CT measurement of main pulmonary artery diameter

The aim of this study was to determine the upper limit of the normal main pulmonary artery diameter using a modern CT system. This was measured at the level of the pulmonary artery bifurcation in 100 normal subjects using unenhanced contiguous 10 mm CT slices viewed at fixed mediastinal window settings (400/20). These normal subjects were then compared with similar unenhanced 10 mm images from 12 patients with proven pulmonary arterial hypertension (mean pulmonary artery pressure > 20 mmHg). The main pulmonary artery diameter in normal subjects was 2.72 cm (SD = 0.3). Main pulmonary artery diameter in patients with pulmonary arterial hypertension was significantly greater (p < 0.01) at 3.47 cm (SD = 0.33). A pulmonary artery diameter of 3.32 cm (main pulmonary artery diameter + 2 SD) had a 58% sensitivity and 95% specificity for the presence of pulmonary arterial hypertension. It is concluded that, using unenhanced axial 10 mm CT sections, the upper limit of normal main pulmonary artery diameter is 3.32 cm. Pulmonary arterial hypertension should be considered in patients with values above this level.     

多层螺旋CT双斜位MPR对骨半规管的全程显示研究

目的:利用多层螺旋CT各向同性扫描进行双斜位多平面重组(multiplanarreformation,MPR)后处理,重建出各半规管全貌。方法:搜集观察对象105例(男52,女53),210耳,年龄范围为9个月至71岁,利用多层螺旋CT各向同性扫描对颞骨进行检查,然后对所得图像进行双斜位多平面重组(multiplanarreformation,MPR)后处理,重建出各半规管全貌。结果:通过双斜位多平面重组(MPR)后骨半规管和外骨半规管均能在一个平面上显示其全貌,部分前骨半规管(105例中6例,5.7%)未能显示全貌。结论:多层螺旋CT各向同性扫描后双斜位多平面重组(MPR)后处理能够很好的显示各骨半规管的全貌。     

Pulmonary metastases: effect of CT section thickness on measurement--initial experience

PURPOSE: To assess the effect of commonly used computed tomographic (CT) section thicknesses on metastatic tumor measurements calculated with unidimensional, bidimensional, area, and volumetric methods. MATERIALS AND METHODS: Analysis and data collection were approved by the Institutional Review Board, with waived informed patient consent. Forty-two pulmonary metastases in 10 patients (three men and seven women; age range, 43-83 years; mean age, 65.4 years) were analyzed on CT scans obtained with 3.75-, 5.0-, and 7.5-mm section thicknesses. The lesions were automatically delineated by using a three-dimensional multicriteria segmentation algorithm. Unidimensional (the largest diameter), bidimensional (the product of the two maximal perpendicular diameters), maximal cross-sectional area, and volumetric measurements were automatically obtained for each pulmonary lesion on each section thickness. Means and variances were calculated, and the differences across the three section thicknesses for each of the four measurements were studied by using linear mixed-effects models. The Levene test was used to study the equality of variances. RESULTS: Differences in the means for unidimensional, bidimensional, and area measurements were significant between a section thickness of 3.75 and 5.0 mm (unidimensional, P=.05; bidimensional, P=.05; area, P=.01) and 3.75 and 7.5 mm (unidimensional, P=.06; bidimensional, P=.03; area, P=.02), but not 5.0 and 7.5 mm. There was a significant difference in volumetric measurement as section thickness decreased from 7.5 to 5.0 mm (P <.001) and from 7.5 to 3.75 mm (P <.001). Although there was a slight trend for differences in the variances across section thickness for each measurement, none of the differences were significant. CONCLUSION: Volumetric tumor measurements change with a reduction in section thickness from 7.5 to 5.0 and 3.75 mm. For unidimensional measurement, no change was found when thickness decreased from 7.5 to 5.0 mm.     

Test object for measurement of section thickness at US

A simple phantom was used to test the ultrasound beam profile in the elevation direction (perpendicular to the scanning plane). Based on the inclined plane method, the phantom allowed direct clear display of the section thickness over the whole exploration depth on a single standard ultrasonographic image. This was demonstrated with one- and one and one-half-dimensional arrays. The results showed the efficiency of electronic focusing in the elevation plane associated with one and one-half-dimensional arrays.     

