Radiology resident interpretation of on-call CT pulmonary angiograms

RATIONALE AND OBJECTIVES: To evaluate the interpretation of computed tomographic pulmonary angiograms performed outside of regular reporting hours, comparing the initial interpretation by the radiology resident to the attending radiologist. MATERIALS AND METHODS: Records for 840 consecutive computed tomographic pulmonary angiograms (CTPA) performed outside of regular reporting hours at two tertiary referral centers from January 1, 2004-December 31, 2005 were reviewed. The preliminary interpretation by the on-call radiology resident was compared to the subsequent final report issued by a subspecialty trained chest radiologist. Studies were stratified as positive, negative, or equivocal for pulmonary embolus. Cases with discordant interpretations or negative CTPA were reviewed to determine impact on clinical outcome. Patients were followed up to 12 months after CTPA to document any subsequent thromboembolic event. RESULTS: Sixteen percent (131/840) of CTPAs were reported positive by the staff radiologist. There was agreement in 90% (752/840) of studies (P = .76, 95% confidence interval, 0.71-0.81) with 86% (114/133) agreement for studies interpreted as positive by residents, 95% (582/612) for studies interpreted as negative by residents, and 63% (60/95) for studies interpreted as equivocal by residents. Studies of optimal quality had higher interobserver agreement than studies of suboptimal quality (P < .0001). In-patient studies were more likely to be positive than emergency room patients (20% vs. 13%) (P = .004). No adverse clinical outcomes were attributed to discordant interpretations. CONCLUSIONS: Radiology residents provide a high level interpretation of on-call CTPA studies, achieving good concordance with the attending radiologists' assessment.     

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.     

CT lower extremity venography in suspected pulmonary embolism in the ED

The purpose of this study was to evaluate the added benefit of computed tomography lower extremity venography (CTLV)—performed following CT pulmonary angiography (CTPA)—in the emergency department (ED) patient suspected of pulmonary embolism (PE). A retrospective review of 427 consecutive patients having both CTPA and CTLV performed to evaluate patients suspected of PE at two community hospitals was conducted. Three-month follow-up was performed on all patients to ensure that no case of PE or deep venous thrombosis (DVT) was missed. Forty patients were positive for PE, and 11 were positive for DVT. There were 6 CTPA studies read as indeterminate for PE and 11 CTLV studies indeterminate for DVT. Only 1 patient was positive for DVT, who did not have a concurrent PE identified by CTPA. The estimated charges for detecting the single case of isolated DVT was US $206,400. In our ED setting, the additional benefit of adding CTLV to the standard ED work-up of PE was minimal.     

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.     

CT venography vs ultrasound in the diagnosis of thromboembolic disease in patients with clinical suspicion of pulmonary embolism

To assess the reliability of indirect computed tomography venography (CTV) in the detection of deep venous thrombosis (DVT) in patients with clinical suspicion of pulmonary embolism (PE). 235 consecutive patients with suspicion of PE underwent an imaging protocol composed of a CT pulmonary angiography (CTPA), a CTV and an ultrasound study of the deep venous system, which was considered the “gold standard.” Sensitivity, specificity, and predictive values were calculated for CTV. ith CTV, 30 (12.8%) cases of DVT were detected, 9 (3.8%) of them without pulmonary embolism in CTPA, increasing the diagnosis of thromboembolic disease in 3.8%. However, six of these nine diagnoses were false positives, and CTV missed six cases of DVT. CTV rendered a sensitivity of 58.8%, specificity of 95.0%, a positive predictive value of 66.7%, and a negative predictive value of 93.2%. In patients with clinical suspicion of pulmonary embolism, ultrasound is preferred to CTV for the detection of DVT.     

Venous thromboembolism: additional diagnostic value and radiation dose of pelvic CT venography in patients with suspected pulmonary embolism

Purpose

To assess the additional diagnostic value of indirect CT venography (CTV) of the pelvis and upper thighs performed after pulmonary CT angiography (CTA) for the diagnosis of venous thromboembolism (VTE).

Materials and methods

In a retrospective analysis, the radiology information system entries between January 2003 and December 2007 were searched for patients who received pulmonary CTA and additional CTV of the pelvis and upper thighs. Of those patients, the radiology reports were reviewed for the diagnosis of pulmonary embolism (PE) and deep venous thrombosis (DVT) in the pelvic veins and veins of the upper thighs. In cases with an isolated pelvic thrombosis at CTV (i.e. which only had a thrombosis in the pelvic veins but not in the veins of the upper thigh) ultrasound reports were reviewed for the presence of DVT of the legs. The estimated radiation dose was calculated for pulmonary CTA and for CTV of the pelvis.

