Multidetector row CT pulmonary angiography and indirect venography for the diagnosis of venous thromboembolic disease in intensive care unit patients

RATIONALE AND OBJECTIVES: To determine the diagnostic quality, performance characteristics and interreader reliability of computed tomography pulmonary angiography (CTPA) and venography (CTV) in intensive care unit (ICU) patients with suspected venous thromboembolism (VTE). MATERIALS AND METHODS: A total of 100 consecutive ICU patient CT examinations performed for clinically suspected VTE on a four-row CT scanner were reviewed. Three readers rated the diagnostic quality of each CTPA and CTV examination as excellent, acceptable, or nondiagnostic. Readers scored the overall determination for pulmonary embolism (PE) and deep venous thrombosis (DVT) using a 5-point scale, and scored the determination for PE by anatomic level. Receiver operator characteristic (ROC) analysis was performed for each reader and the original clinical report, using consensus interpretation as the reference standard. Interobserver variability for PE and DVT was determined using kappa analysis, and was stratified by examination quality. RESULTS: A total of 25% of CTPA examinations were nondiagnostic, most commonly because of motion artifact and poor contrast opacification. A total of 24% of CTV examinations were nondiagnostic, most commonly because of poor contrast opacification and metallic hardware. Using receiver operating characteristic analysis, the areas under the curve (Az) for PE diagnosis were 0.875, 0.923, 0.888, and 0.674 for the three readers and clinical reading, respectively, and for DVT diagnosis were 0.842, 0.859, 0.952 and 0.669. Interobserver agreement for detection of PE was moderate at the supralobar level (kappa = 0.55), very good at the lobar level (kappa = 0.69), and moderate for segmental (kappa = 0.54) and subsegmental arteries (kappa = 0.44). Overall reader agreement was good for excellent/good quality CTPA examinations (kappa = 0.52-0.56), and poor when examination quality was poor (kappa = 0.06). CONCLUSIONS: CTPA and CTV are sufficiently accurate and reliable techniques for evaluating VTE in ICU patients, particularly in light of patient complexity.     

Reproducibility of multi-detector spiral computed tomography in detection of sub-segmental acute pulmonary embolism

The aim of this study was to evaluate the inter-observer and intra-observer agreement of the diagnosis of sub-segmental acute pulmonary embolism (PE) in an inpatient population explored by 16 slice multi-detector spiral computed tomography (MDCT). Four hundred consecutive inpatients were referred for MDCT for the clinical suspicion of acute PE. One hundred and seventy seven (44.2%) had a known cardio-respiratory disease at the time of examination. Inter-observer and intra-observer agreements for the diagnosis of acute PE and of sub-segmental acute PE were assessed blind and independently by three experienced readers and by kappa statistics. Seventy-five patients were diagnosed as having acute PE findings (19.5%), and clots were located exclusively within sub-segmental arteries in nine patients (12%). When clots were limited to sub-segmental or more distal branches of the pulmonary arteries, kappa values were found to be moderate (0.56) to very good (0.85) for the diagnosis of sub-segmental acute PE, whereas for the diagnosis of acute PE in the whole population, kappa values ranged from 0.84 to 0.97. Intra-observer agreement was found to be perfect (kappa=1). MDCT is a reproducible technique for the diagnosis of sub-segmental acute PE as well as for acute PE. In this inpatient population, sub-segmental acute PE was not a rare event.     

Inter-observer variation in the interpretation of chest radiographs for pneumonia in community-acquired lower respiratory tract infections

AIM: To assess inter-observer variation in the interpretation of chest radiographs of individuals with pneumonia versus those without pneumonia. MATERIALS AND METHODS: Chest radiographs of out-patients with a lower respiratory tract infection (LRTI) were assessed for the presence of infiltrates by radiologists from three local hospitals and were reassessed by one university hospital radiologist. Various measures of inter-observer agreement were calculated. RESULTS: The observed proportional agreement was 218 in 243 patients (89.7%). Kappa was 0.53 (moderate agreement) with a 95% confidence interval of 0.37 to 0.69. The observed positive agreement (59%) was much lower than for negative agreement (94%). Kappa was considerably lower, if chronic obstructive pulmonary disease was present (kappa = 0.20) or Streptococcus pneumoniae (kappa = -0.29) was the infective agent. CONCLUSION: The overall inter-observer agreement adjusted for chance was moderate. Inter-observer agreement in cases with pneumonia was much worse than the agreement in negative (i.e. non-pneumonia) cases. A general practitioner's selection of patients with a higher chance of having pneumonia for chest radiography would thus not improve the observer agreement.     