Shape and dimensions of cardiac chambers: importance of CT section thickness and orientation

Three-dimensional (3D) computed tomography (CT) scan data were used to quantitate the geometry of all heart chambers. The Dynamic Spatial Reconstructor (DSR) was used to scan dogs with in situ casts of the cardiac chambers. Chamber volumes estimated from DSR images were accurate within 5% of water displacement volume measurements of the actual casts for chambers greater than 11 ml and within 10% of water displacement volumes for chambers less than 11 ml. Anatomic features of the actual cast correlated closely with anatomy visible in computer-generated surface images of the 3D DSR image data. The important effect of reconstructed section thickness and orientation on the fidelity of 3D cardiac geometry is demonstrated.     

CT测量肾脏皮质厚度与年龄关系的研究

目的研究肾脏皮质厚度与年龄的关系,确定不同年龄段正常肾脏皮质厚度CT测量的参考范围,筛选出与年龄相关性最好、易于临床应用的测量方法.方法(1)确定CT测量肾皮质厚度的准确性选取因肾脏肿瘤而做全肾切除的18例病人的肾脏标本,测量肾脏正常部分的皮质厚度,将测量结果与术前CT影像肾皮质厚度测量的结果行统计学分析,确定差异有无显著性意义;(2)连续选取120例无肾病,无服用肾脏损害药物史,无高血压史病人的腹部CT资料,分为20～40岁、41～60岁、61～80岁3个年龄组,测量每侧肾脏3个层面皮质、实质的厚度和肾脏径线长,统计学分析3个年龄组间差异有无显著性意义及其与年龄的相关性.结果增强螺旋CT图像测量的肾脏皮质厚度与肾标本测量的皮质厚度差异无显著性意义(t=0.08,P=0.43).3个年龄组肾脏皮质厚度均数分别为0.73 cm、0.65 cm、0.53 cm,组间差异有极显著性意义(F=93.403,P＜0.01).肾脏皮质、实质厚度与年龄呈负相关,其中相关性最好的指标是皮质厚度(r=-0.78～-0.79);60岁以前肾皮质与肾实质厚度比与年龄无相关性.体型对肾脏皮质厚度的影响不明显.男女性别间皮质厚度的差异无显著性意义(P＞0.05).结论增强螺旋CT能够准确地测量肾脏皮质的厚度,是研究肾脏形态变化的一种敏感的手段.肾皮质厚度随年龄减小,但肾皮质与肾实质厚度之比随年龄的增加变化不明显.     

正常成人髋臼断面角的CT测量

目的通过ＣＴ测量,建立国内成人髋臼断面角的正常值标准。方法对１２０例因腹部或盆腔病变行ＣＴ检查而无髋部症状的病人加扫双侧髋关节。从中挑选Ｘ线和ＣＴ表现正常的１００例作为统计对象。结果成年男性被研究者髋臼前断面角（ＡＡＳＡ）的范围为５９．００°～８３．００°,平均值为７２．５６°,标准差为５．６１°;髋臼后断面角（ＰＡＳＡ）的范围为８４．００°～１１６．００°,平均值为１００．６２°,标准差为５．７６°。成年女性研究者ＡＡＳＡ的范围为５３．００°～９２．００°,平均值为７０．４５°,标准差为７．７９°;ＰＡＳＡ范围８７．００°～１２０．００°,平均值为１０３．６６°,标准差为７．２２°。结论国内正常成年男性ＡＡＳＡ正常值范围为６１．５６°～８３．５６°,ＰＡＳＡ为８９．３３°～１１１．９１°,成年女性ＡＡＳＡ为５５．１８°～８５．７２°,ＰＡＳＡ为８９．５１°～１１７．８１°     

Measurement of CT section thickness by using the partial volume effect.

A method to calculate section thickness from mean computed tomographic (CT) numbers of two materials in a section (and by varying the ratio of their volume) was developed. A cylindrical water phantom with an acrylic rod at the center was used, and section thickness was measured with two CT scanners. At actual section thicknesses of more than 4 mm, results with this method differed from results of the aluminum ramp method by only about 10%. At section thicknesses of 1-2 mm, however, the difference was about 30%-50%. Measurement with this method was not influenced by filter function and therefore was more accurate than with the aluminum ramp method.     

