320排宽体CT低kV技术在超重患者CCTA成像的应用研究

Application of 320-Row Wide-Detector CT Coronary Angiography with Low Tube-Voltages Technology in Overweight Patients

目的探讨320排宽体CT低管电压(80 kV)扫描在超重患者冠状动脉CT造影(Coronary CT Angiography,CCTA)成像中对图像质量和辐射剂量的影响。方法前瞻性纳入需行CCTA检查的超重患者(25 kg/m2≤BMI<30 kg/m2)60例,随机分为A、B两组,A组(n=30)采用管电压80 kV扫描,B组(n=30)采用管电压100 kV扫描。所有扫描均采用前瞻性心电门控技术和自动管电流控制技术。图像采用AIDR 3D迭代重建技术进行重建。测量所有图像主动脉根部及左前降支、回旋支和右冠状动脉不同节段的CT值及噪声值,并计算出信噪比(Signal to Noise Ratio,SNR)及对比噪声比(Contrast to Noise Ratio,CNR)。由2名经验丰富的放射科医师采用4分评分法对扫描图像进行主观图像质量评估。计算有效辐射剂量。结果A组和B组的BMI值比较,差异无统计学意义(P>0.05);A组的有效辐射剂量为(1.70±0.77)mSv,与B组的(2.98±1.87)m Sv相比,明显降低了42.8%。虽然在80 kV扫描条件下图像噪声较高,差异有统计学意义(P<0.01);但两组图像的SNR及CNR值比较,差异均无统计学意义(P>0.05)。每个冠脉节段主观图像质量评分比较,差异均无统计学意义(P>0.05)。结论佳能320排宽体CT能为超重患者行低千伏(80 kV)CCTA检查,并能有效地降低辐射剂量并保证图像质量。

Objective To investigate the effect of 320-row wide-detector CT with low tube-voltages technology(80 kV)on the image quality and radiation dose of coronary CT angiography(CCTA)of overweight patients.Methods A total of 60 overweight patients(25 kg/m2≤BMI<30 kg/m2)requiring CCTA were prospectively enrolled in the study and randomly divided into two groups.In group A,30 patients were scanned with tube voltage of 80 kV protocol;30 patients in group B were scanned with tube voltage of 100 kV protocol as a control group.All CCTA scans were acquired using prospective electrocardiogram(ECG)gating technology and automated tube current control technology.The image was reconstructed by adaptive iterative dose reduction three-dimensional algorithm.The CT values and noise of aortic root,left anterior descending artery,circumflex artery and right coronary artery were measured;the signal to noise ratio(SNR)and contrast to noise ratio(CNR)were calculated.Two experienced radiologists used the 4-point scoring method to evaluate the quality of scanned images subjectively.Effective radiation dose was calculated.Results There was no significant difference in BMI between group A and group B(P>0.05);The effective radiation dose in group A was significantly reduced by 42.8%,compared with group B(1.70±0.77)mSv and(2.98±1.87)mSv,respectively.Although the image noise was higher under the condition of 80 kV,the difference was statistically significant(P<0.01);However,there was no significant difference in SNR and CNR between two groups(P>0.05).There was no significant difference in the scores of subjective image quality of each coronary segment(P>0.05).Conclusion 320-row wide-detector CT can perform low-kV(80 kV)CCTA for overweighs patients,efficiently reduce radiation dose and ensure the quality of images.