Results

In the defined period 3670 patients were referred to our institution for exclusion of PE. Of those, 642 patients (353 men, 289 women; mean age, 65 ± 15 years, age range 18–98 years) underwent combined pulmonary CTA and CTV. Among them, PE was found in 227 patients (35.4%). In patients without PE CTV was negative in all cases. In patients with PE, CTV demonstrated pelvic thrombosis in 24 patients (3.7%) and thrombosis of the upper thighs in 43 patients (6.6%). Of those patients 14 (2.1%) had DVT in the pelvis and upper thighs. In 10 patients (1.5%) CTV showed an isolated pelvic thrombosis. Of those patients ultrasound reports were available in 7 patients, which revealed DVT of the leg veins in 5 cases (1%). Thus, the estimated prevalence of isolated pelvic thrombosis detected only by pelvic CTV ranges between 1–5/642 patients (0.1–0.7%). Radiation dose ranges between 4.8 and 9.7 mSv for additional CTV of the pelvis.

Conclusion

CTV of the pelvis performed after pulmonary CTA is of neglectable additional diagnostic value for the detection of VTE, because the additional radiation dose is high and isolated pelvic DVT is very rare. Venous imaging of the legs (preferably by radiation-free ultrasound) is sufficient for the diagnosis of underlying DVT in patients with suspected PE.     

Relation between lung perfusion defects and intravascular clots in acute pulmonary thromboembolism: assessment with breath-hold SPECT-CT pulmonary angiography fusion images

PURPOSE: The relation between lung perfusion defects and intravascular clots in acute pulmonary thromboembolism (PTE) was comprehensively assessed on deep-inspiratory breath-hold (DIBrH) perfusion SPECT-computed tomographic pulmonary angiography (CTPA) fusion images. MATERIALS AND METHODS: Subjects were 34 acute PTE patients, who had successfully performed DIBrH perfusion SPECT using a dual-headed SPECT and a respiratory tracking system. Automated DIBrH SPECT-CTPA fusion images were used to assess the relation between lung perfusion defects and intravascular clots detected by CTPA. RESULTS: DIBrH SPECT visualized 175 lobar/segmental or subsegmental defects in 34 patients, and CTPA visualized 61 intravascular clots at variable locations in 30 (88%) patients, but no clots in four (12%) patients. In 30 patients with clots, the fusion images confirmed that 69 (41%) perfusion defects (20 segmental, 45 subsegmental and 4 lobar defects) of total 166 defects were located in lung territories without clots, although the remaining 97 (58%) defects were located in lung territories with clots. Perfusion defect was absent in lung territories with clots (one lobar branch and three segmental branches) in four (12%) of these patients. In four patients without clots, nine perfusion defects including four segmental ones were present. CONCLUSION: Because of unexpected dissociation between intravascular clots and lung perfusion defects, the present fusion images will be a useful adjunct to CTPA in the diagnosis of acute PTE.     

Accuracy of CT angiography versus pulmonary angiography in the diagnosis of acute pulmonary embolism: evaluation of the literature with summary ROC curve analysis

RATIONALE AND OBJECTIVES: The authors performed this study to estimate, by using published data, the sensitivity and specificity of computed tomographic (CT) angiography in the evaluation of suspected acute pulmonary embolism (PE). MATERIALS AND METHODS: Summary receiver operating characteristic (ROC) curve analysis was used to determine the sensitivity and specificity of CT angiography in the diagnosis of acute PE. Pulmonary angiography was used as the diagnostic standard of reference. The authors reviewed the results of 11 independent studies published in the English-language literature between January 1992 and June 1999. RESULTS: The sensitivity of CT angiography in the diagnosis or exclusion of PE in the central pulmonary arteries (to the level of the segmental pulmonary arteries) ranged from 0.74 to 0.81 on the basis of specificities of 0.89-0.91. The sensitivity of CT angiography in the diagnosis or exclusion of PE in all pulmonary arteries (to the level of the subsegmental pulmonary arteries) was 0.68 on the basis of a specificity of 0.91. CONCLUSION: On the basis of the studies in the current literature, most of which used 5.0-mm collimation and single-detector CT, CT angiography may be less accurate in the diagnosis of PE than previously reported. With improvements in data acquisition, particularly the use of thinner section collimation and multidetector CT, and in the increased use of workstations for data analysis, the accuracy and utility of CT angiography will require continued investigation.     

