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[Abstract ] Objective To compare the accuracy between regular computed tomography colonography (CTC)and dual-energy CTC in lesion detection.Methods Twenty-eight patients with clinical suspicious space occupying lesions of the colon were selected.All patients were underwent dual-energy mode contrast-enhanced CT scan and the data were reconstructed with colonography and dual-energy iodine maps methods.The diameter,enhanced computed tomography (CT)value and iodine value were measured.The results of colonoscopy and pathology were taken as gold standard.The sensitivity, specificity,accuracy,positive predictive value and negative predictive value of regular CTC and dual-energy CTC were compared.Variance analysis was performed for measurement data comparison among groups and chi-square test was used for count data analysis.Results Among 28 patients,colorectal lesions were detected in 24 cases by regular CTC,of which four cases were false-positive and one case was false-negative confirmed by colonoscopy and pathology.Colorectal lesions were detected in 20 cases by dual-energy CTC,of which no false-positive and one case was false negative confirmed by colonoscopy and pathology.The contrast enhanced CT value of polyps,adenoma,adenocarcinoma and stool was (38.54± 6.82),(49.16±7.31 ),(52.61 ±5 .93 )and (34.00±1 .41 )Hu,respectively.The enhanced value of adenoma and adenocarcinoma was significantly higher than that of polyps and stool,the differences were statistically significant among groups (F = 10.760,P = 0.001 ).There was no significant difference between polyps and stool (t=1 .44,P =0.188).The sensitivity of regular CTC and dual-energy CTC in lesion detection was 95 .6% (95 %cofidence interval(CI ):77.9%-99.2%)and 95 .6% (95 %CI :77.9%-99.2%),respectively.The specificity was 42.8% (95 %CI :15 .4%-93.5 %)and 100.0% (95 %CI :47.9%-100.0%).Conclusion Compared with traditional CTC,dual-energy CTC would distinguish lesions from stool,help differentiate between benign and malignant tumors and further increase the accuracy of CTC diagnosis.
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Objectives To investigate the image quality,influencing factors and radiation doses of prospectively ECG-triggered spiral acquisition mode (Flash spiral mode)coronary computed tomography angiography (CCTA) using high-pitch dual-source CT in patients with different heart rates.Methods One hundred and thirty-four consecutive patients with mean heart rate (HR) ＞ 65 beats per minute (bpm) and ≤ 100 bpm were included in this study as group A using Flash spiral mode setting at 20％ -30％ of the R-R interval and 134 consecutive patients with mean HR ≤65 bpm were enrolled as group B using Flash spiral scan mode at 55％ of the R-R interval; 134 consecutive patients with mean HR ＞ 65 and≤100 bpm using spiral scan mode were included as group C. The image quality scores, effective radiation dose and influencing factors of image quality in three groups were assessed. All statistical analyses were performed using SPSS.Results (1)The non-diagnostic coronary artery segments in group A (28/1842,1.52％) were more than in group B (8/1819,0.44％ ) ( x2 =10.97,P =0.001 ) and there was no significant difference between group A and group C (32/1838,1.74％) ( x2 =0.280,P =0.345).The number of patients with non-diagnostic coronary segments in group A( 10/134,7.5 ％ )was more than in group B (2/134,1.5 ％,x2 =5.52,P =0.018 ),while there was no significant difference between group A and group C (9/134,6.7％,x2 =0.057,P =0.812).(2)The average heart rate variability (HRV) of patients with different image scores in the three groups wcrc significantly different. In group A,the HRV of score 1,2 and 3 were (2.29 ± 1.06),(5.17 ± 1.37),(8.88 ± 1.53) bpm,respectively (F =170.402,P =0.001 ).In group B were (2.26±1.01),(5.97 ±1.82),(12.00 ±9.64) bpm,respectively (F=95.843,P=0.001).In group C were (2.61 ±1.85),(7.90 ±3.97),(11.22 ±5.62) bpm,respectively (F=68.629,P=0.001 ). (3) The average effective radiation doses in groups A and B were significant lower than in group C [ A group was 1.04 ± 0.16,B group was 1.03 ± 0.16 and C group was 7.05 ± 1.05,t =65.5 ( A vs C),P ＜0.01 ( A vs C) ].Conclusions Flash spiral mode of high-pitch dual-source provides high image quality with significant reduction of radiation exposure in patients with HR ≤ 65 bpm. Patients with heart rates ＞65 bpm and ≤100 bpm without cardiac arrhythmia can perform CCTA using Flash spiral mode with image acquisition time setting at 20％-30％ of the R-R interval.