)与纵裂型花药不同,锦绣杜鹃的药室内壁在花粉成熟时不发生纤维化,但因积累多糖而增厚,具有韧性和弹性。(4)锦绣杜鹃花粉发育过程中小孢子母细胞产生的4个小孢子不分离,成熟花粉为四合花粉,花粉间具有粘丝。推测锦绣杜鹃具多层药室内壁且加厚可使花粉囊空间缩小,从而将上部花粉“挤出”散粉孔,而花粉间的粘丝使昆虫传粉时可将花粉成团带出,其药室内壁多层且积累多糖是与顶孔开裂相适应的特征。

矩镰荚苜蓿地下器官贮藏组织中淀粉粒变化规律

矩镰荚苜蓿(Medicago archiducis-nicolai)分布于青藏高原东缘高寒地区,具有极强的抗寒能力。为了探明矩镰荚苜蓿地下器官的越冬抗寒机理,本研究采用常规石蜡切片法,对自然越冬过程中根、根颈和地下茎贮藏组织中淀粉粒的变化进行动态观测。结果显示:矩镰荚苜蓿越冬过程中,淀粉主要贮藏在地下器官的髓和栓内层薄壁细胞中,少量存在于木质部薄壁细胞,根颈与根内淀粉粒分布较为密集;地下不同器官中淀粉数量在越冬前后变化趋势基本一致,总体呈现出先减少后增加的变化规律,越冬前期淀粉在地下器官中大量积累,越冬中期逐渐消失,后期又逐渐积累起来;各地下器官中根颈对温度变化响应最快,地下茎对低温最敏感。研究发现,矩镰荚苜蓿地下茎除具有扩展、繁殖能力外,还兼具贮藏与抗寒等能力,是该植物不同于其他苜蓿属物种的特殊地下器官;越冬期矩镰荚苜蓿地下器官抗寒力形成的不同步性,可能是其应对高寒环境的适应性策略。

An automated pulmonary parenchyma segmentation method based on an improved region growing algorithm in PET-CT imaging

To address the incomplete problem in pulmonary parenchyma segmentation based on the traditional methods, a novel automated segmentation method based on an eight- neighbor region growing algorithm with left-right scanning and four-corner rotating and scanning is proposed in this pa- per. The proposed method consists of four main stages： image binarization, rough segmentation of lung, image denoising and lung contour refining. First, the binarization of images is done and the regions of interest are extracted. After that, the rough segmentation of lung is performed through a general region growing method. Then the improved eight-neighbor region growing is used to remove noise for the upper, mid- dle, and bottom region of lung. Finally, corrosion and ex- pansion operations are utilized to smooth the lung boundary. The proposed method was validated on chest positron emis- sion tomography-computed tomography （PET-CT） data of 30 cases from a hospital in Shanxi, China. Experimental results show that our method can achieve an average volume overlap ratio of 96.21 ± 0.39% with the manual segmentation results. Compared with the existing methods, the proposed algorithm segments the lung in PET-CT images more efficiently and ac- curately.

