Clinical Application Of Dual-source CT Angiography In Lower Extremity Arteries

Objective1、To investigate the clinical applications of dual-source CT angiography (DSCTA) technique in lower extremity angiography.2、To investigate the diagnostic value of dual-source CT angiography (DSCTA) in lower extremity arteriosclerotic occlusive disease(ASO).3、To compare and evaluate the concordance between dual-source CT angiography(DSCTA) and digital subtraction angiography(DSA) in lower extremity arteriosclerotic occlusive disease(ASO).Material and Methods1、Clinical data1.173patients suspected of the lower extremity arterial diseases from May2010to Feb2011were performed lower extremity DECT angiography with dual-source CT (DSCTA). Among them,55were male,18were female, age range21-87years old with mean age67.95years.2.2Among above patients,62patients with lower extremity arteriosclerotic occlusive disease (49male,13female; age range44-87years; mean age62.83years) were selected for the evaluation of ASO. The clinical diagnosis standard as following ①medical history:diabetes、hypertension or hyperlipemia and so on;②clinical feature:with critical limb ischemia symptoms, as intermittent claudication(IC)、 reduced temperature of skin, rest pain, ulcer and gangrene and so on;③physical examinaiton;④other inspection:as X-ray、US、CTA、MRA、DSA.3.336patients among above patients who underwent DSCTA and DSA during the same period,29male,7female, age range45-87years, mean age72.69years.2、DSCT scan protocolAll the patients were performed with DSCT scanner (SOMATOM Definition, Siemens Medical Solutions, Forchheim, Germany). All the patients take supine and fix their crus. The scan was performed in cranial-caudo direction from the fourth lumbar level to the foot. At frist the abdomen and lower were given a plain scan, then the contrast scan was controlled by bolus tracking. Region of interest(ROI) was placed into the abdominal aorta, and image acquisition was started5s after the attenuation of ROI reached the predefined threshold of150HU.After plain scan the DECT angiography scan was started by continuously injecting a bolus of90-100ml ultravist(concentration:350mgl/ml), followed by40ml saline solution into an antecubital vein via a18-gauge catheter(injection rate3.5mo/s) with high-pressure double-barrel syringe (MEDRAD, America). The scan parameter: A dual-energy protocol was used with both tube A(140kv,56mAs) and tube B(80KV,234mAs), with64x0.6mm collimation, pitch0.6-1, rotation time of0.33s, FOV110cm. The images were reconstructed with1.0cm slice thickness and0.5mm increment by a smooth B30f Siemens kernel. The average scan time was31.08s.3、DSCTA image post-processing and analysis①Two datasets of140KV and80KV were input simultaneously into the dual-energy software, the automatic bone-removal technique was then used to complete the bone removal.②the bones were removed by manually in the3D software.The subtracted images were further processed using maximum intensity projection (MIP) and volume rendering (VR) in order to observe the courser and affection of the lower limb artery.The reconstruction image data of M-0.3was load in advanced semi-automatic vessel analysis software (Inspace, Siemens Healthcare). multiplanar reformation (MPR), Multiplanar reformation(MIP), volume rendering(VR) were applied to observe the lower limb artery.4、Date measurement and acquisition4.1Sorce of image qualityThe lower limb artery was divided four section for the evaluation of image quality:aortoiliac、Femoral popliteal artry、Inferior genicular artery and foot artery. Images quality was measured on a four-point scale:0point, the vascular structures were invisible and not considered diagnosis;1point, the main vascular were visible, but the peripheral and collateral vessels structure were invisible and distorted;2point, all the vascular were clear visible with mild deformation or constructed defect.3point, the vascular structures were visible without any artifacts and diagnostically satisfied.4.2Comparison between3D and dual energy subtract bone removal technique about the vascular erosionThere are two status:①no erosion;②erosion.4.3The section and degrees of stenosis of the lower limb arteryAccording to the anatomy definition, the lower limb artery was divided into nine branches:common iliac artery, internal iliac artery, external iliac artery, femoral artery, deep femoral artery, popliteal artery, anterior tibial artery, posterior tibial artery, peroneal artery.The degree of stenosis was divided into4level:grade0(no stenosis); grade 1(<50%), grade2(50%～74%), grade3(75%～99%), grade4(occlusion). If the stenosis segment is more than one, it’s defined as grade3.5、Statistics analysisAll the data was processed with SPSS13.0statistical package.5.1K Independent Sample Test was used to evaluate primitive score of the four segments, P<0.05was considered statistical significant difference.McNemar test was used to compare the vascular erosion between