双源CT低电压迭代重建联合分次注射法低辐射泌尿系造影的可行性研究

目的 评估双源CT （DSCT）低电压迭代重建联合分次注射法（SBI）行CT泌尿系造影（CTU）的辐射剂量、图像质量和影像诊断准确率。方法 连续80例临床初诊为泌尿道疾病而准备行CTU检查的患者依据随机数字表法分为对照组和试验组两组。对照组40例采用常规注射,常规电压（120 kV）,滤波反投影法（filtered back-project,FBP）重建,试验组40例采用分次注射法,低电压扫描（80 kV）,正弦迭代重建（sinogram affirmed iterative reconstruction,SAFIRE）,评估两组的有效剂量E、图像质量及影像诊断准确率。结果 共77例患者顺利完成检查和图像评估,其中对照组39例,试验组38例。试验组的平均有效剂量E为（3.93±0.85）mSv,低于对照组的（26.68±4.07）mSv （t=-33.78,P<0.05）。两组图像质量主观评分分别为（4.49±0.79）分和（4.39±1.53）分,差异无统计学意义（P>0.05）。试验组的信噪比（SNR）为127.3±15.9,明显高于对照组的109.6±13.2,差异有统计学意义（t=4.49,P<0.05）,但对比噪声比（CNR）分别为100.84±12.92和108.96±14.42,差异无统计学意义（P>0.05）。两组最终诊断准确率分别为84.62%和81.58%,差异无统计学意义（P>0.05）。结论 双源CT低电压扫描迭代重建联合分次注射法CTU检查可大幅度降低辐射剂量,但图像质量主观评分、CNR值和影像诊断准确率未受明显影响。     

Flash双源CT在小儿低剂量CT尿路成像中的应用

目的 探讨Flash双源CT低剂量措施在小儿CT尿路成像（CT Urography,CTU）中的应用可行性.方法 30例经腹部超声（ultrasonography,USG）检查疑患尿路积水或畸形的儿童（≤15kg）行Flash模式低剂量CTU检查.直接行增强后实质期和分泌期扫描,扫描预设参数设为70kV,自适应动态管电流.记录和统计每个病例的扫描时间及剂量长度积（dose-length product,DLP）.每一位病例实质期分别采用传统的滤过反投影法（filtered back projection,FBP）和1～5级迭代重建技术（sinogram affirmed iterativere construction,SAFIRE）对原始数据进行重建,比较不同重建图像在同一层面的平均CT值、噪声、信噪比（signal to noise ratio,SNR）和对比噪声比（contrast to noise ratio,CNR）及主观评分,并进行统计学分析.结果 本组病例Flash双源CTU检查扫描时间范围为o.62～0.82s,实质期和延迟期总体扫描剂量（DLP）范围为20～34mGy＊ cm.有效剂量（effective dose,ED）范围为0.60～0.68mSv,SAFIRE重建图像的SNR值及CNR均高于FBP组,其中CNR随着迭代重建级别的升高呈线性升高.SAFIRE-3级图像评分最优.结论 Flash双源CT的低剂量措施适用于小儿CTU检查,不仅扫描时间短,同时也可以满足临床诊断要求,而且这个扫描条件仍然有降低优化的可能性.     

A study of using a deep learning image reconstruction to improve the image quality of extremely low-dose contrast-enhanced abdominal CT for patients with hepatic lesions