Electrocardiographically gated multi-detector row CT for assessment of valvular morphology and calcification in aortic stenosis

PURPOSE: To evaluate the applicability and image quality of nonenhanced and contrast material-enhanced multi-detector row computed tomography (CT) combined with retrospective electrocardiographic (ECG) gating for visualization of the aortic valve, determination of aortic valve morphology and diameter of the aortic valve annulus, and assessment of the degree of valvular calcification in patients with aortic valve stenosis, as compared with results of surgery and echocardiography. MATERIALS AND METHODS: Prior to surgical valve replacement, 25 patients with aortic valve stenosis and sinus rhythm underwent nonenhanced (n = 15) and contrast-enhanced (n = 25) retrospectively ECG-gated multi-detector row CT. Two readers working in consensus evaluated image quality and assessed valvular morphology and the degree of valvular calcification. In addition, the diameter of the aortic valve annulus was measured. Results were compared with surgical and echocardiographic findings by using the paired sign test, kappa statistics, and the method of Bland and Altman. RESULTS: The aortic valve could be visualized nearly free of motion artifacts on all multi-detector row CT images. Image quality and diagnostic confidence for classification of aortic valve morphology were significantly superior on contrast-enhanced rather than nonenhanced images (P =.004 and P =.006, respectively). Nonenhanced and contrast-enhanced CT showed good agreement with surgical findings with regard to quantification of the degree of aortic valve calcification (kappa = 0.77 and kappa = 0.74, respectively). Measurement of the diameter of the aortic valve annulus was more reliable on contrast-enhanced images. CONCLUSION: Contrast-enhanced retrospectively ECG-gated multi-detector row CT allows determination of aortic valve morphology, measurement of the diameter of the aortic valve annulus, and assessment of the degree of aortic valve calcification in patients with aortic stenosis.     

Thoracic cardiovascular imaging with 16-row multislice Computed Tomography and retrospective ECG-gating. Technical note

PURPOSE: To apply the retrospective ECG-gating to the 16-row MSCT scan of intrathoracic vessels. MATERIALS AND METHODS: Fourty-eight patients underwent MSCT with a new 16-row scanner (Sensation 16-Siemens) for the study of the great intrathoracic vessels. In group 1 (33 patients) a retrospectively ECG-gated protocol was applied; in the control-group 2 (15 patients) a conventional MSCT protocol for thoracic imaging was applied. Images were scored regarding 1) the presence or absence of artefacts determined by breath-hold, beam hardening and mis-triggering; 2) the visualisation (optimal, mild and poor) of great intrathoracic vessels (aorta, pulmonary arteries and veins); 3) the visualisation (presence or absence) of proximal, mid and distal coronary arteries (left main, left anterior descending, circumflex, and right coronary artery). RESULTS: Ascending aorta showed motion artefacts in 3 (20%) cases in group 2 and none in group 1. In group 1, proximal LAD, CX, and RCA were assessable in 94%, 91%, and 91%, respectively. Left main coronary artery was assessable in 32 (97%) and 10 (67%) cases for group 1 and 2, respectively. In group 2, proximal segments of left anterior descending (LAD), circumflex (CX), and right coronary artery (RCA), were almost not assessable. CONCLUSIONS: The retrospectively ECG-gated 16-row MSCT provides more information regarding ascending aorta and coronary arteries.     

