OBJECTIVES:Computed tomography perfusion (CTP) and computed tomography angiography (CTA) have been recommended to select acute ischemic stroke (AIS) patients for endovascular thrombectomy (EVT) but are not widely used for post-treatment evaluation. We aimed to observe abnormalities in CTP and CTA before and after EVT and evaluate post-EVT CTP and CTA as potential tools for improving clinical outcome prediction. METHODS:Patients with AIS who underwent EVT and received CTP and CTA before and after EVT were retrospectively evaluated. The ischemic core was defined as the volume of relative cerebral blood flow <30% and hypoperfusion as the volume of Tmax >6 s. A reduction in hypoperfusion volume >90% between baseline and post-EVT CTP was defined as tissue optimal reperfusion (TOR). The 90-day modified Rankin scale was used to evaluate the clinical outcome. RESULTS:Eighty-three patients were included. Patients with an absent ischemic core or with TOR after EVT had a higher rate of modified Thrombolysis in Cerebral Ischemia score 2c-3 and recanalization of post-treatment vessel condition based on follow-up CTA. Multivariable logistic regression revealed that the baseline ischemic core volume (OR:0.934, p=0.009), TOR (OR:8.322, p=0.029) and immediate NIHSS score after EVT (OR:0.761, p=0.012) were factors significantly associated with good clinical outcome. Combining baseline ischemic core volume and TOR with immediate NIHSS score after EVT showed greatest performance for good outcome prediction after EVT(AUC=0.921). CONCLUSIONS:The addition of pretreatment and post-treatment CTP information to purely clinical NIHSS scores might help to improve the efficacy for good outcome prediction after EVT.

Background:Accurate prediction of subsequent infarct volume in acute ischemic stroke (AIS) patients helps determine appropriate interventions and prognosis. The objectives are to assess whether early multimodal CT imaging characteristics of wake-up stroke (WUS) patients could predict post-reperfusion infarct volume and evaluate the accuracy of baseline infarct and penumbra volumes for predicting follow-up infarct volume.Methods:This retrospective study included WUS patients, last seen well (LSW) >6 h, with multimodal CT imaging at baseline. Baseline non-contrast CT (NCCT) and CT perfusion were analyzed using RAPID software, and CT angiography using maximum intensity projection. Post-reperfusion infarct volume was assessed at 24-h following reperfusion on magnetic resonance diffusion-weighted imaging (DWI). Patients were stratified by treatment module for analyses.Results:Of 34 eligible patients, 9 (26.5%) received intravenous recombinant tissue plasminogen activator (r-tPA) alone and 25 (73.5%) received both endovascular thrombectomy (EVT) and r-tPA. All patients had a strong correlation between baseline NCCT alberta stroke program early CT score, clot burden score (CBS), Tan score, infarct volume, penumbra volume with 24-h post-reperfusion infarct volume (respectively, r=0.172, P=0.015; r=0.118, P=0.047; r=0.149, P=0.024; r=0.311, P=0.001 and r=0.120; P=0.045). Among reperfusion therapies, WUS patients who received EVT had a significantly lower 24-h post-reperfusion infarct volume and had a significant difference between baseline infarct volume and 24-h post-reperfusion infarct volume (respectively, 82 vs. 14, P=0.032 and 47 vs. 14, P=0.04).Conclusions:Primarily obtained multimodal CT imaging characteristics may predict post-reperfusion infarct volume in WUS patients, and those who underwent EVT had a significantly lower post-reperfusion infarct volume.

