双能减影与常规DR检测肺结节模型的实验研究

目的比较双能减影（DES）与常规数字X线成像（CDR）对肺结节模型（SPNs）的检测能力。材料与方法将200个直径为4mm塑料小球作为SPNs置于健康志愿者右胸上部,在屏气状态下拍摄DES和CDR。由3位放射科医师各自独立阅片,计算CDR与DES的敏感性、特异性、阳性试验预测值、阴性试验预测值、准确率,并进行Pearson Chi-square检验。结果DES检测SPNs的敏感性、阴性试验预测值、准确率分别为69．3％、73．9％和77．9％．CDR分别为52．8％、63．9％和70．0％,DES均优于CDR（P〈0．05）。DES检测SPNs的特异性和阳性试验预测值分别为86．4％和83．6％,CDR分别为83．1％和75．6％,DES与CDR接近（P〉0、05）。结论DES可以去除肋骨对SPNs的遮挡．使DES对SPNs的检测能力优于CDR,提示DES对小肺结节的筛查具有良好的应用价值。     

EPID、CR及屏(铜)-片成像在放射治疗射野影像验证中的比较研究(ROC曲线分析)

目的 评价电子射野影像装置（EPID）、计算机X线摄影（CR）及屏（铜）-片成像在放射治疗射野影像验证中的效果. 材料与方法将98颗直径为6 mm的塑料小球作为信号源分别置于丙烯树脂板和仿人体头颅模型上,分别用EPID、CR成像和屏（铜）-片成像方式获取图像.由3名放射科医师用5等级判别法各自独立阅片,用Rockit软件对观察结果进行ROC分析. 结果 当信号置于丙烯树脂板上时,EPID、CR及屏（铜）-片成像的曲线下面积（Az）值分别为0.9923、0.9901及0.9862,两两比较t检验,其P值分别为0.5841、0.3743及0.4236均＞0.05,差异均无统计学意义.当信号置于人体头颅模型上时,EPID、CR及屏（铜）-片成像的Az值分别为0.8237、0.8089及0.7075,两两比较t检验,EPID与CR成像,P=0.4358＞0.05,差异无统计学意义;EPID与屏（铜）-片成像,P=0.0007＜0.01,差异有统计学意义;CR与屏（铜）-片成像,P=0.0002＜0.01,差异有统计学意义. 结论 在具备EPID或CR摄影装置的前提下,尽量不使用屏（铜）-片摄影方式.     

双能减影和常规DR对肺结节或肿块检出能力的比较

目的:比较双能减影和常规DR对肺结节或肿块检出的能力.方法:对经CT证实的50例患者共104个肺结节或肿块(PNM)行双能减影(DES)和常规数字X线减影(CDR)检查.评价DES和CDR对PNM的检出能力,并用配对卡方检验进行差异显著性分析.结果:对于CT证实全部PNM,DES和CDR的检出率分别为67.3%(70/104)和52.9%(55/104).两者差异有极显著性意义(X2=9.33,P＜0.01).对于最大径＞1 cm的PNM.DES和CDR的检出率分别为91.5%(43/47)和89.4%(42/47),两者差异无显著性意义(X2=1,P＞0.05).对于最大径≤1 cm的PNM,DES和CDR的检出率分别为47.4%(27/57)和22.8%(13/57),两者差异有极显著性意义(X2=8.45,P＜0.01).结论:DES对PNM的检出能力优于CDR.     

双能减影与数字X线成像诊断肺内孤立性结节ROC曲线评价

目的　比较双能减影 (DES)与数字X线成像 (DR)对肺内孤立性结节及结节内钙化的诊断价值。资料与方法　对 4 0例肺内有孤立性结节和 4 0例肺内无孤立性结节的病例行CT、DR及DES检查。 4位医师分别对两组影像学资料进行评价 ,结果采用受试者操作特征 (ROC)曲线进行统计分析。结果　在发现肺内孤立性结节方面 ,DES组的ROC曲线下面积 (Az =0 .94 0 )大于DR组 (Az =0 .891) ,两者统计学具有显著性差异 (P <0 .0 5 ) ;在发现肺内孤立性结节内钙化方面 ,DES组的ROC曲线下面积 (Az=0 .90 2 )大于DR组 (Az=0 .82 8) ,两者统计学具有显著性差异 (P <0 .0 5 )。结论　DES在发现肺内孤立性结节及钙化方面优于DR ,是对DR检查的有利补充     