the two bone removal technique, P<0.05was considered statistical significant difference.5.2K Independent Samples Test was used to evaluate the disposition and degrees of the stenosis in the lower limb artery, P<0.05was considered statistical significant difference.5.3The Kappa statistics was used to compare the concordance between DSCTA and DSA. Kappa=0.81-1as very good,0.61-0.80=good,0.41-0.6=common,<0.4=poor. The statistically significant difference was set at P<0.05.Result一、The clinical application of dual-source CT angiography (DSCTA) technique in lower extremity angiography.1、vascular and affection displayOf73cases, all the images showed clearly and the origin and courser is normal. The lesion、stenosis position and degree of the vascular showed clearly. Among them,6cases with operation after trauma,2cases with vascular malformation,3cases with lower limb mass, the other62cases with ischemia symptoms, of which5with stent implantation.2、Evaluation of image qualityRatio of diagnostically satisfied lower extremity vascular on DSCT angiography for aortoilia、Femoral popliteal artery、Inferior genicular artery and foot artery were 100%、100%、66.44%、39.73%respectively, the best ratio of satisfaction were aortoiliac and Femoral popliteal artery. Statistically significant difference (x2=274.888, P<0.001) existed among four sections in Chi-square test.3, Comparison between3D and dual energy subtract bone removal technique about the vascular erosion.There is no significant difference between3D and dual energy subtract bone-removal about vascular erosion in aortoiliac and Femoral popliteal artery (aortoiliac P=0.500, Femoral popliteal artery P=1.000), but significant difference in Inferior genicular artery (P<0.001).二、The diagnostic value of dual-source CT angiography (DSCTA) in lower extremity arteriosclerosis occlusive disease(ASO)There is statistically significant difference in disposition and degrees of the stenosis in the lower extremity artery(χ2=94.865, P<0.001). Among them,81lesions located in femoral artery(65.3%of all femoral artery), with43sections occlusion,30.7%of all occlusive sections.181lesions located in Inferior genicular artery, with the most common in anterior tibial artery, up to16.4%of all occlusive sections.三、The comparison between DSCTA and DSA in evaluation of lower extremity arteriosclerosis occlusive disease(ASO)DSCTA and DSA had an excellent agreement in detecting the degrees of lower extremity arteriosclerosis occlusive disease, with the value of Kappa0.863, P<0.001, existing a statistically significance. In comparison with DSA as reference standard, CTA’s sensitivity, specificity and accuracy were94.67%,86.16%, and90.29%respectively. CTA’s sensitivity, specificity and accuracy were100%、97.70%、98.70%respectively for the detection of larger than grade2occlusive lesion.Conclusions1、The patient preparation before scanning, keeping immobility during the scanning, the correct scan parameters and methods, the injection parameters and modality of contrast agent were the premise for obtaining the high quality images. the best satisfaction rate of lower extremity vascular are aortoiliac(100%) and Femoral popliteal artery(66.44%), but the ratio of foot artery was only39.73%. There was significant difference between3D and dual energy subtract bone-removal vascular erosion in Inferior genicular artery, the erosion is more significant in3D.2, Dual-source CT have many advantages:fast scanning speed, high time and space resolution, widely anatomical coverage, powerful post processing techniques, and so on. With multiple application of post processing techniques, especially MIP and CPR.DSCTA have the obvious advantage in showing the vascular’s shape of OSA and ascertaining the section and degrees of the lesions. It can provide more comprehensive informations for the preoperative and postoperative clinical treatments.3, The risk factors of lower extremity arteriosclerosis occlusive disease are age, gander, smoking, diabetes, hypertension, hyperlipemia, and so on. In our research,30cases suffered with hypertension (48.38%), diabetes16cases(25.81%), smoking38caese(61.29%), hyperlipemia2cases. All the patients suffered with one or more different clinical symptoms, the typical one was intermittent claudication(IC),33caese(53.22%).4, Most of lower extremity arteriosclerosis occlusive disease located in femoral artery,81cases in our research(65.3%of all femoral artery), with the43sections occlusion,30.7%of all occlusive sections.5、DSCTA and DSA had an excellent agreement in detecting the degrees of lower extremity arteriosclerosis occlusive disease. In comparison with DSA as reference standard, CTA’s sensitivity、specificity and accuracy were94.67%、86.16%、90.29%;100%、97.70%、98.70%for the detection of larger than grade2occlusive lesion. DSCTA is a reliable diagnostic method for the detection of lower extremity arterial occlusive disease. It can be the guidance of the clinical treatment...