Survey on the use of pulmonary scintigraphy, spiral CT and conventional pulmonary angiography for suspected pulmonary embolism in the British Isles

AIM: To determine current clinical practice in the radiological diagnosis of acute pulmonary embolism and assess the use of spiral volumetric computed tomography. METHOD: A survey of 327 acute hospitals including cardiothoracic and orthopaedic tertiary referral centres was undertaken to assess current utilization of lung scintigraphy, spiral computed tomography and pulmonary angiography in the investigation of suspected pulmonary embolism. Responses were received from 215/327 (66%) centres. RESULTS: Lung scintigraphy was provided by 208 hospitals (144 on-site and 64 off-site). Spiral CT services were provided by 111 (52%) hospitals (on- or off-site), 142 (66%) units had access to angiographic facilities. Sixty-three centres out of 215 (29%) offered both on-site lung scintigraphy and spiral CT while only 41/215 (19%) hospitals were able to undertake all three tests on-site. On average, 501 perfusion (Q) or ventilation-perfusion (V/Q) scintigrams were performed per hospital per year with 26 spiral CT studies and just 4.6 pulmonary angiograms. CONCLUSION: These data suggest that lung scintigraphy is frequently the only imaging test in patients other than chest radiography, despite the large number of indeterminate results reported in most series.     

CT pulmonary angiography is the first-line imaging test for acute pulmonary embolism: a survey of US clinicians

RATIONALE AND OBJECTIVES: Our aim is to document current imaging practices for diagnosing acute pulmonary embolism (PE) among physicians practicing in the United States and explore factors associated with these practices. MATERIALS AND METHODS: Between September 2004 and February 2005, we surveyed by mail 855 physicians selected at random from membership lists of three professional organizations. Physicians reported their imaging practices and experiences in managing patients with suspected acute PE during the preceding 12 months. RESULTS: Completed questionnaires were received from 240 of 806 eligible participants (29.8%) practicing in 44 states: 86.7% of respondents believed that computed tomographic pulmonary angiography (CTPA) was the most useful imaging procedure for patients with acute PE compared with 8.3% for ventilation-perfusion (V-P) scintigraphy and 2.5% for conventional pulminary angiography (PA). After chest radiography, CTPA was the first imaging test requested 71.4% of the time compared with V-P scintigraphy (19.7%) and lower-limb venous ultrasound (5.8%). Participants received indeterminate or inconclusive results 46.4% of the time for V-P scintigraphy, 10.6% of the time for CTPA, and 2.2% of the time for PA. CTPA was available around the clock to 88.3% of participants compared with 53.8% for V-P scintigraphy and 42.5% for PA. A total of 68.6% of respondents received CTPA results in 2 hours or less (vs 37.5% for V-P scintigraphy and 22.9% for PA). CTPA also provided an alternative diagnosis to PE or showed other significant abnormalities 28.5% of the time, and these findings frequently altered management. CONCLUSION: US clinicians unequivocally prefer CTPA in patients with suspected acute PE. Reasons for this preference include availability and timely reporting, a lower rate of inconclusive results, and the additional diagnostic capabilities that CTPA can provide.     

多层螺旋CT肺动脉造影联合静脉造影诊断深静脉血栓的研究

目的应用16层螺旋CT肺动脉造影联合静脉造影(CTVPA)探讨深静脉血栓发生率及部位,并与下肢彩色超声多普勒对照评价其诊断下肢深静脉血栓(DVT)的价值。方法临床怀疑肺栓塞(PE)的147例病人行CTVPA检查,以病人为单位计算两医师诊断DVT一致性;102例患者同时行下肢超声检查,计算股静脉-腘静脉段DVT诊断敏感度、特异度、阳性预测值、阴性预测值。结果147例患者中33例(22.4%)有DVT,27例合并PE。33例DVT的患者CTV共发现156个部位的血栓,腹盆腔静脉血栓共48个(31%),股静脉-腘静脉段血栓58个(37%),小腿静脉血栓50个(32%)。DVT血栓CT值为(42±13)HU。2医师诊断DVT的一致率为90%,Kappa值为0.86。以超声作为对照,CTV诊断股静脉-腘静脉段DVT的敏感度为92.3%,特异度为100%。结论CTV对股静脉-腘静脉段DVT诊断准确率高,并能显示下腔静脉、滤器内及盆腔静脉血栓,CTV的观察者间诊断一致性非常好。     