目的 通过评价急性缺血性卒中患者CT灌注成像病变区流量提取乘积(FED)和相对流量提取乘积(rFED)与脑动脉取栓术后对比剂外渗的相关性,探讨其对对比剂外渗风险的预测价值.方法 选取责任血管为单侧大脑中动脉,行脑动脉机械取栓术成功再通的急性缺血性卒中患者,术前行CTP检查获得灌注参数FED、rFED(rFED等于患侧FED值/健侧FED值).术后24 h内行双能头颅CT检查,按照结果分为无对比剂外渗组和对比剂外渗组.结果 37例患者纳入分析观察,对比剂外渗组13例、无对比剂外渗组24例.无对比剂外渗组中位FED值为7.17 ml/100 ml × min,中位rFED值为3.83;外渗组中位FED值为8.94 ml/100 ml × min,中位rFED值为7.39,外渗组的中位FED、中位rFED值均高于无对比剂外渗组,二组间差异均有统计学意义(P＜0.05).ROC分析显示FED的cutoff值为6.32,敏感度为100％,特异度为46.0％;rFED的cutoff值为4.79,敏感度为84.6％,特异度为75.0％.结论 rFED用于预测急性卒中患者动脉机械取栓术后发生对比剂外渗的准确性更高.

目的 对比观察醒后卒中(WUS)与时间窗明确卒中(OCS)患者的多模态CT表现.方法 纳入因急性缺血性卒中而接受多模态CT检查的36例WUS患者(WUS组)与41例OCS患者(OCS组,起病时间＜6 h),均经头颈部CT血管造影证实存在前循环大血管闭塞.采用Alberta卒中项目早期CT评分(ASPECTS)评价平扫CT所示早期脑缺血改变.将CT灌注(CTP)存在脑血流量(CBF)与脑血容量(CBV)不匹配区域认定为缺血半暗带,采用ASPECTS评价异常灌注范围(CBF-ASPECTS、CBV-ASPECTS).结果 WUS组与OCS组平扫CT中位ASPECTS均为8.0分,差异无统计学意义(P＞0.05).27 例(27/36,75.00％)WUS 患者、30 例(30/41,73.17％)OCS 患者 CTP 存在缺血半暗带.WUS 组与OCS组中位CBF-ASPECTS分别为3.0分及2.0分,CBV-ASPECTS均为6.0分,差异均无统计学意义(P均＞0.05).结论 WUS与起病6 h内OCS的多模态CT表现相似.

目的 应用脑CT灌注(CT perfusion,CTP)成像技术评价超急性期脑梗死(HIS)后交叉性小脑神经机能联络不能(CCD)的改变,并初步探讨其发生机制.方法 回顾性分析66例超急性期单侧幕上脑梗死患者,所有患者均行全脑CTP检查,将对侧小脑半球出现至少两个层面灌注异常定义为CCD阳性,将所有患者分为CCD阳性组和CCD阴性组.分别比较CCD阳性组和阴性组患者两侧小脑半球各项灌注参数的差异,以及幕上异常灌注范围、运动功能和临床因素的差异;并分析CCD阳性患者幕上灌注异常范围、运动功能与CCD严重程度的相关性.结果 66例患者中CCD阳性38例,CCD阴性28例,统计学分析显示CCD阳性患者两侧小脑半球各灌注参数值均有显著性差异(P＜0.05).CCD阳性组患者幕上异常灌注体积大于CCD阴性组(P＜0.05),患者运动功能降低较CCD阴性组更为显著,差异有统计学意义(P＜0.05),但幕上异常灌注体积及运动功能与CCD的严重程度均无明显相关性(P＞0.05).两组患者的性别、年龄及发病至CTP检查时间差异无统计学意义(P＞0.05).结论 脑CTP成像技术能够评价HIS后CCD改变.患者幕上脑灌注异常体积及临床运动功能与CCD的发生有关,但与CCD严重程度无关.