Objective:To investigate the feasibility of using deep learning image reconstruction (DLIR) to significantly reduce radiation dose and improve image quality in contrast-enhanced abdominal CT.Methods:This was a prospective study. 40 patients with hepatic lesions underwent abdominal CT using routine dose (120kV, noise index (NI) setting of 11 with automatic tube current modulation) in the arterial-phase (AP) and portal-phase (PP), and low dose (NI = 24) in the delayed-phase (DP). All images were reconstructed at 1.25 mm thickness using ASIR-V at 50% strength. In addition, images in DP were reconstructed using DLIR in high setting (DLIR-H). The CT value and standard deviation (SD) of hepatic parenchyma, spleen, paraspinal muscle and lesion were measured. The overall image quality includes subjective noise, sharpness, artifacts and diagnostic confidence were assessed by two radiologists blindly using a 5-point scale (1, unacceptable and 5, excellent). Dose between AP and DP was compared, and image quality among different reconstructions were compared using SPSS20.0.Results:Compared to AP, DP significantly reduced radiation dose by 76% (0.76 ± 0.09 mSv vs 3.18 ± 0.48 mSv), DLIR-H DP images had lower image noise (14.08 ± 2.89 HU vs 16.67 ± 3.74 HU, p < 0.001) but similar overall image quality score as the ASIR-V50% AP images (3.88 ± 0.34 vs 4.05 ± 0.44, p > 0.05). For the DP images, DLIR-H significantly reduced image noise in hepatic parenchyma, spleen, muscle and lesion to (14.77 ± 2.61 HU, 14.26 ± 2.67 HU, 14.08 ± 2.89 HU and 16.25 ± 4.42 HU) from (24.95 ± 4.32 HU, 25.42 ± 4.99 HU, 23.99 ± 5.26 HU and 27.01 ± 7.11) with ASIR-V50%, respectively (all p < 0.001) and improved image quality score (3.88 ± 0.34 vs 2.87 ± 0.53; p < 0.05).Conclusion:DLIR-H significantly reduces image noise and generates images with clinically acceptable quality and diagnostic confidence with 76% dose reduction.Advances in knowledge:(1) DLIR-H yielded a significantly lower image noise, higher CNR and higher overall image quality score and diagnostic confidence than the ASIR-V50% under low signal conditions. (2) Our study demonstrated that at 76% lower radiation dose, the DLIR-H DP images had similar overall image quality to the routine-dose ASIR-V50% AP images.     

64-Slice CT urography: optimisation of radiation dose

Purpose

This study assessed means by which to optimise 64-slice computed tomography urography (CTU) in evaluating the urinary tract, with a view to obtaining the best trade-off between image quality and radiation dose.

Materials and methods

Image quality was analysed in terms of spatial and contrast resolution on several scans of a phantom performed with automatic dose modulation and different reconstruction kernels and accepted noise level. Data were compared with the radiation dose values recorded for 52 patients who underwent CTU examination.

Results

Radiation dose and image quality differed considerably depending on the reconstruction parameters, even though a higher dose did not always imply better image definition. Data obtained in the phantom were consistent with those obtained in patients. Depending on the clinical problem, the radiation dose varied from 6.2 to 17.6 mSv.

Conclusions

CTU cannot be considered a standard examination: the scan parameters need to be adapted to the image quality required for the specific clinical problem.     

螺旋CT尿路成像在小儿上尿路疾病诊断中的价值

目的 比较螺旋CTN水路成像（CTU）与静脉尿路造影（IVU），磁共振尿路成像（RU）在小儿上尿路疾病检查中的应用，探讨CTU对各种上尿路外科疾病的诊断价值。方法 62例疑上尿路病变儿童均做了CTU检查，31例同时行IVU检查，13例同时行MRU检查作为对照。对上尿路各部位的显影清晰度进行了评分，比较3种检查方法对上尿路各段的显示能力。按病种分类，评价CTU对儿童各种上尿路外科疾病的诊断价值，并与IVU，MRU比较。结果 在尿路形态正常组，CTU和IVU对上尿路各段的显影统计学上差异无显著性意义，且均好于MRU（P＜0．01）。在异常组，CTU对肾盏，肾盂的显示优于IVU和MRU（P＜0．01）；上段输尿管的显影，三者间统计学上差异无显著性意义；中，下段输尿管的显示，CTU，MRU均高于IVU，且统计学上差异有显著性意义（P＜0．01）。CTU对重复肾输尿管畸形，肾发育不良的诊断符合率均为100％。高于IVU和RU;峄上尿路积水的诊断符合率，CTU，MRU均为100％，高于IVU（62．5％）。结论 CTU为诊断小儿上尿路外科疾病提供了确切依据，解决了诊断中的难题，提高了诊断率。如疑有肾发育不良，重复肾输尿管畸，肾输尿管重度损伤等上尿路外科疾病，可首选CTU检查。     