Detection and evaluation of intracranial aneurysms with 16-row multislice CT angiography

AIM: The aim of this study was to assess the usefulness of 16-row multislice CT angiography (CTA) in evaluating intracranial aneurysms, by comparison with conventional digital subtraction angiography (DSA) and intraoperative findings. METHODS: A consecutive series of 57 patients, scheduled for DSA for suspected intracranial aneurysm, was prospectively recruited to have CTA. This was performed with a 16-detector row machine, detector interval 0.75 mm, 0.5 rotation/s, table speed 10mm/rotation and reconstruction interval 0.40 mm. CTA studies were independently and randomly assessed by two neuroradiologists and a vascular neurosurgeon blinded to the DSA and surgical findings. Review of CTA was performed on workstations with an interactive 3D volume-rendered algorithm. RESULTS: DSA or intraoperative findings or both confirmed 53 aneurysms in 44 patients. For both independent readers, sensitivity and specificity per aneurysm of DSA were 96.2% and 100%, respectively. Sensitivity and specificity of CTA were also 96.2% and 100%, respectively. Mean diameter of aneurysms was 6.3mm (range 1.9 to 28.1 mm, SD 5.2 mm). For aneurysms of less than 3 mm, CTA had a sensitivity of 91.7% for each reader. Although the neurosurgeon would have been happy to proceed to surgery on the basis of CTA alone in all cases, he judged that DSA might have provided helpful additional anatomical information in 5 patients. CONCLUSION: The diagnostic accuracy of 16-slice CTA is promising and appears equivalent to that of DSA for detection and evaluation of intracranial aneurysms. A strategy of using CTA as the primary imaging method, with DSA reserved for cases of uncertainty, appears to be practical and safe.     

Dual-energy MDCT: Comparison of pulmonary artery enhancement on dedicated CT pulmonary angiography, routine and low contrast volume studies

Purpose

The aim of this study was (a) to compare arterial enhancement in simultaneously acquired high- and low-kilovoltage images; and (b) to determine whether low tube-voltage imaging would permit PE evaluation on routine chest CT studies or CTPA studies performed with a low volume of contrast media.

Materials and methods

We compared 20 CTPA studies (CTPA group), 20 routine thoracic CT studies (RT group) and 10 CTPA studies performed with reduced volume of contrast media (RC group). HU values were measured in all groups at 80 kVp and 140 kVp images in multiple pulmonary arterial segments bilaterally. The diagnostic quality of the central and peripheral vascular enhancement and the image noise were evaluated at both energies using a five-point scale.

Results

For all patients, the mean CT attenuation values were greater at 80 kVp than 140 kVp images (p < 0.001). At 80 kVp, CTPA group attenuation values were greater than RT group (p = 0.03) with a similar trend at 140 kVp (p = 0.08). At both 140 kVp and 80 kVp, CTPA group attenuation values were greater than RC group (p = 0.02 and p = 0.03, respectively). Qualitative analysis showed that at 140 kVp CTPA studies had better global image quality scores than RT (p = 0.003) and RC (p = 0.001) groups. However, at 80 kVp, there was no significant difference of global image quality between CTPA and the other groups (p = 0.4 and p = 0.5, respectively). Although measurable image noise was greater at 80 kVp than 140 kVp (p < 0.001), qualitative analysis revealed lower image noise at 80 kVp images.

Conclusion

DECT at 80 kVp increases arterial enhancement in both CTPA and routine studies. For routine studies this results in central and peripheral enhancement quality equivalent to that of CTPA studies. Low tube-voltage imaging allows marked contrast volume reduction for CTPA. In selected cases, satisfactory lower radiation dose CT might be achievable using lower kVp imaging alone.     

Detection,characterization and endovascular therapy planning of intracranial aneurysms with 16-channel multidetector row CT angiography

Aim

To study the role of multidetector row CT angiography (MDCTA) in detection, characterization and endovascular therapy planning of intracranial aneurysms in comparison with digital subtraction angiography (DSA).

Material and methods

Between April 2011 and March 2012, prospective study of 43 patients with suspected cerebral aneurysms (27 females and 16 males) was done, their ages ranged from 40 to 74 years. Patients were referred to the Radiodiagnosis Department, from neurology and neuro-surgery departments for suspected cerebrovascular lesions. Aneurysm detection with multidetector CT angiography and DSA was analyzed.