Background: Multimodal CT imaging can evaluate cerebral hemodynamics and stroke etiology, playing an important role in predicting prognosis. This study aimed to summarize the comprehensive image characteristics of wake-up stroke (WUS), and to explore its value in prognostication.Methods: WUS patients with anterior circulation large vessel occlusion were recruited into this prospective study. According to the 90-day modified Rankin Scale (mRS), all patients were divided into good outcome (mRS 0-2) or bad (mRS 3-6). Baseline clinical information, multimodal CT imaging characteristics including NECT ASPECTS, clot burden score (CBS), collateral score, volume of penumbra and ischemic core on perfusion were compared. Multivariate logistic regression analysis was further used to analyze predictive factors for good prognosis. Area under curve (AUC) was calculated from the receiver operating characteristic (ROC) curve to assess prognostic value.Results: Forty WUS were analyzed in this study, with 20 (50%) achieving good outcome. Upon univariable analysis, the good outcome group demonstrated higher ASPECTS, higher CBS, higher rate of good collateral filling and lower penumbra volume when compared with the poor outcome group. Upon logistic regression analysis, poor outcome significantly correlated with penumbra volume (OR: 1.023, 95% CI = 1.003-1.043) and collateral score (OR: 0.140, 95% CI = 0.030-0.664). AUC was 0.715 for penumbra volume (95% CI, 0.550-0.846) and 0.825 for good collaterals (95% CI, 0.672-0.927) in predicting outcome.Conclusions:Penumbra volume and collateral score are the most relevant baseline imaging characters in predicting outcome of WUS patients. These imaging characteristics might be instructive to treatment selection. As the small sample size of current study, further studies with larger sample size are needed to confirm these observations.

Purpose: To investigate the characteristics of cervicocephalic spotty calcium (SC) and coronary atherosclerosis in patients with acute ischemic stroke (AIS) and to assess the predictive value of SC for coronary atherosclerosis using combined coronary and cervicocephalic CTA. Materials and Methods: Patients with AIS ( n = 70) confirmed by brain MRI or CT and patients with asymptomatic carotid atherosclerosis ( n = 58) confirmed by carotid ultrasonography were enrolled in our study. Subjects in both groups underwent combined coronary and cervicocephalic CTA. SC was used to evaluate cervicocephalic atherosclerosis. Coronary artery stenosis (CAS) ≥ 50% by segment and coronary artery calcium score (CACS) were used to evaluate coronary atherosclerosis. The SC frequency and the difference in coronary atherosclerosis between the two groups were compared, and the correlation between SC and coronary atherosclerosis was analyzed. Independent factors for CAS ≥ 50% were assessed via logistic regression analysis. Receiver operating characteristic curve analysis was performed to evaluate the added value of SC for predicting CAS ≥ 50%. Results: Both SC and the CACS were significantly higher in the Stroke group than in the Control group (total SC count: 6.83 ± 4.34 vs. 2.98 ± 2.87, P < 0.05; CACS: 477.04 ± 798.01 vs. 136.31 ± 205.65, P < 0.05). There were significant differences in the presence of CAS ≥ 50% (61.4 vs. 27.6%, P < 0.001). SC and coronary atherosclerosis were significantly correlated for both the CACS and CAS ≥ 50% ( r = 0.746 and 0.715, respectively; P < 0.001). SC was an independent predictor for CAS ≥ 50%. Conclusion: SC correlates significantly with the CACS and could serve as an independent predictor of CAS ≥ 50% in patients with AIS, which suggests that combined cerebrovascular and cardiovascular assessments are of importance for such patients.

目的 探讨一站式心脑联合CT血管成像(CTA)对急性脑梗死患者头颈部斑点状钙化(SC)与冠状动脉钙化积分(CACS)的相关性.方法 本研究共纳入45例患者,包括经头颅MRI或CT平扫证实的首次发生急性脑梗死患者25例(急性脑梗死组),以及经颈动脉超声证实亚临床颈动脉粥样硬化患者20例(动脉粥样硬化组).患者均在首次影像学检查后1周内行一站式心脑联合CTA检查.分别以SC及CACS评估头颈部及冠状动脉粥样硬化,比较2组患者SC数量及CACS的差异,并行SC与CACS的相关性分析.结果 急性脑梗死组患者SC及CACS均明显高于动脉粥样硬化组(SC总数:5.76±12.2 vs 1.30±1.89,P<0.001;CACS:307.68±372.99 vs 68.00±110.03,P=0.037).急性脑梗死组与动脉粥样硬化组患者的SC与CACS均呈显著正相关(r=0.814,P<0.001;r=0.688,P=0.001).结论 急性脑梗死患者SC与CACS呈显著正相关,对急性脑梗死患者心脑血管联合评估具有重要意义.

