Microstructure Evolution of Sandstone Cemented by Microbe Cement Using X-ray Computed Tomography

The bio-sandstone, which was cemented by microbe cement, was firstly prepared, and then the microstructure evolution process was studied by X-ray computed tomography(X-CT) technique. The experimental results indicate that the microstructure of bio-sandstone becomes dense with the development of age. The evolution of inner structure at different positions is different due to the different contents of microbial induced precipitation calcite. Besides, the increase rate of microbial induced precipitation calcite gradually decreases because of the reduction of microbe absorption content with the decreasing pore size in bio-sandstone.

Use of high-resolution X-ray computed tomography and 3D image analysis to quantify mineral dissemination and pore space in oxide copper ore particles

Mineral dissemination and pore space distribution in ore particles are important features that influence heap leaching performance. To quantify the mineral dissemination and pore space distribution of an ore particle, a cylindrical copper oxide ore sample(Φ4.6 mm × 5.6 mm) was scanned using high-resolution X-ray computed tomography(HRXCT), a nondestructive imaging technology, at a spatial resolution of 4.85 μm. Combined with three-dimensional(3D) image analysis techniques, the main mineral phases and pore space were segmented and the volume fraction of each phase was calculated. In addition, the mass fraction of each mineral phase was estimated and the result was validated with that obtained using traditional techniques. Furthermore, the pore phase features, including the pore size distribution, pore surface area, pore fractal dimension, pore centerline, and the pore connectivity, were investigated quantitatively. The pore space analysis results indicate that the pore size distribution closely fits a log-normal distribution and that the pore space morphology is complicated, with a large surface area and low connectivity. This study demonstrates that the combination of HRXCT and 3D image analysis is an effective tool for acquiring 3D mineralogical and pore structural data.

In situ compression and X-ray computed tomography of flow battery electrodes

Redox flow batteries offer a potential solution to an increase in renewable energy generation on the grid by offering long-term, large-scale storage and regulation of power. However, they are currently underutilised due to cost and performance issues, many of which are linked to the microstructure of the porous carbon electrodes used. Here, for the first time, we offer a detailed study of the in situ effects of compression on a commercially available carbon felt electrode. Visualisation of electrode structure using X-ray computed tomography shows the non-linear way that these materials compress and various metrics are used to elucidate the changes in porosity, pore size distribution and tortuosity factor under compressions from 0%-90%.

Quantification of 3D macropore networks in forest soils in Touzhai valley(Yunnan,China)using X-ray computed tomography and image analysis

The three dimensional(3D) geometry of soil macropores largely controls preferential flow, which is a significant infiltrating mechanism for rainfall in forest soils and affects slope stability. However, detailed studies on the 3D geometry of macropore networks in forest soils are rare. The intense rainfall-triggered potentially unstable slopes were threatening the villages at the downstream of Touzhai valley(Yunnan, China). We visualized and quantified the 3D macropore networks in undisturbed soil columns(Histosols) taken from a forest hillslope in Touzhai valley, and compared them with those in agricultural soils(corn and soybean in USA; barley, fodder beet and red fescue in Denmark) and grassland soils in USA. We took two large undisturbed soil columns(250 mm×250 mm×500 mm), and scanned the soil columns at in-situ soil water content conditions using X-ray computed tomography at a voxel resolution of 0.945 × 0.945 × 1.500 mm^3. After reconstruction and visualization, we quantified the characteristics of macropore networks. In the studiedforest soils, the main types of macropores were root channels, inter-aggregate voids, macropores without knowing origin, root-soil interface and stone-soil interface. While macropore networks tend to be more complex, larger, deeper and longer. The forest soils have high macroporosity, total macropore wall area density, node density, and large macropore volume, hydraulic radius, mean macropore length, angle, and low tortuosity. The findings suggest that macropore networks in the forest soils have high interconnectivity, vertical continuity, linearity and less vertically oriented.

