全身低剂量CT用于多发性骨髓瘤诊断时的毫安秒设置研究

Study of milliampere second settings in diagnosis of multiple myeloma with whole-body low-dose CT

目的:比较不同毫安秒(mAs)设置下全身低剂量CT(whole body low-dose CT,WB-LDCT)的图像质量,拟发现最优的mAs设置,为多发性骨髓瘤诊断及治疗提供参考。方法:前瞻性选取某院60例身体质量指数(body mass index,BMI)为24.0~28.9 kg/m2的多发性骨髓瘤患者,随机分为3组(50 mAs组、70 mAs组和90 mAs组),每组20例,均行WB-LDCT检查,并计算有效辐射剂量(effective dose,ED)。由2位医师分别对3组CT图像进行客观评分、主观评分及溶骨性病灶识别。采用SPSS 22.0软件进行统计学分析,采用卡方检验和方差分析进行组间比较,采用Kappa值和组内相关系数(intra-group correlation coefficient,ICC)进行一致性检验。结果:90 mAs组、70 mAs组和50 mAs组的ED分别为(10.6±0.9)、(8.0±0.9)和(6.4±0.6)mSv,3组间差异有统计学意义(P<0.05)。90 mAs组右侧肱骨头、胸10椎体、腰4椎体、右侧髂骨翼的SNR和CNR均高于其余2组(P<0.05);90 mAs组颈4椎体、右侧股骨头的SNR和CNR均高于50 mAs组(P<0.05),但与70 mAs组差异无统计学意义(P>0.05)。70 mAs组右侧肱骨头的SNR和CNR高于50 mAs组(P<0.05),其余部位2组间差异无统计学意义。50 mAs组所有部位的主观评分、总评分均低于其余2组(P<0.05),70 mAs组与90 mAs组的主观评分、总评分差异均无统计学意义(P>0.05)。70 mAs组和90 mAs组的所有部位病灶计数一致性均较好(ICC>0.80)。结论:WB-LDCT采用70 mAs检查时图像客观评分、主观评分及多发性骨髓瘤病灶识别均较好,且有效辐射剂量较低。

Objective To compare the image quality of whole body low-dose CT(WB-LDCT)in the diagnosis of multiple myeloma(MM)at different milliampere second(mAs)settings to find the optimal mAs setting for the diagnosis and treatment of MM.Methods A total of 60 MM patients with BMI ranging from 24.0 to 28.9 kg/m2 in some hospital were prospectively examined by WB-LDCT and were randomly divided into 3 groups:50 mAs group,70 mAs group and 90 mAs group,20 patients in each group,all of whom underwent WB-LDCT examination and effective dose(ED)calculation.Two physicians identified osteolytic lesions and scored the CT images of the three groups objectively and subjectively.Statistical analysis was performed using SPSS 22.0 software,with Chi-square test and ANOVA used for inter-group comparison and Kappa value and intra-group correlation coefficient(ICC)for consistency test.Results The EDs of 90 mAs group,70 mAs group and 50 mAs group were(10.6±0.9),(8.0±0.9)and(6.4±0.6)mSv,respectively,with statistically significant differences between the three groups(P<0.05).90 mAs group had higher values of SNR and CNR of the right humeral head,the 10th thoracic vertebral body,the 4th lumbar vertebral body and right iliac wing than the remaining 2 groups(P<0.05);90 mAs group gained higher values of SNR and CNR of the 4th cervical vertebral body and right femoral head than 50 mAs group(P<0.05),while no statistical difference with 70 mAs group(P>0.05).70 mAs group had higher values of SNR and CNR of right humeral head than 50 mAs group(P<0.05),and there were no significant differences between the 2 groups for the remaining sites.50 mAs group gained lower subjective and total scores of all the sites than the remaining 2 groups(P<0.05),and there were no statistical differences between the subjective and overall scores in 70 mAs and 90 mAs groups(P>0.05).70 mAs and 90 mAs groups had high consistency of lesion counts at all the sites(ICC>0.80).Conclusion WB-LDCT with 70 mAs setting behaves well in image objective and subjective scores,MM lesion identification and low ED.