Application of low-tube current with iterative model reconstruction on Philips Brilliance iCT Elite FHD in the accuracy of spinal QCT using a European spine phantom
Application of low-tube current with iterative model reconstruction on Philips Brilliance iCT Elite FHD in the accuracy of spinal QCT using a European spine phantom
复制标题
低管电流迭代模型重建在飞利浦华晨 iCT Elite FHD 上的应用在欧洲脊柱体模脊柱 QCT 准确性中的应用
DOI：
10.21037/qims.2018.02.03
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发表时间：
2018-02-01
影响因子：
2.8
通讯作者：
Gao, Jianbo
中科院分区：
文献类型：
--
作者：
Wu, Yan;Jiang, Yaojun;Gao, Jianbo
背景：探讨基于幻影模型的迭代模型重建（IMR）技术在低mas骨矿物质密度（BMD）定量CT （QCT）测量中的重复性和准确性。方法：选择欧洲脊柱假体（ESP），在Philips Brilliance iCT Elite FHD仪上测量10次。将数据传输到QCT PRO工作站，测量ESP （L1、L2、L3）的骨密度（mg/cm(3)）。扫描方法：x射线管电压为120 kV， x射线管输出电流A-E组分别为：20、30、40、50、60 mAs。重建：所有数据使用滤波后投影（FBP），混合迭代重建的IR水平（iDose(4)，使用水平1、2、3、4、5、6）和IMR（使用水平1、2、3）重建。各组分别在L1、L2、L3椎体中部放置roi。测量并计算CT值、噪声和噪比（CNR）。采用单因素方差分析（ANOVA）比较不同mAs和不同IMR的BMD值。结果：辐射剂量[体积CT剂量指数（CTDIvol）和剂量长度积（DLP）]与管电流呈正相关。在低骨密度L1中，FBP的不同mAs值P< 0.05，表明ESP的骨密度有统计学意义。在其他迭代算法中，相同迭代算法下的不同mAs值P< 0.05，表明骨密度无差异。相同mAs联合不同迭代重建下，L1、L2、L3椎体骨密度差异P < 0.05。FBP重建期间，L1的骨密度变化较大，而IMR[1]和IMR bb0的重建变化较小。在FBP重建期间，L2的骨密度变化更大，而在IMR bb0中观察到的变化较小。在FBP重建期间，L3的BMD变化较大，而在所有水平的iDose4和IMR[2]重建期间，BMD变化较小。此外，随着mAs的持续激励，各种算法的cnr持续增加。其中，FBP算法的CNR最低，IMR[3]算法的CNR最高。结论：用QCT在ESP多中心重复测量骨密度显示，IMR[2]算法下L1-L3骨密度变化最小。建议结合IMR[2]算法，在120kv、20ma下进行扫描。这样可以准确测量脊柱的骨密度，同时显著降低辐射剂量，提高成像质量。
Background: To investigate the repeatability and accuracy of quantitative CT (QCT) measurement of bone mineral density (BMD) by low-mAs using iterative model reconstruction (IMR) technique based on phantom model.Methods: European spine phantom (ESP) was selected and measured on the Philips Brilliance iCT Elite FHD machine for 10 times. Data were transmitted to the QCT PRO workstation to measure BMD (mg/cm(3)) of the ESP (L1, L2, L3). Scanning method: the voltage of X-ray tube is 120 kV, the electric current of X-ray tube output in five respective groups A-E were: 20, 30, 40, 50 and 60 mAs. Reconstruction: all data were reconstructed using filtered back projection (FBP), IR levels of hybrid iterative reconstruction (iDose(4), levels 1, 2, 3, 4, 5, 6 were used) and IMR (levels 1, 2, 3 were used). ROIs were placed in the middle of L1, L2 and L3 spine phantom in each group. CT values, noise and contrast-to-noise ratio (CNR) were measured and calculated. One-way analysis of variance (ANOVA) was used to compare BMD values of different mAs and different IMR.Results: Radiation dose [volume CT dose index (CTDIvol) and dose length product (DLP)] was positively correlated with tube current. In L1 with low BMD, different mAs in FBP showed P< 0.05, indicating statistically significant BMD in ESP. In other iterative algorithms, different mAs under same iterative algorithms showed P> 0.05, indicating no difference in BMD. And P> 0.05 was observed among BMD of spine phantom in L1, L2 and L3 under same mAs joined with varied iterative reconstruction. The BMD in L1 varied greatly during FBP reconstruction, and less variation was observed in reconstruction of IMR [1] and IMR [2]. The BMD of L2 changed more during FBP reconstruction, where less was observed in IMR [2]. The BMD of L3 varied greatly during FBP reconstruction, and was less varied in all levels of iDose4 and reconstruction of IMR [2]. In addition, along with continuous mAs incensement, the CNRs in various algorithms continued to increase. Among them, CNR with the FBP algorithm is the lowest, and CNR of the IMR [3] algorithm is the highest.Conclusions: Repeated measurements of BMD with QCT in the ESP multicenter showed that BMD changes in L1-L3 are the least varied at IMR [2] algorithm. It is recommended to scan at 120 kV with 20 mAs combined with IMR [2] algorithm. In this way, the BMD of spine by QCT could be accurately measured, while radiation dosage significantly reduced and imaging quality improved at the same time.