X-ray Computed Tomography Characterization of 3D Tufted Twill Textile Composite for Aerostructures

Damage assessments in three dimensional (3D) textile composites subjected to mechanical loading can be performed by non-destructive and destructive techniques.This paper applies the two techniques to investigate the fracture behavior of 3D tufted textile composites.X-ray computed tomography as a non-destructive evaluation method is appropriate to detect damage locations and identify their progression in 3D textile composites.Destructive methods such as sectioning toward observing damage provide valuable information about damage patterns.The results of this research could be utilized to evaluate the initial cause of rupture in 3D tufted composites used in aerospace structures and analyze fracture modes and damage progression.

X-Ray Computed Tomography for Root Quantification

Soil cores from a field growing barley and barley mutants without root hairs under conventional and minimum tillage were sampled. They were X-ray scanned to produce a 3D image and then the roots were washed out and weight and length were determined by conventional means. Root volume and surface area were then calculated from the 3D images using state of the art software and methodology, and the measured and calculated measures were correlated. The only strong and significant correlation was between measured weight and calculated volume for mutants without root hairs. It is concluded that the software cannot segment out very small roots, but segmentation accuracy also depends on root structure in some unknown way. Any study using X-ray computed tomography to quantify roots as they grow in situ should start with a calibration for the conditions in question.

Usefulness of Chest Computed Tomography for Diagnosis of Idiopathic Pneumomediastinum with Negative Findings on Plain X-Ray

Idiopathic pneumomediastinum is rare in children. Few cases of patients with pneumomediastinum show negative findings on X-ray examination. Chest computed tomography (CT) was very useful for the diagnosis and evaluation of the extent of pneumomediastinum. We report here a case of idiopathic pneumomediastinum in a 15-year-old boy who exhibited no significant chest X-ray finding. The patient was referred to our institute for the further evaluation of pre-cordial pain and breathing difficulty. Precordial pain suddenly developed, when he was carrying a portable shrine on his shoulder (day of onset). He was admitted to another institute 3 days after onset because of worsening precordial pain. On admission, he presented with 98% saturation of hemoglobin in the peripheral blood under room air. Plain chest X-ray also revealed no abnormal findings. A half-dissolved gastrographin swallow showed no leakage of gastrographin from the pharynx and esophagus to the mediastinum, and no diverticulum within the esophagus. Plain chest CT revealed extensive emphysema around the trachea from the neck to the portion inferior to the carina of trachea. The patient was diagnosed with idiopathic pneumomediastinum because the cause was unclear. We decided to admit him to our institute under fasting conditions and rest. His symptoms improved 3 days after onset. The lesion had disap-peared 8 days after onset on chest CT. When young people experience precordial pain which increases on inspiration, we must consider pneumomediastinum in a differential diagnosis, and it is important to perform chest CT.

Computed tomography versus transthoracic echocardiography in the detection of complex congenial heart diseases in china:a meta-analysis

Objective:To perform a meta-analysis to evaluate the diagnostic performance of computed tomography(CT) and transthoracic echocardiography(TTE) in complex congenital heart diseases(CHD) in China.Methods:MEDLINE,Cochrane library and China National Knowledge Infrastructure(CNKI) database from January 1966 to October 2010,were searched for initial studies in China.All the studies,published in English or Chinese,used TTE,CT,or both as diagnostic tests for CHD and reported the rate of true-positive,true-negative,false-positive and false-negative diagnoses of CHD from TTE and CT findings with the surgical results as the 'gold-standard'(15 studies,XX patients) were collected.The statistic software package,'Meta-Disc 1.4',was used to conduct data analysis.A covariate analysis was used to evaluate the influence of patient or study-related factors on sensitivity.Results:Pooled sensitivity for diagnosis of CHD were 95% [95% confidence interval(CI):94%~96%] for CT studies and 87%(95% CI:85%~88%) for TTE studies.The difference between the pooled sensitivity of CT and that of TTE was statistically significant(P<0.001).TTE had higher sensitivity [0.96(95% CI:0.94~0.97)] for cardiac malformation but lower sensitivity [0.78(95% CI:0.76~0.81)] for extracardiac malformation than CT.Conclusion:CT can provide added diagnostic information compared with TTE in patients with CHD in China,especially for patients suspected of extracardiac malformation.