C-TIRADS及超微血管成像技术评估桥本甲状腺炎合并甲状腺结节性质的价值

目的探讨2020甲状腺结节超声恶性危险分层中国指南(C-TIRADS)联合超微血管显像技术(SMI)诊断桥本甲状腺炎(HT)合并甲状腺结节性质的价值。方法选择HT合并甲状腺结节患者272例,术前对结节和甲状腺实质分别行二维超声和SMI检测,分析结节的超声征象及甲状腺实质的血流情况。依据二维超声特征对所有结节进行C-TIRADS分类,评估二维超声及二维超声联合SMI诊断HT合并结节性质的诊断效能。结果113例HT患者合并124个甲状腺良性结节(良性组),159例HT患者合并178个甲状腺恶性结节(恶性组),恶性组女性比例和年龄高于良性组(P<0.05),结节平均直径差异无统计学意义。恶性结节多表现为实性低回声或极低回声,并伴有甲状腺外侵犯和局灶性强回声;良性结节多为无局灶性强回声的高/等回声的结节。恶性组甲状腺实质血供类型以无明显改变或轻度增多为主,良性组甲状腺实质血供以中度增多及无明显改变或轻度增多较为常见。C-TIRADS诊断HT合并甲状腺结节性质分级标准的计算恶性率均在建议恶性率范围内。受试者工作特征(ROC)曲线结果显示,C-TIRADS诊断HT合并甲状腺结节性质的最佳诊断截点为C-TIRADS 4C类,C-TIRADS联合SMI诊断HT合并甲状腺结节性质的诊断截点为C-TIRADS 4C类且甲状腺实质血供无明显改变或轻度增多,C-TIRADS联合SMI的特异度和准确性高于C-TIRADS(P<0.05),敏感度和阴性预测值与C-TIRADS差异无统计学意义(P>0.05)。结论C-TIRADS联合SMI探查甲状腺实质血供有助于提高HT合并结节性质的诊断效能。

橡胶树树皮细胞木质素显示方法的比较分析

巴西橡胶树是最重要的人工栽培产胶植物,树干割胶是当前从橡胶树乳管组织中获取天然橡胶的唯一途径。割胶后的排胶特性直接决定胶乳的产量,但其排胶机理目前尚不完全清楚。橡胶树树皮的膨压是乳管排胶的主要初动力,而细胞壁的主要成分木质素含量的高低与膨压密切相关。目前关于橡胶树树干树皮细胞中木质素含量的研究较少,缺乏通过形态结构研究分析木质素含量高低的研究。以橡胶树RY8-79和PR107成龄树树皮为研究材料,制备石蜡切片,分别以Wiesner反应方法、Maule反应方法以及番红染色结合荧光显色的方法对树皮组织中的木质素进行了染色定位分析。研究结果表明:光镜明场下,Wiesner反应方法和Maule反应方法能显色薄壁细胞壁中的木质素成分,但颜色浅淡,很难区分不同品系之间的差异;番红染色后能观察到薄壁细胞中浅紫红色的木质素成分,但不同组织以及不同品系之间同样很难区分;番红显色后结合546 nm绿光激发则能观察到木质素组织明显的红色荧光,不同细胞类型和不同品系之间差异明显,RY8-79薄壁细胞中木质素荧光明显弱于PR107,表明该品系中木质素的含量低于PR107。碘-溴染色显示次生乳管的结果表明,次生乳管分布的位置和木质素显色较深尤其是荧光强的部位一致。由此推测乳管及其周围的细胞中木质素含量较高,这一现象在PR107中尤其明显。此外,Wiesner反应和Maule反应不仅需要间苯三酚、盐酸和高锰酸钾(KMnO_(4))等危险化学试剂,而且反应时间不好把控,切片容易从载玻片上脱落以及细胞壁易破损;而番红染色结合荧光观察所用试剂则是安全无毒的且细胞结构完整。综合比较不同的方法,番红染色结合荧光显色是当前最适合橡胶树树皮组织细胞中木质素显色的方法,不仅能清晰区分木质素含量的高低,而且安全、简便易操作。

Dramatic changes in anatomical traits of a C4 grass Chrysopogon serrulatus Trin.(Poaceae)over a 1000 m elevational gradient

Chrysopogon serrulatus(false beard-grass)is a dominant component of vegetation in the foothills of the Himalayas.To study whole plant morphology,individuals of C.serrulatus were collected from three plots at each of six locations spanning from 400 to 1,400 m.The population colonizing the highest elevation modifications in different plant organs.Roots showed increased metaxylem number and area.In the stem,especially outside of the vascular tissue,there was intensive sclerification indicative of increased xeromorphy as a survival strategy.At the highest elevation,leaves were wider;aerenchyma formation and increased sclerification were noted in the leaf sheath;and a greater proportion of storage parenchyma was observed in the leaf blade,all indicators of succulence.In contrast,leaves at lower elevations had xeric morphological features such as increased epidermal thickness,sclerification and more developed metaxylem area.In conclusion,shifting of morphological features in below-and above-ground plant parts of C.serrulatus were linked to shifts in environmental factors along this elevation gradient,thus enabling the successful distribution of this species along this elevation gradient.