Low-dose whole-body CT using deep learning image reconstruction: image quality and lesion detection

Objectives:To evaluate image quality and lesion detection capabilities of low-dose (LD) portal venous phase whole-body computed tomography (CT) using deep learning image reconstruction (DLIR).Methods:The study cohort of 59 consecutive patients (mean age, 67.2 years) who underwent whole-body LD CT and a prior standard-dose (SD) CT reconstructed with hybrid iterative reconstruction (SD-IR) within one year for surveillance of malignancy were assessed. The LD CT images were reconstructed with hybrid iterative reconstruction of 40% (LD-IR) and DLIR (LD-DLIR). The radiologists independently evaluated image quality (5-point scale) and lesion detection. Attenuation values in Hounsfield units (HU) of the liver, pancreas, spleen, abdominal aorta, and portal vein; the background noise and signal-to-noise ratio (SNR) of the liver, pancreas, and spleen were calculated. Qualitative and quantitative parameters were compared between the SD-IR, LD-IR, and LD-DLIR images. The CT dose-index volumes (CTDI_vol) and dose-length product (DLP) were compared between SD and LD scans.Results:The image quality and lesion detection rate of the LD-DLIR was comparable to the SD-IR. The image quality was significantly better in SD-IR than in LD-IR (p < 0.017). The attenuation values of all anatomical structures were comparable between the SD-IR and LD-DLIR (p = 0.28–0.96). However, background noise was significantly lower in the LD-DLIR (p < 0.001) and resulted in improved SNRs (p < 0.001) compared to the SD-IR and LD-IR images. The mean CTDI_vol and DLP were significantly lower in the LD (2.9 mGy and 216.2 mGy•cm) than in the SD (13.5 mGy and 1011.6 mGy•cm) (p < 0.0001).Conclusion:LD CT images reconstructed with DLIR enable radiation dose reduction of >75% while maintaining image quality and lesion detection rate and superior SNR in comparison to SD-IR.Advances in knowledge:Deep learning image reconstruction algorithm enables around 80% reduction in radiation dose while maintaining the image quality and lesion detection compared to standard-dose whole-body CT.     

Delineation of upper urinary tract segments at MDCT urography in patients with extra-urinary mass lesions: retrospective comparison of standard and low-dose protocols for the excretory phase of imaging

Purpose  

Excretory-phase CT urography (CTU) may replace excretory urography in patients without urinary tumors. However, radiation exposure is a concern. We retrospectively compared upper urinary tract (UUT) delineation in low-dose and standard CTU.     

64排螺旋CT尿路成像质量与肾脏功能的相关性研究

目的探讨64排螺旋cT尿路成像（CTU）质量与年龄、图像捕获时间相关性．并依据肾脏功能差异,探讨CTU技术操作规范及成像标准。方法回顾性分析78例患者的CTU质量。结果对照组年龄〈45岁延迟3～5min图像显示好,45～60岁组延迟6-8min显示好,〉60岁组延迟9～10min显示好;肾功能异常组成像质量与对照组基本一致。结论CTU成像质量与肾脏排泄功能无明显相关性,主要与图像捕获时间以及患者年龄有关。     

Image quality of ultra-low-dose dual-source CT angiography using high-pitch spiral acquisition and iterative reconstruction in young children with congenital heart disease

BackgroundObtaining diagnostic CT image quality with ultra-low radiation dose in young children with congenital heart disease remains challenging.ObjectiveWe evaluated the feasibility and image quality of prospectively electrocardiogram (ECG)-triggered high-pitch spiral acquisition with iterative reconstruction for pediatric cardiovascular CT angiography.MethodsSixty-two consecutive pediatric patients younger than 2 years with congenital heart disease underwent prospectively ECG-triggered high-pitch spiral dual-source CT acquisition. Patients were randomly assigned into 2 groups: full tube current (40–70 mAs) scans with filtered back projection reconstruction (group A) and half tube current (20–35 mAs) scans with sinogram-affirmed iterative reconstruction (group B). Attenuation, noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and subjective image quality were compared between the 2 groups. Effective radiation dose was also estimated for both groups.ResultsNo significant difference was found in the attenuation, image noise, SNR, and CNR between the 2 groups in the same evaluated anatomic regions, whereas the attenuation and image noise were slightly lower, and the SNR and CNR were slightly higher in group B. No significant difference was found in subjective image quality between the 2 groups (4.27 ± 0.73 vs. 4.34 ± 0.42; P = .813). Effective dose was 0.06 ± 0.03 mSv in group B and 0.13 ± 0.04 mSv in group A, reflecting dose savings of 53.8% by using iterative reconstruction.ConclusionsA combination of prospectively ECG-triggered high-pitch spiral acquisition, low tube current, and iterative reconstruction may offer diagnostic image quality in pediatric cardiovascular CT angiography with effective radiation dose < 0.1 mSv.     