放疗射野影像验证中CR不同摄影剂量对图像显示效果的影响(ROC曲线分析)

目的:评价CR不同摄影剂量在放疗射野影像验证中的图像显示效果。方法:将98颗直径为6mm的塑料小球作为信号源置于仿人体头颅模型上,以6MV的能量分别在1~8MU的剂量下由CR成像板获取信息并打印出照片,由3位放射学医师用5等级判别法各自独立阅片,用Rockit软件对观察结果进行ROC曲线分析。结果:1、2、3、4、5、6、7和8MU之Az值分别为0.7672、0.8253、0.8723、0.8832、0.8856、0.8604、0.8148和0.6869,以摄影剂量为5MU的Az值最高。将其与其它摄影剂量的Az值做两两比较t检验发现,与1MU和8MU比较,其P值分别为0.0013和0.0042,均小于0.01,说明差异有显著性意义;其与2、3、4、6和7MU比较,其P值分别为0.2537、0.3328、0.4536、0.3736、0.1894,均大于0.05,说明差异均无显著性意义。结论:CR用于放疗射野影像验证的摄影剂量为2~7MU较为适宜。     

CT肺结节分析软件在肺部筛查中的应用价值

目的:对比分析肺结节分析软件在肺部筛查中的应用价值。方法:80例肺部结节患者随机均分为A、B、C、D 4组。3位放射科医师(D1、D2、D3)分别采用常规阅片法和计算机辅助检测(computer aided detection,CAD)联合阅片法,分别在无限时和限时模式下,对这4组患者行CT阅片,记录肺部结节数量。其中A组采用无限时常规阅片法,B组采用无限时CAD联合阅片法,C组采用限时常规阅片法,D组采用限时CAD联合阅片法。将所有记录的肺结节结果与金标准进行对比,绘制受试者工作特性曲线(ROC曲线),记录曲线下面积(Az值)。通过Az值的比较,判断肺结节分析软件对于诊断者的辅助价值。结果:D1、D2、D3的Az值A组分别为0.777、0.693、0.506,B组分别为0.816、0.759、0.599,C组分别为0.666、0.559、0.295,D组分别为0.779、0.744、0.542。各诊断者于无限时模式下的Az值均高于限时模式下的Az值,差异具有统计学意义。在2种模式下,CAD联合阅片法的Az值均较常规阅片法升高,但是在无限时模式下差异无统计学意义,在限时模式下差异有统计学意义;Az值的升高有随着诊断经验的增加而下降的趋势。结论:肺结节分析软件能够帮助提高诊断者在肺结节检测中的诊断价值,尤其对快速诊断及低年资诊断者的帮助意义更大。     

双能减影与常规数字X线摄影诊断肋骨骨折的对比研究

目的 研究双能减影（DES）对肋骨骨折（RF）的诊断价值. 资料与方法 对40例共121处RF进行DES与常规数字X线摄影（CDR）检查.比较DES与CDR对各病程RF的显示能力.采用Pearson Chi-square检验进行差异统计学分析. 结果 对于所有RF,DES显示为优者占81.0%,CDR显示为优者占17.4%,经统计学检验,两者差异具有统计学意义（χ2=98.027,P= 0.000＜0.01）.DES对愈合期和已愈合RF的显示优于CDR,其差异有统计学意义（P=0.000＜0.01）;而对于新鲜RF,两种检查方法之间差异无统计学意义（P=0.151＞0.01）. 结论 在RF诊断中,DES是一项有价值的检查方法,是CDR的有益补充.     

数字化双能量减影技术在胸部结节性病变诊断中的应用价值

目的探讨数字化双能量减影(dual-energy subtraction,DES)摄片技术在胸部结节性病变临床诊断中的优势。资料与方法搜集在本院行DES胸部摄影和CT检查,发现胸部结节的36例患者及证实无胸部结节的16例患者的资料,由两名高年资放射科医师对其普通数字化摄影(DR)图像与DES图像采用双盲法进行分析,评价两者对胸部结节的显示情况。结果DES软组织图像比普通DR图像检出更多的结节,同时对结节边缘的显示更清晰,有利于定位定性诊断。结论DES能将骨与软组织单独分开显示,分别得出标准影像、软组织影像和骨组织影像,有效地去除胸廓骨组织影的遮挡影响,提高肺结节性病变的可视性,是对DR图像诊断胸部结节的有效补充。     

