Soil Macropore Structure Characterized by X-Ray Computed Tomography

Undisturbed soil core with many macropores and disturbed soil core with onlyone macropore (diameter is 10 mm) were probed by X-ray computed tomography (CT). The size, number,shape and continuity of macropores in the transverse and vertical sectionsof soil were characterizedusing CT scanning images. The probability densities of macropores in the transverse section of soilcore exhibited a logarithmic P distribution. Results indicated that CT scanning was a promisingnondestructive method for characterizing macropores in soils.

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^25o mmxsoo 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 × 1.500o mm^3. After reconstruction and visualization, we quantified the characteristics of macropore networks. In the studied forest soils, the main types of maeropores were root channels, inter-aggregate voids, maeropores without knowing origin, root-soil interfaee and stone-soil interface. While maeropore networks tend to be more eomplex, larger, deeper and longer. The forest soils have high maeroporosity, total maeropore wall area density, node density, and large maeropore volume, hydraulie radius, mean maeropore length, angle, and low tortuosity. The findings suggest that maeropore networks in the forest soils have high inter- connectivity, vertical continuity, linearity and less vertically oriented.

Studies of Microstructure of Kernels of Macadamia integrifolia and Its Hybrids through MRI, X-Ray Tomography and Confocal Microscopy

The aim of this study was to apply the existing techniques that enable examination ofmacadamia kernels to provide a better understanding of physico-chemical properties of kernels during postharvest processing. These techniques, such as X-ray tomography, could be applied for quality monitoring in the macadamia industry. The objectives of this study were to investigate the browning centre symptoms that usually occur in macadamia nuts-in-shell. The applied techniques included confocal microscopy, X-ray tomography and magnetic resonance imaging （MRI）. Five different varieties of macadamia nuts （A38, 246, 816, 842 and Daddow） were selected to include distinct characteristics, such as drop pattern and growing location. Analysis of the microstructure of kernels by confocal microscopy showed the distribution of possible brown pigment compounds as well as the distribution of lipids, carbohydrates and proteins inside macadamia cells. Physical properties data, including shell density and seed to volume ratio, were obtained by X-ray tomography. Magnetic resonance diffusion tensor imaging used in this study showed marked differences in microstructure which indicate that different varieties exhibit different microstructures expressed as fraction ofanisotropy and apparent diffusion coefficient that appear to be related to the occurrence of the brown centre. Hence, the findings of this study have potential to improve the existing postharvest techniques used in the macadamia processing industry. They will be of benefit to the industry in terms of improved quality control and cost reduction.

老年人脑白质疏松的影像学表现

目的 探讨脑白质疏松的影像学表现 ,提高脑白质疏松的诊断水平。方法 对 32 4例 60～ 90岁的老年人进行 CT与 MRI检查并进行对比分析。结果 CT表现为双侧脑室旁脑白质呈对称性低密度灶 ,MRI表现为双侧脑室旁脑白质呈长 T1 WI、长 T2 WI信号。结论 脑白质疏松形成的主要原因是脑血流量减少所致 ,CT、MRI均能诊断 ,但 MRI更具敏感性。

螺旋CT阴茎动脉成像技术和临床应用价值

目的 :探讨螺旋CT阴茎动脉成像技术和临床应用价值。方法 :对 18例血管性阳萎患者行螺旋CT容积扫描 ,图像经后处理获得阴部动脉立体图像。结果 :①螺旋CT阴茎动脉成像图像的质量与扫描方法、图像重建方法等密切相关 ;②三维图像可以清晰显示髂内动脉、阴部内动脉、阴茎海绵体动脉的分支、走行 ;③ 6例动脉性阳萎者 ,阴茎动脉成像可见病变位于阴部内动脉 3例 ,阴茎海绵体动脉 3例。结论 :螺旋CT阴茎动脉成像可以多方位观察 ,从二维及三维立体图像上获得更多诊断信息 。