深度学习重建算法改善颅脑低剂量CT图像质量的可行性研究

目的探讨深度学习重建算法(DLIR)较自适应统计迭代重建(ASIR-V)算法在改善颅脑低剂量CT图像质量方面的效果。方法回顾性纳入2021年11月至2022年8月在解放军总医院第二医学中心接受颅脑CT检查的患者, 对所有患者的低剂量CT采用4种不同算法重建:获得30%强度ASIR-V(ASIR-V-30%)图像、低强度DLIR(DLIR-L)图像、中等强度DLIR(DLIR-M)图像和高强度DLIR(DLIR-H)图像。在4组图像的表浅白质、表浅灰质、深部白质和深部灰质内选取感兴趣区并测量其CT值, 计算信噪比(SNR)和对比噪声比(CNR)。由3名神经影像医师按照Likert 5分量表对图像质量进行主观评分。对4组图像的客观、主观评分进行分析, 若总体存在差异, 则进行组内两两比较。结果共纳入109例患者, 男104例、女5例, 年龄65～110岁, 平均(89.16±9.53)岁。颅脑CT低剂量扫描的辐射剂量为(0.93±0.01)mSv, 显著低于常规扫描(2.92±0.01)mSv(t = 56.15, P < 0.05 )。颅脑低剂量CT的4组图像的SNR深部灰质、SN...     

The adaptive statistical iterative reconstruction-V technique for radiation dose reduction in abdominal CT: comparison with the adaptive statistical iterative reconstruction technique

Objective:

To investigate whether reduced radiation dose abdominal CT images reconstructed with adaptive statistical iterative reconstruction V (ASIR-V) compromise the depiction of clinically competent features when compared with the currently used routine radiation dose CT images reconstructed with ASIR.

Methods:

27 consecutive patients (mean body mass index: 23.55 kg m⁻² underwent CT of the abdomen at two time points. At the first time point, abdominal CT was scanned at 21.45 noise index levels of automatic current modulation at 120 kV. Images were reconstructed with 40% ASIR, the routine protocol of Dong-A University Hospital. At the second time point, follow-up scans were performed at 30 noise index levels. Images were reconstructed with filtered back projection (FBP), 40% ASIR, 30% ASIR-V, 50% ASIR-V and 70% ASIR-V for the reduced radiation dose. Both quantitative and qualitative analyses of image quality were conducted. The CT dose index was also recorded.

Results:

At the follow-up study, the mean dose reduction relative to the currently used common radiation dose was 35.37% (range: 19–49%). The overall subjective image quality and diagnostic acceptability of the 50% ASIR-V scores at the reduced radiation dose were nearly identical to those recorded when using the initial routine-dose CT with 40% ASIR. Subjective ratings of the qualitative analysis revealed that of all reduced radiation dose CT series reconstructed, 30% ASIR-V and 50% ASIR-V were associated with higher image quality with lower noise and artefacts as well as good sharpness when compared with 40% ASIR and FBP. However, the sharpness score at 70% ASIR-V was considered to be worse than that at 40% ASIR. Objective image noise for 50% ASIR-V was 34.24% and 46.34% which was lower than 40% ASIR and FBP.

Conclusion:

Abdominal CT images reconstructed with ASIR-V facilitate radiation dose reductions of to 35% when compared with the ASIR.