CT层厚的测量技术及其相关影响因素研究

目的：测量ＣＴ的层厚,探讨与层厚相关的各项参数。方法：采用３种不同方法对１０台ＣＴ进行测试,计算出ＣＴ的层厚并测量了不同层厚条件下ＣＴ的噪声和空间分辨力。结果：３种测试方法各有优缺点,有多种因素影响ＣＴ层厚。结论：必须通过测试校准来确保ＣＴ设备层厚的准确性。     

健康成年人骨性半规管和椭圆囊的MSCT显微解剖研究

目的:利用MSCT测量骨性半规管的径线、相互间的角度,椭圆囊的径线及体积,并估算健康成年人前庭器官参考值。方法:对60例健康成人行颞骨MSCT靶扫描及双斜位MPR,以显示各骨性半规管的全程和椭圆囊的全貌,并测量骨性半规管的径线、半规管间夹角以及椭圆囊的长径、短径和体积。用SPSS v16软件进行差异性t检验和参考值估算。结果:①前骨性半规管的内径、高度、跨度的测量值分别为(1.82±0.16)mm、(5.34±0.32)mm、(4.90±0.62)mm;后骨性半规管分别为:(1.57±0.14)mm、(4.89±0.50)mm、(3.06±0.47)mm;外骨性半规管分别为:(2.32±0.31)mm、(2.11±0.46)mm、(3.74±0.44)mm;椭圆囊的长径、短径分别为:(5.01±0.34)mm、(3.51±0.43)mm,体积为(56.7±7.71)mm3。②相应骨性半规管的径线及椭圆囊的体积比较在性别及侧别上差异均无统计学意义(P>0.05);不同半规管间的径线比较差异有统计学意义(P<0.05)。③骨性半规管间夹角测量值:前骨性半规管和后骨性半规管间91.80°±7.18°,前骨性半规管和外骨性半规管间89.71°±4.95°,后骨性半规管和外骨性半规管间91.19°±1.46°。④骨性半规管间夹角比较在性别及侧别上差异均无统计学意义(P>0.05)。结论:①利用MSCT靶扫描结合双斜位MPR可以很好地显示骨性半规管的全程和椭圆囊的全貌。②本组骨性半规管的径线和椭圆囊的测量值处于95%的置信区间内,可以作为正常参考值。③外骨性半规管的内径最大,前骨半规管最小;前骨半规管的高度和跨度最大,外骨半规管最小。骨性半规管间的相互夹角并非严格相互垂直。     

CT measurement of the calcaneal varus angle in the normal and fractured hindfoot.

The calcaneal varus angle is an important parameter used by orthopedic surgeons in their assessment of calcaneal fractures, and restoration of this angle is a major goal in the intraoperative reduction of such fractures. Plain radiographic techniques for the measurement of this angle may be difficult to apply. It is much simpler to measure this angle on CT, which is superior in demonstrating the complex anatomy of the calcaneus. However, a standardized method of measuring this angle by CT has not yet been developed. We measured the calcaneal varus angle in 48 subjects (31 normal feet and 62 feet with fractured calcanei) with three methods. The axial calcaneocuboid angle (the angle in the axial plane between the longitudinal axis of the calcaneus and a line drawn perpendicular to the calcaneocuboid joint) measured 25.3 +/- 7.3 degrees (mean +/- 1 SD) in normal feet and 28.9 +/- 8.5 degrees in fractured feet. The axial talocalcaneal angle (the angle between the longitudinal axes of the talus and the calcaneus in the axial plane) measured 20.9 +/- 9.2 degrees in normal feet and 29.2 +/- 11.3 degrees in fractured feet. The coronal talocalcaneal angle (the angle between the vertical axes of the talus and calcaneus in the coronal plane) measured 12.5 +/- 3.8 degrees in normal feet and 21.8 +/- 7.6 degrees in fractured feet. There was a statistically significant difference between the varus angle for normals and for fractured calcanei by all three methods of measurement (p less than or equal to 0.05). These measurements provide preliminary normative data for three methods of estimating the calcaneal varus angle in the normal and fractured hindfoot. These may be of value not only in the surgical restoration of the normal anatomic alignment of the fractured hindfoot but also in the preoperative assessment of congenital foot abnormalities. Although clinical validation is not yet available, our study suggests that the axial calcaneocuboid angle has several significant advantages over the other two methods.     

Chronic obstructive pulmonary disease: thin-section CT measurement of airway wall thickness and lung attenuation