Infective severe acute pancreatitis:A comparison of ^(99m)Tc-ciprofloxacin scintigraphy and computed tomography

AIM:To evaluate 99mTc-ciprofloxacin scintigraphy compared with computed tomography(CT)for detecting secondary infections associated with severe acute pancreatitis(SAP)in swine.METHODS:Six healthy swine were assigned to a normal control group(group A,n = 6).SAP was induced in group B(n = 9)and C(n = 18),followed by inoculation of the resulting pancreatic necroses with inactive Escherichia coli(E.coli)(group B)and active E.coli(group C),respectively.At 7 d after inoculation,a CT scan and a series of analyses using infecton imaging(at 0.5,1,2,3,4 and 6 h after the administration of 370 MBq of intravenous infecton)were performed.The scintigrams were visually evaluated and semi-quantitatively analyzed using region of interest assignments.The differences in infecton uptake and changes in the lesion-background radioactive count ratios(L/B)in the 3 groups were recorded and compared.After imaging detection,histopathology and bacterial examinations were performed,and infected SAP was regarded as positive.The imaging findings were compared with histopathological and bacteriological results.RESULTS:In group A,6 animals survived without infection in the pancreas.In group B,7/9 swine survived and one suffered from infection.In group C,15/18 animals survived with infection.Hence,the number of normal,non-infected and infected SAP swine was 6,6 and 16,respectively.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of the infecton method were 93.8%(15/16),91.7%(11/12),92.9%(26/28),93.8%(15/16)and 91.7%(11/12),whereas these values for CT were 12.5%(2/16),100.0%(12/12),50.0%(14/28),100.0%(2/2)and 46.2%(12/26),respectively.The changes in L/B for the infected SAP were significantly different from those of the non-infected and normal swine(P < 0.001).The mean L/B of the infectious foci at 0.5,1,2,3,4 and 6 h was 1.17 ± 0.10,1.71 ± 0.30,2.46 ± 0.45,3.36 ± 0.33,2.04 ± 0.37 and 1.1988 ± 0.09,respectively.At 3 h,the radioactive counts(2350.25 ± 602.35 k)and the mean L/B of the infectious foci were significantly higher than that at 0.5 h(P = 0.000),1 h(P = 0.000),2 h(P = 0.04),4 h(P = 0.000)and 6 h(P = 0.000).CONCLUSION:99m Tc-ciprofloxacin scintigraphy may be an effective procedure for detecting SAP secondary infections with higher sensitivity and accuracy than CT.

Investigation of noise properties in grating-based x-ray phase tomography with reverse projection method

The relationship between noise variance and spatial resolution in grating-based x-ray phase computed tomography(PCT) imaging is investigated with reverse projection extraction method, and the noise variances of the reconstructed absorption coefficient and refractive index decrement are compared. For the differential phase contrast method, the noise variance in the differential projection images follows the same inverse-square law with spatial resolution as in conventional absorption-based x-ray imaging projections. However, both theoretical analysis and simulations demonstrate that in PCT the noise variance of the reconstructed refractive index decrement scales with spatial resolution follows an inverse linear relationship at fixed slice thickness, while the noise variance of the reconstructed absorption coefficient conforms with the inverse cubic law. The results indicate that, for the same noise variance level, PCT imaging may enable higher spatial resolution than conventional absorption computed tomography(ACT), while ACT benefits more from degraded spatial resolution. This could be a useful guidance in imaging the inner structure of the sample in higher spatial resolution.

