CT定量测量腹部脂肪面积的研究

目的：确定ＣＴ定量测量腹部脂肪面积的价值。方法：对３５ 例病人进行ＣＴ定量测量腹部脂肪面积。结果：腹内与皮下脂肪面积比值（Ｉ／Ｓ）≥０．６者易患中风、高血压、高脂血症等病（Ｐ＜ ０．００１）,其敏感性９４％ ,特异性６７％ ,准确性８０％ 。结论：ＣＴ定量测量腹部脂肪面积是一种检查肥胖并发症的有效手段,正常人腹内与皮下脂肪面积的比值应＜ ０．６。     

CT评估腹部脂肪体积的立体测量法与手动面积法比较

正摘要目的运用和评价立体点测量技术用于CT对上腹部内脏(VAF)和皮下(SAF)脂肪体积测量。方法对14例病人的腹部CT行基于点计算和系统抽样的立体体积评估。为了实现方法的最优化,结合100点和200点对5个样本的强度进行测试。在相同的扫描中,将最优化的立体测量与源于手动面积法的VAF和SAF体积进行比较。结果优化分析结果显示1/8抽样强度所选择的200个点可以在4 min内提供     

定量CT评估腹部脂肪面积与非酒精性脂肪性肝病相关性的研究进展

<正>非酒精性脂肪性肝病(nonalcoholic fatty liver disease, NAFLD)是一类除酒精和其他明确损肝因素所致的肝细胞内脂肪过度沉积为主要特征的临床综合征^[1]。随着肥胖及其相关代谢综合征全球化的流行趋势,NAFLD患病率逐年增高且呈低龄化,西方国家患病率约15%～30%,在我国更是在过去的十年里患病率从18%增加到29%,且年龄中位数更年轻^[2]。有研究表明[3],NAFLD在肥胖人群中的患病率更高,     

腹部脂肪和肝脏脂肪含量与骨密度相关性的定量CT分析

【摘要】目的：探讨定量CT（QCT）测量不同性别和不同年龄组人群的腹部脂肪、肝脏脂肪含量及骨密度（BMD）之间的相关性。方法：选取1448例行低剂量胸部CT联合QCT检查的健康体检者，其中男532例，女916例，据年龄、性别、骨质疏松程度、脂肪肝程度分组，分别比较腹部脂肪、肝脏脂肪与BMD的相关性。结果：年龄与BMD之间呈显著负相关性（r=-0.642，P<0.001）。男脂肪肝患病率较女高（P<0.001），肝脏脂肪含量与BMD之间呈正相关（r=0.061,P=0.020），与腹部总脂肪（TAT）、内脏脂肪（VAT）、皮下脂肪（SAT）亦呈正相关，其中与TAT关系最紧密（r=0.768,P<0.001）。BMD与女VAT(r=-0.260，P<0.001)、TAT（r=-0.128,P<0.001）之间呈负相关，与男VAT之间亦存在负相关（r=-0.109,P=0.012）。结论：BMD随年龄增加而逐渐减低，而与肝脏脂肪含量之间可能存在一定的正相关。肝脏脂肪含量可能是BMD的保护因素，而VAT可能是BMD的负性影响因素。     

数码照相结合Photoshop软件测量太田痣病变面积

太田痣是激光门诊中非常常见的一种色素性皮肤制,病变面积的准确测量是病历描述及治疗费用评估的基础。2008年以来,笔者采用数码照相结合Photoshop软件测量太田痣病变面积取得满意结果,现介绍如下。     

腹部CT应用脂肪密度口服造影剂

作者对62例做腹部CT的病人使用了口服调味12.5%玉米油乳浊液(COE)作为胃肠道造影剂。同期105例同类病人用传统阳性口服造影剂,包括稀硫酸钡悬浊液52例、Hypaque53例做为对照。病人随机选择。COE用量300～500ml,检查前无特殊胃肠道准备。对药物的耐受性,包括恶心、呕吐、肠痉挛和腹泻,两组病人无有意义差别。服用COE病人的腹部CT,胃肠腔内CT值为     