Advances in knowledge:

This study represents the first clinical research experiment to use ASIR-V, the newest version of iterative reconstruction. Use of the ASIR-V algorithm decreased image noise and increased image quality when compared with the ASIR and FBP methods. These results suggest that high-quality low-dose CT may represent a new clinical option.     

Impact of 80 kVp with iterative reconstruction algorithm and low-dose contrast medium on the image quality of craniocervical CT angiography

PurposeTo assess the image quality of 80-kVp craniocervical CT angiography (CCCTA) protocol combined with adaptive statistical iterative reconstruction-V (ASIR-V) and low-dose contrast medium (CM).MethodsA total of 119 patients were randomly divided into three groups. For group A, 120-kVp protocol was followed with 60 ml CM and filtered back projection; for group B, 80-kVp protocol with 60 ml CM and ASIR-V; and for group C, 80-kVp protocol with 45 ml CM and ASIR-V. Both subjective and objective image quality and radiation doses were evaluated.ResultsArterial attenuation, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the head, neck, and shoulder regions were significantly higher in groups B and C compared with group A. Group C yielded significantly better subjective image quality than that observed in groups A and B (both p < .05). As compared with group A, effective radiation dose and the iodine load of group C were reduced by 51.4% and 25%, respectively.ConclusionsThe CCCTA protocol with 80 kVp, ASIR-V, and 45 ml of CM injected at 3 ml/s significantly reduced the radiation dose, iodine load, and iodine delivery rate while providing better subjective and objective image quality, including higher arterial enhancement and a higher SNR and CNR compared with the 120-kVp protocol.     

Comparison of quality of urinary bladder filling in CT urography with different doses of furosemide in the work-up of patients with macroscopic hematuria

IntroductionThe protocol for preparation of computed tomography urography (CTU) examinations at our hospital was changed in 2013 to improve the quality of urinary bladder filling in the excretory phase. The aim of this study was to evaluate the quality of urinary bladder filling on CTU after different doses of furosemide were administered to patients with macroscopic hematuria.MethodsThe cohort was 215 patients who underwent elective CTU due to macroscopic hematuria between 2014 and 2018. 5 mg furosemide were administrated to 100 patients, 2.5 mg to 100 patients and 0 mg to 15 patients. Contrast medium layered bladders were excluded, leaving 193 patients: 92, 89 and 12 in each group. Urinary bladder volume was calculated in corticomedullary (CMP) and excretory phase (EP). Bladder distension was classified as satisfactory or not. Attenuation of bladder content in EP was noted.ResultsAverage volume in EP was 370 ± 224 ml (28–1052) after 5 mg furosemide, 274 ± 120 ml (43–628) after 2.5 mg and 180 ± 104 ml (53–351) after 0 mg. 85% of the bladders were satisfactory distended after 5 mg, 80% after 2.5 mg and 58% after 0 mg. Average attenuation was 266 ± 89 HU (103–524) after 5 mg, 362 ± 156 HU (118–948) after 2.5 mg and 761 ± 331 HU (347–1206) after 0 mg. The differences in volume and attenuation were significant.Conclusion5 mg furosemide is preferred rather than 2.5 mg in preparation for CTU examinations of patients with macroscopic hematuria. There was no difference between the doses concerning rate of satisfactory bladder distension, but the higher dose resulted in larger bladder volume and more suitable attenuation of bladder content.Implications for practiceDevelopment of CTU-image quality could improve bladder cancer diagnostics.     

CT尿路造影对非结石性尿路梗阻疾病的诊断作用

目的评价CT尿路造影(CTU)对非结石性尿路梗阻疾病的诊断作用。方法40例非结石性尿路梗阻病例给予实质期、分泌期增强螺旋扫描。分泌期数据经第2次重建后在工作站以三维方式获得CTU影像。结果40例中，24例良性梗阻呈轻度或重度积水。18例先天畸形CTU呈现各自特征；4例输尿管炎表现为鸟嘴样狭窄，2例前列腺增生可见膀胱后壁压迹。16例肿瘤患者梗阻端呈截断或锥状狭窄伴局部软组织影，12例尿路中度积水，4例重度积水。其中4例呈双侧积水。对6例一侧无分泌功能者，可采用最小强度投影等予以显示，并与对侧最大强度投影像等整合。结论CTU对非结石性尿路梗阻疾病的诊断具有良好的效果。     