Effective Atomic Number Measurement with Energy-Resolved Computed Tomography Using Two-Dimensional “transXend” Detector

Introduction: We have previously developed an effective atomic number (Zeff) measurement method using linear attenuation coefficients (LACs) obtained by energy-resolved computed tomography (CT) with one-dimensional (1D) detector. The energy-resolved CT was performed with a “transXend” detector, which measured X-rays as electric current and then gave X-ray energy distribution with unfolding analysis using pre-estimated response function (RF). The purpose of this study is to measure Zeff by the energy-resolved CT using a flat panel detector (FPD). Methods: To demonstrate a 2D transXend detector, we developed the stripe absorbers for the FPD. Eleven human tissue-equivalent material rods which were grouped into four material categories were measured by X-rays with 120 kVp tube voltage, 2.3 mA tube current, and 1.0 s exposure time. Zeff is measured by the ratio of LACs with two different pseudo-monochromatic X-ray energies. RFs of each rod material were estimated by numerical calculation. First, we employed the RF estimated for the same rod material (self-RF scenario). Second, we employed the RF estimated for the different rod materials in the same material category (cross-RF scenario). The purpose of the cross-RF scenario was to find representative rod materials in each material category. Results: Upon the self-RF scenario, measured Zeffs were systematically underestimated. Median relative error to theoretical Zeff was -6.92% (range: -7.89% - -4.60%). After normalizing measured Zeffs to the theoretical one for Breast, median relative error improved to -0.75% (range: -1.79% - +1.73%). Upon the cross-RF scenario, the representative rod materials were found in two material categories. Conclusion: Zeff measurements were performed by energy-resolved CT using 2D transXend detector with numerically-estimated RF data. Normalized Zeffs for all rod materials in the self-RF scenario were in good agreement with the theoretical ones.

Reduction of the Beam Hardening Artifacts in the X-Ray Computer Tomography: Energy Discrimination with a Photon-Counting Detector

The material identification is a pressing requirement for the sensitive security applications. Dual-energy X-ray computer tomography (DXCT) has been investigated for material identification in the medical and security fields. It requires two tomographic images at sufficiently different energies. To discriminate dangerous materials of light elements such as plastic bombs in luggage, it is needed to measure accurately with several tens of kilo electron volts where such materials exhibit significant spectral differences. However, CT images in that energy region often include artifacts from beam hardening. To reduce these artifacts, a novel reconstruction method has been investigated. It is an extension of the Al-gebraic Reconstruction Technique and Total Variation (ART-TV) method that reduces the artifacts in a lower-energy CT image by referencing it to an image obtained at higher energy. The CT image of a titanium sample was recon-structed using this method in order to demonstrate the artifact reduction capability.

Assessment of the hepatic microvascular changes in liver cirrhosis by perfusion computed tomography

AIM:To assess the hepatic microvascular parameters in patients with liver cirrhosis by perfusion computed tomography(CT).METHODS:Perfusion CT was performed in 29 patients without liver disease(control subjects) and 39 patients with liver cirrhosis, including 22 patients with compensated cirrhosis and 17 patients with decompensated cirrhosis, proved by clinical and laboratory parameters.CT cine-scans were obtained over 50 s beginning with the injection of 50 mL of contrast agent.Hepatic microvascular parameters, mean transit time(MTT) and permeability surface area product(PS) were obtained with the Perfusion 3 software(General Electric, ADW 4.2).RESULTS:The overall differences of MTT and PS between control subjects, patients with compensated cirrhosis and those with decompensated cirrhosis were statistically signif icant(P = 0.010 and P = 0.002, respectively).MTT values were 15.613 ± 4.1746 s, 12.592 ± 4.7518 s, and 11.721 ± 4.5681 s for the three groups, respectively, while PS were 18.945 ± 7.2347 mL/min per 100 mL, 22.767 ± 8.3936 mL/min per 100 mL, and 28.735 ± 13.0654 mL/min per 100 mL.MTT in decompensated cirrhotic patients were significantly decreased compared to controls(P = 0.017), whereas PS values were remarkably increased(P = 0.001).CONCLUSION:The hepatic microvascular changes in patients with liver cirrhosis can be quantitatively assessed by perfusion CT.Hepatic microvascular parameters(MTT and PS), as measured by perfusion CT, were significantly altered in decompensated cirrhosis.