腹部巨大脂肪肉瘤 CT、MRI 表现及病理对照分析

目的：探讨腹部巨大脂肪肉瘤的 CT、MRI 表现,以提高术前诊断准确率。方法回顾性分析经手术病理证实的17例腹部巨大脂肪肉瘤的 CT、MRI 表现,并与病理各亚型进行对照分析。结果17例中,16例位于腹膜后,1例位于腹腔。肿块平均最大径约17 cm,其中分化良好型7例,CT、MRI 大多以脂肪密度为主,增强后轻度强化,1例硬化型含大量斑片状钙化,1例硬化型无脂肪成分,3例为多发病灶。黏液型5例,CT、MRI 表现为囊性密度及信号,增强后可见云絮状、网格状轻中度强化。去分化型2例,脂肪和软组织混杂,两者分界清楚,软组织肿块呈不均匀明显强化。混合型 3例,具有以上各型影像学表现,2例不含脂肪成分。结论脂肪肉瘤病理亚型多样,各亚型 CT、MRI 影像表现具有一定特征性。     

腹部脂肪坏死的临床和CT表现

腹部脂肪坏死是一种常见的病理改变,可引起腹部疼痛,与急腹症的表现相似;也可无症状而由机体其他病理生理变化而引发.腹部脂肪坏死实际上是脂肪组织因代谢或机械性原因发生变性的结果.常见的腹部脂肪坏死包括肠脂垂炎、大网膜梗死、创伤性或缺血性损伤所导致的局灶性脂肪坏死以及胰腺炎所导致的脂肪坏死.脂肪坏死作为一种相对常见的脂肪组织病变应为临床和影像医师所熟知.介绍腹部脂肪坏死和相关疾病的各种临床及CT表现.     

猪腹部脂肪的低剂量螺旋CT扫描

目的：利用猪腹部脂肪组织作模型,确定低剂量CT扫描检测脂肪组织的准确性。方法：采用不同剂量和不同层厚,对模型进行扫描。在3个模型上分别设置4条扫描线,每条线相距1 cm。扫描分9组,每组分10 mm,5 mm,2 mm三种层厚,每种层厚分别采用100 mA,50 mA,20 mA剂量扫描。扫描时间1 s。结果：模型扫描显示扫描层厚为10 mm时,剂量100 mA、50 mA、20 mA之间,脂肪CT值均数比较,差异无统计学意义（P〉0.05）;扫描层厚为5 mm时,剂量100 mA、50 mA、20 mA之间,脂肪CT值均数比较,差异无统计学意义（P〉0.05）;扫描层厚为2 mm时,剂量100 mA、50 mA、20 mA之间,脂肪CT值均数比较,差异无统计学意义（P〉0.05）。结论：低剂量扫描能准确测量脂肪CT值,可用于区域脂肪定量。     

定量CT分析年龄、腹部脂肪与骨密度的关系

目的采用定量CT(QCT)探讨腹部脂肪及骨密度(BMD)随年龄变化的规律及腹内脂肪(VAT)与BMD的相关性。资料与方法选取行低剂量胸部CT联合QCT检查的健康体检者2442例,其中男1522例,女920例,根据年龄分为5个年龄段:30~39、40~49、50~59、60~69、70~90岁。采用QCT测量L2中心层面腹部总脂肪(TAT)、VAT、皮下脂肪(SAT)及腰椎BMD。分析不同性别各年龄段间TAT、VAT、SAT、BMD的差异及TAT、VAT、SAT与BMD的相关性。结果50岁以上男性各年龄段TAT、VAT高于30~39岁男性(P均<0.01),而SAT低于30~39岁男性(P均<0.05)。50岁以上女性各年龄段TAT、VAT、SAT高于30~39岁女性(P均<0.001)。50岁以上男性及女性各年龄段间TAT、VAT、SAT比较,差异均无统计学意义(P均>0.05),40~49、50~59岁年龄段分别较上一年龄段VAT明显增多(P均<0.01),BMD随年龄增长逐渐减低(P均<0.001)。多元逐步回归分析显示,VAT是女性BMD的独立影响因素(β=-0.089,P=0.007),TAT、SAT不是BMD的独立影响因素(P均>0.05)。结论腹部脂肪和BMD随年龄发生变化,男性和女性均在40~59岁出现VAT明显增多。VAT可能是女性BMD的独立负性影响因素。     

