Application of optimizing contrast medium injection protocol for dual-source CT high-pitch spiral acquisition in children with complex congenital heart disease

Objective To explore clinical value of optimizing the contrast medium injection protocol for dual-source CT high-pitch spiral acquisition in children with complex congenital heart disease. Methods Sixty patients with complex congenital heart disease were prospectively recruited and randomly divided into group A and group B by the random number table method. Patients in group A received a conventional contrast medium injection protocol, i.e. a diluted contrast material with fast and slow rate respectively, and then a flush with normal saline. The volume of contrast medium was 2.0 ml/kg. Patients in group B received an optimized injection protocol, i.e. a four-phase diluted contrast material with contrast/saline ratio of 8∶2, 6∶4, 4∶6, 2∶8 respectively. The volume of contrast medium was 1.0—1.5 ml/kg. Attenuation and noise were measured in superior vena cava, right atrium, right ventricle, the main pulmonary artery, left atrium, left ventricle, ascending and the descending aorta in the two groups and compared by t test. The image uniformity was assessed by t test. Subjective image quality and artifacts of superior vena cava were analyzed by the Mann-Whitney U test. Diagnostic accuracy was evaluated by χ2 test. All the patients undergone the surgical treatment and demonstrated 121 abnormalities (22 species) of internal and external heart structure, i.e. 56 in group A and 65 in group B. Results There was no significant difference in diagnostic accuracy between group A and group B (A: 96.9%, 52/56, vs. B: 96.4%, 62/65; χ2=0.28, P=0.59). While, significant difference was found in the amount of consumed iodine between the two groups [A: (15.7±6.5) ml vs. B: (10.4±2.4) ml; t=4.14, P<0.01]. Furthermore, the image uniformity in group B was statistically higher than that in group A[A: (36.5±18.0) HU vs. B: (272.0±124.5) HU; t=10.30, P<0.01]. As for subjective image quality, no significant difference were observed (A: 3.3±0.5 vs. B: 3.5±0.5; Z=396.00, P=0.39); while significant difference was found in artifacts of superior vena cava (A: 3.2±0.9 vs. B: 3.7 ± 0.7; Z=300.50, P=0.02). Conclusion The optimized contrast medium injection protocol for children with complex congenital heart disease could eliminate the image artifacts of superior vena cava and improve the image quality. Key words: Heart defects, congenital; Tomography, X-ray computed; Contrast media