Hepatic angiomyolipoma: Dynamic computed tomography features and clinical correlation

AIM: To study the dynamic computed tomography (CT) features of hepatic angiomyolipoma (AML) in patients with or without tuberous sclerosis complex (TSC).METHODS: The clinical information, CT fi ndings and histopathological results of hepatic AML were analyzed retrospectively in 10 patients.RESULTS: Hepatic AML was prone to occur in female patients (7/10), and most of the patients (8/10) had no specific symptoms. All tumors presented as well-def ined, unenveloped nodules in the liver. Six patients with sporadic hepatic AML had a solitary hepatic nodule with a definite fat component. Non-fat components of the hepatic lesions were enhanced earlier and persistently. Prominent central vessels were noted in the portal venous phase in three patients. In four patients with hepatic AML and TSC, most of the nodules were within the peripheral liver. Seven fat-deficient nodules were found with earlier contrast enhancement and rapid contrast material washout in two patients. Lymphangioleiomyomatosis was found in one patient.CONCLUSION: Imaging features of hepatic AML are characteristic. Correct diagnosis preoperatively can be made in combination with clinical features.

Radiomic features from computed tomography to differentiate invasive pulmonary adenocarcinomas from non-invasive pulmonary adenocarcinomas appearing as part-solid groundglass nodules

Objective:We aim to investigate radiomic imaging features extracted in computed tomography(CT)images to differentiate invasive pulmonary adenocarcinomas(IPAs)from non-IPAs appearing as part-solid ground-glass nodules(GGNs),and to incorporate significant radiomic features with other clinically-assessed features to develop a diagnostic nomogram model for IPAs.Methods:This retrospective study was performed,with Institutional Review Board approval,on 88 patients with a total of 100 part-solid nodules(56 IPAs and 44 non-IPAs)that were surgically confirmed between February 2014and November 2016 in the First Affiliated Hospital of China Medical University.Quantitative radiomic features were computed automatically on 3D nodule volume segmented from arterial-phase contrast-enhanced CT images.A set of regular risk factors and visually-assessed qualitative CT imaging features were compared with the radiomic features using logistic regression analysis.Three diagnostic models,i.e.,a basis model using the clinical factors and qualitative CT features,a radiomics model using significant radiomic features,and a nomogram model combining all significant features,were built and compared in terms of receiver operating characteristic(ROC)curves.Decision curve analysis was performed for the nomogram model to explore its potential clinical benefit.Results:In addition to three visually-assessed qualitative imaging features,another three quantitative features selected from hundreds of radiomic features were found to be significantly(all P<0.05)associated with IPAs.The diagnostic nomogram model showed a significantly higher performance[area under the ROC curve(AUC)=0.903]in differentiating IPAs from non-IPAs than either the basis model(AUC=0.853,P=0.0009)or the radiomics model(AUC=0.769,P<0.0001).Decision curve analysis indicates a potential benefit of using such a nomogram model in clinical diagnosis.Conclusions:Quantitative radiomic features provide additional information over clinically-assessed qualitative features for differentiating IPAs from non-IPAs appearing as GGNs,and a diagnostic nomogram model including all these significant features may be clinically useful in preoperative strategy planning.

