双层探测器光谱CT低keV虚拟单能级图像在小肝癌评估中的应用

Application of dual-layer spectral detector CT with low kiloelectron volt virtual monoenergetic imaging in evaluation of small liver cancer

目的探讨双层探测器光谱CT(DLCT)低千电子伏特(keV)虚拟单能级图像(VMI)重建在小肝癌评估中的价值。方法回顾性分析2020年3月至2021年2月中山大学附属第三医院采用DLCT行肝胆胰脾增强扫描的28例小肝癌患者临床影像资料。其中男24例,女4例;年龄29~67岁,中位年龄55岁。患者均签署知情同意书,符合医学伦理学规定。术前1周行DLCT检查,利用后处理工作站将全息光谱图像数据包分解及整合重建,患者图像分为常规CT图像组(CI组)、40 keV虚拟单能级图像组(VMI40组)、50 keV虚拟单能级图像组(VMI50组)。CT值、信噪比(SNR)、对比噪声比(CNR)等客观评分比较采用配对样本t检验。图像的整体图像质量、图像噪声、图像锐利度、病灶显著性等主观评分比较采用Wilcoxon秩和检验。结果客观图像质量评估中,VMI40组病灶CT值、SNR和CNR分别为242±51、14.1±5.9、8.9±4.5,明显高于VMI50组的176±32、12.2±4.4、6.7±3.1(t=18.12,5.08,7.07;P<0.05);VMI50组CT值、SNR和CNR亦明显高于CI组的114±17、7.8±2.4、3.2±1.4(t=18.01,5.60,7.29;P<0.05)。主观图像质量分数评估中,VMI40组病灶显著性分数为5(1)分,明显高于VMI50组和CI组的4(2)、3(2)(Z=4.00,4.77;P<0.05)。结论与CI相比,DLCT低keV VMI可提高小肝癌病灶图像质量和检出率。

Objective To evaluate the application of dual-layer spectral detector CT(DLCT)with low kiloelectron volt(keV)virtual monoenergetic imaging(VMI)reconstruction in the evaluation of small liver cancer.Methods Clinical imaging data of 28 patients with small liver cancer receiving enhanced DLCT scan of the liver,gallbladder,pancreas and spleen in the Third Affiliated Hospital of Sun Yat-sen University from March 2020 to February 2021 were retrospectively analyzed.Among them,24 patients were male and 4 female,aged from 29 to 67 years,with a median age of 55 years.The informed consents of the patients were obtained and the local ethical committee approval was received.At 1 week before operation,patients received DLCT examination.The holographic spectral imaging data packages were decomposed and reconstructed by post-processing workstation.The patients'images were divided into the conventional CT image group(CI group),40 keV VMI group(VMI40 group)and 50 keV VMI group(VMI50 group).CT value,signal-to-noise ratio(SNR),contrast-to-noise ratio(CNR)and other objective scores were statistically compared by paired t test.The subjective scores such as the overall image quality,image noise,image sharpness and lesion significance were compared by Wilcoxon signed rank-sum test.Results In the objective image quality assessment,the CT value,SNR and CNR in the VMI40 group were 242±51,14.1±5.9 and 8.9±4.5,significantly higher than 176±32,12.2±4.4 and 6.7±3.1 in the VMI50 group(t=18.12,5.08,7.07;P<0.05).The CT value,SNR and CNR in the VMI50 group were also significantly higher than 114±17,7.8±2.4 and 3.2±1.4 in the CI group(t=18.01,5.60,7.29;P<0.05).In the subjective image quality evaluation,the lesion significance score in the VMI40 group was 5(1),significantly higher than 4(2)and 3(2)in the VMI50 and CI groups(Z=4.00,4.77;P<0.05).Conclusions Compared with CI,DLCT with low keV VMI can improve the image quality and detection rate of small liver cancer lesions.