双能量扫描对正常成人甲状腺能谱及辐射剂量的影响

Effect of dual energy scan on thyroid energy spectrum and radiation dose in normal adults

目的 应用双源CT研究正常成人甲状腺能谱曲线及碘图特点,为甲状腺占位性病变的鉴别诊断提供依据。方法 选取70例受试者均经超声检查排除甲状腺疾病,男32例,女38例,进行双源CT颈部扫描。分别利用Liver VNC和Monoenergetic软件得到碘图及能谱曲线,分析甲状腺能谱曲线及碘含量。结果 甲状腺平扫碘含量为（1.35±0.19）mg/ml,其中左叶为（1.35±0.23） mg/ml,右叶为（1.35±0.21） mg/ml,二者比较差异无统计学意义（P〉0.05）。男、女两组甲状腺碘含量比较差异无统计学意义（P〉0.05）。甲状腺左、右叶的能谱曲线斜率分别为9.98±2.43和9.74±1.63,男、女组分别为9.88±1.74和9.74±0.09,差异均无统计学意义（P〉0.05）。双能量扫描剂量长度乘积（DLP）为（208.29±21.80）mGy ·cm,平均有效剂量为（1.23±0.13）mSv。结论 正常成人甲状腺双能量扫描获得能谱曲线有一定特征性,且可以测量甲状腺碘浓度,对于诊断甲状腺占位有指导价值。

Objective To analyze spectral curves and iodine levels in normal adult thyroid by using dual-source CT scanning technique and provide the basis for the differential diagnosis of thyroid space-occupying lesions. Methods A total of 70 subjects were selected for this study, including 38 females and 32 males. They were excluded from thyroid disease by ultrasound examination and had all taken the dual-source CT scan. The image data were transported to the CT workstation, the analysis of iodine levels and spectral curves were completed in the ＂Liver VNC＂and ＂Monoenergetic＂ modes respectively. The gender differences in ratio iodine content were compared. Results The iodine ratio of thyroid was （1.35±0.19） mg/ml in plain scan, （1.35±0.23） and （1.35±0.21） mg/ml in left lobe and right lobe respectively. There was no statistically significant difference between left and right lobe （P〉0.05）, as well as between females and males （P〉0.05）. The slopes of the energy spectrum curve in the left and right lobe of the thyroid were 9.98±2.43 and 9.74±1.63, respectively, and 9.88±1.74 and 9.74±0.09 for the male and female, respectively. There was no significant difference of slopes of the energy spectrum curve between the left and right lobe, as well as the male and female. The average dose length product of all patients was （208.29±21.80） mGy ·cm,and the average effective dose was （1.23±0.13） mSv. Conclusions Dual-source dual-energy CT scanning technique have definitive, diagnostic characteristic in the measurement of spectral curves and calculation of the ratio of iodine in normal adult thyroid tissue, and therefore has guidance value in the diagnosis of thyroid space-occupying lesions.