NON-INVASIVE IMAGING OF CORONARY ARTERY WITH 16-SLICE SPIRAL COMPUTED TOMOGRAPHY

To evaluate the value of 16-slice spiral CT in the demonstration of coronary artery and in the diagnose of coronary artery stenosis. Methods Plain and enhanced CT scans were performed with a 16-slice CT scanner (Sensation 16, Siemens, Germany) in 230 patients with suspected coronary heart disease (CHD). Parameters of the plain scan were: 120 kV, 133 mA, slice col-limation 16 mm×1.5 mm, rotation time 0.42 seconds, increment 1.5 mm, and slice width 3 mm. Parameters of the enhanced scan were: 120 kV, 500 mA, slice collimation 16 mm×0.75 mm, rotation time 0.42 seconds, increment 0.5 mm, and slice width 1 mm. Enhanced CT scan was performed with a rapid intravenous injection of 100 mL iothalamate meglumine (Ultravist) (370 mgI/mL) or Omnipaque (350 mgI/mL) and 30 mL 0.9% NaCl chaser bolus at a flow rate of 3.5 mL/s. Calcium scoring with plain scan images and two and three dimensional reconstruction with enhanced scan images were made in all cases, among which 30 cases underwent conventional coronary angiography. Demonstration of coronary arteries and their stenosis were evaluated and the factors that might influence the image quality were analyzed. Results Coronary calcium scores were calculated and coronary artery was demonstrated in our study. In the evaluationof image quality with volume rendering technique (VRT) images, 78.3% of the images were of the first class, 12.2% the sec-ond class, and 9.6% the third class. Multi-planar reconstruction (MPR) and maximal intensity projection (MIP) were better than VRT in the demonstration of small branches. The image quality was related to the heart rate, with or without arrhythmia, and breath-hold ability of patients. Comparative study of the stenosis of coronary arteries in 30 cases showed that the sensi-tivity and specificity of 16-slice coronary CT angiography (CTA) to diagnose significant stenosis were 95.8% and 94.8% resp-ectively. Conclusion As a non-invasive and quick method, 16-slice coronary CTA is sensitive and specific to diagnose the stenosis of coronary arteries and can be used as a screening method in the diagnosis of CHD.

Tuberculosis versus non-Hodgkin's lymphomas involving small bowel mesentery:Evaluation with contrast-enhanced computed tomography

AIM: To evaluate the specific computed tomography (CT) imaging criteria for differentiating tuberculosis involving the small bowel mesenteric lymph nodes from lymphomas. METHODS: We retrospectively reviewed the anatomic distribution,CT enhancement patterns of lymphoma in 18 patients with mesenteric tuberculosis and 22 with untreated non-Hodgkin’s lymphomas (NHL) involving small bowel mesentery (SBM). Of the 18 patients with tuberculosis,9 had purely mesenteric tuberculous lymphadenopathy (TL),and 9 had mesenteric TL accompanied with tuberculous mesenteritis (TLM). RESULTS: CT showed that tuberculosis and NHL mainly affected lymph nodes in the body and root of SBM. Homogeneously enhanced lymph nodes in the body and root of SBM were found more often in the NHL (P < 0.05). Homogeneously mixed peripheral enhanced lymph nodes in the body of SBM were found more often in mesenteric TL and TLM (P < 0.05). Peripheral enhanced lymph nodes in the root of SBM were found more often in mesenteric TL and TLM (P < 0.01). "Sandwich sign" in the root of SBM was observed more often in NHL (P < 0.05). CONCLUSION: Anatomic lymph node distribution,sandwich sign and specific enhancement patterns of lymphadenopathy in SBM on CT images can be used in differentiating between tuberculosis and untreated NHL involving SBM.

Preliminary assessing no-surgical treatment response in bronchogenic carcinoma with double-phase contrast material-enhanced computed tomography

评估双阶段的功效的目的在 preliminarily 在 bronchogenic 癌估计没有外科的治疗反应对比提高材料的计算断层摄影术(CT ) 。有在没有外科的治疗以后的 bronchogenic 癌的 52 个病人经历了双阶段的方法对比提高材料的计算断层摄影术。在非离子的对比材料经由赌注被管理以后，二螺线 CT 扫描分别地在 25 和 90 秒点被获得以由使用一个汽车注射者的 4 mL/s 的率的肘的静脉。每扫描上的 Precontrast 和柱子对比变细被记录，山峰高度是计算的。改进模式在在对比媒介的注射以后在 25 和 90 秒点获得的图象上被评估。结果 Precontrast 变细，在 25 和 90 秒点的柱子对比变细是 42.20 ± 7.43 胡， 57.35 ± 10.09 胡和 71.85 ± 12.45 胡分别地。在 precontrast 变细的统计上重要的差别都没在我们在治疗前在情况中被获得的旧学习(吝啬的 precontrast 变细 40.70 胡) 在学习和结果在我们的结果之间被发现(t = 1.455， P = 0.152 】 0.05 ) 。在没有外科的治疗以后的 bronchogenic 癌的山峰高度(29.46 ± 10.85 胡) 是比在在我们的旧学习获得的治疗前的 bronchogenic 癌的显著地低的(吝啬的山峰高度 35.79 胡；t = 4.206， P = 0.001 【 0.05 ) 。52 个盒子中的 32 个在 90 秒点显示出同类的改进。32 个盒子，与不同类的改进有 21， 7 与不同类的改进， 2 与中央改进并且 2 与在 25 秒点的外部改进。在没有外科的处理以后的结论 Bronchogenic 癌在对比材料的管理以后显示出渐渐的增加到山峰高度。山峰高度能反映 bronchogenic 癌的血供应并且可能是为在 bronchogenic 癌的没有外科的治疗反应的评估的索引。

