成人正常胸、腰椎体双源双能CT虚拟去钙骨髓成像量化标准值研究

目的 探讨成人正常胸、腰椎体双源双能CT虚拟去钙(VNCa)骨髓成像的量化标准值。方法 对2016年8—11月山东大学齐鲁医院200名正常体检者进行前瞻性胸、腰椎双源双能量CT扫描,按年龄、性别分为<45岁的男性和女性组以及≥45岁的男性和女性组,4组各50人。在虚拟去钙技术下,测量获得T₃~L₅各椎体的骨髓CT值,再根据测得的各椎体的骨髓CT值的相近程度分成T₃~T₅、T₆~T₉、T₁₀~L₁、L₂~L₅ 4部分并取均值,采用独立样本t检验探讨上述测量参数在不同年龄分组及性别分组之间的差异。结果 ＜45岁组胸、腰椎的骨髓CT值分别为(-29.00±10.62)HU、(-35.81±12.36)HU,均高于≥45岁组的(-41.67±17.16)HU、(-44.81±14.35)HU,差异均有统计学意义(t=-6.326、-4.746,P值均<0.01)。<45岁女性组胸、腰椎的骨髓CT值分别为(-27.76±9.55)HU、(-37.56±9.05)HU,均分别高于≥45岁女性组的(-37.80±15.97)HU、(-45.45±14.04)HU,差异均有统计学意义(t=3.818、3.339,P值均＜0.01);<45岁男性组胸、腰椎的骨髓CT值分别为(-30.73±12.16)HU、(-33.91±14.64)HU,均分别高于≥45岁男性组的(-46.07±17.42)HU、(-44.68±14.84)HU,差异均有统计学意义(t=5.105、3.653,P值均＜0.05);<45岁组的男、女性的胸椎骨髓CT值比较差异无统计学意义(P＞0.05),但≥45岁组的男、女性的胸椎骨髓CT值比较差异有统计学意义(t=2.474,P＜0.05);<45岁组和≥45岁组的男、女性间腰椎的骨髓CT值比较,差异均无统计学意义(P值均＞0.05)。观察对象胸、腰椎体的骨髓CT值均与年龄呈负相关(r=-0.463、-0.402,P值均＜0.01)。对于T₃~T₅、T₆~T₉、T₁₀~L₁、L₂~L₅ 4段椎体平均骨髓CT值而言,<45岁组的各段骨髓CT值均高于≥45岁组的骨髓CT值(P值均＜0.01);不同性别间比较,仅≥45岁组的T₆~T₉、T₁₀~L₁椎体节段骨髓CT值比较差异有统计学意义(t=3.177、-2.326,P值均＜0.05)。本组检测者CT辐射剂量容积CT剂量指数和剂量长度乘积分别为4.53～18.79(8.73±2.98)mGy和117.34～1678.42(421.53±230.85)mGy·cm,有效辐射剂量为(6.35±3.43) mSv。结论 正常人胸、腰椎双源双能VNCa骨髓成像的量化CT值较为稳定,可为椎体疾病的诊断提供客观的量化标准值,且其辐射剂量值并未增加甚至降低。

Reference CT values of bone marrow in adults' normal thoracolumbar vertebrae on dual-source dual-energy CT virtual noncalcium technique

Objective To obtain the reference CT values of bone marrow in adults' normal thoracolumbar vertebrae by using bone marrow imaging virtual non-calcium technique in dual-source dual-energy CT.Methods Together 200 individuals who received physical examination between August 2016 and November 2016 in Qilu Hospital of Shandong University were prospectively recruited to perform thoracolumbar bone marrow imaging on dual-source dual-energy CT. All the subjects were divided into male and female groups of <45 years old and ≥45 years old, with 50 individuals in each group. The bone marrow CT values (HU) of T₃-L₅ vertebrae body were measured through the virtual non-calcium technique, and then, according to the approximate degree, above measured CT values of each vertebral body were divided into T₃-T₅, T₆-T₉, T₁₀-L₁, L₂-L₅, followed by calculating the mean values. Finally, differences in bone marrow CT values regarding as age and gender were also analyzed by using the independent sample t test.Results The bone marrow CT values of thoracic and lumbar vertebrae in the <45 years old group were (-29.00±10.62) HU and (-35.81±12.36) HU, respectively, which were both higher than those in the ≥45 years old group with (-41.67±17.16) HU and (-44.81±14.35) HU, and the differences were significant (t=-6.326, -4.746, all P values<0.01). The bone marrow CT values of thoracic and lumbar vertebrae in the <45 years old female group were significantly higher than those in the ≥45 years old female group (-27.76±9.55) HU and (-37.56±9.05) HU vs. (-37.80±15.97) HU and (-45.45±14.04) HU], and the differences were significant (t=3.818, 3.339, all P values <0.01). The bone marrow CT values of thoracic and lumbar vertebrae in the <45 years old male group were (-30.73±12.16) HU and (-33. 91±14.64) HU, respectively, which were also significantly higher than those in the ≥45 years old male group with (-46.07±17.42) HU and (-44.68±14.84) HU, and the differences were significant (t=5.105, 3.653, all P values<0.05). For thoracic vertebrae, there was no significant difference in bone marrow CT values in both female and male groups of <45 years old (P>0.05), but except for that in the ≥45 years old group (t=2.474, P<0.05); as for lumbar vertebrae, there was no significant difference in CT values of bone marrow in both female and male either in the <45 years old or ≥45 years old groups (all P values >0.05). The measured bone marrow CT values both in thoracic and lumbar vertebrae were negatively correlated with age (r=-0.463, -0.402, all P values<0.01). The average bone marrow CT values of T₃-T₅, T₆-T₉, T₁₀-L₁, and L₂-L₅ in the <45 years old group were all higher than those in the ≥45 years old group, and the differences were statistically significant (all P values <0.01). However, statistical differences were only observed between bone marrow CT values of segments of T₆-T₉ and T₁₀-L₁ vertebrae in the ≥45 years old group (t=3.177, -2.326, all P values<0.05) when compared between genders, and other CT values did not approach significant difference (all P values>0.05). The average CT dose index volume and dose length product values were 4.53-18.79 (8.73±2.98) mGy and 117.34-1678.42(421.53±230.85)mGy·cm, respectively, and meanwhile the effective radiation dose in this study was (6.35 ± 3.43) mSv.Conclusions Reference thoracolumbar vertebrae bone marrow CT values are stable, which may provide an objective quantitative standard for vertebral disease diagnosis. Meanwhile, the radiation dose is not very high or even decreased.