PURPOSE: To prospectively evaluate airway wall thickness and lung attenuation at spirometrically gated thin-section computed tomography (CT) in patients with chronic obstructive pulmonary disease (COPD) and to correlate gated CT findings with pulmonary function test (PFT) results. MATERIALS AND METHODS: The ethical committee approved the study, and all patients gave informed consent. Forty-two consecutive patients with COPD (20 with and 22 without chronic bronchitis [CB]) underwent gated thin-section CT and PFTs on the same day. The percentage wall area (PWA) and the thickness-to-diameter ratio (TDR) for all depicted bronchi that were round and larger than 2 mm in diameter, the mean lung attenuation (MLA), and the pixel index (PI) at -950 HU were determined. The reproducibility of the airway measurements was preliminarily tested by performing a five-trial examination in a patient with COPD and in a control patient. Differences in airway and lung attenuation measurements between the patients with and those without CB were evaluated at Mann-Whitney U testing. Simple and multiple regression analyses were used to assess the correlation between thin-section CT and PFT measurements. RESULTS: The mean intraoperator coefficient of variation for airway measurements was 7.8% (range, 3.8%-13.4%). An average of nine bronchi per patient were assessed. Patients with CB had significantly higher PWAs, TDRs, and MLAs and significantly lower PIs than patients without CB (P < .05 for all values). The combination of PWA, TDR, and PWA normalized to body weight correlated significantly (P < .05) with the forced expiratory volume in 1 second-to-slow vital capacity ratio and the diffusing capacity of the lung for carbon monoxide in patients with but not in patients without CB. PFT results correlated better with MLA and PI in patients without CB. CONCLUSION: Bronchial wall measurements differ between patients who have COPD with CB and those who have COPD without CB. The correlation between airway dimensions and indexes of airway obstruction in patients with COPD and CB indicates that the bronchial tree is the site of anatomic-functional alterations in this patient group.     

肾脏形态与肾小球滤过功能相关性的CT研究

目的研究 CT 测量的肾脏皮质、实质厚度与肾脏滤过功能的关系,并评价 CT 预测肾脏滤过功能的价值。方法选择同时行增强螺旋 CT 检查和~(99)锝~m-二乙三胺五醋酸(~(99)Tc~m-DTPA)肾动态显像的89例患者,局部肾脏疾病患者排除在外。根据肾脏滤过功能把178个肾脏分为正常组、肾功能轻度受损组、肾功能重度受损组,比较3组间 CT 测量的肾脏皮质、实质厚度的差异,分析肾脏皮质、实质厚度与肾脏滤过功能的相关性,并用受试者操作特性曲线(ROC)法评价 CT 预测肾脏功能的价值。结果正常组、肾功能轻度受损组、肾功能重度受损组3组间肾脏皮质厚度分别为(5.9±1.1)、(4.6±1.1)、(3.3±1.0)mm,3组间肾脏实质厚度分别为(26.3±4.2)、(21.3±4.6)、(16.2±4.6)mm。3组间肾脏皮质、实质厚度差异有统计学意义(F 值分别为54.78、43.90,P 值均<0.01)。肾脏皮质(r=0.752,P<0.01)、实质(r=0.738,P<0.01)厚度与肾脏滤过功能有良好的相关性,CT测量的皮质厚度在预测单侧肾脏功能轻度异常和重度异常时 ROC 曲线下面积(Az)分别为0.860和0.905;实质分别为0.868和0.884。结论 CT 测量肾脏皮质、实质厚度能较准确反映肾脏滤过功能,CT 可以作为评价肾脏滤过功能的一种补充方法。     

Automated detection of pulmonary nodules on CT images: effect of section thickness and reconstruction interval--initial results

Institutional review board approval was obtained. Informed patient consent was not required. Study was compliant with HIPAA. Performance of an automated pulmonary nodule detection program was evaluated on multi-detector row CT images that were acquired once but reconstructed retrospectively at different section thicknesses and reconstruction intervals. From raw CT data in 10 patients with pulmonary nodules, three sets of CT images were reconstructed separately in each patient by selecting two section thickness and reconstruction combinations, respectively: thin group, 1 and 1 mm; overlap group, 5 and 1 mm; and thick group, 5 and 5 mm. Nodules 3 mm in diameter and larger were detected in each group (thin group, 126 nodules; overlap group, 121 nodules; and thick group, 114 nodules) by means of consensus of two radiologists. Findings were used as the reference standard for evaluation of the computer-aided detection (CAD) program. Sensitivity and number of false-positive findings per patient by CAD were: thin group, 95.2% (120 of 126 nodules) and 5.4 findings; overlap group, 94.2% (114 of 121 nodules) and 9.7 findings; and thick group, 88.6% (101 of 114 nodules) and 23.6 findings, indicating that nodule detection degraded with increase in section thickness but improved substantially with a small reconstruction interval.     

Internal rotation angle measurement of the elbow with 3D reformatted CT image

The examination of internal rotation angle at the elbow is difficult on conventional radiographs. The angle of internal rotation has been measured with three dimensional reformatted CT image of GE CT/T9800. The angle of internal rotation with the cubitus varus deformity was measured both preoperatively and postoperatively. Postoperatively the angle of internal rotation became equal on both sides. Three dimensional CT reconstruction is useful in determining the internal rotation angle of elbow.     