Head and neck single- and dual-energy CT: differences in radiation dose and image quality of 2nd and 3rd generation dual-source CT

Objectives:To compare radiation dose and image quality of single-energy (SECT) and dual-energy (DECT) head and neck CT examinations performed with second- and third-generation dual-source CT (DSCT) in matched patient cohorts.Methods:200 patients (mean age 55.1 ± 16.9 years) who underwent venous phase head and neck CT with a vendor-preset protocol were retrospectively divided into four equal groups (n = 50) matched by gender and BMI: second (Group A, SECT, 100-kV; Group B, DECT, 80/Sn140-kV), and third-generation DSCT (Group C, SECT, 100-kV; Group D, DECT, 90/Sn150-kV). Assessment of radiation dose was performed for an average scan length of 27 cm. Contrast-to-noise ratio measurements and dose-independent figure-of-merit calculations of the submandibular gland, thyroid, internal jugular vein, and common carotid artery were analyzed quantitatively. Qualitative image parameters were evaluated regarding overall image quality, artifacts and reader confidence using 5-point Likert scales.Results:Effective radiation dose (ED) was not significantly different between SECT and DECT acquisition for each scanner generation (p = 0.10). Significantly lower effective radiation dose (p < 0.01) values were observed for third-generation DSCT groups C (1.1 ± 0.2 mSv) and D (1.0 ± 0.3 mSv) compared to second-generation DSCT groups A (1.8 ± 0.1 mSv) and B (1.6 ± 0.2 mSv). Figure-of-merit/contrast-to-noise ratio analysis revealed superior results for third-generation DECT Group D compared to all other groups. Qualitative image parameters showed non-significant differences between all groups (p > 0.06).Conclusion:Contrast-enhanced head and neck DECT can be performed with second- and third-generation DSCT systems without radiation penalty or impaired image quality compared with SECT, while third-generation DSCT is the most dose efficient acquisition method.Advances in knowledge:Differences in radiation dose between SECT and DECT of the dose-vulnerable head and neck region using DSCT systems have not been evaluated so far. Therefore, this study directly compares radiation dose and image quality of standard SECT and DECT protocols of second- and third-generation DSCT platforms.     

基于多模型的迭代重建技术对低剂量CT结肠成像图像质量的影响

目的 评价Revolution CT应用不同水平基于多模型的迭代重建算法（ASIR-V）对提高低剂量CT结肠成像图像质量的能力。方法 选用离体猪结肠获得模拟息肉30个,使用Revolution CT在不同扫描条件（管电压120 kVp,管电流10、30、50、70、90、100、120、140、160、180、200、220、240、260 mA）下扫描,分别应用6种不同水平ASIR-V（0、10%、30%、50%、70%、90%）算法进行图像重建。两名观察者盲法对84组CT结肠成像重组图像[CT仿真内镜（CTVE）、多平面重建（MPR）、容积再现（VR）、虚拟分割（VD）]分别进行主观质量评分（4分制）,同时独立测量图像噪声（SD）、信噪比（SNR）及对比噪声比（CNR）。比较图像质量主观评分一致性及不同管电流、不同水平ASIR-V重建图像的SD、SNR、CNR差异。结果 两观察者图像质量主观评分一致性好（Kappa值=0.683）,管电流（r=0.734,P=0.000）及ASIR-V水平（r=0.220,P=0.044）的变化与图像质量主观评分相关,相同管电流条件下,50% ASIR-V重建图像质量主观评分最高。两观察者客观数据一致性良好。不同管电流、不同水平ASIR-V重建图像的SD、SNR及CNR差异均具有统计学意义（F=423.58、124.26、1 030.17,P<0.05）。同一管电流水平下,随着ASIR-V水平增高,图像SD降低,CNR增大;图像SNR在管电流为10、120、140、160、220、240、260 mA水平下差异具有统计学意义（F=8.75~31.36,P<0.05）。相同水平的ASIR-V重建,随管电流增大,图像SD下降,SNR及CNR逐渐升高。结论 CT结肠成像中,应用ASIR-V算法可以显著降低噪声,提高图像对比噪声比,提高图像质量,且50% ASIR-V水平在降噪能力方面更为显著。     