A comparison of the CT-dosimetry software packages based on stylized and boundary representation phantoms

IntroductionWith the rapid development of computed tomography (CT) equipment, the assessment of effective and organ dose using suitable tools becomes an important issue and will provide health professionals with useful information regarding the radiation risks and the development of standard imaging protocols. Different clinical centres and/or institutions may use several software packages, each with different methods and algorithms for CT dose evaluation. Consequently, radiation doses calculated with these computer software packages might be different for the same patient and representative scanner models.MethodsThe effective and organ doses calculated by VirtualDose, CT-expo, and ImPACT software were compared for both males and females using kidney, chest, head, pelvis, abdomen, and whole-body CT protocols. The calculation of radiation dose in these software depends on the use of stylized and boundary representation (BREP) phantoms.ResultsIn general, the results showed that there was a discrepancy between the effective dose values calculated by the three packages. The effective dose in all examinations varied by factors ranging from 1.1 to 1.5 for male and from 1.1 to 1.3 for female. For the female phantom, the VirtualDose shows the highest effective doses in kidney and abdomen examinations while CT-expo gives the highest doses for head and pelvis examinations. For the male phantom, the VirtualDose shows the highest effective doses were for chest examinations.ConclusionVirtualDose approach gives the most accurate estimation, however, further work using a size-based method are necessary to improve the assessment of the effective and equivalent organ dose in CT examinations using these packages.Implications for practiceThe re-evaluation dosimetry software in comparison with patient size would allow for a more accurate estimation of dose and support the optimization process.     

Absolute myocardial flow quantification with 82Rb PET/CT: comparison of different software packages and methods

Purpose

In clinical cardiac ⁸²Rb PET, globally impaired coronary flow reserve (CFR) is a relevant marker for predicting short-term cardiovascular events. However, there are limited data on the impact of different software and methods for estimation of myocardial blood flow (MBF) and CFR. Our objective was to compare quantitative results obtained from previously validated software tools.

Methods

We retrospectively analyzed cardiac ⁸²Rb PET/CT data from 25 subjects (group 1, 62?±?11 years) with low-to-intermediate probability of coronary artery disease (CAD) and 26 patients (group 2, 57?±?10 years; P?=?0.07) with known CAD. Resting and vasodilator-stress MBF and CFR were derived using three software applications: (1) Corridor4DM (4DM) based on factor analysis (FA) and kinetic modeling, (2) 4DM based on region-of-interest (ROI) and kinetic modeling, (3) MunichHeart (MH), which uses a simplified ROI-based retention model approach, and (4) FlowQuant (FQ) based on ROI and compartmental modeling with constant distribution volume.

Results

Resting and stress MBF values (in milliliters per minute per gram) derived using the different methods were significantly different: using 4DM-FA, 4DM-ROI, FQ, and MH resting MBF values were 1.47?±?0.59, 1.16?±?0.51, 0.91?±?0.39, and 0.90?±?0.44, respectively (P?<?0.001), and stress MBF values were 3.05?±?1.66, 2.26?±?1.01, 1.90?±?0.82, and 1.83?±?0.81, respectively (P?<?0.001). However, there were no statistically significant differences among the CFR values (2.15?±?1.08, 2.05?±?0.83, 2.23?±?0.89, and 2.21?±?0.90, respectively; P?=?0.17). Regional MBF and CFR according to vascular territories showed similar results. Linear correlation coefficient for global CFR varied between 0.71 (MH vs. 4DM-ROI) and 0.90 (FQ vs. 4DM-ROI). Using a cut-off value of 2.0 for abnormal CFR, the agreement among the software programs ranged between 76 % (MH vs. FQ) and 90 % (FQ vs. 4DM-ROI). Interobserver agreement was in general excellent with all software packages.

Conclusion

Quantitative assessment of resting and stress MBF with ⁸²Rb PET is dependent on the software and methods used, whereas CFR appears to be more comparable. Follow-up and treatment assessment should be done with the same software and method.     