脑星形细胞瘤动态CT指标与微血管密度的关系

目的 探讨脑星形细胞瘤动态CT扫描与微血管密度 (MVD)的关系。方法 收集动态CT扫描资料完整、手术病理证实的脑星形细胞瘤 3 8例 ,并根据动态CT扫描产生的时间 密度曲线分析瘤组织的TBRp、TBRL、Sa(曲线升段斜率 )、AR(动态曲线下面积 )。同时对切除的瘤组织标本采用免疫组织化学技术标记微血管 ,测定微血管密度 ,并将其与时间 密度曲线分析结果相对照。结果 星形细胞瘤的MVD与其病理级别、患者复发密切相关。TBRp、TBRL、Sa、AR在Ⅲ～Ⅳ级星形细胞瘤与Ⅰ、Ⅱ级之间相差显著(P <0 0 5 ,P <0 0 1) ,而且均与MVD呈正相关 (P <0 0 5 )。结论 活体动态CT反映星形细胞瘤的血管生成活性是可行的。认真分析星形细胞瘤的时间

Computed tomography perfusion in evaluating the therapeutic effect of transarterial chemoembolization for hepatocellular carcinoma

AIM： To prospectively assess the changes in parameters of computed tomography （CT） perfusion pre- and post-transarterial chemoembolization （TACE） of hepatocellular carcinoma （HCC） in different treatment response groups, and to correlate the changes with various responses of HCC to TACE. METHODS： Thirty-nine HCC patients underwent CT perfusion examinations pre-（1 d before TACE） and post-treatment （4 wk after TACE）. The response evaluation criteria for solid tumors （RECIST） were referred to when treatment responses were distributed. Wilcoxon-signed ranks test was used to compare the differences in CT perfusion parameters pre- and post- TACE for different response groups. RESULTS： Only one case had treatment response to CR and the CT perfusion maps of post-treatment lesion displayed complete absence of signals. In the PR treatment response group, hepatic artery perfusion （HAP）, hepatic arterial fracture （HAF） and hepatic blood volume （HBV） of viable tumors post-TACE were reduced compared with pre-TACE （P = 0.001, 0.030 and 0.001, respectively）. In the SD group, all CT perfusion parameters were not significantly different pre- and post-TACE. In the PD group, HAP, HAl=, portal vein perfusion （PVP） and hepatic blood flow （HBF） of viable tumors post-TACE were significantly increased compared with pre-TACE （P = 0.005, 0.012, 0.035 and 0.005, respectively）. CONCLUSION： Changes in CT perfusion parameters of viable tumors are correlated with different responses of HCC to TACE. Therefore, CT perfusion imaging is a feasible technique for monitoring response of HCC to TACE.

Assessment of hepatic functional reserve by cirrhosis grading and liver volume measurement using CT

AIM： To explore a method for quantitative assessment of hepatic functional reserve by combining computed tomography （CT） volumetry with CT grading of liver cirrhosis before liver resection in patients with hepatocellular carcinoma. METHODS： CT images of 55 patients undergoing liver resection were studied prospectively. The degree of liver cirrhosis was referred as ＂CT grade＂ and the percentage of remnant liver volume （PRLV） [PRLV = predicted RLV/predicted total liver volume （PTLV） × 100%; PTLV （mL） = 121.75 ＋ 16.49 × body mass （kg）] were calculated by adding slice by slice of CT liver images. The postoperative RLV, pathologic stages of liver fibrosis in non-tumor area and survival time in these cases were analyzed. RESULTS： There was a significant difference in survival time between the group with PRLV ≤ 50% and the group with PRLV 〉 50% （X^2= 4.988, P = 0.026）, and between the group with CT grade 0/1 and the group with CT grade 2/3 （X^2= 5.429, P = 0.026）. With combination of the both parameters, an oblique line was identified according to the distribution of 32 survivors versus 23 deceased subjects. The mortality rate above the line was 7.1% （1/14）, and that below the line was 53.7% （22/41）, indicating a significant difference between the two rates （X^2 = 9.281, P = 0.002, P 〈 0.05）. CONCLUSION： PRLV and CT grades are significantly correlated with hepatic functional reserve. The predicted line using these two parameters is useful in candidates undergoing liver resection for judging hepatic functional reserve.