Electrocardiographic assistance in multidetector CT of thoracic disorders

ECG-synchronized multislice spiral CT (MSCT) allows a significant reduction of cardiac motion artefacts and as a result a virtually artefact-free display of intrathoracic structures. With their advantages in imaging geometry and continuous spiral image acquisition multislice CT scanners provide superior image quality and spatial resolution in these patients. Possible clinical applications for ECG assistance in MSCT include CT angiography of the coronary arteries, functional cardiac CT imaging and imaging of the cardiac valves, CT angiography of the aorta or pulmonary vascular tree as well as ECG-gated imaging of the lung parenchyma. Prospective ECG triggering and retrospectively ECG-gated image reconstruction comprise the technical corsage for reduction of pulsation artefacts in cardiac and other thoracic CT applications. In addition the development of time-optimised reconstruction algorithms for retrospective cardiac gating in 8- and 16 slice spiral CT scanners have enabled further improvements in temporal resolution. This overview describes the technique, its clinical indications and the merits of electrocardiographic assistance in MSCT of chest disorders.     

Visual assessment of left ventricular perfusion and function with electrocardiography-gated SPECT has high intraobserver and interobserver reproducibility among experienced nuclear cardiologists and cardiology trainees

BACKGROUND: Stress electrocardiography (ECG)-gated single photon emission computed tomography (SPECT) for assessment of left ventricular perfusion and function improves the confidence of interpretation and enhances specificity for detection of coronary artery disease. The reproducibility of visual interpretation of ECG-gated SPECT images and the significance of training and experience have not been reported previously in a large series of consecutive patients. We evaluated both intraobserver and interobserver agreement of interpretation of ECG-gated SPECT images among 3 cardiology trainees and 3 experienced nuclear cardiologists from 3 institutions. METHODS AND RESULTS: Three nuclear cardiologists and 3 cardiology trainees who had fulfilled American College of Cardiology/American Society of Nuclear Cardiology Core Cardiology Training Symposium (ACC/ASNC COCATS) guidelines for level II training in nuclear cardiology independently evaluated 106 consecutive technetium 99m sestamibi SPECT images with ECG gating of either the stress or rest images. All cases were interpreted blindly, twice in random sequence, without clinical data. We assessed intraobserver and interobserver agreement for myocardial perfusion, left ventricular regional and global systolic function, and overall clinical impression, by means of percent agreement and Cohen's kappa statistic. Intraobserver agreement was good (82%-92%, kappa = 0.54-0.84) for assessment of myocardial perfusion, systolic function, and overall impression. Interobserver agreement was also good, ranging from 65% to 90% (kappa = 0.32-0.76), with better agreement found for assessment of function (77%-85%, kappa = 0.52-0.7) than for perfusion (65%-80%, kappa = 0.32-0.6). For all measures, there were no significant differences in reproducibility between nuclear cardiologists and cardiology trainees. CONCLUSIONS: Interpretation of ECG-gated SPECT images has high reproducibility and agreement among both nuclear cardiologists and cardiology trainees.     

Does multi-detector row CT pulmonary angiography reduce the incremental value of indirect CT venography compared with single-detector row CT pulmonary angiography?

PURPOSE: To compare retrospectively the incremental value of indirect computed tomographic (CT) venography performed after multi-detector row CT pulmonary angiography and single-detector row CT pulmonary angiography for the diagnosis of venous thromboembolism (VTE). MATERIALS AND METHODS: The institutional ethics committee approved this study; informed consent was not required. The authors retrospectively reviewed results of 1100 combined single-detector row CT pulmonary angiographic and indirect CT venographic examinations (542 men, 558 women; mean age, 61 years +/- 17 [standard deviation]) (group 1) and 308 combined multi-detector row CT pulmonary angiographic and indirect CT venographic examinations (150 men, 158 women; mean age, 62 years +/- 18) (group 2), performed in 1408 patients suspected of having pulmonary embolism (PE). Frequency of deep venous thrombosis (DVT), PE, and VTE, and the incremental value of indirect CT venography were recorded in both groups. Data were compared by means of the Student t test for continuous data and z statistics for independent proportions. RESULTS: VTE, PE, and DVT were found in 23.3% (n = 256), 19.9% (n = 219), and 18.3% (n = 201) of the 1100 patients in group 1, respectively, and in 23.7% (n = 73), 17.2% (n = 53), and 18.8% (n = 58) of the 308 patients in group 2, respectively (P values ranging from .273 to .876). The incremental value of indirect CT venography was 14.4% (37 of 256 patients) in group 1 and 27.4% (20 of 73 patients) in group 2. CONCLUSION: Despite potential improved accuracy of multi-detector row CT pulmonary angiography for the diagnosis of PE, the addition of indirect CT venography increased the diagnosis of VTE in 27.4% of patients.     

