CT angiography of peripheral arterial occlusive disease

Lower extremity computed tomography angiography (CTA) is an effective, noninvasive, and robust imaging modality that is being used increasingly to evaluate patients with peripheral arterial occlusive disease (PAOD). It is important for vascular and interventional radiologists, and vascular surgeons to be familiar with the strengths and limitations, diagnostic accuracy, and practical application of lower extremity CTA. In this article, we review the technical principles of image acquisition, visualization techniques to effectively interpret the large volumetric datasets generated, and the current practical application of lower extremity CTA with respect to PAOD.     

Whole-body 3D MR angiography of patients with peripheral arterial occlusive disease

OBJECTIVE: We assessed the diagnostic performance of whole-body 3D contrast-enhanced MR angiography in comparison with digital subtraction angiography (DSA) of the lower extremities in patients with peripheral arterial occlusive disease. SUBJECTS AND METHODS. Fifty-one patients with clinically documented peripheral arterial occlusive disease referred for DSA of the lower extremity arterial system underwent whole-body MR angiography on a 1.5-T MR scanner. Paramagnetic gadobutrol was administered and five contiguous stations were acquired with 3D T1-weighted gradient-echo sequences in a total scanning time of 72 sec. DSA was available as a reference standard for the peripheral vasculature in all patients. Separate blinded data analyses were performed by two radiologists. Additional vascular disease detected by whole-body MR angiography was subsequently assessed on sonography, dedicated MR angiography, or both. RESULTS: All whole-body MR angiography examinations were feasible and well tolerated. AngioSURF-based whole-body MR angiography had overall sensitivities of 92.3% and 93.1% (both 95% confidence intervals [CIs], 78-100%) with specificities of 89.2% and 87.6% (both CIs, 84-98%) and excellent interobserver agreement (kappa = 0.82) for the detection of high-grade stenoses. Additional vascular disease was detected in 12 patients (23%). CONCLUSION: Whole-body MR angiography permits a rapid, noninvasive, and accurate evaluation of the lower peripheral arterial system in patients with peripheral arterial occlusive disease, and it may allow identification of additional relevant vascular disease that was previously undetected.     

16层螺旋CT血管造影对下肢动脉闭塞性疾病的诊断及其临床价值简

目的：探讨16层螺旋CT血管造影对下肢动脉狭窄及闭塞性病变的临床应用价值。方法对20例下肢动脉闭塞性疾病患者行16层螺旋CT血管造影（CTA）,CTA重建采用最大密度投影（MIP）、容积再现技术（VR）、多平面重组（MPR）及曲面重建（CPR）。将下肢血管分成8段,每段血管的狭窄程度分为：正常、轻度狭窄、中度狭窄、重度狭窄、闭塞5个级别。结果20例患者共显示狭窄段72个,其中髂总动脉狭窄5段,髂外动脉狭窄8段,股动脉狭窄10段,动脉狭窄22段,胫前动脉狭窄11段,胫后动脉狭窄12段,腓动脉狭窄4段。结论16层螺旋CT是下肢动脉狭窄及闭塞性病变的可靠评估方法。     

Graph-matching-based computed tomography angiography in peripheral arterial occlusive disease

The objective of this study is to compare a graph-matching-based software and a conventional tool for postprocessing of computed tomography angiography (CTA) in correlation with the gold standard digital subtraction angiography. Sensitivity, specificity, accuracy, and interobserver agreement increased from 80.3% to 92.9%, from 69.1% to 92.4%, from 73.5% to 92.8%, and from 0.45 to 0.96, respectively, using the graph-matching-based technique. Graph-matching-based CTA increases sensitivity, specificity, accuracy, and interobserver agreement in comparison to a conventional bone elimination tool in the assessment of peripheral arterial occlusive disease.     

