Low Concentration Of Iodixanol With Low Tube Voltage Used In CT Angiography Of Lower Extremity Arteriosclerosis Obliterans

Objective Evaluate the clinical diagnostic value of low concentration of iodixanolwith low tube voltage used in CT angiography (CTA) of lower extremity arteriosclerosisobliterans (LEASO).Material and methodsObject of study: We collected42patients (32male,10female, average age62.10±6.11years old) which were suspect diagnosed with LEASO in Yancheng Third People’sHospital from May2012to November2013. Patients were divided to A group (270mg I/mliodixanol, Tube voltage100kV) and B group (350mg I/ml iohexol, Tube voltage120kV)to do CTA of lower extremity,21patients in each group. Measure the height and weight ofevery patient before CTA for the calculation of body mass index (BMI).38patients diddigital subtraction angiography (DSA) voluntarily for further diagnosis or treatment withintwo weeks (20patients in A group,18patients in B group). Record the scan length (L),volume computed tomography dose index (CTDIvol), dose length product (DLP) of eachpatient scanning which displayed by machine automatically. To calculate effective dose(ED) value based on the formula of ED (mSv)=k(mSv·mGy-1·cm-1)×DLP (mGy·cm)(k=0.019).Among these patients, there were clinical symptoms of intermittent claudication (24patients), resting pain of lower limb (22patients), dorsalis pedis artery pulse weaken (18patients), limb gangrene (6patients). This research was authorized by ethics committee ofYancheng Third People’s Hospital.And every patient signed informed consent form.Method of examination: CTA images getted from GE Lightspeed VCT64spiral CT from the general electric company in America. Scan range: From the abdominal aorta (topof common iliac artery bifurcation) to foot. Scan methods: Foot get into firstly, patient wassupine position, hands up, strephenopodia and quiet breathing meanwhile when scanning.Scan parameters: scan thickness0.625mm, reconstruction thickness0.625mm, collimation40×0.625mm,pitch0.969:1, rotation time0.8s, tube voltage100kV (A group) and120kV(B group), tube current350mA. Puncture the anterior elbow vein and embedding18-gaugecatheter,100ml non-ionic contrast medium270mg I/ml (A group) iodixanol and350mgI/ml (B group) iohexol were bolus injected from the catheter by high-pressuredouble-barrel syringe using4.0ml/s with contrast medium automatic excitated scanning.DSA images getted from GE INNOVA3100-IQ angiography machine from thegeneral electric company in America. Puncture into right femoral artery and place the4Fcatheter sheath, then4F COBRA catheter was placed in external iliac artery to trackingimaging of double lower limbs artery respectively with320mg I/ml iodixanol (flow rate3ml/s, total20ml, pressure300PSI). If there was serious narrow artery, we put catheter intoproximal part of the narrow artery guided by thread to magnification angiography with3ml/s contrast for show lesions and distal arteries.Image analysis: Data was transported to AW4.5workstation after scan. And werestructured three-dimensional lower limb artery images with post-processing technologyof maximum intensity projection (MIP), multiplanar reformation (MPR), volume rendering(VR), and so on. Observation range: From the common iliac artery bifurcation to plantararteries.Statistical analysis: Data analysis by using of SPSS20.0software. Calculate thesensitivity and specificity, accuracy, positive predictive and negative predictive value oftwo groups CTA for lower extremity artery stenosis separately with DSA as the goldstandard. And the results of CTA and DSA did consistency Kappa test. The normaldistribution test and homogeneity test of variance were used in the age, BMI, L,DLP, EDand the CT value of the bifurcation of profunda femoral artery and superficial femoralartery, upper segment of anterior tibial artery and posterior tibial artery of two groups, which were compared by independent samples t test, there is statistically significantdifference when P<0.05(Statistics: t value, data: mean±SD). Use χ2test to compare thegender composition ratio and diagnostic efficiency (the sensitivity, specificity, accuracy,positive predictive and negative predictive value) of CTA for lower extremity arterystenosis disease between groups, there is statistically significant difference when P<0.05(Statistics: χ2value).Results: There were no statistical difference of age, gender and BMI between A and Bgroup. There was no statistical difference of L between Aand B group. The DLP and ED ofA group significant lower than that of B group (P<0.001). The CTDIvolof A group reducedby44.88%compared with B group. There were no statistical difference of the CT value ofthe bifurcation of profunda femoral artery and superficial femoral artery, upper segment ofanterior tibial artery and posterior tibial artery between A and B group. The diagnosticsensitivity and specificity of A and B groups of CTA were97.0%,99.1%and98.3%,99.5%for occlusion. Regard artery more than moderate stenosis (include moderatestenosis) as the overall statistics, the diagnostic sensitivity and specificity of A and Bgroups of CTA were99.2%,99.3%and99.1%,99.3%, the accuracy were92.9%and93.0%, the positive predictive and negative predictive value were96.9%,99.3%and96.6%,99.3%, respectively. The Kappa value of A and B groups of CTA and DSA consistency testwere0.930and0.927, respectively.Conclusion: The CTA with low concentration of iodixanol combine with low tubevoltage not only can reduce the iodine load as well as the radiation dose, but also achievethe equal image quality of routine CTA. It has great clinical value in the diagnosis ofLEASO, also is an effective method for the inspection, evaluation and follow-up.