Perfusion abnormalities in pulmonary embolism studied with perfusion MRI and ventilation-perfusion scintigraphy: an intra-modality and inter-modality agreement study

PURPOSE: To compare perfusion magnetic resonance imaging (MRI) and ventilation-perfusion scintigraphy (V-P scan) in the study of perfusion abnormalities in pulmonary embolism (PE) and to compare the PE results to the findings previously reported for pneumonia and chronic obstructive pulmonary disease (COPD), in terms of perfusion abnormalities. MATERIALS AND METHODS: Dynamic contrast-enhanced MR images and V-P scans of 20 patients with PE, 11 patients with acute pneumonia, and 13 patients with exacerbation of COPD were studied. Five categories of perfusion abnormalities within each imaging modality were defined. Intra- and inter-modality agreement (kappa values) in the evaluation of perfusion abnormalities were calculated, based on the two observers of each imaging modality (all blinded to each other and true diagnosis). Finally, three categories of perfusion MRI diagnosis (PE, pneumonia, and COPD) were also defined and the inter-observer agreement (kappa value) was calculated. RESULTS: For PE, the intra-modality agreement (kappa value) in the evaluation of perfusion abnormalities was 0.77 for MRI and 0.65 for V-P scan. The inter-modality agreement varied from 0.52 to 0.57, respectively, and was observer-dependent. For the pooled group of PE, pneumonia, and COPD, the intra-modality agreement of perfusion abnormalities was 0.76 for MRI and 0.65 for V-P scan, and the inter-modality agreement varied from 0.51 to 0.56. The kappa value for inter-observer agreement for MRI diagnosis was 0.92. CONCLUSION: Evaluation of perfusion abnormalities in PE, pneumonia, and COPD using perfusion MRI and V-P scan showed a high intra-modality agreement that was higher than the inter-modality agreement. Further studies are now needed in patients presenting with possible PE to evaluate the sensitivity and specificity of the method.     

心率对256层CT前瞻性心电门控冠状动脉成像质量的影响

目的：探讨心率对256层螺旋CT前瞻性心电门控冠状动脉成像质量的影响,并与回顾性心电门控进行对照分析。方法：156例患者行前瞻性心电门控冠状动脉检查,73例行回顾性心电门控冠状动脉检查,所有病例按心率分为＜60次/分,60～69次/分,70～79次/分,80～89次/分,90～99次/分及≥100次/分共6组。对所有冠...     

前瞻性心电门控技术在CT肺动脉血管成像中的应用

目的：研究256层螺旋CT前瞻性心电门控技术在肺动脉血管成像（CTPA）中的应用价值。方法：连续选取本院使用Philips 256层螺旋CT行CTPA检查的患者资料90例,利用完全随机设计每组30例分为3组：①非心电门控螺旋扫描组（简称非门控组）;②前瞻性心电门控组（简称前瞻组）;③回顾性心电门控组（简称回顾组）。记录各组患者年龄、性别、心率、扫描时间、扫描范围、容积CT剂量指数（CTDIvol）、剂量长度乘积（DLP）,根据公式计算出有效放射剂量（ED）。由3位有经验的放射科医生以双盲法对肺动脉图像质量进行评分,并评价在扫描范围内的冠状动脉运动伪影。结果：三组95.6%（86/90）的病例评分≥3分。图像质量评分、冠状动脉运动伪影出现率、扫描时间、辐射剂量差异有显著性意义。图像评分：前瞻组明显优于非门控组,与回顾组相近;冠状动脉运动伪影出现率：三组分别为88.1%、21.5%和15.9%,前瞻组和回顾组明显低于非门控组;辐射剂量：前瞻组和非门控组的辐射剂量分别为（7.59±0.87）和（7.49±0.80）mSv,两者差异无显著性意义,明显低于回顾组辐射剂量[（18.96±1.60）mSv];扫描时间：前瞻组平均扫描时间为（8.66±0.86）s,比回顾组和非门控组分别增加1.0s和5.5s。不同心率患者前瞻性心电门控CTPA的图像质量评分差异无显著性意义。结论：应用256层螺旋CT前瞻性心电门控技术行CTPA检查是一种可行方法,在不增加患者辐射剂量的前提下,明显改善肺动脉图像质量。     