^(18)F-DG PET/CT in detection of recurrence and metastasis ofcolorectal cancer

AIM: To evaluate the value of 18F-DG PET/CT in detecting recurrence and/or metastasis of colorectal cancer (CRC). METHODS: Combined visual analysis with semiquantitative analysis, the 18F-DG PET/CT whole- body imaging results and the corresponding clinical data of 68 postoperative CRC patients including 48 male and 20 female with average age of 58.1 were analyzed retrospectively. RESULTS: Recurrence and/or metastasis were confirmed in 56 patients in the clinical follow-up after the PET/CT imaging. The sensitivity of PET/CT diagnosis of CRC recurrence and/or metastasis was 94.6%, and the specificity was 83.3%. The positive predictive value (PPV) was 96.4% and the negative predictive value (NPV) was 76.9%. PET/CT imaging detected one or more occult malignant lesions in 8 cases where abdominal/pelvic CT and/or ultrasonography showed negative findings, and also detected more lesions than CT or ultrasonography did in 30.4% (17/56) cases. Recurrence and/or metastasis was detected in 91.7% (22/24) cases with elevated serum CEA levels by 18F-DG PET/CT imaging. CONCLUSION: 18F-DG PET/CT could detect the recurrence and/or metastasis of CRC with high sensitivity and specificity.

Left-sided gallbladder:Its clinical significance and imaging presentations

AIM: To assess the importance of preoperative diagnosis and presentation of left-sided gallbladder using ultrasound (US),CT and angiography. METHODS: Retrospective review of 1482 patients who underwent enhanced CT scanning was performed. Left-sided gallbladder was diagnosed if a right-sided ligamentum teres was present. The image presentations on US,CT and angiography were also reviewed. RESULTS: Left-sided gallbladder was diagnosed in nine patients. The associated abnormalities on CT imaging included portal vein anomalies,absence of umbilical portion of the portal vein in the left lobe of the liver,club-shaped portal vein in the right lobe of the liver,and difficulty in identifying segment Ⅳ. Angiography in six of nine patients demonstrated abnormal portal venous system (trifurcation type in four of six patients). The main hepatic arteries followed the portal veins in all six patients. The segment Ⅳ artery was identified in four of six patients using angiography,although segment Ⅳ was difficult to define on CT imaging. Hepatectomy was performed in three patients with concomitant liver tumor and the diagnosis of left-sided gallbladder was confirmed intraoperatively. CONCLUSION: Left-sided gallbladder is an important clinical entity in hepatectomy due to its associated portal venous and biliary anomalies. It should be considered in US,CT and angiography images that demonstrate no definite segment Ⅳ,absence of umbilical portion of the portal vein in the left lobe,and club-shaped right anterior portal vein.

Segmental radiofrequency ablation of pulmonary vein ostia for patients with refractory paroxysmal atrial fibrillation using multi-slice spiral computed tomography guidance

Objective： To evaluate the safety and clinical efficacy of segmental radiofrequency ablation of pulmonary vein （PV） ostia for patients with refractory paroxysmal atrial fibrillation （AF） under multi-slice spiral computed tomography （MSCT） guidance before the procedure. Methods： A series of 58 consecutive patients with refractory paroxysmal AF were enrolled to undergo segmental radiofrequency ablation ofPV ostia. The 36 male and 22 female patients with mean age of （57.4±9.5） （32-79） years and no obvious organic heart disease. Before ablation, patients received MSCT to generate 3-dimentional image of the left atrium （LA） and proximal PVs. Patients then underwent segmental radiofrequency ablation ofPV ostia using PV circular mapping catheter manipulated several times to ensure complete isolation between PVs and LA. Results： No complications occurred during the procedure. One patient developed delayed cardiac tamponade, which was drained percutaneously. The mean follow-up time was （17.1±9.3） months. Forty-one patients （95%） experienced improved quality of life one month after the procedure. Thirty-six patients （83%） showed stable sinus rhythm, while 10 patients （23%） required additional anti-arrhythmic drugs. AF returned≥1 time in 6 （14%） patients who underwent anti-arrhythmic drug therapy, but the number of episodes was less than that before the procedure. However, one patient experienced recurrent episodes of atrial flutter. Conclusion： It is safe and effective to perform segmental radiofrequency ablation of PV ostia for patients with refractory paroxysmal AF using MSCT guidance mappening.

Calcified reticulate rind sign:A characteristic feature of gossypiboma on computed tomography

We herein report a gossypiboma resulting from a retained surgical swab, which had been left in peritoneum for 20years after appendectomy. CT revealed a cystic mass with a calcified reticulate rind. Subsequent surgery and pathological examination showed a gossypiboma. A simple experiment, using a barium-soaked surgical swab demonstrating similar CT appearance, supported our postulation that calcium deposition on the reticulated fibers of a surgical swab could generate such a characteristic 'calcified reticulate rind' sign. We believe that identification of this CT sign facilitates the diagnosis of gossypibomas.

