| Objective:To explore the clinical value of lower extremity(distal)arterial CTA with low kV combined iterative algorithm in the transplantation of anterior and lateral perforator flap.Methods:Selected the inpatients from August 2016 to July 2017 for ALTF transplantion.The patiens were divided into three groups(A,B,and C three groups,each group of 20 patients,the contrast agents are omeprazole 350mg I/m L).A group was the conventional dose protocol(using 120KV scan,filter back projection algorithm(FBT)image reconstruction).Group B and group C were low dose protocol,group B(100KV,Iterative algorithm,IR)image reconstruction,and group C(80KV,iterative algorithm IR image reconstruction)respectively.Selcted the common iliac arteries,the arteria femoralis,and the descending branch of LCFA as target,we recorded the scan length,and CTDI,and measured the CT values of artery,surrounding soft tissue,and background noise,and calculated SNR,CNR,CTDI,ED,and FOM.The datas were sent to AW Server2.0 workstation for postprocessing,and get VR,MPR,MIP and CPR,which gave the access to multi-faceted lower limb vascular images.The image quality subjective score was assessed by two imaging diagnostic deputy chief physician using double-blind reading.The scan range,CTDI,and DLP were recorded and ED was calculated.The CT values,soft tissue CT values,noise,SNR,CNR,CTDI,DLP,ED,FOM of three sets of images were compared by one-way ANOVA,respectively,and pairwise comparison was by LSD t test.The radiographic physician’s conformance test for image diagnosis was performed using a multi-assessor’s Kappa analysis.The diagnostic accuracy rate of the three groups of CTA on the location of the ALTF were compared using the Kruskal-Wallis H test to assess the compliance rate between preoperative positioning and intraoperative exploration.Results:The images’FOM of the descending branch of LCFA were:120kV(7.85±3.06)HU,100kV(10.92±4.56)HU,and 80kV(61.98±10.55)HU,respectively,with F=392.31 and P=0.00.The subjective score of the image of the descending branch of LCFA were 120 k V protocol including 17 cases as 1 point(85%)and 3 cases as 2 point(15%),and100 kV protocol including 14 cases as 1 point(70%)and 6 cases as 2point(30%),while80kV protocol including 12 cases as 1 point(60%),6 cases as 2 point(30%),and 2 cases as3 point(10%),withχ2=3.496 and P=0.174,respectively.Two radiologists had high degree of coherence in the assessment of CTA images(kappa=0.76,P<0.05).The coincidence rate of preoperative CTA location and inoperative finding was 96.7%(58/60).The scan length of three protocols was(61.80±4.15)cm,(64.50±3.69)cm,and(64.04±3.30)cm,respectively,with F=3.003,P=0.058.The ED of each protocol was(39.59±3.24)mSv,(32.68±2.31)mSv,and(13.86±0.63)mSv,respectively,with F=655.25,P=0.00.Conclusion:The application of low voltage protocols combined with iterative algorithm for CT angiography in the location of ALTF pre-operation(BMI range from 18 to27 kg/m~2)could reduce the radiation dose significantly under the premise of guaranteeing image quality despite the noise increased,but FOM and subjective score didn`t go down.So the protocols deserved clinical location and designment of ALTF. |
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