Differentiation of intraductal papillary mucinous neoplasms from other pancreatic cystic masses: comparison of multirow-detector CT and MR imaging using ROC analysis

PURPOSE: To compare the diagnostic performance of multirow-detector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the differentiation of intraductal papillary mucinous neoplasms (IPMNs) from other pancreatic cystic masses. MATERIALS AND METHODS: A total of 53 patients with pathologically proven pancreatic cystic lesions who had undergone MDCT and MRI were included in this study. Two radiologists analyzed the morphologic features of the lesions and graded the lesion conspicuity on each examination. The readers assigned their confidence level regarding the differentiation of IPMN from other lesions and predicting ductal communication of the lesion. The radiologists' diagnostic confidence was compared using receiver operating characteristic (ROC) analysis. RESULTS: The Az values for each observer for predicting ductal communication of the lesion and differentiating IPMN from other lesions were as follows: For MRI they were respectively 0.949 and 0.995 for reader 1, and 0.916 and 0.932 for reader 2. For MDCT they were respectively 0.790 and 0.875 for reader 1, and 0.774 and 0.850 for reader 2. In addition, for differentiating IPMNs from other lesions, MRI was significantly more accurate than MDCT (P < 0.05) for one observer, but for the other observer there was no significant difference between the two examinations (P = 0.059). For predicting ductal communication of the cystic lesions for both observers, MRI was significantly more accurate than MDCT (P < 0.05). The weighted kappa values indicate good agreement (kappa = 0.61) between observers for MDCT, and excellent agreement (kappa = 0.82) for MRI. CONCLUSION: Pancreatic MRI shows better diagnostic performance than MDCT for differentiating IPMNs from other cystic lesions of the pancreas.     

Comparison of artifacts on coronal reformation and axial CT pulmonary angiography images using single-detector and 4- and 8-detector multidetector-row helical CT scanners

RATIONALE AND OBJECTIVES: The aim of this study is to compare the degree of stair-step artifact on coronal reformation computed tomographic (CT) pulmonary angiography images obtained using single-detector helical CT (SDCT), four-detector (4-MDCT), and eight-detector multidetector-row CT (8-MDCT) and compare the degree of motion artifact on the corresponding axial CT images. MATERIALS AND METHODS: Three groups of consecutive patients imaged by means of CT angiography for suspected pulmonary embolus were retrospectively identified by using CT records at our institution: (1) group A (n = 38), SDCT; (2) group B (n = 36), 4-MDCT; and (3) group C (n = 74), 8-MDCT. For each case, coronal multiplanar volume reformation maximal intensity projection images were created by using a standard technique. All images were reviewed in a randomized fashion by two thoracic radiologists who were blinded to the type of CT scanner. Stair-step artifact of pulmonary arteries on coronal reformation images was graded by consensus agreement using a four-point scale (0 = no artifact to 3 = severe artifact). Axial images were assessed for six parameters of motion artifact. The sum of these grades resulted in a total motion score, with a potential range of 0 (no motion) to 12 (severe motion). Statistical analysis was performed using the Mann-Whitney test. RESULTS: Stair-step artifacts were significantly higher for SDCT (mean, 2.9; median, 3) compared with 4-MDCT (mean, 2.2; median, 2; P < .0001) and 8-MDCT (mean, 1.5; median, 1; P < .0001). Total motion scores were significantly higher for SDCT (mean, 9.3) compared with 4-MDCT (mean, 8.4; P = .03) and 8-MDCT (mean, 6.8; P < .0001). CONCLUSION: Stair-step artifacts are significantly higher with SDCT compared with MDCT. For MDCT, eight-detector scanners produce images with significantly less artifact than four-detector scanners.     