Hepatic focal nodular hyperplasia in children:Imaging features on multi-slice computed tomography

AIM:To retrospectively analyze the imaging features of hepatic focal nodular hyperplasia(FNH) in children on dynamic contrast-enhanced multi-slice computed tomography(MSCT) and computed tomography angiography(CTA) images.METHODS:From September 1999 to April 2012,a total of 218 cases of hepatic FNH were confirmed by either surgical resection or biopsy in the Sun Yat-sen Memorial Hospital of Sun Yat-sen University and the Cancer center of Sun Yat-sen University,including 12 cases(5.5%) of FNH in children(age ≤ 18 years old).All the 12 pediatric patients underwent MSCT.We retrospectively analyzed the imaging features of FNH lesions,including the number,location,size,margin,density of FNH demonstrated on pre-contrast and contrastenhanced computed tomography(CT) scanning,central scar,fibrous septa,pseudocapsule,the morphology of the feeding arteries and the presence of draining vessels(portal vein or hepatic vein).RESULTS:All the 12 pediatric cases of FNH had solitary lesion.The maximum diameter of the lesions was 4.0-12.9 cm,with an average diameter of 5.5 ± 2.5 cm.The majority of the FNH lesions(10/12,83.3%) had well-defined margins.Central scar(10/12,83.3%) and fibrous septa(11/12,91.7%) were commonly found in children with FNH.Central scar was either isodense(n = 7) or hypodense(n = 3) on pre-contrast CT images and showed progressive enhancement in 8 cases in the equilibrium phase.Fibrous septa were linear hypodense areas in the arterial phase and isodense in the portal and equilibrium phases.Pseudocapsule was very rare(1/12,8.3%) in pediatric FNH.With the exception of central scars and fibrous septa within the lesions,all 12 cases of pediatric FNH were homogenously enhanced on the contrast-enhanced CT images,significantly hyperdense in the arterial phase(12/12,100.0%),and isodense in the portal venous phase(7/12,58.3%) and equilibrium phase(11/12,91.7%).Central feeding arteries inside the tumors were observed on CTA images for all 12 cases of FNH,whereas no neovascularization of malignant tumors was noted.In 9 cases(75.0%),there was a spoke-wheel shaped centrifugal blood supply inside the tumors.The draining hepatic vein was detected in 8 cases of pediatric FNH.However,the draining vessels in the other 4 cases could not be detected.No associated hepatic adenoma or hemangioma was observed in the livers of the 12 pediatric cases.CONCLUSION:The characteristic imaging appearances of MSCT and CTA may reflect the pathological and hemodynamic features of pediatric FNH.Dynamic multi-phase MSCT and CTA imaging is an effective method for diagnosing FNH in children.

Tuberculous abscess in hepatoduodenal ligament: Evaluation with contrast-enhanced computed tomography

Two patients with tuberculous abscess in the hepatoduodenal ligament were studied. Both patients underwent contrast-enhanced computed tomography (CT) scan. The abscess showed a low density with an irregular thick wall in the hepatoduodenal ligament on CT images, the margin was poorly defined. Contrastenhanced CT images showed the contrast-enhanced thick wall, homogeneous and peripheral-enhanced lymph nodes. Although features of the tuberculous abscess in the hepatoduodenal ligament could be conspicuously shown with contrast-enhanced CT, further experience is needed to evaluate the potential value of CT in detecting early tuberculous abscess in relation to other entities in the hepatoduodenal ligament.