螺旋CT血管造影诊断肾动脉狭窄的临床价值

目的评价螺旋ＣＴ血管造影（ＳＣＴＡ）在诊断肾动脉狭窄中的价值。材料与方法４０例临床拟诊为肾动脉狭窄者行ＳＣＴＡ检查，其中２０例经ＤＳＡ对照。ＳＣＴＡ扫描参数取准直宽度３．２ｍｍ，螺距（ｐｉｔｃｈ）１，以小剂量试验获得最佳延迟扫描时间。综合分析ＣＴ轴位断面像、多层面重建（ＭＰＲ）与曲面重建、最大强度投影（ＭＩＰ）及表面遮盖显示（ＳＳＤ）三种方法重建的血管影像，完成诊断。结果４０例中ＳＣＴＡ显示肾动脉正常６５条，肾动脉狭窄１６条，共８１条。２０例有ＤＳＡ对照者，ＤＳＡ显示肾动脉正常２１条，肾动脉狭窄１７条；ＳＣＴＡ显示正常肾动脉２２条，肾动脉狭窄１６条。诊断肾动脉狭窄的敏感性、特异性、阳性预告值及阴性预告值分别为９４．１％、１００．０％、１００．０％及９５．５％。结论ＳＣＴＡ能清晰显示肾动脉并对肾动脉狭窄作出可靠诊断，在很大程度上可代替创伤性ＤＳＡ检查     

CT angiography of peripheral arterial disease

Lower-extremity computed tomographic (CT) angiography (ie, peripheral CT angiography) is increasingly used to evaluate patients with peripheral arterial disease. It is therefore increasingly important for all vascular specialists to become familiar with the strengths and limitations of this new technique. The aims of this review are to explain the principles of scanning and injection technique for a wide range of CT scanners, to explain and illustrate the properties of current image postprocessing tools for effective visualization and treatment planning, and to provide an overview of current clinical applications of peripheral CT angiography.     

Prospective evaluation of peripheral arterial occlusive disease by 2D MR subtraction angiography

The purpose of this study was to assess the diagnostic value of two-dimensional (2D) MR subtraction angiography of lower extremities in patients with symptomatic peripheral arterial occlusive disease with conventional angiography as the standard of reference. Twenty patients were prospectively included. 2D subtraction MR angiography (MRA) consisted of multisection gradient-recalled echo (GRE) acquisitions with the shortest TE available on our machine (4 msec), obtained in the coronal plane before and after intravenous bolus administration of gadolinium chelate. MR images were reconstructed after subtraction with a maximum-pixel-intensity-projection (MIP) algorithm. MRA was performed in all cases 1–4 days before diagnostic angiography. In a prospective blinded analysis, the number and location of significant (ie, >50%) stenoses and occlusions were evaluated for each vascular segment. Sensitivity and specificity were used to evaluate MRA data. Significant stenoses (38 of 46, 83%) and occlusions (66 of 67, 99%) seen at conventional angiography were identified with MRA. The sensitivity and specificity of MRA for determination of stenoses >50% or occlusions was 100% and 97%, respectively. The location and extent of stenoses and/or occlusions on MRA and angiograms were well correlated (kappa values, r = .73, P < .05). Contrast 2D MR subtraction angiography, by providing comparable information to that of conventional angiography, is well suited to evaluate the presence and severity of atherosclerotic lesions of the lower limbs.     

Total-body 3D magnetic resonance angiography influences the management of patients with peripheral arterial occlusive disease

High-resolution total-body 3D MR angiography (MRA) has recently become available, revealing additional clinically relevant disease in patients with peripheral arterial occlusive disease (PAOD). However, the actual impact of total-body MRA on patient management in patients with PAOD has not been investigated so far. Two hundred forty-nine consecutive patients with angiographically proven PAOD were prospectively examined by means of contrast-enhanced total-body 3D MRA on a 1.5-T MR scanner. All correlative imaging studies performed within 60 days of total-body MRA were included in the efficacy analysis. Additional clinically relevant disease (luminal narrowing >50%, aneurysmal changes or dissections) was found in 73 segments (52 patients), including the renal arteries (36 segments), carotid arteries (28 segments), subclavian arteries (four segments) and abdominal aortic aneurysms (AAA) (five segments). Of the 73 segments, 36 were deemed necessary for further investigation by means of focused MRA examinations; the diagnosis was confirmed in all cases. Within the 60-day follow-up period, interventional or surgical therapy outside the peripheral arterial tree was performed in nine patients (11 segments), including carotid endatherectomy and renal artery angioplasty. The outlined total-body 3D MRA approach permits a comprehensive evaluation of the arterial system in patients with atherosclerosis and does indeed have an impact on patient management in patients with PAOD.     