Deep vein thrombosis of the upper extremity: intra- and interobserver study of digital subtraction venography

Our objective was to assess the inter-observer and intra-observer agreement in the interpretation of digital subtraction venography (DSV) in patients with suspected deep vein thrombosis of the upper extremity (DVTUE). Prospectively, 62 consecutive DSV studies in 54 patients with clinically suspected DVTUE were included. Hard copies were presented without demographic data or original report. All venograms were read twice, at 3-month intervals, by an interventional vascular radiologist (observer 1) and an experienced general radiologist (observer 2). Consensus reading took place in the presence of a third experienced interventional radiologist. Inter-observer and intra-observer agreement were assessed using kappa statistics. Initial reading in 62 venograms showed an inter-observer agreement of 71% (kappa 0.48). The inter-observer agreement of the second reading was 83% (kappa 0.71). The agreement with the consensus report ranged from 76 to 94%. The intra-observer agreement for the first and second observer was 94% (kappa 0.89) and 76% (kappa 0.56), respectively (p<0.01). Digital subtraction venography has moderate to excellent intra- and inter-observer agreement, suggesting that digital subtraction venography is reliable for the diagnosis of DVTUE. Electronic Publication     

二代双源CT对冠状动脉支架的显示及辐射剂量的研究

目的 对比分析二代双源CT前瞻性心电触发高螺距螺旋扫描模式(Flash模式)和回顾性心电门控螺旋扫描模式(常规模式)下冠状动脉支架的显示质量和辐射剂量.方法 常规模式和Flash模式下共计120例患者的155个冠状动脉植入支架纳入本研究,平均年龄(64.9±10.6)岁,所有患者的心率均控制在≤65次/min,且心律规则.所有患者分成两组,分别接受Flash模式和常规模式的冠状动脉成像.冠状动脉原始图像均进行Kernel B26和Kernel B46的数据重建,并由两位医师对支架的显示质量进行独立的4级评分.两种模式下的冠状动脉显示质量利用卡方检验进行统计分析,而不同冠状动脉扫描模式下的容积CT剂量指数值(CTDIvol)和剂量长度乘积值(DLP),利用t检验进行辐射剂量的对比研究.结果 2位医师对所有冠状动脉支架显示质量的评分具有较好的一致性(Kappa=0.764,P＜0.001),Flash模式和常规模式的平均评分分别为:1.61±0.77和1.65±0.82.两种冠状动脉扫描模式的图像质量差异无统计学意义(x2=0.865,P=0.834).Flash模式的CTDIvol(3.24±1.21)明显低于常规模式(31.26±10.79),差异有统计学意义(t=19.83,P<0.001);Flash模式的DLP(54.61±19.88)同样低于常规模式(468.30±174.88),差异有统计学意义(t=18.06,P＜0.001).结论 控制患者心率≤65次/min且心律规则,Flash模式在降低辐射剂量的前提下可获得与常规模式相同质量的冠状动脉支架图像.

Abstract：

Objective To compare a prospective ECG-gated high-pitch spiral technique (Flash) and conventional retrospective ECG-gated spiral technique for the image quality of coronary artery stent and radiation dose with a dual source CT.Methods One hundred and fifty five coronary stents in one hundred and twenty patients (mean age 64.9 ± 10.6 years,heart rates≤65 bpm) were examined using a dual source CT.All patients were divided in two groups,receiving either Flash or conventional coronary artery CT angiography separately.After images of coronary artery were reconstructed using both the smooth (B26) and sharp (B46) kernel,the coronary stent image quality and stent lumen were scored by two observers individually using four point scale (1 = excellent,4 = unvaluable) .The effective radiation dose of volume CT dose index (CTDIvol,mGy) and dose length product (DLP,mGy x cm) were also calculated for each patient.x2-test analysis of image quality and t-test analysis of radiation dose were used respectively for statistical difference between two groups.Results Interobserver agreement for stent image quality was good (Kappa =0.764,P＜0.001).The mean scores were 1.61 ±0.77 and 1.65 ±0.82 in Flash group and conventional group respectively.There was no significant difference in image quality between the two groups (x2 = 0.865,P = 0.834).The effective radiation dose in Flash group was significantly lower than that in conventional group.The mean values of CTDIvol were 3.24 ± 1.21 in Flash group and 31.26 ± 10.79 in conventional group (t = 19.83,P < 0.001) ,and the mean values of DLP in Flash group and conventional group were 54.61 ±19.88 and 468.30 ± 174.88,respectively (t = 18.06,P < 0.001).Conclusions Compared with the conventiaonal coronary artery CT angiography,the Flash coronary artery CT angiography technique has a similar coronary stent image quality,but at a lower radiation dose in patients with heart rates lower than 65 beats per minute.     

