Application Of Three-low Scanning Technology In Thyroid Enhanced CT Scan

Objectives:To discuss the clinical value of three-low scanning technology---low tube voltage 80kV,low contrast dose,low injection rate and sinogram affirmed iterative reconstruction(SAFIRJE)in thyroid enhanced CT examination compared with conventional 120kV,conventional contrast medium injection scheme and FBP technique.Methods:60 cases of patients who received thyroid CT enhanced scan in our hospital from January 2017 to January 2018 were selected prospectively as the research subjects.They were randomly assigned to 2 protocol groups:protocol A was routine dose:including 8 cases of male,12 cases of female,received tube voltage 120kV,contrast agent concentration 3 70mgl/ml,according to 1.2ml/kg,injection rate 3ml/s combined with FBP;protocol B was three-low dose:including 15 cases of male,15 cases of female,received tube voltage 80kV,contrast agent concentration 270mgl/ml,according to 1.0ml/kg,injection rate 2.5ml/s combined with SAFIRE.CT value,difference value,signal noise ratio(SNR),contrast noise ratio(CNR),background noise of normal and lesion thyroid tissues during arterial and venous phase of images in the two groups were compared objectively.Lesion thyroid details,lymph gland were compared subjectively.The diagnose difference of sensitivity,specificity and accuracy of two scanning plans were analyzed compared with pathology.The radiation dose,contrast dose and effusion rate were compared.Result:1.60 cases of thyroid patients,including 35 cases of multiple nodules and 25 cases of single nodule.The pathological result showed 47 cases of malignant tumor,including 42 cases of papillary carcinoma,4 cases of follicular carcinoma,1 case of medullary carcinoma,and 13 cases of benign tumor,including 7 cases of nodular goiter,5 cases of thyroid cyst,1 case of adenoma.The age,sex,BMI,the number and size of benign and malignant nodules in two groups had no significant difference(P>0.05).2.The difference of background noise during arterial and venous phase had no statistical significance(P>0.05),CT value and difference value in three-low dose group of normal and lesion thyroid tissues during arterial and venous phase were higher than those of routine dose group,the difference had statistical significance(P<0.05).3.Difference of SNR and CNR of normal thyroid during arterial phase and venous phase had no statistical significance(P>0.05).4.Subjective scoring of thyroid details in three-low dose group were higher than those in routine dose group,the difference had statistical significance(P<0.05).The difference of subjective scoring of lymph gland and the diagnose difference had no statistical significance(P>0.05).5.Pathology result showed the accuracy of three-low dose group was 80%and of routine dose group was 76%.6.The difference of CTDIvol.DLP and ED had statistical significance(P<0.05),the three-low dose group decreased by 60%than routine dose group.7.The contrast dose and total iodine had significant difference(P<0.05),A>B,three-low dose group were reduced by 37%.The difference of effusion rate between two groups had no statistical significance(P>0.05).Conclusions:Under the premise of ensuring the image quality to meet the diagnostic requirements,the thee-low technique improved the CT difference between normal and lesion thyroid tissues,which may be more conductive to the display of thyroid lesions and detection of small lesions.The arterial phase is superior to the venous phase and plain scan.At the same time,the effective radiation dose of CT examination was reduced about 60%.The total amount of contrast agent decreased by about 10ml,and the total amount of iodine decreased by about 3 7%,and got the same diagnostic efficacy.lt is feasible in CT enhancement of thyroid gland.