Comparison of CT angiography with conventional arterial angiography in aortoiliac occlusive disease

This study compared the results of conventional and CT angiography of the aortoiliac segment in 35 patients with occlusive disease. Disease severity was graded into five categories. Two assessors independently assessed the segment from the distal abdominal aorta to the proximal superficial femoral artery and a consensus was formed. There was interobserver agreement in 87% of segments for conventional angiography and in 78% for CT angiography. Comparison of the two modalities gave identical grading in 84% of segments. Dissimilar grading was found in 16%, with a roughly equal number of undergrading and overgrading. CT angiography has the advantages of being minimally invasive, requiring only an intravenous injection of contrast medium and imaging surrounding soft tissues. Multiplanar reconstruction aids the visualization of asymmetrical stenoses, and collateral blood supply is readily appreciated. However, CT angiography may fail to demonstrate short stenoses owing to limited z-axis resolution.     

低剂量多层CT血管成像对于肾下动脉及周围动脉闭塞性疾病的评价

目的应用3种不同的CT血管成像术的采集方案对于周围动脉的电离辐射剂量、影像质量及诊断能力进行研究,以预先进行的数字减影血管造影(DSA)为参考标准。材料与方法本研究经机构审查委员会批准,并通过1990赫尔     

多层螺旋CT血管成像与外周动脉疾病治疗方案选择

目的：探讨以多层螺旋CT血管成像（MDCTA）为依据制定外周动脉闭塞性疾病（PAOD）治疗方案的可靠性。方法：对38例PAOD患者的MDCTA检查资料和其中20例数字减影血管造影（DSA）资料进行回顾性分析。由血管外科专家采用盲法分别根据MDCTA和DSA诊断结果为主要依据并结合临床症状、体征进行分析,对病变血管段制定出治疗方案。结果：通过CTA和DSA两种检查方法共评价了402段血管,两种方法选择的治疗方案差异无统计学意义,χ2=3.4,P=0.493。结论：MDCTA大范围血管成像是准确、无创的检查技术,以MDCTA发现为主要依据制定治疗方案是非常准确的。     

多层螺旋CT冠状动脉造影的扫描技术及临床应用

目的：探讨多层螺旋CT冠状动脉造影的成像技术及临床应用价值。方法：对68例[包括40例无明显心脏疾患的志愿者，25例冠心病患者，2例经皮冠冠状动脉成形术（PTCA）术后5个月和1例主动脉瓣膜置换术后的患者]进行了多层螺旋CT冠状动脉造影（multi-slice spiral CT coronary angiography,MSSCTCA)并行冠状动脉三维重建，其中25例冠心病患者并进行了选择性冠状动脉造影检查，以此为金标准，比较MSSCTCA对冠状动脉病变的检出率（未作冠状动脉造影的，只是用于评价多层螺旋CT对冠脉各支的显示能力，如显示哪几支、显示长度，示涉及有否冠状动脉疾患的显示）。结果：MSSCTCA对冠状动脉近中段显示清晰，显示率可达90％以上；对冠状动脉狭窄检出率为87．5％。结论：MSSCTCA可作为冠状动脉粥样硬化疾患的筛选手段及冠状动脉术后复查的首选方法。     

Sixteen-detector row CT angiography for lower-leg arterial occlusive disease: analysis of section width

Institutional review board approval and written informed consent from all patients were obtained. Diagnostic accuracy of three reconstructions of 16-detector row computed tomographic (CT) angiography data with different section widths and increments (2.0 and 1.0 mm [CT data set 1], 1.0 and 0.5 mm [CT data set 2], and 0.75 and 0.4 mm [CT data set 3]) was compared with that of digital subtraction angiography (DSA) in 163 arterial segments in 17 patients with occlusive peripheral arterial disease (PAD). Arterial visibility was superior with CT as compared with DSA (P < .008). Sensitivity for stenosis detection did not differ between the CT reconstructions, whereas specificity was significantly improved when CT data set 3 was used (P < .017). Stenosis length did not differ significantly between CT angiography and DSA. Accuracy of stenosis detection was 88.2%, 90.8%, and 96.1% with CT data sets 1, 2, and 3, respectively. CT angiography has excellent diagnostic accuracy in the assessment of lower-leg PAD provided that the thinnest possible section width is used.     