目的 分析新型冠状病毒肺炎(COVID-19)疫情前后急性缺血性卒中"一站式多模态"CT检查流程改变及疫情对到院至用药时间(door-to-needle time,DNT)和患者预后的影响.方法 分别选取2019年1-8月及2020年1-8月就诊于首都医科大学宣武医院进入脑卒中溶栓绿色通道并溶栓治疗的患者,设为疫情前绿道组(108例)和疫情后绿道组(132例).比较疫情后"一站式多模态"CT检查流程变化前后患者各环节用时、DNT、患者预后及护理满意度.结果 疫情后绿道组患者"一站式多模态"CT检查各环节耗时增加(P<0.001),就诊-完成CT检查时间、DNT较疫情前绿道组明显延长(P<0.001);患美国国立卫生研究院脑卒中量表(NIH Stroke Scale,NIHSS)评分及护理满意度无显著变化(P>0.05);住院时间明显延长(P<0.001).结论 疫情后绿道组患者"一站式多模态"CT检查各环节耗时增加,患者短期预后无明显变化.

目的:分析“一站式多模态”CT检查流程优化对缩短患者就诊至应用静脉溶栓药时间(DNT)、提升缺血性脑卒中救护质量的效果.方法:选取2015年12月至2018年3月在某三级甲等医院就诊并进入脑卒中溶栓绿色通道患者145例,分为对照组和实验组.实验组进行流程优化,采用“并联模式”并删减耗时环节,比较流程优化前后患者各关键环节用时、DNT、患者预后及护理满意度.结果:流程优化后实验组患者就诊至完成CT检查时间、DNT较对照组明显缩短(P＜0.001);护理满意度明显提升(P＜0.05);住院时间明显缩短(P＜0.001).结论:“一站式多模态”CT检查流程优化提升了缺血性脑卒中患者救护质量,缩短了DNT,提高了患者护理满意度.

Objective This study is to investigate the relationship between different coronary computed tomography angiography (CCTA) examination modes and the radiation dose, in order to achieve as low as reasonable radiation dose, guiding and regulating the legitimation and optimization of coronary CTA examination. Materials and Methods Analyzed the effects of different models of MSCT and different scanning modes for coronary CTA on radiation dose in 30 tertiary hospitals of Beijing. All cases were divided into different groups according to CT models (general 64-slice CT and post 64-slice CT) and scanning modes (prospective ECG-triggering axial acquisition mode, retrospectively ECG-gated spiral data acquisition mode and prospectively ECG-gated high-pitch spiral acquisition mode). Achieved the mean values of CTDI, DLP and ED respectively and using independent sample t-test to analyze the radiation dose difference between different models and scanning modes. Results The statistical data on CTDI, DLP and ED of the post 64-slice CT is(27.61±19.61)mGy、(412.56±328.74) mGy?cm、(5.78±4.60) mSv, respectively, lower than those of the general 64-slice CT (57.09±27.58 ) mGy、(950.93±552.91) mGy?cm、(14.53±8.81) mSv, and the difference was statistically significant (P<0.05). The mean values of CTDI,DLP and ED were (17.98±11.27) mGy、(229.63±158.31) mGy?cm、(3.24±2.20) mSv in the prospective ECG-triggering axial acquisition mode group, retrospectively, while the mean values of CTDI, DLP and ED in ECG-gated spiral data acquisition mode group were (50.89±25.01) mGy、(839.80±469.56) mGy?cm、(12.40±7.42) mSv, respectively , the difference was statistically signiifcant (P<0.05). Conclusion Post 64-slice CT and low-dose scanning mode are both helpful for radiation dose reduction in coronary CTA.