计算机X线摄影能量减影与直接数字摄影对胸部软组织病变检测能力比较

目的 比较计算机X线摄影能量减影技术(ES-CR)与直接数字摄影技术(DR)对肺内软组织信号的探测能力。方法 应用胸部放射学体模和X线摄影统计学体模摄取ES-CR和DR影像,由6位放射科医师用5等级判别法各自独立阅读影像,编写程序对观察结果进行受试者操作特性曲线(ROC)分析。收集28例病理证实小肺癌患者的胸部DR影像和ES-CR影像,由3位放射科医师一起做出诊断,分析其真阳性率的差异性。结果 体模影像的ROC分析,ES-CR和DR的 Az 值分别为0.727和0.827,差异有统计学意义( Z =2.96, P<0.05)。28例小肺癌两成像系统的差异也有统计学意义(χ²=5.14, P<0.05)。结论 用DR诊断的真阳性率要高于ES-CR。ES-CR对胸部软组织信号的检出能力尚不如DR。     

DDR双能量减影与常规DR检测腹部碘剂造影模型的实验研究

目的 比较双能量减影(DES)与常规数字X线成像(CDR)对腹部碘剂造影模型的检测能力.资料与方法 制造腹部碘剂造影模型,分别拍摄DES和CDR,比较其密度分辨率.结果 DES检测出泛影葡胺的浓度可达0.593%,而CDR仅为4.75%.结论 DES对碘剂浓度的检测能力明显优于CDR.     

Acute cerebral infarction: effect of JPEG compression on detection at CT

PURPOSE: To evaluate the effect of Joint Photographic Experts Group (JPEG) compression ratios of 10:1 and 20:1 on detection of acute cerebral infarction at computed tomography (CT). MATERIALS AND METHODS: CT images obtained in 25 patients with acute cerebral infarction and 25 patients with no lesions were compressed by means of a JPEG algorithm at ratios of 10:1 and 20:1. Normal and abnormal sections (on original and compressed images) were reviewed by using a color soft-copy computed monochrome cathode ray tube monitor. Five observers rated the presence or absence of a lesion with a 50-point scale (0, definitely absent; 25, equivocal; and 50, definitely present). Diagnostic accuracy was evaluated with receiver operating characteristic (ROC) curve analysis. Significant difference was defined as a P value less than.05 for the area tested with a two-tailed paired Student t test. RESULTS: At ROC analysis, no statistically significant difference was detected for all cases considered together (Az [area under the ROC curve] = 0.887 +/- 0.038 [mean +/- SD] on noncompressed images, Az = 0.897 +/- 0.038 on 10:1 compressed images, and Az = 0.842 +/- 0.073 on 20:1 compressed images; P >.05). CONCLUSION: JPEG compression at ratios of 10:1 and 20:1 was tolerated in the detection of acute cerebral infarction at CT.     

Linear and logarithmic subtraction for detecting enamel subsurface demineralization

OBJECTIVE: To compare the diagnostic performance of linear and logarithmically contrast-enhanced subtraction images, acquired with digital and digitized radiographs, in detecting approximal enamel subsurface demineralization. METHODS: Fifty caries-free human third molars were immersed in a demineralizing solution for 60, 75, 90, and 120 days, in order to induce artificial enamel subsurface demineralization. The teeth were coated with nail varnish, leaving only a circular window of approximately 7 mm2 in one of the approximal surfaces, allowing contact with the solution. Standardized radiographs of the teeth were taken prior to and after the demineralization period with three digital systems, CygnusRay MPS, DenOptix and DIGORA, and InSight film. Conventional, digital and digitized radiographs were assessed by three experienced radiologists. Linear and logarithmically contrast-enhanced subtraction images were acquired and then examined by a fourth independent radiologist. For the validation of the radiographic diagnosis, the enamel test areas were submitted to Knoop microhardness profiling. Radiographic interpretation data was evaluated using ROC analysis. The areas under the ROC curves (Az) were compared by the chi-squared test. The level of significance was set at P=0.05. RESULTS: No significant differences were found between linear and logarithmically contrast- enhanced subtraction images, acquired with the four studied modalities: CygnusRay MPSlinear (Az=0.95), CygnusRay MPSlog (Az=0.98), DenOptixlinear (Az=0.97), DenOptixlog (Az=0.99), DIGORAlinear (Az=0.98), DIGORAlog (Az=0.98), digitized radiographylinear (Az=0.99), digitized radiographylog (Az=0.99). CONCLUSION: Linear and logarithmically contrast-enhanced subtraction images, acquired with digital and digitized radiographs, were diagnostically comparable for assessing enamel subsurface demineralization.     