三维增强MR血管成像在周围型动脉闭塞症分级中的应用价值

目的探讨三维增强MR血管成像（3DCE-MRA）在周围型动脉闭塞症（PAOD）分级中的应用价值。方法选择25例临床诊断为PAOD的患者进行3D CE-MRA扫描，采用连续动床三段采集法，高压注射36ml钆喷替酸葡甲胺（GD-DTPA），将采集到的图像进行最大信号投影（MIP）、多平面重组（MPR）或者容积重组（VRT）。结果25例患者成功行3DCE-MRA检查，腹主动脉下段至小腿动脉显示对比度均可达到诊断要求，与DSA和（或）手术结果相比较，3DCE-MRA诊断PAOD总符合率达96．95％（509／525），诊断轻度狭窄、中度狭窄、重度狭窄和闭塞的符合率分别为84．62％（44／52）、84．85％（28／33）、95．45％（21／22）、98．67％（74／75），对轻度、中度、重度狭窄的高估率分别为11．54％（6／52）、12．12％（4／33）、4．55％（1／22），对轻度、中度、重度狭窄和闭塞的低估率分别为3．85％（2／52）、3．03％（1／33）、0（0／22）、1．33％（1／75）。结论3DCE-MRA可以对下肢动脉的狭窄和闭塞进行准确定位和分级，在临床应用中具有重要价值。     

下肢动脉闭塞性疾病64层CT血管成像中腘动脉小剂量对比剂试验的意义

目的 探讨下肢动脉闭塞性疾病采用64层CT血管成像时,在腘动脉行小剂量对比剂试验的意义.方法 连续选取28例临床怀疑下肢动脉闭塞性疾病患者,应用64层CT在两侧腘动脉(膝关节层面)各设置一ROI进行小剂量对比剂试验,明确显示峰值及达峰时间者认为曲线获取成功.分析两侧腘动脉峰值、达峰时间、左右两侧的差异,及其对下肢动脉CTA的影响,并采用Pearson相关法分析达峰时间与峰值的相关性.根据达峰时间采用快速模式启动扫描,并将图像质量分为优、良、差3个级别按节段进行评价,计算优和良的动脉节段数占总节段数的百分比即优良率.结果 28例患者中获取腘动脉小剂量对比剂曲线的成功率为96%(54/56).26例获得双侧小剂量对比剂曲线的患者中,腘动脉峰值及达峰时间差异较大,分别为60～178(135±28)HU,21～46(31±6)s.左右腘动脉峰值及达峰时间差异亦较大,19例左右峰值不一致,差值10～80 HU,平均(32±18)HU;21例左右达峰时间不一致,差值1～12 s,平均(5±3)s.达峰时间与峰值呈负相关(r= -0.526,P<0.01).下肢CTA 616个动脉节段中,成像质量优598个,良12个,优良率为99%(610/616).结论 下肢动脉闭塞性疾病采用64层CT血管成像时,应用腘动脉小剂量对比剂试验可以准确把握扫描时机,从而获得良好的血管成像质量.

Abstract：

Objective To investigate the clinical value of the test injection at popliteal arteries on 64-slice CTA in lower extremity peripheral arterial occlusive disease (PAOD). Methods Twenty-eight patients with PAOD referred for 64-slice CTA were enrolled consecutively in the study. Test injection was performed at bilateral popliteal arteries (the level of knee joints) and the clinic value of the peak value and the time to peak was analyzed. The relationship between the time to peak and the peak value was evaluated with Pearson test. The time to peak was used for programming of the CT angiographic acquisitions with fast scanning mode. The quality of visualization of each arterial segment was determined independently by two radiologists. Results Fifty-four (96%, 54/56) time-attenuation curves were obtained in 28 patients. The wide interindividual variation in the peak value and the time to peak was observed in 52 curves of 26 patients with range of 60-178 HU,21-46 s and an average of (135±28) HU,(31±6) s, respectively. The difference in the peak value and the time to peak between bilateral popliteal arteries was also observed with range of 10-80 HU and an average of (32±18) HU in 19 patients,with range of 1-12 s and an average of (5±3) s in 21 patients. There was negative relationship between the peak value and the time to peak (r=-0.526, P<0.01). The CTA images were of good (598 segments) or medium quality (12 segments) in 99% segments (610/616). Conclusions The test injection at popliteal arteries was useful for 64-slice CTA in the patients with PAOD, as it could accurately specify the delay time of CT angiographic acquisitions.     

