颈部淋巴结病变的具有SPS双能量扫描图像质量评估

Evaluation of Image Quality of Dual Energy Scan Technique with Selective Photon Shield in Enlarged Cervical Lymph Nodes

目的:探讨颈部淋巴结肿大患者中采用具有选择性能谱纯化技术(SPS)的双能量(DE)CT扫描的图像质量。方法:经病理证实的46例颈部淋巴结肿大患者纳入研究,随机分为两组,每组23人,分别对应SPS-DECT组和未用SPS的DECT组,扫描前将两组的CTDIVOI设置为14.87 mGy,SPS-DECT组扫描参数:管电压分别为100kV,Sn140kV,管电流分别为157mAs和100mAs;DECT组的2个球管电压分别为140kV和80kV,球管电流分别为50mAs和213mAs,其余参数均相同。由两名有经验的医师对两组图像质量进行双官法评分,利用Kappa检验比较观察者间评分的一致性;采用独立样本t检验比较两组患者平均CT值、噪声、信噪比(SNR)、对比噪声比(CNR)、图像质量评分,并对两组淋巴结钙化显示情况进行分析。以病理证实为金标准,比较两组扫描对病变淋巴结的诊断准确率。结果:共显示110枚肿大淋巴结,两组平均CT值、噪声和信噪比无统计学明显差异(P>0.05),但SPS-DECT组的CNR明显高于DECT组(P=0.015,t=2.581)。两组图像质量的主观评分无统计学差异(P>0.05)。SPS-DECT组对淋巴结内微小钙化的检出无漏检情况,而DECT对微小钙化显示存在漏检情况。SPS-DECT与DECT组对病变诊断准确率均为95.65%(22/23)。结论:在相同曝光剂量条件下,SPS-DECT具有更高的图像质量,具有潜在降低辐射剂量的作用。

Purpose： To evaluate the image quality of dual energy scan technique with selective photon shield （SPS） in the enlarged cervical lymph nodes. Methods： Forty-six patients with a total of 110 pathologically confirmed enlarged cervical lymph nodes were undergone dual energy scan. They were randomly divided into two groups before scan： group with selected spectral purification technology （SPS-DECT group, 23 patients） and group with no spectrum purification technology （DECT group, 23 patients）. CTDIvoI of the two groups was set to 14.87 mGy before scanning. The scanning parameters of SPS-DECT group was： tube voltages, 100kV and Sn140kV; tube currents, 157mAs and 100mAs; that of DECT group was： tube voltages, 140kV and 80kV, tube currents, 50mAs and 213mAs. The rest protocols were the same. The image quality of the two groups was evaluated by two experienced physicians in a double blind way. Independent samples t-test was used to compare the mean CT value, noise, signal to noise ratio （SNR）, contrast to noise ratio （CNR）, the image quality score and the cervical lymph node calcification between these two groups of patients. Taken the pathology results as the gold standard, the diagnostic accurate rate of the lymph nodes between the two groups was compared. Results： The mean CT value, noise, signal to noise ratio of the lymph nodes images between the two groups were with no statistical significant difference （P〉0.05） the contrast to noise ratio between the two groups was with statistical significant difference （P=0.015, t=2.581）, that in SPS-DECT group was higher than that in DECT group. Image quality score of the two groups was with no statistical significant difference （P〉0.05）. No micro calcification was missed in SPS-DECT group, but some micro calcifications were missed in DECT. The diagnosis accurate rate of the SPS-DECT and DECT groups was 95.65%. Conclusion： Under the same exposure conditions, SPS-DECT has a higher image quality, and has the potential to reduce the effects of radiation dose.