Does addition of CT pelvic venography to CT pulmonary angiography protocols contribute to the diagnosis of thromboembolic disease?

AIM: To evaluate the contribution which addition of pelvic computed tomography venography (CTV) to a standard CT pulmonary angiography (CTPA) imaging protocol makes to a definitive diagnosis of thromboembolic disease. MATERIALS AND METHODS: One hundred and six consecutive patients over the age of 55 years referred for (CTPA) for suspected pulmonary embolism between June and November 1999 had pelvic CTV performed at the time of the CTPA study. RESULTS: Ninety-six of 106 CTPA studies were technically adequate. In total, 29/96 (29.6%) CTPA studies were positive for pulmonary embolism, 10/96 (10.4%) CTV studies were positive and five of these 10 examinations showed venous thrombus when the CTPA study was negative (n = 4) or equivocal (n = 1). CONCLUSION: Addition of CTV shows residual thrombus in the pelvis in a proportion of patients with positive CTPA studies and demonstrates venous thrombus in a small number of patients with no CT evidence of pulmonary embolism.     

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.     

Multislice CT coronary angiography: how to do it and what is the current clinical performance?

The introduction of multislice computed tomography (MSCT) has allowed non-invasive coronary angiography. Although widely applied, extensive information on technical details of the technique is lacking. This survey offers detailed information on patient preparation, data acquisition, reconstruction and interpretation. In addition, a summary of the available studies using MSCT for non-invasive angiography is provided. Based on pooled analysis of direct comparisons between MSCT and invasive angiography, the weighted mean sensitivity and specificity of current 16-slice MSCT for the detection of coronary artery disease are 88% and 96%, respectively. At present, the technique is particularly well suited for reliable exclusion of coronary artery disease. It is important to emphasise that MSCT only provides anatomical images, visualising the presence of atherosclerosis; information on the haemodynamic significance of these lesions (i.e. ischaemia) cannot be derived.     

Acute subarachnoid hemorrhage: using 64-slice multidetector CT angiography to “triage” patients’ treatment

Introduction To evaluate the clinical role of CT angiography (CTA) in patients with acute subarachnoid hemorrhage (SAH) for treatment decision-making.Methods Consecutive patients with acute SAH had CTA using a 64-slice scanner for initial clinical decision-making. Image processing included multiplanar volume reformatted (MPVR) maximum intensity projections (MIP) and 3D volume-rendered reconstructions. CTAs were used for (1) evaluating the cause of SAH, and (2) triaging aneurysm-bearing patients to the more appropriate management, either surgical clipping or endovascular coiling. CTA findings were confirmed by neurosurgical exploration or catheter angiography (digital subtraction angiography, DSA). Successful coiling provided evidence that triaging to endovascular treatment was correct.Results Included in the study were 73 patients. CTA findings were confirmed by DSA or neurosurgical operation in 65 patients, and of these 65, 47 had aneurysmal SAH, 3 had vasculitis, 1 had arterial dissection and 14 had no underlying arterial abnormality. The cause of SAH was detected with CTA in 62 out of the 65 patients (95.4%, sensitivity 94%, specificity 100%). CTA revealed the aneurysm in 46 of 47 patients (98%, sensitivity 98%, specificity 100%, positive predictive value 100%, negative predictive value 82.3%), 1 of 3 vasculitides and 1 of 1 dissection. Of the 46 patients with aneurysm, 44 (95.7%) were referred for treatment based on CTA. In 2 patients (2 of 46, 4.4%) CTA was not informative enough to choose treatment requiring DSA. Of the 44 patients, 27 (61.4%) were referred to endovascular treatment and successful coiling was achieved in 25 (25 of 27, 92.6%).Conclusion CTA using a 64-slice scanner is an accurate tool for detecting and characterizing aneurysms in acute SAH. CTA is useful in the decision process whether to coil or clip an aneurysm.     

CT angiography helps to differentiate acute from chronic carotid occlusion: the “carotid ring sign”

Introduction  

Currently, there is no reliable method to differentiate acute from chronic carotid occlusion. We propose a novel CTA-based method to differentiate acute from chronic carotid occlusions that could potentially aid clinical management of patients.     