Diagnostic accuracy of multislice CT angiography in peripheral arterial disease

A systematic search of the PubMed and Medline databases of English literature was performed to determine the diagnostic accuracy of multislice computed tomographic (CT; MSCT) angiography in peripheral arterial disease (PAD) compared with digital subtraction angiography (DSA). Studies comparing MSCT angiography with DSA in peripheral vascular disease were included, and the diagnostic value of MSCT angiography in terms of sensitivity, specificity, and diagnostic accuracy was compared and analyzed. Ten studies (19 comparisons) met the criteria and were included for analysis. The pooled sensitivity, specificity, and accuracy rates were 92%, 91%, and 91%, respectively, at all arterial levels; 92%, 94%, and 93%, respectively, at aortoiliac arteries; 96%, 85%, and 92%, respectively, at femoropopliteal arteries; and 91%, 85%, and 87%, respectively, at infrapopliteal arteries. A significant difference was found in the sensitivity of MSCT angiography in PAD between four-slice CT and 16-slice CT, between aortoiliac and femoropopliteal arterial segments, and between femoropopliteal and infrapopliteal arterial segments (P<.05). This review demonstrates that MSCT angiography has a high diagnostic value and could be a reliable alternative to DSA in the diagnosis of PAD.     

Intraarterial MR angiography and DSA in patients with peripheral arterial occlusive disease: prospective comparison

PURPOSE: To prospectively evaluate the accuracy of intraarterial magnetic resonance (MR) angiography in the depiction of significant stenoses and occlusions, with intraarterial digital subtraction angiography (DSA) serving as the reference standard. MATERIALS AND METHODS: Approval of the local ethics committee and informed consent were obtained. Twenty patients (11 men; nine women; age range, 48-86 years; mean age, 69.5 years+/-11.2 [standard deviation]) with symptomatic peripheral arterial occlusive disease (PAOD) were prospectively enrolled. After percutaneous transluminal angioplasty (PTA), intraarterial MR angiography was performed in the thigh and the calf with a 1.5-T MR imager in two consecutive runs. Intraarterial MR angiography was performed with a low-dose injection protocol (ie, two 20-mL injections of a 50-mmol gadolinium-based contrast agent). Moderate stenoses (luminal narrowing50%) or vessel occlusions; 95% confidence intervals (CIs) were calculated for sensitivity and specificity. RESULTS: Intraarterial DSA revealed 78 moderate stenoses, 57 significant stenoses, and 28 occlusions. Sensitivity, specificity, and accuracy of intraarterial MR angiography in the characterization of significant stenoses or occlusions were 92% (95% CI: 72%, 99%), 94% (95% CI: 82%, 98%), and 93%, respectively, in femoropopliteal arteries and 93% (95% CI: 83%, 98%), 71% (95% CI: 51%, 86%), and 86%, respectively, in infrapopliteal arteries. The main artifact observed with intraarterial MR angiography was venous contamination (12%). CONCLUSION: Intraarterial MR angiography is an accurate method used to depict significant stenoses and occlusions in lower extremity arteries with a low-dose injection protocol.     

Intracranial vascular stenosis and occlusive disease: evaluation with CT angiography, MR angiography, and digital subtraction angiography

BACKGROUND AND PURPOSE: Although digital subtraction angiography (DSA) provides excellent visualization of the intracranial vasculature, it has several limitations. Our purpose was to evaluate the ability of helical CT angiography (CTA) to help detect and quantify intracranial stenosis and occlusion compared with DSA and MR angiography (MRA). METHODS: Twenty-eight patients underwent CTA, DSA, and 3D time-of-flight (TOF) MRA for suspected cerebrovascular lesions. All three studies were performed within a 30-day period. Two readers blinded to prior estimated or calculated stenoses, patient history and clinical information examined 672 vessel segments. Lesions were categorized as normal (0-9%), mild (10-29%), moderate (30-69%), severe (70-99%), or occluded (no flow detected). DSA was the reference standard. Unblinded consensus readings were obtained for all discrepancies. RESULTS: A total of 115 diseased vessel segments were identified. After consensus interpretation, CTA revealed higher sensitivity than that of MRA for intracranial stenosis (98% versus 70%, P < .001) and occlusion (100% versus 87%, P = .02). CTA had a higher positive predictive value than that of MRA for both stenosis (93% versus 65%, P < .001) and occlusion (100% versus 59%, P < .001). CTA had a high interoperator reliability. In 6 of 28 patients (21%), all 6 with low-flow states in the posterior circulation, CTA was superior to DSA in detection of vessel patency. CONCLUSION: CTA has a higher sensitivity and positive predictive value than MRA and is recommended over TOF MRA for detection of intracranial stenosis and occlusion. CTA has a high interoperator reliability. CTA is superior to DSA in the evaluation of posterior circulation steno-occlusive disease when slow flow is present. CTA results had a significant effect on patient clinical management.