Clinical comparison of standard-dose and 50% reduced-dose abdominal CT: effect on image quality

OBJECTIVE. We hypothesized that radiation doses for abdominal CT could be reduced by adjusting the dose for a patient's weight and cross-sectional abdominal dimensions, with the resultant scans still being of diagnostic quality. SUBJECTS AND METHODS. Using a multidetector CT scanner, we prospectively studied 39 patients who were 65 years and older who had a known history of cancer. After performing a diagnostic contrast-enhanced CT examination, we obtained four slices each (centered at the top of the right kidney) at a standard radiation dose (240-300 mA) and at a 50% reduced dose (120-150 mA) at a constant kilovoltage of 140. Scans were obtained during a single breath-hold, with a 2.5-mm detector configuration and a slice pitch of 6:1. Reconstructed slice thickness was 5 mm. In a blinded review, two radiologists rated the randomized CT scans for overall image quality and anatomic details of liver, spleen, adrenal glands, kidneys, pancreas, and abdominal wall, using a 5-point scale (1 = unacceptable, 2 = substandard, 3 = acceptable, 4 = above average, and 5 = superior). Patients' weight and abdominal circumference, area, and anteroposterior and transverse diameters were correlated with image quality of scans obtained at standard-dose and 50% reduced-dose CT. Statistical analysis of the data was performed using Wilcoxon's signed rank test. RESULTS. Overall, the image quality score was significantly higher (p < 0.005) on the scans obtained with standard-dose CT. No statistically significant difference in image quality was noted in the 50% reduced- and standard-dose CT scans in patients who weighed less than 180 lb, or 81 kg, (p > 0.05) and who had a transverse abdominal diameter of less than 34.5 cm (p > 0.05), an anteroposterior diameter of less than 28 cm (p > 0.05), a cross-sectional circumference of less than 105 cm (p > 0.05), and a cross-sectional area of less than 800 cm(2) (p > 0.05). Good interobserver agreement (p > 0.5) was found between the two reviewing radiologists. CONCLUSION. Abdominal CT scan quality appears to be acceptable even with a 50% reduction in radiation dose except in patients with large anthropometric measurements. A reduction in CT radiation dose is possible if the tube current is optimized for the patient's weight and abdominal dimensions.     

Assessment of left ventricular volumes with cardiac MRI: comparison between two semiautomated quantitative software packages

Purpose

This study compared two quantitative semiautomated software packages for volumetric analysis of the left ventricle (LV) by magnetic resonance (MR) imaging using two-dimensional (2D) cine balanced steady-state free precession (b-SSFP) sequences.

Materials and methods

We included 46 consecutive patients who underwent cardiac MR imaging for various indications. Two-dimensional cine b-SSFP sequences were used to assess the LV. Data sets were evaluated with two dedicated software packages: ViewForum, version 4.2, and Argus, version Va60C. Results were compared with Student’s t test for paired samples, Pearson’s r correlation coefficient and R2 coefficient of determination; ejection fraction differences were assessed with Bland-Altman analysis. The time required for analysis was also recorded.

Results

We observed very high levels of concordance and reproducibility. High correlation was observed for ejection fraction (p>0.05; r=0.9; R ²=0.82). The time required for analysis was 7.6±2.78 min vs. 7.52±2.4 min (p>0.05; r=0.85; R ²=0.73). Intraobserver and interobserver variability did not show significant differences.

Conclusions

LV volume evaluation is an integral part of cardiac MR imaging. In our experience, there is no significant difference between the commonly used software packages in either quantitative output or time required for analysis.     

