两种基于模型迭代重建算法在腹部低剂量CT中的应用  

Dose Reduction and Image Quality Improvement Potential in Abdominal CT with Model-based Iterative Reconstruction Algorithm with Two Different Pre-settings

作　　者：樊秋菊 郭炎兵[1,2] 张兆国 师卫华 张兰欣[1] 谷春雨 杨创勃 FAN Qiu-ju;GUO Yan-bin;ZHANG Zhao-guo(Department of Imaging,the Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine,Xianyang 712000,Shaanxi Province,China)

机构地区：[1]陕西中医药大学附属医院影像科,陕西咸阳712000 [2]陕西中医药大学,陕西咸阳712046

出　　处：《中国CT和MRI杂志》2019年第2期101-104,共4页Chinese Journal of CT and MRI

摘　　要：目的以腹部常规剂量40%ASIR重建来评价两种基于模型迭代重建算法(MBIRSTND与MBIRNR40)在低辐射剂量扫描时的图像质量及辐射剂量减低率。方法连续纳入接受腹部增强复查的患者20例,首次检查行常规剂量(NI=10)扫描并ASIR40%重建;复查时,采用低剂量扫描(NI=20),并采用MBIRSTND与MBIRNR40重建。客观测量图像噪声值(SD)和CT值,计算SNR、CNR,比较各参数之间差异;由2名医师对通图像进行主观评分,包括图像锐利度、噪声、伪影和诊断接受度,并进行对比分析。记录每例患者每次检查的剂量长度乘积(DLP)和CT剂量指数(CTDIVOL),计算剂量减低率。结果对于腹部脏器,低剂量MBIRSTND(NI=20)图像与常规剂量40%ASIR(NI=10)在图像噪声(SD)、信噪比(SNR)和对比噪声比(CNR)方面无统计学差异(P>0.05),低剂量MBIRSTND、MBIRNR40重建比40%ASIR图像有更低伪影和噪声,MBIRNR40图像SNR、CNR最高,主观评价结果更佳(P<0.05)。低剂量扫描的DLP值和CTDIVOL值分别为(95.56±47.17)mGy*cm和(3.04±1.48)mGy,而常规剂量ASIR40%重建的DLP值和CTDIVOL分别为(376.39±160.40)mGy*cm和(12.16±5.18)mGy,辐射剂量减低约75%。结论相比常规剂量扫描(NI=10)ASIR40%重建,低剂量扫描(NI=20)MBIRSTND、MBIRNR40重建在扫描辐射剂量降低75%的情况下,能有效降低噪声,提高图像SNR及CNR。Objective To evaluate the dose reduction and image quality potential in abdominal low-dose CT reconstructed with model-based iterative reconstruction(MBIR)with two different pre-settings(MBIRSTND and MBIRNR40),in comparison with the state-of-the-art adaptive statistical interactive reconstruction(ASIR)in routine-dose CT.Methods Twenty patients underwent two contrast-enhanced abdominal CT scans within two weeks on a 64-slice CT(Discovery CT750HD)with standard-dose(noise index=10HU)and low-dose(noise index=20HU)in the follow-up scan.The routinedose CT was reconstructed with ASIR40(40%ASIR and 60%FBP mix)and the lowdose CT was reconstructed with both the ASIR40 and the two types of MBIR algorithms.Two radiologists assessed the images blindly according to the sharpness,image noise,diagnostic acceptability and artifacts with 5-point scoring.Image noise,signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)of abdominal organs relative to erector spinae were assessed.The volume CT dose index(CTDIvol),dose-length product(DLP)and dose reduction rate were also determined.Results CTDIvol and DLP for the lowdose CT were(95.56±47.17m)Gy*cm and(3.04±1.48)mGy,respectively,compared with(376.39±160.40)mGy*cm and(12.16±5.18)mGy in the routine-dose CT with 75%reduction(P<0.001).Low-dose(NI=20HU)MBIR images with MBIRSTND setting had similar image noise,SNR and CNR as the routine-dose(NI=10HU)ASIR40 images(all P >0.05).On the other hand,the low-dose MBIR images with MBIRNR40 setting further improved image quality with higher image quality score,reduced image noise and improved SNR and CNR compared with the routine-dose ASIR40 images(all P<0.001).Conclusion MBIR significantly reduced image noise and improved SNR and CNR even at 75%dose reduction,compared with the routine-dose,state-of-the-art ASIR images.

关 键 词：体层摄影术 X线计算机 低剂量 迭代重建 

分 类 号：R816.5[医药卫生—放射医学]