A retrospectively ECG-gated multislice spiral CT scan and reconstruction technique with suppression of heart pulsation artifacts for cardio-thoracic imaging with extended volume coverage

A method for cardio-thoracic multislice spiral CT imaging with ECG gating for suppression of heart pulsation artifacts is introduced. The proposed technique offers extended volume coverage compared with standard ECG-gated spiral scan and reconstruction approaches for cardiac applications: Thin-slice data of the entire thorax can be acquired within one breath-hold period using a four-slice CT system. The extended volume coverage is enabled by a modified approach for ECG-gated image reconstruction. For a CT system with 0.5-s gantry rotation time, images are reconstructed with 250-ms image temporal resolution. Instead of selecting scan data acquired in exactly the same phase of the cardiac cycle for each image as in standard ECG-gated reconstruction techniques, the patient's ECG signal is used to omit scan data acquired during the systolic phase of highest cardiac motion. With this approach cardiac pulsation artifacts in CT studies of the aorta, of paracardiac lung segments, and of coronary bypass grafts can be effectively reduced.     

MDCT in emergency radiology: is a standardized chest or abdominal protocol sufficient for evaluation of thoracic and lumbar spine trauma?

OBJECTIVE: The objective of our study was to assess the diagnostic performance of a standardized 4-MDCT trauma protocol for the evaluation of the thoracic and lumbar spine in patients with multiple injuries. MATERIALS AND METHODS: Eighty-two patients with multiple injuries underwent MDCT for the chest and abdomen using a standardized 4-MDCT trauma protocol (collimation, 4 x 2.5 mm). Secondary reconstructions targeted to the spine were performed (slice width, 3 mm; reconstruction interval, 1.5 mm). All spinal fractures were additionally scanned using a collimation of 4 x 1 mm, and these images served as the standard of reference for fracture classification. An additional 50 patients with no spinal fracture served as the control group. A total of 65 major spinal fractures were present in 55 of the patients with multiple injuries. Two observers (observer 1 and observer 2) independently evaluated all CT data for spinal fractures using a 5-point confidence scale, classified the different fracture types, and rated the image quality of spinal structures on axial images and multiplanar reformations. RESULTS: Image quality for axial images was excellent in 80% and in 68% using 4 x 1 mm and 4 x 2.5 mm collimation, respectively. Image quality of the multiplanar reformations was excellent in 75% and good in 65% using 4 x 1 mm and 4 x 2.5 mm collimation, respectively. Spinal fractures were detected by observer 1 and observer 2 with a sensitivity and specificity of 98% and 97% and of 97% and 97%, respectively. Interobserver agreement regarding the confidence scale for fracture detection was substantial (kappa = 0.80), and agreement between the different imaging protocols for fracture classification was excellent for observer 1 (kappa = 0.95) and observer 2 (kappa = 0.97). CONCLUSION: Accurate evaluation of the thoracolumbar spine is possible with targeted image reconstruction based on a standardized 4-MDCT trauma protocol of the chest and abdomen.     