Highly metabolic thrombus of the portal vein:^(18)F fluorodeoxyglucose positron emission tomography/computer tomography demonstration and clinical significance in hepatocellular carcinoma

AIM： To assess the ability of ^18F-fluorodeoxyglucose positron emission tomography/computer tomography （^18F-FDG PET/CT） to differentiate between benign and malignant portal vein thrombosis in hepatocellular carcinoma （HCC） patients.METHODS： Five consecutive patients who had HBV cirrhosis, biopsy-proven HCC, and thrombosis of the main portal vein and/or left/right portal vein on ultrasound （US）, computer tomography （CT） or magnetic resonance imaging （MRI） were studied with ^18F-FDG PET/CT. The presence or absence of a highly metabolic thrombus on ^18F-FDG PET/CT was considered diagnostic for malignant or benign portal vein thrombosis, respectively. All patients were followed-up monthly with US, CT or MRI. Shrinkage of the thrombus or recanalization of the vessels on US, CT or MRI during follow-up was considered to be definitive evidence of the benign nature of the thrombosis, whereas enlargement of the thrombus, disruption of the vessel wall, and parenchymal infiltration over follow-up were considered to be consistent with malignancy. ^18SF-FDG PET/CT, and US, CT or MRI results were compared.RESULTS： Follow-up （1 to 10 mo） showed signs of malignant thrombosis in 4 of the 5 patients. US, CT or MRI produced a true-positive result for malignancy in 4 of the patients, and a false-positive result in 1. ^18F-FDG PET/CT showed a highly metabolic thrombus in 4 of the 5 patients. ^18F-FDG PET/CT achieved a true-positive result in all 4 of these patients, and a true-negative result in the other patient. No false-positive result was observed using ^18F-FDG PET/CT.CONCLUSION： ^18F-FDG PET/CT may be helpful in discriminating between benign and malignant portal vein thrombi. Patients may benefit from ^18F-FDG PET/CT when portal vein thrombi can not be diagnosed exactly by US, CT or MRI.

Alpha-fetoprotein-producing colon cancer with atypical bulky lymph node metastasis

Alpha-fetoprotein (AFP)-producing colorectal cancer is extremely rarely reported until now. All of the reported cases harboring synchronous hematogenous spread including liver and/or lung metastasis had a poor prognosis and died within 12 mo. We here describe a 71-year old man with AFP-producing colon cancer who presented with an unusual bulky lymph node metastasis instead of hematogenous spread. He underwent adjuvant chemotherapy in addition to curative surgical resection, which prolonged his survival.

Acute ulcerative jejunal diverticulitis:Case report of an uncommon entity

Jejunal diverticulosis is a rare entity with variable clinical and anatomical presentations.Its reported incidence varies from 0.05% to 6%.Although there is no consensus on the management of asymptomatic jejunal diverticular disease,some complications are potentially life threatening and require early surgical treatment.We report a case of an 88-year-old man investigated for acute abdominal pain with a high biological inflammatory syndrome.Inflammation of multiple giant jejunal diverticulum was discovered at abdominal computed tomography (CT).As a result of the clinical and biological signs of early peritonitis,an emergency surgical exploration was performed.The first jejunal loop showed clear signs of jejunal diverticulitis.Primary segmental jejunum resection with end-to-end anastomosis was performed.Histopathology report confirmed an ulcerative jejunal diverticulitis with imminent perforation and acute local peritonitis.The patient made an excellent rapid postoperative recovery.Jejunal diverticulum is rare but may cause serious complications.It should be considered a possible etiology of acute abdomen,especially in elderly patients with unusual symptomatology.Abdominal CT is the diagnostic tool of choice.The best treatment is emergency surgical management.

Peliosis and gummatous syphilis of the liver: A case report

Peliosis hepatis is a rare benign vascular disorder of the liver that may be associated with malignancy, infection and drugs. The imaging manifestation of this disorder is often variable and nonspecific making its diagnosis difficult. We describe a rare case of peliosis hepatis and gummatous syphilis of the liver with emphasis on CT findings. Image characteristics of our patient included pseudotumoral appearance of peliosis hepatis, isodensity to the adjacent liver parenchyma on unenhanced and dual-phase scanning. To our knowledge, peliosis hepatis associated with syphilis and unique enhancement pattern has not been reported. Considering the imaging features of peliosis hepatis, it should be considered in the differential diagnosis of atypical focal hepatic lesion.

