Feasibility of Dual Source CT Virtual Unenhanced Replacing Conventional Plain Scan in Displaying Parotid Gland Mass / 中国医学影像学杂志

ABSTRACT

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.