Hydrocephalic cerebrospinal fluid flowing rotationally with pulsatile boundaries:A mathematical simulation of the thermodynamical approach

To study the kinematics of flow rate and ventricular dilatation,an analytical perturbation approach of hydrocephalus has been devised.This research provides a comprehensive investigation of the characteristics of cerebrospinal fluid(CSF)flow and pressure in a hydrocephalic patient.The influence of hydrocephalic CSF,flowing rotationally with realistic dynamical characteristics on pulsatile boundaries of subarachnoid space,was demonstrated using a nonlinear controlling system of CSF.An analytical perturbation method of hydrocephalus has been developed to investigate the biomechanics of fluid flow rate and the ventricular enlargement.In this paper presents a detailed analysis of CSF flow and pressure dynamics in a hydrocephalic patient.It was elaborated with a nonlinear governing model of CSF to show the influence of hydrocephalic CSF,flowing rotationally with realistic dynamical behaviors on pulsatile boundaries of subarachnoid space.In accordance with the suggested model,the elasticity factor changes depending on how much a porous layer,in this case the brain parenchyma,is stretched.It was improved to include the relaxation of internal mechanical stresses for various perturbation orders,modelling the potential plasticity of brain tissue.The initial geometry that was utilised to create the framework of CSF with pathological disease hydrocephalus and indeed the output of simulations using this model were compared to the actual progression of ventricular dimensions and shapes in patients.According to this observation,the non-linear and elastic mechanical phenomena incorporated into the current model are probably true.Further modelling of ventricular dilation at a normal pressure may benefit from the existence of a valid model whose parameters approximate genuine mechanical characteristics of the cerebral cortex.

E成像定量技术对IgA肾脏病患者经皮超声引导下肾脏活检后血肿的预测价值

目的探讨基于E成像定量技术(SWE)的肾实质杨氏模量均值及相关因素对经皮肾实质活检(PRB)的IgA肾病患者肾实质血肿的预测价值。方法分析比较经病理证实的90例IgA肾病患者的相关超声图像特征。将IgA肾病患者分为PRB术后有血肿和无血肿两组,分析两组患者在实验室检查、灰阶超声检查和EMean实质方面的差异。采用受试者工作特征曲线(ROC)评价EMean实质对肾实质活检血肿的预测价值。采用Logistic回归分析,以年龄、性别及EMean实质为影响因素,寻找PRB术后肾脏血肿发生的危险因素。采用spearman相关性分析对PRB术后血肿大小的相关性因素进行分析。结果90例IgA肾脏病患者中,PRB术后血肿68例(75.6%),无血肿22例(24.4%)。两组患者的年龄、性别、血红蛋白、血肌酐、尿素氮、肾小球滤过率、肾脏深度、肾脏长度、肾脏宽度、肾实质厚度以及慢性肾脏病(CKD)分期差异无统计学意义(P>0.05)。与无血肿的患者相比,术后血肿患者的EMean实质显著增高(4.70kPa VS.9.80 kPa),差异有统计学意义(P<0.001)。ROC曲线分析表明,EMean实质对PRB术后肾脏血肿有良好的预测价值,曲线下面积(AUC)为0.878,当EMean实质最佳截断值为6.20 kPa时,灵敏度为77.3%,特异性为94.1%。Logistic回归分析显示,EMean实质是PRB术后血肿的独立危险因素。此外,肾实质厚度与肾穿后血肿大小呈负相关关系,而EMean实质与肾穿后血肿大小呈正相关关系,相关系数分别为-0.292(P=0.016)、0.669(P<0.0001)。结论基于E成像定量技术得到的EMean实质对IgA肾病患者经皮肾实质活检的血肿发生有良好的预测效能。

