CAJ | 학술논문

目的探讨16层CT进行低剂量CTA的可行性,以及与平扫噪声和增强值的关系.方法选取连续上腹部增强检查中,动脉期主动脉增强CT值300.0 HU以上的43例患者,采用16层CT扫描,回顾性动脉期重建和标准算法.在平扫图像上选择右侧后膈脚水平图像测定腹主动脉腔的CT值,CT值的标准差(SD)定义为图像噪声;增强图像上测定腹腔动脉根部水平的主动脉CT值.动脉期数据进行VR后处理,其图像评价分优、良、差,并以此为标准进行图像质量与主动脉增强值和平扫SD值之间关系的受试者操作特性曲线(ROC)分析.结果增强主动脉CT值在300.0～400.0 HU之间共25例,SD=12.00时,图像为优的敏感性75%,特异性62%.主动脉CT值在400.0 HU以上共18例,SD=12.25时,图像为优的敏感性和特异性均为100%;SD=13.35时,图像为优的敏感性100%,特异性75%.按主动脉强化值与CTA VR图像质量相关性分析,ROC曲线下面积0.907,图像为优的敏感性100%、特异性60%时的强化值阈值为356.7 HU;敏感性78%、特异性80%时的强化值阈值为389.8 HU;特异性100%时的最低强化值为442.4 HU,此时敏感性56%.结论低剂量CTA切实可行,保证良好成像效果的前提下,平扫SD值越小,使用的mAs就越小;而成像效果越好,则可以使用的mAs值也可以减小.
목적 탐토16층CT진행저제량CTA적가행성,이급여평소조성화증강치적관계.방법 선취련속상복부증강검사중,동맥기주동맥증강CT치300.0 HU이상적43례환자,채용16층CT소묘,회고성동맥기중건화표준산법.재평소도상상선택우측후격각수평도상측정복주동맥강적CT치,CT치적표준차(SD)정의위도상조성;증강도상상측정복강동맥근부수평적주동맥CT치.동맥기수거진행VR후처리,기도상평개분우、량、차,병이차위표준진행도상질량여주동맥증강치화평소SD치지간관계적수시자조작특성곡선(ROC)분석.결과 증강주동맥CT치재300.0～400.0 HU지간공25례,SD=12.00시,도상위우적민감성75%,특이성62%.주동맥CT치재400.0 HU이상공18례,SD=12.25시,도상위우적민감성화특이성균위100%;SD=13.35시,도상위우적민감성100%,특이성75%.안주동맥강화치여CTA VR도상질량상관성분석,ROC곡선하면적0.907,도상위우적민감성100%、특이성60%시적강화치역치위356.7 HU;민감성78%、특이성80%시적강화치역치위389.8 HU;특이성100%시적최저강화치위442.4 HU,차시민감성56%.결론 저제량CTA절실가행,보증량호성상효과적전제하,평소SD치월소,사용적mAs취월소;이성상효과월호,칙가이사용적mAs치야가이감소.
Objective To characterize the feasibility of low-dose CT angingraphy on 16-slice multislice computed tomography (16-MSCT), and its relationship to the noise in the pre-contrast image and enhancement value.Methods Forty-three consecutive patients (male 21, female 22, mean age 59 years, median age 56 years) underwent abdominal 16-MSCT (Toshiba Aquilion 16) with constant scanning parameters including 120 kVp, a 0.5-second gantry rotation time, a pitch of 0.938: 1, and 16×1-mm detector collimation.The mA was set at 200 in the pre-contrast scan and 160 in the contrast-enhanced scan.The arterial phase images were retrospectively reconstructed with 1-mm slice thickness, 0.8 mm interval.The pre-contrast noise was defined as the standard deviation (SD) of the aorta at the level of right posterior crura of diaphragm.The enhancement of aorta was also measured at level of celiac artery.The volume rendering of CT angiography was made and classified into three grades (excellent, good, bad).Receiver operating characteristic curve (ROC) was used to evaluate the relationship between the image quality of CT angiography and noise in the pre-contrast image and enhancement value.Results Twenty-five cases had the aorta enhancement between 300.0--400.0 HU.The sensitivity and specificity of excellent CTA image was 75% and 62%, respectively when the SD was 12.00.Eighteen cases had the aorta enhancement more than 400.0 HU.The sensitivity and specificity of excellent CTA image was all 100% when the SD was 12.25, and 100% and 75%, respectively when the SD was 13.35.The area under curve of CTA image quality and enhancement in receiver-operated characteristic analysis was O.907.The enhancement was more than 356.7 HU when the sensitivity and specificity of excellent CTA image was 100% and 60%, respectively, and 389.8 HU when 78% and 80%.When the enhancement was more than 442.4 HU, the specificity of excellent CTA image was 100%.Conclusions MSCT angiography with low radiation dose is feasible.Good CT angiography demands great enhancement, and then, the needed mAs is lower when the SD is smaller.