Results

The MDCT angiograms were interpreted for the presence, location, size, ratios of the aneurysm (dome to neck ratio (D/N), aspect ratio), neck width, lobularity of the aneurysms and relationship of the aneurysm with the adjacent arterial branches, by using volume-rendering techniques.MDCT and DSA were done for all patients. Twenty-three patients had a single aneurysm, 4 had 2 aneurysms, 2 had 5 aneurysms and no aneurysms were detected in 14 patients presented with subarachnoid hemorrhage on unenhanced CT, the most common shape was saccular aneurysm (90%) and the most common size was medium size (43.9%). We determined the neck of 28 aneurysm (68%) and the remaining 13 could not be determined (32%).Among 41 cerebral aneurysms, 26 aneurysms were detected in anterior circulation (63.4%) and 15 in posterior circulation (36.5%). The middle cerebral artery (29.2%) was the most common site.In 55% of studied cases presented with aneurysmal rupture SAH was the commonest type of hemorrhage. According to Hunt and Hiss classification grades 2 and 3 were the most prevalent (17 patients and 6 patients respectively) followed by grade 4 (4 patients) and lastly grades 0 and 1 (one patient for each).

Conclusion

Sixteen channel Multidetector CT angiography offers high diagnostic accuracy nearly equivalent to that of DSA in the detection of intracranial aneurysms. However, 16 channel- MDCTA still has limited sensitivity in detecting aneurysms of 3 mm or less, despite its technical advances. MDCT can be used as a reliable alternative imaging technique to DSA in selected cases.     

急性肺动脉栓塞患者CT阻塞指数与缺氧严重程度的相关性研究

目的:评价急性肺动脉栓塞患者CT阻塞指数(CTOI)与缺氧严重程度的相关性。方法:对24例急性肺动脉栓塞患者(栓塞组)的CT肺动脉造影(CTPA)资料进行回顾性分析,了解肺动脉CTOI与血氧饱和度(SO2)的相关性;以30例无栓塞的患者作为对照组,了解栓塞患者及无栓塞患者的SO2是否有差异;以SO2值94%为标准,将肺动脉栓塞患者分为缺氧组(<94%)和非缺氧组(≥94%),了解引起缺氧的肺动脉栓塞程度。结果:肺动脉栓塞组和对照组的SO2分别为:(89.96±7.68)%和(97.53±5.26)%,肺动脉栓塞组的SO2明显低于对照组(P<0.05);CTOI与SO2之间呈明显负相关(r=0.45,P=0.03),随着CTOI的增加,SO2降低越明显;肺动脉栓塞患者中,非缺氧组CTOI值的95%可信区间为0%～49.20%,缺氧组CTOI值的95%可信区间为39.88%～100%,CTOI值为40%～50%时,患者处于氧供不足的临界状态。结论:急性肺动脉栓塞患者CTOI与缺氧严重程度具有相关性,SO2值低于94%时,提示肺动脉栓塞超过约50%。     

双源CT肺动脉成像不同扫描模式图像质量及辐射剂量的对比研究

目的 探讨双源CT肺动脉成像双能量扫描与普通扫描(单能量扫描)对图像质量及辐射剂量的影响.方法 临床怀疑肺栓塞并行炫速双源CT肺动脉成像单、双能量扫描患者各61例,按扫描方式不同分为A、B2组,A组为双能量扫描(80/Sn140 kV),B组为普通扫描(Care kV选择输出管电压).对2组图像进行图像质量评分及测量2组肺动脉CT值、空气标准差(背景噪声)并计算信噪比(SNR),同时对2组图像的辐射剂量进行对比分析,以P＜0.05为具有统计学意义.结果 2组图像质量主观评分2名观察者间一致性较好,Kappa分别为0.705、0.827,2组图像质量评分差异无统计学意义(P＞0.05);A组右下肺动脉CT值高于B组,差异有统计学意义(P＜0.05),其余肺动脉的CT值差异均无统计学意义(P＞0.05);A组图像噪声稍高于B组,SNR稍低于B组,差异无统计学意义(P＞0.05);A、B2组CT剂量指数(CTDIvol)、剂量长度乘积(DLP)有效剂量(ED)分别为(6.13± 1.09)mGy和(12.41±3.42) mGy、(172.49士41.35)mGy· cm和(332.16±115.65) mGy.cm、(2.41±0.58) mSv和(4.65±1.62) mSv,差异具有统计学意义(P=0.000),A组CTDIvol、DLP、ED较B组分别减少50.60％、48.07％、48.17％.结论 双源CT肺动脉成像双能量扫描(80/Sn140 kV)的图像质量与单能量扫描相近,X线辐射剂量较单能量扫描明显降低.     