Purpose: To investigate the potential of noise-based tube current reduction method with iterative reconstruction to reduce radiation exposure while achieving consistent image quality in coronary CT angiography (CCTA).Materials and methods: 294 patients underwent CCTA on a 64-detector row CT equipped with iterative reconstruction. 102 patients with fixed tube current were assigned to Group 1, which was used to establish noise-based tube current modulation formulas, where tube current was modulated by the noise of test bolus image. 192 patients with noise-based tube current were randomly assigned to Group 2 and Group 3. Filtered back projection was applied for Group 2 and iterative reconstruction for Group 3. Qualitative image quality was assessed with a 5 point score. Image noise, signal intensity, volume CT dose index, and dose-length product were measured.Results: The noise-based tube current modulation formulas were established through regression analysis using image noise measurements in Group 1. Image noise was precisely maintained at the target value of 35.00 HU with small interquartile ranges for Group 2 (34.17-35.08 HU) and Group 3 (34.34-35.03 HU), while it was from 28.41 to 36.49 HU for Group 1. All images in the three groups were acceptable for diagnosis. A relative 14% and 41% reduction in effective dose for Group 2 and Group 3 were observed compared with Group 1.Conclusion: Adequate image quality could be maintained at a desired and consistent noise level with overall 14% dose reduction using noise-based tube current reduction method. The use of iterative reconstruction further achieved approximately 40% reduction in effective dose. (c) 2012 Elsevier Ireland Ltd. All rights reserved.

Objective To evaluate the effect of noise-based low tube current scanning combined with low kilovoltage on image quality and radiation dose in coronary CT angiography(CCTA).Methods Totally 156patients of suspected coronary artery disease who underwent CCTA with prospective ECG-triggering were involved.The patients were divided into regular kilovoltage group(n=103)scanned with noise-based tube current and normal kilovoltage(120kV),and low kilovoltage group(n=53)scanned with noise-based tube current and low kilovoltage(100kV).Image quality,CT value, noise,SNR,CNR and radiation dose were compared between the two groups.Results In low kilovoltage group,image quality score,CT value,noise,SNR and CNR value were all higher than those in regular kilovoltage group(all P0.05). There was no significant difference in radiation dose between the two groups.Conclusion Noise-based low tube current scanning combined with low kilovoltage can not only decrease radiation dose but also improve image quality in CCTA.

OBJECTIVES: To evaluate the clinical value of noise-based tube current reduction method with iterative reconstruction for obtaining consistent image quality with dose optimization in prospective electrocardiogram (ECG)-triggered coronary CT angiography (CCTA). MATERIALS AND METHODS: We performed a prospective randomized study evaluating 338 patients undergoing CCTA with prospective ECG-triggering. Patients were randomly assigned to fixed tube current with filtered back projection (Group 1, n = 113), noise-based tube current with filtered back projection (Group 2, n = 109) or with iterative reconstruction (Group 3, n = 116). Tube voltage was fixed at 120 kV. Qualitative image quality was rated on a 5-point scale (1 = impaired, to 5 = excellent, with 3-5 defined as diagnostic). Image noise and signal intensity were measured; signal-to-noise ratio was calculated; radiation dose parameters were recorded. Statistical analyses included one-way analysis of variance, chi-square test, Kruskal-Wallis test and multivariable linear regression. RESULTS: Image noise was maintained at the target value of 35HU with small interquartile range for Group 2 (35.00-35.03HU) and Group 3 (34.99-35.02HU), while from 28.73 to 37.87HU for Group 1. All images in the three groups were acceptable for diagnosis. A relative 20% and 51% reduction in effective dose for Group 2 (2.9 mSv) and Group 3 (1.8 mSv) were achieved compared with Group 1 (3.7 mSv). After adjustment for scan characteristics, iterative reconstruction was associated with 26% reduction in effective dose. CONCLUSION: Noise-based tube current reduction method with iterative reconstruction maintains image noise precisely at the desired level and achieves consistent image quality. Meanwhile, effective dose can be reduced by more than 50%.

Objective: To evaluate the effect of noise-based low tube current scanning combined with low kilovoltage on image quality and radiation dose in coronary CT angiography (CCTA). Methods: Totally 156 patients of suspected coronary artery disease who underwent CCTA with prospective ECG-triggering were involved. The patients were divided into regular kilovoltage group (n=103) scanned with noise-based tube current and normal kilovoltage (120 kV), and low kilovoltage group (n=53) scanned with noise-based tube current and low kilovoltage (100 kV). Image quality, CT value, noise, SNR, CNR and radiation dose were compared between the two groups. Results: In low kilovoltage group, image quality score, CT value, noise, SNR and CNR value were all higher than those in regular kilovoltage group (all P<0.05). There was no significant difference in radiation dose between the two groups. Conclusion: Noise-based low tube current scanning combined with low kilovoltage can not only decrease radiation dose but also improve image quality in CCTA. Copyright © 2013 by the Press of Chinese Journal of Medical Imaging Technology.