Reducing contrast medium dose with low photon energy images in renal dual-energy spectral CT angiography and adaptive statistical iterative reconstruction (ASIR)

Objective:To evaluate the value of using low energy (keV) images in renal dual-energy spectral CT angiography (CTA) and adaptive statistical iterative reconstruction (ASIR) to reduce contrast medium dose.Methods:40 patients with renal CTA on a Discovery CT750HD were randomly divided into two groups: 20 cases (Group A) with 600 mgI kg⁻¹ and 20 cases (Group B) with 300 mgI kg⁻¹. The scan protocol for both groups was: dual-energy mode with mA selection for noise index of 10 HU, pitch 1.375:1, rotating speed 0.6 s/r. Images were reconstructed at 0.625 mm thickness with 40%ASIR, Group A used the conventional 70keV monochromatic images, and Group B used monochromatic images from 40 to 70 keV at 5 keV interval for analysis. The CT values and standard deviation (SD) values of the renal artery and erector spine in the plain and arterial phases were measured with the erector spine SD value representing image noise. The enhancement degree of the renal artery (ΔCT = CT(arterial) -CT(plain)), signal-to-noise ratio (SNR=CT_renal-artery/SD_renal-artery) and contrast-to-noise ratio (CNR=(CT_renal-artery-CT_{erector spine})/SD_{erector-spine}) were calculated. The single factor analysis of variance was used to analyze the difference of ΔCT, SNR and CNR among image groups with p < 0.05 being statistically significant. The subjective image scores of the groups were assessed blindly by two experienced physicians using a 5-point system and the score consistency was compared by the κ test.Results:Contrast medium dose in the 300 mgI kg⁻¹ group was reduced by 50% compared with the 600 mgI kg⁻¹ group, while radiation dose was similar between the two groups. The subjective scores were 4.00 ± 0.65, 4.50 ± 0.60 and 3.70 ± 0.80 for images at 70 keV (600 mgI kg⁻¹ group), 40 keV (300 mgI kg⁻¹ group) and 45 keV (300 mgI kg⁻¹ group), respectively with good consistency between the two reviewers (p > 0.05). The 40 keV images in the 300 mgI kg⁻¹ group had similar ΔCT (469.77 ± 86.95 HU vs 398.54 ± 73.68 HU) and CNR (15.52 ± 3.32 vs 18.78 ± 6.71) values as the 70 keV images in the 600 mgI kg⁻¹) group but higher SNR values (30.19 ± 4.41 vs 16.91 ± 11.12, p < 0,05)Conclusion:Contrast dose may be reduced by 50% while maintaining image quality by using lower energy images combined with ASIR in renal dual-energy CTA.Advances in knowledge:Combined with ASIR and energy spectrum, can reduce the amount of contrast dose in renal CTA.     

The clinical effectiveness of reconstructing 18F-sodium fluoride PET/CT bone using Bayesian penalized likelihood algorithm for evaluation of metastatic bone disease in obese patients

