双源CT虚拟平扫代替常规平扫显示腮腺肿块的可行性

Feasibility of Dual Source CT Virtual Unenhanced Replacing Conventional Plain Scan in Displaying Parotid Gland Mass

目的探讨腮腺肿块检查中双源CT虚拟平扫代替常规平扫的可行性。资料与方法回顾性分析昆明医科大学第一附属医院行双源CT检查并经手术病理证实的腮腺肿块35例(38个病灶),包括腮腺多形性腺瘤13例,腺淋巴瘤14例(17个病灶),恶性肿瘤5例,炎症病变3例。所有患者均进行常规平扫及双能量增强扫描。利用Liver虚拟平扫软件处理得到动脉期虚拟平扫图像,比较常规平扫与虚拟平扫图像显示腮腺肿块能力的一致性;比较常规平扫及虚拟平扫正常腮腺组织、病灶区、颌下腺、胸锁乳突肌、下颌骨平均CT值、信噪比(SNR)、对比噪声比(CNR)、图像质量评分、辐射剂量、有效剂量(ED)。结果常规平扫与虚拟平扫主观图像质量评分分别为(4.34±0.80)分、(4.17±0.82)分,差异无统计学意义(P>0.05)。35例腮腺占位患者常规平扫与虚拟平扫在下颌角层面胸锁乳突肌、颌下腺及正常腮腺的平均CT值差异均无统计学意义(P>0.05)。常规平扫腮腺肿块及下颌骨平均CT值与虚拟平扫差异有统计学意义(P<0.05);腮腺肿块SNR差异有统计学意义(P<0.05);两组CNR差异无统计学意义(P>0.05)。虚拟平扫有效剂量低于常规平扫,差异有统计学意义(P<0.05),辐射剂量降低约38.6%。结论常规平扫与虚拟平扫在腮腺肿块检出及诊断中具有很高的一致性,且虚拟平扫辐射剂量更小。

Purpose To explore the feasibility of dual source CT virtual unenhanced replacing conventional plain scan in parotid gland mass examination. Materials and Methods Thirty-five parotid gland mass（38 focus） confirmed through dual source CT and surgical operative pathology in the First Affiliated Hospital of Kunming Medical University were retrospectively analyzed, including 13 pleomorphic adenoma parotid, 14 adenolymphoma（17 focus）, 5 malignant tumor and 3 inflammatory lesions. All patients received conventional plain scan and dual energy enhanced scan. Liver virtual unenhanced software was adopted to obtain virtual unenhanced image in arterial phase and concordance of parotid gland mass displayed on conventional plain scan and virtual unenhanced images was compared. Normal parotid tissue, focal area, salivary gland, thoracic paraspinal muscle, average CT value of lower jawbone, signal noise ratio noise ratio（SNR）, contrast noise ratio noise ratio（CNR）, image quality score, radiation dose and effective dose（ED） for conventional plain and virtual unenhanced were compared. Results Subjective image quality score for conventional plain scan and virtual unenhanced was 4.34±0.80 and 4.17±0.82, respectively; and difference between the two was of no statistical significance（P〉 0.05）. Average CT value difference of angulus mandibulae thoracic paraspinal muscle, submandibular gland and normal parotid for 35 patients with parotid space-occupying lesions with conventional plain scan and virtual plain scan was of no statistical difference（P〉0.05）. The average CT value of conventional plain scan parotid mass and mandible compared with the virtual plain scan, the difference was statistically significant（P〈0.05）. SNR difference for parotid gland mass was of statistical significance（P〈0.05）. Difference of CNR between the two groups was of no statistical significance（P〉0.05）. ED of virtual plain scan was lower than that of conventional plain scan and the difference was of statistical significance（P〈0.05）. The reduced radiation dose was about 38.6%. Conclusion Conventional plain scan and virtual unenhanced are of highly concordance in examination and diagnosis of parotid gland mass and radiation dose for virtual unenhanced is less.