白皮松木质部分化中轴向管胞和射线细胞的微观构造与木质化研究

以白皮松(Pinus bungeana)为研究对象,采用光学显微镜、偏光显微镜和扫描电子显微镜结合细胞壁组织化学染色等木材解剖学方法,探究木质部分化中轴向管胞与射线细胞的微观构造特征变化及其木质化进程。组织离析与形态学分析结果表明:木质部分化中轴向管胞在细胞扩大后其细胞长度基本稳定,随着木质部的分化,射线管胞的细胞壁厚度不断增加,而在当年生木质部中未发现射线薄壁细胞的细胞壁加厚。木质素的自发荧光及其特异性染色分析结果表明:轴向管胞的木质化进程开始于次生壁S1层加厚阶段的胞间层与细胞角隅,射线管胞的木质化进程与轴向管胞类似,在当年生木质部内射线薄壁细胞未发生木质化。木质部分化过程中管胞(轴向、射线)与射线薄壁细胞的细胞壁加厚及木质化进程具有明显差异。

MRI放射组学特征诊断肝实质及肝细胞癌的准确性研究

目的评价肝细胞癌(hepatoellular careinomna,HCC)肿瘤及肝实质MRI影像组学特征的准确性,以期为临床诊治提供参考。方法研究人群包括52名患者,包括16名未经治疗的肝癌患者,他们在1个月内接受了两次重复的腹部MRI检查,以评估:(1)使用相同MRI系统的测试-重测重复性(n=28,10个HCC);(2)不同MRI系统之间的平台间重复性(n=27,6个HCC);(3)观察者间的重复性(n=16,16个HCC)。在增强前T1加权像(WI)、门静脉期(PVP)、T2WI和表观弥散系数(ADC)、肝脏感兴趣区(ROI)和肝细胞癌感兴趣区(VOIS)上量化形态和一、二阶放射组学特征。通过计算组内相关系数(ICC)、一致性相关系数(CCC)和变异系数(CV)来评估精密度。结果肝细胞癌的形状和一阶和二阶特征的重测重复性中等到极好(ICC:0.53~0.99;CV:3%~29%),T1WI的一阶和二阶特征和肝脏的二阶特征的重测重复性中等到良好(ICC:0.53~0.73;CV:12%~19%)。除肝细胞癌T1WI上的形状和一阶特征外(CCC:0.58~0.99;CV:3%~15%),所有特征和序列的跨平台重复性差。肝细胞癌的所有特征和序列的观察者间重复性良好(CCC:0.80~0.99;CV:4%~15%),肝脏的重复性中等至好(CCC:0.45~0.86;CV:6%~25%)。结论当使用相同的MRI诊断时,MRI放射组学特征在肝脏和肝细胞癌中具有可接受的重复性,但在MR系统中的重复性较低。在进行多平台放射组学研究时,必须谨慎解释数据。

新型架构下的密集网络在肺部影像的分割研究

在医学图像分割领域中,肺实质的分割对肺结节检测有着至关重要的作用,在考虑到模型参数量的情况下追求更高的精度一直是研究热点之一;为此提出了新的三层密集卷积神经网络DA-UNet,首先用密集卷积模块代替在传统U-Net使用的普通3×3卷积,利用密集卷积特征重用特点,加强了网络的特征提取能力。再者在没有太过影响分割网络精确度的前提下加以修剪,减少了上下采样次数,减少不必要的算力消耗。此外,使用了注意力门(Attention gate),加强了跳跃连接中高底层信息融合效果,并且使用空洞空间金字塔池化(Atrous spatial pyramid pooling),模型加入了不同尺度的特征信息,进一步加强图像中任务相关的区域特征,有效减小噪声干扰,提高网络分割精度。通过实验证明:三次上下采样改进模型的参数量只有传统四次上下采样的75.2%左右,但是分割效果没有太大的影响,用LUNA竞赛肺部影像数据集进行了分割验证,实验结果在测试集上的准确率达到了0.991,而IoU则为0.961,比起传统U-Net的评价指标IoU提升了2.9%;在泛化实验的肝脏图像中,DA-UNet的IoU稳定在0.929左右,而U-Net稳定在0.838左右。这些结果证明了改进的U-Net有更佳的分割效果。