能谱CT对甲状腺微小癌的诊断价值初步研究

Preliminary study on spectral CT in the diagnosis of papillary thyroid microcarcinoma

目的分析甲状腺微小乳头状癌病人的能谱CT影像,旨在探讨能谱CT在微小癌诊断中的价值。方法回顾性分析本院2015年1月—2016年1月行颈部能谱CT扫描并经手术病理证实甲状腺微小癌33例(35枚病灶),采用Discovery CT 750 HD扫描机,通过能谱扫描和GSI viewer影像分析软件获得:140 k Vp混合能量影像(A组);最佳单能量影像(B组);最佳单能量影像与物质分离(碘基)影像融合获得的影像(C组)。对A、B组影像质量的客观指标采用配对t检验进行比较。并对3组影像检出性能的主观评分采用单因素方差分析进行比较,多重比较采用LSD-t检验对所有病灶的影像表现及能谱参数进行分析和测量。结果 B组的对比噪声比高于A组,噪声低于A组,差异均有统计学意义(P<0.05)。3组影像对微小病灶的检出率分别为91.4%、97.1%、100%,主观评分分别为2.54±1.15、3.31±0.93、3.46±0.74,单能量与碘基融合影像在病灶的检出方面优于混合能量CT,并与单能量影像相仿。微小癌表现为形态不规则19例(54.3%),边缘不清楚24例(68.6%),密度不均匀24例(68.6%)、可见微小钙化灶(16例,45.7%)及淋巴结转移(20例,57.1%)。病灶碘含量平均(2.50±1.03)mg/m L,标化碘含量平均0.33±0.14、能谱曲线斜率平均2.99±1.59。结论能谱CT可为甲状腺微小癌诊断提供更多信息,有助于病灶的检出与诊断。

Objective The aim of the current study was to retrospectively analyze spectral CT images of papillary thyroid microcarcinoma （PTMC） and to evaluate the diagnostic value for PTMC. Methods Thirty-three cases （35 lesions） with pathological confirmed PTMC from 2015 to 2016 were included in this retrospective study. All the patients underwent spectral CT scan using Discovery CT 750 HD scanner. All the spectral CT images were divided into 3 groups：polychromatic image （group A）, optimal monochromatic image （group B）, and the fused image which blended optimal monochromatic image and iodine-based material decomposition image together （group C）. The paired t-test was used to compare the objective evaluations of image quality in group A and group B. The subjective scores of three groups were compared by one-way ANOVA and multiple comparisons using LSD-t test. The imaging features and spectral parameters of all the lesions were analyzed and measured. Result The contrast-to-noise ratio of optimal monochromatic image was higher than that of polychromatic image, and the noise of optimal monochromatic image was lower than that of polychromatic image, and the differences were significant （P〈0.05）. The detection rate of the 3 groups of images for microcarcinoma lesions were 91.4%, 97.1%, and 100%, respectively;the subjective scores of the 3 groups of images were 2.54 ±1.15,3.31 ±0.93, and 3.46 ±0.74, respectively. The detection ability of fused image was better than that of polychromatic image andwas similar to that of optimal monochromatic image.The characteristics of microcarcinomaincludedirregular shape（19 cases, 54.3%）, indistinct margin （24 cases, 68.6%）, heterogeneous density （24 cases, 68.6%）, presenceof microcalcification （16 cases, 45.7%）, and lymph node metastasis （20 cases, 57.1%）. The lesions’ average iodine concentration, normalized iodine concentration, and the average spectral HU curve slope values were 2.50 ±1.03mg/mL, 0.33 ±0.14, and 2.99 ±1.59, respectively. Conclusion Spectral CT could provide more detailed information for PTMC diagnosis, and it may be useful for PTMC detection in the clinics.