BodyTom移动CT的辐射剂量和图像质量评估

目的 通过对新一代全身移动CT（BodyTom CT）与常用固定CT机的比较,对其辐射剂量和图像质量评估。方法 用CATPHAN 500性能测试体模评价图像质量,用常规的100 mm笔形电离室、CT聚甲基丙烯酸甲酯（PMMA）体部体模及头部体模测量辐射剂量（头模直径为160 mm,体部体模直径为320 mm,它们宽度均为140 mm）。结果 BodyTom CT的空间分辨率、密度分辨率与两类固定CT接近,差异无统计学意义（P>0.05）。对比度噪声比（CNR）降低20%左右：头部扫描模式下,明显低于飞利浦64排CT和东芝320排CT（重建函数soft时,t=-4.82、-6.98,P<0.05;重建函数standard时t=-20.60、-20.09,P<0.05）;体部扫描模式下,也明显低于飞利浦64排CT和东芝320排CT（重建函数soft时,t=-5.67、-12.82,P<0.05;重建函数standard时,t=-3.39、-9.18,P<0.05;重建函数sharp时,t=-3.88、-3.21,P<0.05）。BodyTom CT的辐射剂量高于固定CT,相同参数下体部体模比飞利浦64排CT机剂量高22.97%（t=9.48,P<0.05）,比东芝320排CT机高29.60%（t=11.66,P<0.05）;头模比飞利浦64排CT机高29.76%（t=23.44,P<0.05）,比东芝320排CT机高33.22%（t=23.11,P<0.05）。结论 移动CT的图像与常规CT图像质量相当时,辐射剂量增高20%以上。     

Agreement between objective and subjective assessment of image quality in ultrasound abdominal aortic aneurism screening

Objective:

To investigate agreement between objective and subjective assessment of image quality of ultrasound scanners used for abdominal aortic aneurysm (AAA) screening.

Methods:

Nine ultrasound scanners were used to acquire longitudinal and transverse images of the abdominal aorta. 100 images were acquired per scanner from which 5 longitudinal and 5 transverse images were randomly selected. 33 practitioners scored 90 images blinded to the scanner type and subject characteristics and were required to state whether or not the images were of adequate diagnostic quality. Odds ratios were used to rank the subjective image quality of the scanners. For objective testing, three standard test objects were used to assess penetration and resolution and used to rank the scanners.

Results:

The subjective diagnostic image quality was ten times greater for the highest ranked scanner than for the lowest ranked scanner. It was greater at depths of <5.0 cm (odds ratio, 6.69; 95% confidence interval, 3.56, 12.57) than at depths of 15.1–20.0 cm. There was a larger range of odds ratios for transverse images than for longitudinal images. No relationship was seen between subjective scanner rankings and test object scores.

Conclusion:

Large variation was seen in the image quality when evaluated both subjectively and objectively. Objective scores did not predict subjective scanner rankings. Further work is needed to investigate the utility of both subjective and objective image quality measurements.

Advances in knowledge:

Ratings of clinical image quality and image quality measured using test objects did not agree, even in the limited scenario of AAA screening.The quality of images produced by a medical imaging device is an important consideration when gauging its suitability for a specific clinical task—it is essential that the system produces images that are of sufficient fidelity for the clinical user. As such, image quality will form an important consideration in the selection of equipment and in the ongoing quality assurance procedures following installation.The assessment of medical image quality can be performed in a number of ways, both subjectively (for example, using visual grading^1,2) and objectively using test phantoms specifically designed for that purpose.^3,4 Even for a specific imaging modality such as ultrasound, the level of agreement between these methods has not been thoroughly investigated, although there is some evidence of poor agreement between ratings of quality scores from test objects with those of clinical users when asked to rate clinical images from the same scanner.⁵The need to provide more objective image quality assessment is highlighted when there are national programmes requiring common standards. The breast cancer, foetal abnormalities and abdominal aortic aneurysm (AAA) detection programmes are good examples requiring ultrasound imaging of a uniform quality. It is critical that there is good agreement between clinical users as to what constitutes an acceptable image for these purposes. This will form the basis of a gold standard of performance against which the utility of any objective testing can be evaluated.In this study, we have used the ultrasound-based aortic aneurysm screening programme as an exemplar. In the UK, the National Abdominal Aortic Aneurysm Screening Programme (NAAASP) was implemented in 2013.⁶ This programme is primarily community based, necessitating the use of portable ultrasound scanners to allow transportation to screening centres. Measurements of the anteroposterior (A-P) inner to inner (ITI) abdominal aortic diameter in longitudinal section (LS) and transverse section (TS) planes are taken.The quality of images depends upon the skill of the practitioner, the habitus of the patient and the performance of the scanner. Together they may influence the reliability and accuracy of measurements.^7,8 Small errors in measurements may impact on clinical decision making, for example, resulting in inappropriate enrolment into the surveillance programme, at the 30-mm threshold, or delayed referral for a vascular surgical opinion, at the 55-mm threshold.Selection of the ultrasound scanner to carry out national screening is the responsibility of the service provider, although in the UK, some guidance on specification is available from the National Screening Committee. It is less clear what method providers should use to make their choice of scanner and whether this choice has any impact on the diagnostic image adequacy and the service provided. When faced with similar procurement decisions, providers have invited competing manufacturers to supply equipment for evaluation over a short time. The service providers commonly use subjective assessment of the image quality to make a decision, while recognizing on a small sample, differences between subjects, e.g. body habitus, may affect differences between scanners.^5,9 An alternative approach is to use one or more test objects to objectively assess image adequacy thus removing intersubject variation. Such objective measures also have the potential advantages that they are quick to perform, can be reproduced exactly at different centres and are ought to be less affected by the subjective opinion of the operator. A variety of test objects have been described for evaluation of ultrasound image quality, and each of these can be used to measure a range of different parameters.⁴ However, there is a paucity of evidence as to how results from such tests relate to subjective assessment. We are not aware of any specific advice or publication aimed at evaluating portable AAA scanners.The aim of this study was to investigate the level of agreement between the subjective assessment of the aortic images from portable ultrasound scanners and objective assessments obtained using test objects. If the agreement is good, then the implication is that test objects could be used with confidence in the assessment of image quality both for purposes of scanner selection and in monitoring ongoing performance. If the agreement is poor, then either the use of test objects as objective evaluators of performance should be seriously questioned or the assumption that clinical subjective performance is useful is called into question.     

不同肠道准备对腹部增强CT图像质量的影响

目前,在临床CT检查前的肠道准备方法有很多,为了探讨不同肠道准备对腹部增强CT图像质量的影响,本文收集2010年9月～2012年2月分别采用3％甘露醇和1％泛影葡胺同时、分次口服对56例腹部增强CT检查患者进行检查前肠道准备,并与采用1％肥皂水清洁灌肠后分次服用1％泛影葡胺的肠道准备方法的对照组患者进行肠道充盈效果、CT图像质量、肠道准备所需时间、不良反应对比研究,取得了良好的临床效果,现将结果报道如下.     

An assessment of abdominal fatty tissue distribution in obese children. A comparison between echography and computed tomography

PURPOSE: Computed tomography (CT) and, more recently, ultrasound (US), have proved excellent tools for quantifying adipose tissue distribution. Body fat distribution is an important factor in the treatment of obesity and its complications. We investigated the correlation between CT and US measurements in pediatric obesity. MATERIAL AND METHODS: Forty obese children and adolescents aged 4.1-14.8 years were submitted to CT and US. Intra-abdominal, subcutaneous and total body fat were calculated (in cm2), with the CT image analysis software. The rectus muscle-spine and rectus muscle-aorta distances, as indicative of visceral fat thickness, were measured on US images with(out) compression. The distance between skin-fat and fat-rectus muscle interfaces was measured as subcutaneous fat thickness. We also compared US-CT findings with other morphometric variables--i.e., patient's (ideal) body weight and skin fold measures. RESULTS: At US, the rectus muscle-aorta and rectus muscle-spine distances ranged 2.4-7.5 cm (mean: 4.47 cm) and 3.6-8.9 cm (mean: 5.79 cm), respectively. The skin-rectus muscle distance ranged 1.2-7.5 cm (mean: 3.14 cm). A statistically significant correlation was found between the CT measurement of visceral fat and the aorta-rectus muscle and rectus muscle-spine distances (r = 0.80 and 0.74, respectively). The US measurements of subcutaneous fat were correlated with CT subcutaneous fat area (r = 0.82). No correlation was found between overweight, as calculated by body mass index, and CT or US fat. CONCLUSION: Our findings indicate that US is as useful as CT in evaluating body fat distribution in pediatric obesity.