| Purpose: Preliminary discussion on the feasibility of spectral CT bronchial artery angiography using low concentration isotonic contrast agent. We plan to look for the range of the best ke V in spectral CT bronchial artery angiography. And we plan to contrast image grade, CT value, signal noise ratio, contrast noise ratio between the best ke V images in spectral CT bronchial artery angiography using low concentration isotonic contrast agent with its quality check images. at the same time, the same contrast would be completed between the best ke V images using low concentration isotonic contrast agent and conventional CT images using higher permeability contrast agent.Materials and methods:2.1 30 patients were enrolled in this research, whose consecutively underwent chest enhanced CT scan on by spectral CT using low concentration isotonic contrast agent(iodixanol: 270 mg I/ml). According to matching principle of age, sex, body mass index, 30 patients were selected in this research, whose underwent chest enhanced CT scan on conventional CT using higher permeability contrast agent(Iohexol Injection: 300 mg I/ml). GSI(Gem Stone spectral imaging, GSI) scan mode of spectral CT when using low concentration isotonic contrast agent were completed. 120 ke V conventional CT scan were completed when using higher permeability contrast agent. The same scan conditions including: tube current Automatic m A modulation, slice thickness and slice interspace 5.0 mm, Pitch 1.375:1, Matrix 512 x 512, rotate speed 0.6 or 0.8 s/rots, reconstruction layer thickness and interspace 0.625 mm, contrast agent dosage 70 ml, velocity of flow 4.0 ml/s.2.2 All the post-processing data were completed on AW4.5 workstation. We planed to look for the range of the best ke V in spectral CT bronchial artery angiography using low concentration isotonic contrast agent by general software. Bronchial arterial reconstruction were completed on the best ke V images and its quality check images in spectral CT bronchial artery angiography using low concentration isotonic contrast agent. Bronchial arterial reconstruction included volume rendering(Volume Rendering, VR), Maximum intensity projection(Maximum Intensity Projection, MIP), multi-planar reconstruction(Multi-planar Reconstruction, MPR). The same bronchial artery reconstructions were completed in conventional CT images using higher permeability contrast agent.2.3 With double blind and five grades method, subjective scores of two doctors were acquired about bronchial arterial reconstruction image, on the best ke V images and its quality check images in spectral CT bronchial artery angiography using lowconcentration isotonic contrast agent, and on conventional CT images using higher permeability contrast agent. At the same time, under the three condition, we would measure the following indexes, including subcutaneous fat layer CT value(that is, CT value of the background noise), standard deviation of subcutaneous fat layer CT value(background noise), proximal bronchial artery CT values, signal-to-noise ratio(SNR) and contrast to noise ratio(CNR) by further calculation。And total iodine dose during CT scan were calculated respectively under the condition of low concentration isotonic contrast agent and higher permeability contrast agent.2.4 Using SPSS17.0 software for statistical analysis.2.4.1 Consistency check was completed respectively between subjective scores of two doctors on the best ke V images and its quality check images in spectral CT bronchial artery angiography using low concentration isotonic contrast agent, using Kappa test. The difference of bronchial artery subjective scores were compared between the best ke V images and its quality check images in spectral CT bronchial artery angiography using low concentration isotonic contrast agent, using the paired-sample T test.2.4.2 The difference of bronchial artery CT value, SNR and CNR were compared between the best ke V images and its quality check images in spectral CT bronchial artery angiography using low concentration isotonic contrast agent, using the paired-sample T test.2.4.3 Patients age and body mass index were compared between the condition of low concentration isotonic contrast agent and higher permeability contrast agent, using independent-sample T test.2.4.4 Consistency check was completed respectively between subjective scores of two doctors on the best ke V images