肺内肿块性病变双能量CT扫描技术的可行性分析

Application of dual-energy scanning technique with dual-source CT in pulmonary mass lesions

目的分析双能量CT（DSCT）技术对肺内肿块性病变检查的可行性。方法100例肺内肿块行CT常规平扫及双能量增强扫描，经后处理得到虚拟平扫图像（VNC）和肺灌注图。利用F检验或t检验对比分析VNC和常规平扫肿块平均CT值、强化值、信噪比（SNR）、图像质量及辐射剂量；采用Wilcoxon分析VNC和常规平扫对肿块病灶显示情况。结果动脉期[VNC（A）]CT值[（32．89±12．58）HU]、实质期[VNC（S）]CT值[（30．86±9．60）HU]和常规平扫肿块平均CT值[（35．89±9．99）HU]差异无统计学意义（F=2．08，P〉0．05）。VNC（A）SNR（3．29±1．45）、VNC（S）SNR（3．934-1．49）与常规平扫SNR（4．61士1．50）差异有统计学意义（F=6．01，P〈0．05），常规平扫高于VNC。常规增强动脉期肿块强化值[（60．74±13．9）HU]与VNC（A）碘分布图肿块强化CT值[（58．26±31．99）HU]差异无统计学意义（t=0．48，P〉0．05）；常规增强实质期肿块强化CT值[（56．51±17．94）HU]与VNC（s）[（52．65±16．78）HU]差异有统计学意义（t=4．45，P〈0．05）。常规平扫图像质量评分[（4．69±0．06）分]与VNC（A）[（4．60±0．09）分]、VNC（S）[（4．61±0．11）分]比较差异无统计学意义（F=3．014，P〉0．05）。整个扫描期间DSCT扫描辐射剂量（6．4mGy×2）较常规扫描辐射剂量（7．5mGy×3）降低9．7mGy（43．1％，9．7／22．5）。41例肺门肿块中18例肺叶或段性出现灌注降低或缺损区；59例外周型肿块均表现为肿块区域灌注缺损。结论DSCT技术通过一次增强扫描可获得VNC图像、碘分布图及全肺虚拟灌注图像，对肺内肿块性病变的检查具有潜在临床价值。

Objective To explore the feasibility of DSCT dual-energy technique in pulmonary mass lesions. Methods A total of 100 patients with pulmonary masses underwent conventional plain CT scan and dual-energy enhanced CT scan. The virtual non-contrast （VNC） images were obtained at post-processing workstation. The mean CT value, enhancement value, signal to noise ratio （SNR）, image quality and radiation dose of pulmonary masses were compared between the two scan techniques using F or t test and the detectability of lesions was compared using Wilcoxon test. Results There was no statistically significant difference among VNC （ A ） （ 32. 89 ± 12. 58 ） HU, VNC （ S ） （ 30. 86 ± 9. 60 ） HU and conventional plain images （ 35.89 ± 9. 99 ） HU in mean CT value of mass （ F = 2.08, P 〉 0. 05 ）. There was statistically significant difference among VNC（A） （3.29 ± 1.45） ,VNC（S） （3.93 ± 1.49） and conventional plain image （4. 61 ± 1.50） in SNR （ F = 6. 01, P 〈 0. 05 ） , which of conventional plain scan was higher than that of ±NC. The enhancement value of mass in conventional enhanced scan（60.74 ± 13.9）HU and distribution of iodine from VNC （A） （ 58.26 ± 31.99 ） HU was no statistically significant difference （ t = 0. 48, P 〉 0. 05 ）, but there was a significant difference between conventional enhanced scan （56. 51 ± 17. 94 ） HU and distribution of iodine from VNC（S） （52. 65 ± 16. 78 ） HU （ t = 4. 45 ,P 〈 0. 05 ）. There was no statistically significant difference among conventional plain scan （4. 69 ± 0. 06 ） and VNC （ A ） （ 4. 60 ± 0. 09 ）, VNC （S） （4. 61 ± 0. 11 ） in image quality at mediastinal window （ F = 3. 014, P 〉 0. 05 ）. The appearance, size,internal features of mass （ such as necrosis, calcification and cavity） were showed the same in conventional plain scan, VNC （A） and VNC （S）. Of 41 patients with hilar mass, 18 patients were found to have lobular and segmental perfusion decrease or defect. Perfusion defect area was found in 59 patients with peripheral lung mass. The radiation dose of dual-energy enhanced scan was lower than that of conventional scan. Conclusion The virtual non-contrast, distribution of iodine and pulmonary virtual perfusion images can be obtained by DSCT dual-energy technique in one scan, which has a potential clinical value in the thorax.