Clinically and mammographically occult breast lesions on MR images: potential effect of computerized assessment on clinical reading

PURPOSE: To investigate if and how computerized analysis complements characterization of breast lesions with clinical reading at magnetic resonance imaging. MATERIALS AND METHODS: The institutional review board approved the use of data obtained prospectively and analyzed either prospectively with informed patient consent or retrospectively with waiver of consent. An existing computerized analysis system was retrained with 100 breast lesions (in 78 patients with mean age of 46.5 years) and tested with 136 other lesions (in 113 patients with mean age of 48.9 years; P=.15 for age difference between groups). Seventy-five lesions in the training set were previously rated by one of three radiologists in daily clinical practice. Lesion rating (as benign, probably benign, indeterminate, suspicious, or highly suggestive of malignancy) and probability of malignancy calculated with computerized analysis were included as covariates in logistic regression analysis to obtain a combined model. The performance of the model was compared with that of clinical reading alone in a set of 72 clinically and mammographically occult lesions not used to train the computerized analysis system (in 60 patients with mean age of 43.5 years; P=.09 for age difference between training and testing groups). Receiver operating characteristic (ROC) curves were plotted, and areas under the ROC curves were calculated and compared. RESULTS: Performance of reading in the clinical setting, as indicated by area under the ROC curve (Az=0.86), was similar to that of computerized analysis (Az=0.85; P=.99). Significant overall improvement in performance was obtained with the combined model (Az=0.91; P=.03). Improvement was accomplished mostly in characterization of lesions rated indeterminate or suspicious by radiologists. CONCLUSION: Computerized analysis complements clinical reading and makes computer-aided diagnosis feasible. The complementary information has the potential to increase overall performance for clinically and mammographically occult lesions.     

Effect of a computer-aided diagnosis system on clinicians' performance in detection of small acute intracranial hemorrhage on computed tomography

RATIONALE AND OBJECTIVES: To analyze the effect of a computer-aided diagnosis (CAD) system on clinicians' performance in detection of small acute intracranial hemorrhage (AIH) on computed tomography (CT). MATERIALS AND METHODS: The authors have developed a CAD scheme that used both image processing techniques and anatomic knowledge based classification system to improve diagnosis of small AIH on CT. A multiple-reader, multiple-case receiver operating characteristic (ROC) study was performed. Twenty clinicians, including seven emergency physicians, seven radiology residents, and six radiology specialists were recruited as readers of 60 sets of brain CT, including 30 cases that show AIH smaller than 1 cm, and 30 controls. Each reader read the same 60 cases twice, first without, then with the prompts produced by the CAD system. The clinicians ranked their confidence in diagnosing a case of showing AIH, which produced the ROC curves. RESULTS: Significantly improved performance is observed in emergency physicians, average area under the ROC curve (Az) increased from 0.8422 to 0.9294 (P = .0107) when they make the diagnosis without and with the support of CAD. Az for radiology residents increased from 0.9371 to 0.9762 (P = .0088). Az for radiology specialists increased from 0.9742 to 0.9868, but was statistically insignificant (P = .1755). CONCLUSIONS: CAD can improve the clinicians' performance in detecting AIH on CT. In particular, emergency physicians can benefit most from the CAD and improve their performance to a level approaching that of the average radiology residents.     

相同分辨力不同品牌影像诊断显示器对孤立性肺结节识读的影响

目的：通过不同品牌间相同分辨力的影像诊断显示器对胸部数字化X线摄影（DR）肺结节检出准确率的比较,评价品牌之间显示器的诊断效能。方法：从图像存储与传输系统（PACS）数据库中搜寻本院2005年3月～2008年12月胸部DR中发现或可疑有肺结节者行CT检查,CT发现单发、直径≤30mm的结节,列为阳性组;而CT证实无结节者列入阴性组。5位医师分别应用三种品牌显示器用5分法：肯定有、可能有、不确定、可能无、肯定无,独立判断结节有无。利用识读结果绘制ROC曲线,并比较曲线下面积及各品牌显示器之间的诊断效能。结果：5位影像诊断医师在3个品牌显示器中对1～10mm组孤立性肺结节识读的总平均值分别为Az（A）=0.877±0.053,Az（B）=0.895±0.050,Az（C）=0.887±0.051,对10～30mm组孤立性肺结节识读的总平均值分别为Az（A）=0.891±0.045,Az（B）=0.901±0.044,Az（C）=0.892±0.045。所使用的三种显示器中,由于分辨力相同,3百万象素（3MP）,从ROC曲线中可以看出,曲线下的面积Az虽然是有差别的,但都接近于0.9,说明3MP的液晶显示器（LCD）在孤立性肺结节的诊断效能是比较高的,其中品牌B的面积最大。经过统计学检验,P值有所不同。结论：3MP显示器在肺结节识读影像上差异具有统计学意义,但总的诊断效能无明显差异。     