in spectral CT bronchial artery angiography using 270 low concentration isotonic contrast agent and 300 conventional imaging group, using Kappa test. The difference of bronchial artery subjective scores were compared between the best ke V images in spectral CT bronchial artery angiography using 270 low concentration isotonic contrast agent and 300 conventional imaging group, using independent-sample T test.2.4.5 The difference of bronchial artery CT value, SNR and CNR were compared between the best ke V images in spectral CT bronchial artery angiography using 270 low concentration isotonic contrast agent and 300 conventional imaging group, using independent-sample T test.Results:3.1 The range of the best ke V in spectral CT bronchial artery angiography using 270 low concentration isotonic contrast agent was 57-60 ke V, among these, 90%(27/30) in 59 ke V,mean 59 ke V.3.2 Consistency check was completed respectively between subjective scores of two doctors on the best ke V images and its quality check images in spectral CT bronchial artery angiography using low concentration isotonic contrast agent, using Kappa test. Result showing: the kappa value of the 270 best ke V images group was 0.87(>0.75), and the kappa value of its quality check images was 0.90(>0.75). Image quality scores between two radiologists under different conditions had better consistency. Meanwhile, the bronchial artery subjective scores on the best ke V images group(4.53±0.68) wassignificantly higher than its quality check images(4.27±0.79), t=2.28, p=0.03.3.3 The bronchial artery CT value, SNR, CNR on the 270 best ke V images group were significantly higher than 270 quality check images group(126.73±65.43 Hu, 89.44±40.30 Hu, t=3.74, p=0.00; 21.67±6.31, 18.30±3.65, t=3.75, p=0.00; 27.62±6.65, 25.18±3.97, t=2.24, p=0.03). It had statistical significance between both groups3.4 Patients age and body mass index between the condition of low concentration isotonic contrast agent and higher permeability contrast agent were not statistically significant(60.10±12.64 years, 60.08±11.62 years, t=-2.23, p=0.82; 23.59±2.18kg/m2, 23.43±1.96kg/m2, t=0.30, p=0.77).3.5 Consistency check was completed respectively between subjective scores of two doctors on the best ke V images in spectral CT bronchial artery angiography using 270 low concentration isotonic contrast agent and 300 conventional imaging group, using Kappa test. Result showing: the kappa value of the 270 best ke V images group was 0.87(>0.75), and the kappa value of the 300 conventional imaging group was 0.83(>0.75). Image quality scores between two radiologists under different conditions had better consistency. Meanwhile, the bronchial artery subjective scores between on the best ke V images group(4.53±0.68) and on 300 conventional imaging group were not statistically significant(4.30±0.79), t=1.22, P=0.23.3.6 Bronchial artery CT values on the best ke V images group were significantly higher than these on the 300 conventional imaging group(126.73±65.43 Hu, 95.11±47.26 Hu, t=2.15, p=0.04). There was a difference between the both groups. There weren’t statistical difference on the SNR and CNR between the 270 best ke V images group and 300 conventional imaging group(SNR:21.67±6.31, 19.90±4.71, t=1.23, p=0.23; CNR:27.62±6.65, 26.84±5.24, t=0.51, p=0.61).3.7 Each patient could intake 18900 mg I total iodine doses under the condition of low concentration isotonic contrast agent, and 21000 mg I total iodine doses under the condition of higher permeability contrast agent. So, total iodine doses under the condition of low concentration isotonic contrast agent would reduce 10% of total iodine doses under the condition of higher permeability contrast agent.Conclusions:4.1 At first, we detected the range of the best ke V in spectral CT bronchial artery angiography using 270 low concentration isotonic contrast agent(57-60 ke V). In addition, we could acquire superior bronchial artery images using the best ke V images than the quality check images.4.2 Bronchial artery images of the best ke V in spectral CT bronchial artery angiography using 270 low concentration isotonic contrast agent were the same as these in conventional CT imaging using higher permeability contrast agent. But, total iodine doses and the patient’s renal toxicity under the condition of low concentration isotonic contrast agent would be reduced obviously. |
PDF Full Text Request