摘要
目的定性和定量比较能谱cT虚拟平扫物质压碘图像、水基图和常规平扫（CU）对胃癌的检出与显示，探讨能谱cT虚拟平扫代替常规平扫的可行性。方法回顾性分析郑州大学第一附属医院2013年12月至2015年5月在DiscoverCT宝石CT能谱成像（GSI）机行能谱CT平扫加增强扫描的91例胃癌患者。对动脉期（AP）能谱数据在工作站进行后处理得到相应的物质压碘（MSI）和水基（WB）图像。由两位放射科医师对CU，MSI和WB三组图像分别进行5分制主观图像质量及病灶显示清晰度评分，两位医师评价结果一致性行kappa检验。以增强图像为参考标准，评估CU，MSI和WB三组图像对胃癌病灶的检出敏感性。测量CU和MSI两组图像各个部位的CT值、皮下脂肪噪声，并计算胃癌病灶、淋巴结及肝转移灶的相对强化值。以胃腔内水为背景，测量CU、MSI及WB三组图像胃癌病灶对比噪声比（CNR）。计算三期扫描与省略常规平扫双期扫描的有效辐射剂量（ED）。统计学采用Wilcoxon秩和检验和配对t检验比较，多组间比较以Bonferroni校正。结果91例胃癌患者，男58例、女33例，年龄20—87岁，中位年龄54岁。图像质量主观评分CU（4．30±0．63）与MSI图像（4．17±0．58）间差异无统计学意义（P〉0．05），均高于WB图像（3．87±0．84）（P〈0．01）。病灶显示清晰度在CU（3．86±0．50）与MSI图像（3．73±0．55）间差异无统计学意义（P〉0．05），均高于wB图像（3．34±0．38）（P〈0．01）。CU，MSI和WB三组图像对胃癌病灶的检出率分别为91．2％、95．6％、93．4％，差异无统计学意义。MSI图像胃癌病灶、肝转移及主动脉的cT值高于CU图像（P〈0．05），淋巴结、肝脏、肌肉cT值两组图像间差异无统计学意义（P〉0．05）。胃癌病灶、淋巴结及肝转移灶的相对强化值在MSI及CU图像间差异均无统计学意义（均P〉0．05）。MSI图像噪声稍高于CU图像（P〈0．01）。胃癌病灶CNR两两比较，WB图像高于MSI图像，MSI图像高于CU，差异均有统计学意义（均P〈0．01）。与标准三期增强扫描相比，省略了常规平扫的双期能谱扫描ED降低约8．2mSv（32％）。结论能谱CT虚拟平扫MSI图像可以为胃癌评估提供好的图像质量和可靠的诊断信息，优于WB图像；代替常规平扫可降低32％的辐射剂量。
Objective To qualitatively and quantitatively compare MSI images and derived from spectral CT imaging with CU images in accessing gastric carcinoma. Methods WB images The clinical data and imaging findings of 91 cases of gastric carcinomas between December 2013 and May 2015 were analyzed retrospectively. All patients underwent CU CT and enhanced CT with spectral imaging in AP and VP. MSI images were reconstructed based on monochromatic images of 70 keV in AP. WB images were obtained by water-iodine pair substance isolation of the AP images. Two abdominal radiologists independently evaluated the image quality and the depiction of gastric carcinoma in CU, MSI and WB images using a 5- point scale. The sensitivities of gastric cancer were evaluated by using enhanced images as the reference standard. The CT number of various regions, image noise, relative enhancement CT value of tumors and metastasis were measured and calculated on CU and MSI images. The CNR of gastric tumor were measured on CU, MSI and WB images. Effective radiation doses for triple-phase and dual-phase scan were calculated. Differences were tested for statistical significance using the Wileoxon＇s signed rank test and the paired t- test. Results Interobserver agreement with regard to image quality and the depiction of gastric carcinoma was good（all kappa 〉 0. 70）. There was no statistical significant difference in image quality between CU （4. 30 ±0. 63） and MSI（4. 17 ± 0. 58） images（P 〉 0. 05 ）, both higher than WB（3.87 ±0. 84） images （both P 〈0.01 ）. The depiction of gastric carcinoma in CU（3.86±0. 50） and MSI（3.73±0. 55 ） images had no statistical significant difference （P 〉0.05）, and both higher than WB（3.34 ±0. 38） images（ both P 〈0. 01 ）. The sensitivities of CU, MSI and WB images were 91.2% , 95.6% , 93.4%. The CT number of gastric tumors, liver metastasis and aorta, image noise on MSI images were slightly higher than on TNE images （P 〈 0. 05 ）. The CT number of gastric tumors, liver metastasis and aorta, image noise on MSI images were slightly higher than on TNE images （ P 〈 0.05 ）. The CT number of lymph nodes, liver and muscle, CT relative enhancement value of gastric tumors, lymph nodes and liver metastasis had no significant difference between TNE and MSI images （ all P 〉 0.05 ）. The CNR of gastric tumors had significant difference between groups ： WB images were higher than MSI and MSI were higher than CU images （ all P 〈 0. 01 ）. The dose saving by removing the CU was 8.2 mSv （32%）. Conclusion The MSI images derived from spectral CT can provide comparable image quality to CU images and reliable diagnostic information for gastric tumors, which is superior to WB images, replacing CU images will lower radiation exposure by 32%.
出处
《中华医学杂志》
CAS
CSCD
北大核心
2016年第5期329-333,共5页
National Medical Journal of China
基金
国家自然科学基金（81271573）
关键词
体层摄影术
X线计算机
胃肿瘤
辐射剂量
虚拟平扫
Tomography, X-ray computed
Stomach neoplasms
Radiation dosage
Virtual unenhanced
