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| Clinical value of individual contrast dosage and low radiation dose CTU with monochromatic imaging in spectral CT |
| LIU Lei, LI Quan-lin, PU Ren-wang, ZHENG Shao-wei, GE Ying, TIAN Shi-feng |
| First Affiliated Hospital of Dalian Medical University, Dalian Liaoning 116011, China |
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Abstract Objective: To investigate the feasibility and advantages of individual contrast dosage and low radiation dose scan using monochromatic CTU imaging. Methods: Ninety-five patients underwent CTU scanning on GE Discovery HD CT were divided into 2 groups, including 57 cases in control group(group A) and 38 cases in study group(group B). Group A was given conventional scanning program: 120 kVp, 3D auto mA and noise index 15 HU, scan time 0.8 s, thickness 5 mm, pitch 1.375∶1, the image processing 50% ASIR, reconstruction Stnd, thickness 1.25 mm, the amount of contrast agent are 100 mL, injection speed of 4.0 mL/s. Group B was given GSI scanning mode: 80/140 kVp fast switching, 275 mA. Other parameters were same with group A, reconstruction 85 keV, 1.25 mm thickness of a monochromatic image, the amount of contrast agent was 300 mgI/kg, speed of contrast agent injection was volume(mL)/30 s. Iohexol were used in two groups as contrast agent (iodine content of 350 mg/mL). CT values and SD value(noise) of gluteus maximums and contrast agent in bladder were measured in both two groups for calculation of CNR. Patients’ weight, volume dose index CTDIvol and DLP were recorded. CT values, SD values, CNR, CTDIvol, DLP, the amount of contrast agent and injection rates were compared between two groups using independent sample t test. The quality of VR and MIP images were evaluated by two radiology physicians with five years of experience using five-point scale, and the results of the consistency test using Kappa analysis, subjective rating were compared by Mann-Whitney U. Results: There were no significant difference of patients weight and SD value between two groups. The mean CT value of bladder contrast agent in group B (569.73±265.74) was statistically higher than group A(437.37±227.50)(P<0.05). The value of CNR in group B(40.14±22.35) was statistically higher than group A(29.23±19.03)(P<0.05). The value of CTDIvol, DLP, amount of contrast agent and injection rate of group B were statistically lower than group A(P<0.05). No significant difference in the image quality evaluation was observed between two groups(4.65±0.57 vs. 4.68±0.56). Conclusions: Individual contrast dosage and low radiation dose CTU imaging using single energy CTU imaging can effectively reduce the radiation dose and the amount of contrast agent and improve the beam hardening artifact images.
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Received: 20 November 2014
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Corresponding Authors:
LI Quan-lin
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2015, Vol. 26 