岩矢角的CT测定在岩锥X线摄影中的应用

目的评价CT测定头颅指数与岩矢角的动态关系在颞骨岩部X线摄影中的应用价值。方法选择无畸形的正常头颅1000例,在其CT平扫所得骨窗像中应用CT的功能测量岩锥角及头颅的最大前后径与横径,计算出修正的头颅指数,寻求二者之间的动态关系。结果成年男性头颅最大前后径在166mm～195mm之间,最大横径在140mm～163mm之间。头颅指数在76%～93%之间。岩矢角最大范围为51°～66°,其中短头型者平均在58～61之间,中头型者平均在54°～56°之间。成年女性头颅最大前后径在164mm～187mm之间,最大横径在130mm～153mm之间。头颅指数在75%～86%,岩矢角最大范围为51°～66°,其中短头型者平均在55°～57°之间,中头型者平均在53°～54°之间。结论通过CT测量可以方便、精确地计算岩矢角的大小,对于头颅复杂部位的特殊摄影,提高耳部及岩骨等病变的影像诊断具有较高的价值。     

锥形束CT测量牙龈厚度准确性的初步研究

目的评价锥形束CT(CBCT)法测量牙龈厚度的可信度及准确性。方法选择20例牙龈健康者的120颗上颌前牙,采用CBCT法和牙龈穿刺法测量唇侧中央龈缘下2mm处牙龈厚度,比较两组差异并用Kappa系数评价两种方法的一致性;应用Kappa系数评价不同检查者用CBCT法测量牙龈厚度的一致性,以及组内相关系数ICC评价同一检查者重复测量数据的可信度。结果CBCT法测量牙龈厚度为(1.23±0.27)mm,牙龈穿刺法测量结果为(1.24±0.26)mm,差异无统计学意义(P>0.05),两组之间一致率为83.33%(Kappa=0.547)。不同的检查者CBCT法测量牙龈厚度的一致性检验Kappa系数为0.814,可信度良好(ICC=0.795),同一检查者CBCT法重复测量数据之间一致性检验Kappa系数为0.864,可信度良好(ICC=0.893);CBCT法对厚牙龈生物型具有高的灵敏度(92.05%)和低的特异度(59.38%)。结论CBCT测量牙龈厚度的结果与牙龈穿刺法的结果较一致,具有良好的可信度。     

Pulmonary emphysema: radiation dose and section thickness at multidetector CT quantification--comparison with macroscopic and microscopic morphometry

PURPOSE: To prospectively investigate the effects of radiation dose and section thickness on quantitative multidetector computed tomographic (CT) indexes of pulmonary emphysema. MATERIALS AND METHODS: The institutional review board approved this protocol. Written informed consent was obtained from all patients. Seventy patients (49 men, 21 women; age range, 38-79 years) referred for surgical resection of a lung tumor underwent multidetector CT with 4 x 1-mm collimation, 120 kVp, and 20 and 120 effective mAs. At each radiation dose, 1.25-, 5.0-, and 10.0-mm-thick sections were reconstructed at 10-mm intervals. From scans of the lobe or whole lung to be resected, relative areas (RAs) of lung with attenuation coefficients lower than nine thresholds and eight percentiles of the distribution of attenuation coefficients were compared with the histopathologic extent of emphysema, which was measured microscopically--by using the corrected mean interwall distance (MIWD) and the corrected mean perimeter (MP)--and macroscopically. Correlations between the data obtained by using attenuation thresholds and percentiles and the parameters macroscopic extent of emphysema, MIWD, and MP were investigated by using Spearman coefficients. RESULTS: The 1st percentile (r range, -0.394 to -0.675; P < .001) and attenuation coefficients of -980, -970, and -960 HU (r range, 0.478-0.664; P < .001) yielded the strongest correlations with macroscopic extent, MIWD, and MP, regardless of radiation dose or section thickness. The effects of radiation dose and section thickness on RAs of lung with attenuation coefficients lower than -960 HU (P = .007 and P < .001, respectively) and lower than -970 HU (P = .001 and P < .001, respectively) were significant. The effect of section thickness on the 1st percentile was significant (P < .001), whereas the effect of dose was not (P = .910). CONCLUSION: At CT quantification of pulmonary emphysema, the tube current-time product can be reduced to 20 mAs, but both tube current-time product and section thickness should be kept constant in follow-up examinations.