Negative spiral CT in acute pulmonary embolism

PURPOSE: To retrospectively evaluate the clinical outcome of non-anticoagulated patients with clinically suspected acute pulmonary embolism (PE) and no symptoms or signs of deep venous thrombosis (DVT) following a negative contrast medium-enhanced spiral CT of the pulmonary arteries (s-CTPA). MATERIAL AND METHODS: During a 24-month period, 739 of 751 patients underwent s-CTPA with acceptable diagnostic quality for clinically suspected acute PE. All patients who had a CT study not positive for PE were followed up with a questionnaire, a telephone interview and review of all medical reports, including autopsies and death certificates for any episodes of venous thromboembolism (VTE) during a 3-month period. RESULTS: PE was diagnosed in 158 patients. Of the remaining 581 patients with a negative s-CTPA, 45 patients were lost to follow-up. 88 patients were excluded because of anticoagulation treatment (cardiac disorder n=32, chronic VTE or acute symptomatic DVT n=31, PE diagnosed at pulmonary angiography n=1, thrombus prophylaxis during diagnostic work-up or other reasons than VTE n=24) and 7 patients undergoing lower extremity venous studies because of symptoms of DVT (all negative). Thus, 441 patients with a negative s-CTPA and no DVT symptoms, venous studies or anticoagulant treatment constituted the follow-up cohort. Four of these patients had proven VTE (all PE) during the 3-month follow-up period. Two of the PE episodes contributed to the patient's death. CONCLUSION: Patients with clinically suspected acute PE, no symptoms or signs of DVT and a negative single slice s-CTPA using 3-5 mm collimation, may safely be left without anticoagulation treatment unless they are critically ill, have a limited cardiopulmonary reserve and/or if a high clinical suspicion remains.     

自适应迭代重建技术对儿童低剂量胸部CT图像质量的优化

目的比较应用自适应迭代重建技术（adaptive statistical iterative reconstruction,ASIR）儿童低剂量胸部CT与传统的滤过反向投影（filteredbackprojection,FBP）的图像质量、噪声和放射剂量。方法回顾性分析80例应用自动管电流调节技术（ATCM）扫描的胸部CT检查作为试验组,年龄29天～16岁（中位年龄3．3岁）,检查时根据年龄分为4组,o～12月预设噪声指数11HU,1～3岁预设噪声指数13HU,4～6岁预设噪声指数15Hu,7～17岁预设噪声指数17HU,将所有图像经ASIR30％重建;对照组选取同时期80例经ATCM扫描的儿童胸部CT检查,1～7岁预设噪声指数8HU,7～17岁预设噪声指数12HU,未经ASIR技术重建图像。测量所有病例左心室及同层面图像的背部肌肉客观噪声值,由两位医师分别用5分制主观评价图像质量和噪声程度,并用kappa检验评价观察者间的一致性。同时记录CT剂量指数（CTDIv01）及剂量长度乘积（DLP）。结果试验组客观噪声平均值为10．49±1．65,对照组客观噪声9．16±1．52,无统计学差异,同时,试验组和对照组的主观图像质量接受率为3．90和3．98,所有图像合乎诊断要求,观察者间的评估具有一致性（k=0．64）;试验组和对照组间的CTDIv01分别为（1.19±0．78）mGy和（2．62±0．93）mGy,试验组CT-DIvol比对照组降低了54．6％,两者间差异明显（Pd0．001）。结论应用ASIR技术可获得稳定图像质量,满足诊断的前提下,可以能进一步有效减低射线剂量。     

Detection of significant coronary artery stenosis with 64-section MDCT angiography

PURPOSE: To prospectively evaluate the diagnostic performance of 64-section multidetector computed tomography (MDCT) to detect significant coronary artery stenosis using conventional coronary angiography (CCA) as the reference standard. MATERIALS AND METHODS: Institutional Review Board approval and informed consent were obtained. In this prospective study, 80 patients (61 male, 19 female, mean age 56) were examined. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated. McNemar test was used to search for the significant difference between 64-section MDCT angiography and CCA to detect stenosis. Also, kappa index (kappa) for the agreement between MDCT angiography and CCA was calculated. RESULTS: The sensitivity, specificity, positive (PPV) and negative predictive values (NPV) for detecting significant stenosis were 96%, 98%, 91%, 99%, respectively. The sensitivity, specificity, PPV and NPV for classification of patients with or without CAD were 100% for all. McNemar test demonstrated no significant difference between 64-section MDCT angiography and CCA. Also, kappa index (kappa) indicated excellent agreement. CONCLUSION: Sixty-four section MDCT angiography is an effective diagnostic tool for the detection of significant coronary artery stenosis. Especially, the potential to differentiate patients with and without CAD may provide MDCT an important role in the prevention of unnecessary invasive diagnostic procedures.