Study of dual-source CT coronary angiography using low tube voltage setting in patients with low body mass index

Abstract

Objective To explore the feasibility of dual-source CT coronary angiography (CTCA) using 80 k V tube voltage setting in patients with low body mass index (BMI). Methods A total of 240 patients with suspected coronary artery disease (BMI range 18.6—21.5 kg/m2) underwent dual-source CTCA.They were randomly assigned to group A (120 k V tube voltage),B (100 k V tube voltage) and C (80 k V tube voltage) based on a random number table.The contrast media dose,volume CT dose index (CTDIvol),dose length product (DLP),and effective dose (ED) were evaluated for each patient.Image noise,CT value,contrast,signal-to-noise ratio (SNR),contrast-tonoise ratio (CNR) and figure of merit (FOM) of coronary artery were all evaluated.The image quality of coronary artery was assessed with a three-point scale (3 points: excellent,2 points: general,1 point: poor).Scan length,CTDIvol,DLP,ED,and contrast media dose for patients,image noise,CT value,contrast,SNR,CNR,and FOM of coronary artery were all analyzed using one-way ANOVA analysis for 3 groups.Time windows of ECG-pulsing protocol were analyzed usingχ2test,and the image quality scores of coronary artery were analyzed using Kruskal-Wallis test. Results There were no differences in scan length and Time windows of ECG-pulsing protocol among 3 groups (scan lengthF=2.58,P>0.05,Time windows of ECG-pulsing protocolχ2=0.77,P>0.05).The average contrast media doses were (82.0±6.4),(76.8±6.1),and (59.1±3.5) ml,the average CTDIvol were (27.5±6.2),(18.7±4.4),and (11.4±2.4) mGy,the average DLPs were (427.7±92.4),(295.4±77.1),and (183.9±41.3) mGy·cm,and the average EDs were (6.1±1.3),(4.1±1.1),and (2.6±0.6) mSv for group A,B and C,respectively.There were statistical differences in contrast media dose,CTDIvol,DLP,and ED among 3 groups (theFvalues for contrast media dose,CTDIvol,DLP,and ED were 383.08,248.13,221.05,and 234.81,respectively,allP 0.05,>0.05,and 0.05). Conclusion For the patient with BMI≤21.5 kg/m2,dualsource CTCA with 80 k V tube voltage setting can be used to diagnose coronary artery disease and the contrast media dose and radiation dosage can be reduced obviously. Key words: Coronary vessels; Tomography,X-ray computed; Radiation dosage; Contrast media