CT及核医学技术在肺栓塞诊断中的应用价值

肺动脉栓塞是指内源性或外源性栓子经静脉回流最终嵌塞在肺动脉及其分支,导致组织血液供应受阻所引起的一系列临床和病理生理综合征,其发病率和病死率均很高。CT和核医学技术是目前临床上诊断肺栓塞最常用的影像技术。随着计算机技术的不断更新,这两种技术也取得了一定的进展。综述CT及核医学技术在肺栓塞诊断上的进展,比较各种诊断方法的优势与不足,以期为临床选择合适的诊断方法提供参考。     

迭代模型重建技术在肺动脉“双低”成像中的应用研究

目的：探讨迭代模型重建(IMR)技术在肺动脉低剂量、低对比剂成像中的应用价值。方法对60例临床怀疑肺动脉栓塞(PE)患者行256层螺旋CT肺动脉成像,根据随机表法将患者随机分为实验组、对照组,每组30例。实验组原始数据分别采用滤波反投射(FBP)、IMR技术重建图像(A、B组),对照组原始数据采用 FBP 重建(C 组)。采用5分制方法评价肺动脉主干及其分支的图像质量,测量并计算肺动脉强化值(CT 值)、图像噪声值、图像信噪比(SNR)、对比噪声比(CNR),记录 CT 容积剂量指数(CTDIvol)、剂量长度乘积(DLP),计算有效剂量(ED)。比较 A组与 B组,B组与 C组肺动脉 CT值、图像噪声、SNR、CNR 及主观图像质量。结果实验组与对照组体质量指数(BMI)差异无统计学意义(P=0.096)。实验组CTDIvol、ED低于对照组(P<0.001)。A、B组肺动脉CT值差异无统计学意义(P=0.999),B组肺动脉CT值高于C组(P=0.005)。B组图像噪声明显低于A组(P<0.001),B组图像噪声高于C组(P<0.001)。B组 SNR、CNR高于 A组(P<0.001),B、C组 SNR、CNR差异无统计学意义(P=0.831,P=0.958)。B组图像可诊断率、优良率高于 A组(P<0.001),B、C 2组图像优良率差异无统计学意义(P=1.000)。结论肺动脉“双低”成像扫描模式联合更优化的迭代重建技术的应用,能够保证图像质量的同时大幅度降低患者辐射剂量及对比剂应用。     

Detection and characterization of Budd-Chiari syndrome with inferior vena cava obstruction: Comparison of fixed and flexible delayed scan time of computed tomography venography

PurposeTo compare the results of computed tomography venography (CTV) with a fixed and a flexible delayed scan time for Budd-Chiari syndrome (BCS) with inferior vena cava (IVC) obstruction.Material and methodsA total of 209 consecutive BCS patients with IVC obstruction underwent either a CTV with a fixed delayed scan time of 180 s (n = 87) or a flexible delayed scan time for good image quality according to IVC blood flow in color Doppler ultrasonography (n = 122). The IVC blood flow velocity was measured using a color Doppler ultrasound prior to CT scan. Image quality was classified as either good, moderate, or poor. Image quality, surrounding structures and the morphology of the IVC obstruction were compared between the two groups using a χ²-test or paired or unpaired t-tests as appropriate. Inter-observer agreement was assessed using Kappa statistics.ResultsThere was no significant difference in IVC blood flow velocity between the two groups. Overall image quality, surrounding structures and IVC obstruction morphology delineation on the flexible delayed scan time of CTV images were rated better relative to those obtained by fixed delayed scan time of CTV images (p < 0.001). Evaluation of CTV data sets was significantly facilitated with flexible delayed scan time of CTV. There were no significant differences in Kappa statistics between Group A and Group B.ConclusionThe flexible delayed scan time of CTV was associated with better detection and more reliable characterization of BCS with IVC obstruction compared to a fixed delayed scan time.     

Solitary fibrous tumor of the trachea: CT findings with a pathological correlation.

We present the multidetector CT findings with a pathologic correlation for the case of a solitary fibrous tumor located in the trachea. The MDCT revealed a well-circumscribed intraluminal mass arising from the trachea, with strong nodular enhancement in the periphery of the mass. The enhancement pattern of the mass corresponded histopathologically to a focal hypocellular area in the center and prominent blood vessels along the periphery of the mass. We also present volume-rendered and virtual bronchoscopic images of this rare submucosal tracheal tumor.