Three-dimensional phase-contrast magnetic resonance angiography: a useful clinical adjunct to gadolinium-enhanced three-dimensional renal magnetic resonance angiography?

OBJECTIVE: To assess the value of three-dimensional (3D) phase-contrast (PC) magnetic resonance angiography (MRA) after gadolinium (Gd)-enhanced 3D MRA for renal artery imaging. METHODS: Twenty-one patients with suspected renal artery hypertension were reviewed. All studies included Gd-enhanced 3D MRA and 3D PC MRA. Blinded interpretation of the images was performed for each technique independently and in combination. Conventional X-ray angiography was used for diagnostic correlation when available. RESULTS: Renal artery stenosis was present in 7 (16.3%) of 43 renal arteries, confirmed by X-ray angiography. MRA images demonstrated 100% sensitivity and 74% specificity for Gd-enhanced 3D MRA and 100% sensitivity and 94% specificity for 3D PC MRA. All vessels were diagnosed correctly when both image sets were viewed. CONCLUSION: 3D PC MRA can improve the specificity of renal MRA by decreasing the number of false-positive Gd-enhanced 3D MRA interpretations.     

儿科CT实用技术(二)

三、胸部CT(一)CT方法的选择1.优点:较详细——对连续、横断解剖的显示敏感,对异常密度显示较高的敏感性;解剖——纵隔,间质,胸壁;和CTMM——硬膜外延伸。2.不足:昂贵、费时间、接受电离放射,可能需要静脉内注入造影剂,可能要用麻醉,病人环境改变。(二) 指征1.一般:显示病变位置和范围的精确解剖层面;衰减系数(密度)——特征性;辨别胸片显示的异常;转移疾病的存在与否;对治疗的反应等等。2.特殊:胸壁——即软组织,骨性胸廓,胸膜     

儿科CT实用技术(一)

本材料是根据1982年在美国louisiana,NewOrleans 召开的国际儿科放射学25届特别会议上的报告。一、颅脑CT Fitz CR(一)CT 和其他检查比较(表1)(二)准备     

Efficacy of ‘fine’ focal spot imaging in CT abdominal angiography

Objectives

To assess the efficacy of fine focal spot imaging in calcification beam-hardening artefact reduction and vessel clarity on CT abdominal angiography (CTAA).

Methods

Adult patients of any age and gender who presented for CTAA were included. Thirty-nine patients were examined with a standard focal spot size (SFSS) of 1?×?1 mm in the first 3 months while 31 consecutive patients were examined with a fine focal spot size (FFSS) of 1?×?0.5 mm in the following 3 months. Vessel clarity and calcification beam-hardening artefacts of the abdominal aorta, celiac axis, superior mesenteric artery, inferior mesenteric artery, renal arteries, and iliac arteries were assessed using a 5-point grading scale by two blinded radiologists randomly.

Results

Cohen’s Kappa test indicated that on average, there was substantial agreement among reviewers for vessel wall clarity and calcification artefact grading. Mann-Whitney test showed that there was a significant difference between the two groups, with FFSS performing significantly better for vessel clarity (U, 6481.50; p?r, 0.73) and calcification artefact reduction (U, 1916; p?r, 0.77).

Conclusion

Fine focus CT angiography produces images with better vessel wall clarity and less vessel calcification beam-hardening artefact.

Key Points

? Focal spot size affects the spatial resolution of a CT system. ? Fine focus CTAA produces images with improved vessel wall clarity. ? Fine focus CTAA is associated with fewer calcification beam-hardening artefacts. ? Fine focus CTAA may improve accuracy in assessment of luminal stenosis.     

Does pregnancy affect vascular enhancement in patients undergoing CT pulmonary angiography?