Satisfaction of search in diagnostic radiology

A subset of underreading errors (false-negative responses) in radiology has been attributed to "satisfaction of search," which occurs when lesions remain undetected after detection of an initial lesion. This phenomenon has not been studied in the experimental laboratory. A primary goal of this study was to develop a procedure or paradigm to study satisfaction of search. The authors measured detection accuracy for native lesions in images before and after the addition of a simulated nodular lesion. Simulated and native lesions were not spatially superimposed and the native abnormalities were physically identical with and without the nodules. Only responses related to the native lesion were analyzed. Accuracy parameters of receiver operating characteristic (ROC) curves were estimated by the method of maximum likelihood and jackknife. The average perceptual accuracy of the individual ROC curves as measured by Az and de' was significantly reduced with addition of the nodules (t = 2.364, p = 0.025, t = 2.648, p = 0.017, respectively). Az and de' parameters of the pooled ROC curve showed a similar effect (t = 1.573, p = 0.080; t = 1.934, p = 0.047, respectively). The results indicated a substantial satisfaction-of-search effect, with diminished accuracy in perception of native lesions.     

多层螺旋CT胸部平扫预测贫血的价值探讨

目的：探讨多层螺旋CT胸部平扫预测贫血的价值。方法：对82例确诊为贫血的患者及与之性别、年龄相对应的82例非贫血患者评价。每例患者的胸部CT平扫与血红蛋白检查间隔不超过36h。对每例患者的CT图像进行主观及客观评价,主观指标包括主动脉环征、室间隔高密度征,客观指标为升主动脉CT值。计算各个指标评价贫血的敏感性、特异性、准确度、阳性预测值、阴性预测值,并对各个诊断指标进行受试着特异性工作曲线分析。结果：①主动脉腔CT值与血红蛋白水平之间有较好的相关性（r=0．826,P=0．000）;②对单个诊断指标进行受试着特异性工作曲线分析,发现主动脉CT值ROC曲线下面积最大（Az=0．866）,其最佳工作点为CT值≤36HU,此时,其诊断贫血的敏感性、特异性分别为76．6％、100％;③主动脉环征的敏感性高于室间隔高密度征（81．0％：67．4％）,而后者的特异性较高（98．7％：88．9％）;④将主观指标和客观指标联合起来分析能获得较好的敏感性（84．7％）、特异性（100％）、准确度（92．1％）,ROC曲线下面积最大（Az=0．921）。结论：利用多层螺旋CT胸部平扫预测贫血是可行的,将主观指标和客观指标联合起来分析能获得较好的诊断效果。     

Comparison of LCD and CRT monitors for detection of pulmonary nodules and interstitial lung diseases on digital chest radiographs by using receiver operating characteristic analysis

Soft copy reading of digital images has been practiced commonly in the PACS environment. In this study, we compared liquid-crystal display (LCD) and cathode-ray tube (CRT) monitors for detection of pulmonary nodules and interstitial lung diseases on digital chest radiographs by using receiver operating characteristic (ROC) analysis. Digital chest images with a 1000x1000 matrix size and a 8 bit grayscale were displayed on LCD/CRT monitor with 2M pixels in each observer test. Eight and ten radiologists participated in the observer tests for detection of nodules and interstitial diseases, respectively. In each observer test, radiologists marked their confidence levels for diagnosis of pulmonary nodules or interstitial diseases. The detection performance of radiologists was evaluated by ROC analyses. The average Az values (area under the ROC curve) in detecting pulmonary nodules with LCD and CRT monitors were 0.792 and 0.814, respectively. In addition, the average Az values in detecting interstitial diseases with LCD and CRT monitors were 0.951 and 0.953, respectively. There was no statistically significant difference between LCD and CRT for both detection of pulmonary nodules (P=0.522) and interstitial lung diseases (P=0.869). Therefore, we believe that the LCD monitor instead of the CRT monitor can be used for the diagnosis of pulmonary nodules and interstitial lung diseases in digital chest images.