Objective To investigate the diagnostic value of susceptibility⁃weighted imaging (SWI) in grading diffusely infiltrating astrocytomas. Methods Forty⁃three patients with pathologically proven diffusely infiltrating astrocytomas were collected, and underwent preoperative MRI conventional sequences (including axial T1WI, T2WI and FLAIR) and axial SWI. The ability of showing intratumoral small vessels and hemorrhagic focuses were compared between SWI and conventional techniques. The signal intensities, distribution of venules and bleeding incidence of the tumors were observed respectively on SWI, and the numbers of intratumoral small vessels and cerebral microbleeds, and the sectional areas of bleedings were compared within the three grades of astrocytomas. Results There were significant differences between SWI and conventional sequences in displaying numbers of small vessels and microbleeds and sizes of bleedings (P < 0.01, for all). Low⁃grade astrocytomas (WHO Ⅱ) displayed mainly as hyperintense, while high ⁃ grade (WHO Ⅲ, Ⅳ) ones showed mainly equisignal or low intensities; venules inside low ⁃ grade astrocytomas were sparse, but abundant inside high⁃grade ones; the incidence of hemorrhage in low⁃grade astrocytomas was less frequent than that in high⁃grade ones. The numbers of venules in three groups were 3.77 ± 1.11, 11.86 ± 1.22 and 20.00 ± 1.32, respectively. The numbers of cerebral microbleeds were 0.47 ± 0.39, 3.32 ± 0.42 and 4.38 ± 0.46, respectively. The sectional areas of bleedings were (0.78 ± 1.31) cm2, (3.05 ± 4.40) cm2 and (4.23 ± 4.55) cm2, respectively. The differences among the three groups were all statistically significant (P < 0.01, for all). Conclusion SWI was more sensitive than conventional techniques in showing small vessels and bleeding sites in astrocytomas. The signal intensities, distribution of venules and bleeding incidence of tumors were significantly different between low⁃grade and high⁃grade astrocytomas. The numbers of small vessels and cerebral microbleeds, and the sectional areas of bleedings may help to facilitate the grading of astrocytomas in clinical practice. DOI：10.3969/j.issn.1672⁃6731.2012.06.009

Objective To investigate the clinical value of gemstone spectral imaging(GSI) and multi artifact reduction system(MARs)in reducing metal artifacts on HDCT,and find the best monochromatic images.Methods Fifteen patients with metal implants of spine in our hospital received GSI examination and MARs reconstruction.Eleven groups of monochromatic images and 11 groups monochromatic + MARs images were obtained from 40 keV to 140 keV every interval of 10 keV by the special GSI viewer,respectively.The images of severe artifacts level(A) and no or less artifacts level(B) were selected for every group monochromatic image or monochromatic + MARs image.The CT value and SD value of the region of interest(ROI) and adjacent fatty tissue were measured and analyzed.Results In the monochromatic images at 110 keV,the SD value of A and B levels were 54.12±8.35 and 34.77±3.50.There was no significant difference(t=2.32,P0.05).Other 10 groups had significant difference(P0.05).There was significant difference(P0.05) on SD value of A and B levels in every monochromatic + MARs group.The optimal CNR was acquired at the energy level of 70 keV(CNR=9.2±5.07).Although hyperdensity metal artifacts were decreased in 110 keV+MARS images,image distortion was generated.Conclusion The monochromatic images at 110 keV have the best image quality in reducing metal artifacts on HDCT.The image quality of 110 keV is better than that of 110 keV+MARs images.Although 70 keV images have the optimal CNR,noise is higher than 110 keV images,it is not beneficial for diagnosis.