Objective:A new Bayesian penalized likelihood reconstruction algorithm for positron emission tomography (PET) (Q.Clear) is now in clinical use for fludeoxyglucose (FDG) PET/CT. However, experience with non-FDG tracers and in special patient populations is limited. This pilot study aims to compare Q.Clear to standard PET reconstructions for ¹⁸F sodium fluoride (¹⁸F-NaF) PET in obese patients.Methods:30 whole body ¹⁸F-NaF PET/CT scans (10 patients with BMI 30–40 Kg/m² and 20 patients with BMI >40 Kg/m²) and a NEMA image quality phantom scans were analyzed using ordered subset expectation maximization (OSEM) and Q.Clear reconstructions methods with B400, 600, 800 and 1000. The images were assessed for overall image quality (IQ), noise level, background soft tissue, and lesion detectability, contrast recovery (CR), background variability (BV) and contrast-to-noise ratio (CNR) for both algorithms.Results:CNR for clinical cases was higher for Q.Clear than OSEM (p < 0.05). Mean CNR for OSEM was (21.62 ± 8.9), and for Q.Clear B400 (31.82 ± 14.6), B600 (35.54 ± 14.9), B800 (39.81 ± 16.1), and B1000 (40.9 ± 17.8). As the β value increased the CNR increased in all clinical cases. B600 was the preferred β value for reconstruction in obese patients. The phantom study showed Q.Clear reconstructions gave lower CR and lower BV than OSEM. The CNR for all spheres was significantly higher for Q.Clear (independent of β) than OSEM (p < 0.05), suggesting superiority of Q.Clear.Conclusion:This pilot clinical study shows that Q.Clear reconstruction algorithm improves overall IQ of ¹⁸F-NaF PET in obese patients. Our clinical and phantom measurement results demonstrate improved CNR and reduced BV when using Q.Clear. A β value of 600 is preferred for reconstructing ¹⁸F-NaF PET/CT with Q.Clear in obese patients.Advances in knowledge:¹⁸F-NaF PET/CT is less susceptible to artifacts induced by body habitus. Bayesian penalized likelihood reconstruction with¹⁸F-NaF PET improves overall IQ in obese patients.     

自适应迭代技术（ASIR-V）不同级别重建对于低剂量CT图像质量影响的研究

目的 探讨新一代自适应迭代重建-V(ASIR-V)不同重建级别对低剂量CT图像质量的影响及最佳重建级别。方法 选取临床需要进行胸腹部增强CT扫描的患者96例,门静脉期扫描选择能谱序列,图像后处理均采用ASIR-V技术,并设置6个不同重建级别（0%、20%、40%、60%、80%、100%）。测量肝脏、脾脏、肾脏、竖脊肌及脂肪的CT和SD值并计算信噪比（SNR）、对比噪声比（CNR）和图像噪声（SD）;图像质量按1～5分予以主观评分。采用SPSS 22.0软件进行统计学分析,P<0.05为差异有统计学意义。结果 1）客观评价：肝脏、脾脏、肾脏实质不同重建级别的CNR、SNR及SD值差异均有统计学意义。随着重建级别的增加,图像SNR、CNR值逐渐增大,噪声SD逐渐降低,图像质量提高;2）主观评价：ASIR-V 0%、100%重建的图像质量最差,60%～80%范围图像质量评分最高;40%和100%、60%和80%组间对比差异无统计学意义,余各组间差异均具有统计学意义。结论 综合主客观评价,设置ASIR-V重建级别能够不同程度优化低剂量扫描图像质量,过度迭代图像蜡样质感较严重,组织对比明...     

MSCT曲面重组尿路成像与MRU对泌尿系病变的诊断比较

目的:比较MSCT曲面重组尿路成像(CTU)与磁共振尿路成像(MRU)在泌尿系病变检查中显示和诊断疾病的能力,探讨CTU、MRU对泌尿系病变的定位、定性诊断价值。方法:24例临床提示有泌尿系病变的患者,行MRI检查,采用单次激发快速自旋回波(SSFSE)序列,行MRU检查,同期采用10mm层厚层距,完成从肾上极至耻骨联合下缘CT平扫及增强扫描,获得原始横断面图像,将22例肾实质期和6例肾排泄期图像进行后处理,获得冠状面、矢状面及任意斜面尿路图像,在此基础上,再沿尿路走行方向管腔中心划曲线,进行曲面重组(CPR),获得CTU图像。采用盲法,比较CTU、MRU对泌尿系病变的定位、定性诊断价值。结果:CTU、MRU均对泌尿系梗阻病变部位作出明确诊断,定位诊断符合率为100%;CTU、MRU定性诊断符合率分别为100%和58.8%。对输尿管下段的显示CTU优于MRU,CTU能清楚地显示尿路全貌及其周围组织结构。结论:CTU、MRU对泌尿系梗阻病变均能明确定位;CTU定性诊断符合率明显高于MRU,能更直观显示泌尿系病变与扩张肾盂、输尿管的关系,在泌尿系病变诊断方面具有独特的优势。