The aim of this study was to evaluate whether pregnancy affects contrast enhancement within the pulmonary arteries during computed tomography pulmonary angiography (CTPA). This was a retrospective analysis of the CTPA examinations of 16 pregnant and 16 non-pregnant female patients, suspected of having an acute pulmonary embolus (PE), during the same time period. Pulmonary vascular enhancement was evaluated by measuring the CT density within the pulmonary arteries. In a blinded evaluation, subjective grading of contrast enhancement within the pulmonary arteries was also performed. There was a significant difference in arterial enhancement between the two groups, with pregnant patients having a mean pulmonary arterial density 112 HU less than patients in the control group [mean attenuation of 259.79 ± 59.31 HU in pregnant patients versus 371.88 ± 60.63 HU in non-pregnant patients (p < 0.001)]. The mean subjective pulmonary arterial enhancement score in the pregnant group was 8.19 ± 2.51 versus 13.69 ± 3.07 in the control group (p < 0.001). Pregnant women undergoing CTPA have significantly decreased pulmonary arterial enhancement compared to non-pregnant patients, probably due to the increase in cardiac output in pregnancy. We may need to reconsider how we perform CTPA in this group in order to ensure adequate opacification for diagnosis.     

多层螺旋CT(一)

自从Ｈｏｕｎｓｆｉｅｌｄ发明第一台ＣＴ以来 ,提高检查速度始终是开发者的主要追求目标之一。早期得到提高的仅仅是旋转一周的速度 ,从数分钟一周缩短至数秒钟。但是往返式扫描这个致命弱点 ,使两层扫描间的时间间隔无法消除。1985年 ,滑环ＣＴ(ｓｌｉｐｒｉｎｇ)问世 ,使单向连续扫描成为可能 ,单周扫描时间缩短至 1秒。 1989年 ,应用滑环技术的螺旋ＣＴ推向市场 ,彻底消除了扫描时间间隔 ,从二维成像的常规扫描跨入三维采样的容积扫描 ,随之高质量的多方位重组(ＭＰＲ)和各种重建功能如表面遮蔽显示 (ＳＳＤ)、最大 (小 )密度投影 (ＭＩ…     

Coronary CT angiography after stress testing: An efficient use of resources? Implications of the Advanced Cardiovascular Imaging Consortium (ACIC) results

Coronary CT angiography (CCTA) has matured to be a fast noninvasive imaging test in the evaluation of coronary artery disease (CAD). It has demonstrated excellent accuracy for defining the presence and the severity of luminal coronary artery stenoses and is probably the best noninvasive test to reliably exclude atherosclerotic coronary disease. Furthermore, accumulating CCTA data indicate that it can identify individuals at risk for all-cause mortality. It is also well known that despite the wealth of data regarding diagnostic and prognostic values of stress testing in CAD, up to 10% of stress imaging studies are considered inconclusive, leading to subsequent invasive coronary angiography for definitive diagnosis often with negative results. Moreover, recent data indicate that up to 30 % of patients undergoing angiography have no significant CAD despite a majority of them having had a prior stress test. Whether CCTA can serve as a cost-effective methodology to invasive angiography has been a source of active research. In this context, we will discuss the implications of the recently published data from the Advanced Cardiovascular Imaging Consortium registry looking at the use of CCTA after stress testing in Michigan.     

Pulmonary arteriovenous fistula within a pulmonary cyst – evaluation with CT pulmonary angiography

Pulmonary arteriovenous malformations (PAVMs) are abnormal direct communications between pulmonary arteries and pulmonary veins. These abnormal communications result in an anatomical right-to-left shunt that reduces the arterial oxygen saturation and may cause hypoxaemia and dyspnoea. Although PAVMs frequently remain undiagnosed, they are associated with severe morbidity in the form of ischaemic strokes and brain abscesses. We report a case of incidental CT angiography depiction of a PAVM within a pulmonary cyst. To the best of our knowledge, no such case has been described previously. On the basis of its appearance and lack of typical clinical features of hereditary haemorrhagic telangiectasia (HHT), we suggest that this PAVM actually represents an acquired fistula from a previously unrecognised focal pulmonary insult, such as trauma or infection, that simultaneously evolved into a pulmonary arteriovenous fistula (PAVF) within a traumatic pulmonary cyst or pneumatocele.Pulmonary arteriovenous malformations (PAVMs) are abnormal direct communications between pulmonary arteries and pulmonary veins. These abnormal communications result in an anatomical right-to-left shunt that reduces the arterial oxygen saturation and may cause hypoxaemia and dyspnoea. Although PAVMs frequently remain undiagnosed, they are associated with severe morbidity in the form of ischaemic strokes and brain abscesses from paradoxical emboli [1–3].