A novel technique of three-dimensional reconstruction segmentation and analysis for sliced images of biological tissues

A novel technique of three-dimensional (3D) reconstruction, segmentation, display and analysis of series slices of images including microscopic wide field optical sectioning by deconvolution method, cryo-electron microscope slices by Fou-rier-Bessel synthesis and electron tomography (ET), and a series of computed tomography (CT) was developed to perform si-multaneous measurement on the structure and function of biomedical samples. The paper presents the 3D reconstruction seg-mentation display and analysis results of pollen spore, chaperonin, virus, head, cervical bone, tibia and carpus. At the same time, it also puts forward some potential applications of the new technique in the biomedical realm.

A case of multiple intra-abdominal splenosis with computed tomography and magnetic resonance imaging correlative findings

Hepatic splenosis refers to heterotopic auto- transplantation and implantation of splenic tissue resulting from the spillage of cells from the spleen after splenic trauma or splenectomy. The true incidence of splenosis is unknown, because this entity is usually an incidental finding at surgery. Splenic implants are usually multiple, and can be localized anywhere in the peritoneal cavity. Splenic implants in the peritoneal cavity may be confused with renal tumors, abdominal lymphomas and endometriosis. We describe computed tomography (CT) and magnetic resonance imaging (MRI) findings in a rare case of multiple intra-abdominal splenosis located along the hepatic surface and adjacent to the upper pole of the right kidney, mimicking a renal neoplasm.

Positron emission tomography/computed tomography with ^(18)F-fluorodeoxyglucose identifies tumor growth or thrombosis in the portal vein with hepatocellular carcinoma

Patients suffering from hepatocellular carcinoma (HCC) with tumor thrombus in the portal vein generally have a poor prognosis. Portal vein tumor thrombus must be distinguished from portal vein blood thrombus, and this identification plays a very important role in management of HCC. Conventional imaging modalities have limitations in discrimination of portal vein tumor thrombus. The application of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) for discrimination between tumor extension and blood thrombus has been reported in few cases of HCC, while portal tumor thrombosis and portal vein clot identified by 18F-FDG PET/CT in HCC patients has not been reported so far. We present two HCC cases, one with portal vein tumor thrombus and one thrombosis who were identified with 18F-FDG PET/CT. This report illustrates the complimentary value of combining the morphological and functional imaging in achieving a correct diagnosis in such clinical situations.

CORONARY ANGIOGRAPHY WITH DUAL SOURCE COMPUTED TOMOGRAPHY:INITIAL EXPERIENCE

Objective To explore the scan technique and image quality of coronary angiography with dual source computed tomography(CT) without oral metoprolol preparation.Methods Plain and enhanced dual source CT coronary angiography without oral metoprolol preparation was prospectively performed in 600 patients.Calcium scoring with plain scan images as well as multi-planar reconstruction(MPR),maximum intensity projection(MIP),and volume rendering technique(VRT) reconstruction with enhanced scan images were performed in all cases.The scan technique and post-reconstruction experience was summarized.The image quality was classified as 1 to 4 points,and coronary segments classified according to the American Heart Association standards were evaluated.Results The average calcium score of the 600 cases was 213.6±298.7(0-3 216.5).The average heart rate of the enhanced scan was 82.1±16.2(47-139) bpm.The post-reconstruction methods with which coronary segments could be shown as best as possible consisted of single phase reconstruction method,two or more phases supplemented method,and electrocardiogram editing method.Altogether 8 457 coronary segments were evaluated,among which 97.2% were evaluated as point 1,1.7% point 2,0.5% point 3,and 0.6% point 4.The coronary segments in 261 cases were completely normal,while 360 segments were diagnosed with <50% stenosis and 625 segments with ≥50% stenosis.Conclusions Excellent coronary artery image can be obtained with dual source CT in patients with any heart rate without oral metoprolol preparation.Heart rate is not a major source of the artifact,coronary segments can be well shown with single or multiple-phase reconstruction method.