Objective To apply a non-invasive and feasible method for the quantification of local wall shear stress (WSS) in vivo using magnetic resonance imaging. Methods The fight common carotid artery of a young healthy male volunteer was examined using cine phase-contrast MR sequence. The cross- sectional area, average flow velocity, maximum velocity and flow rate were obtained. Three dimensional paraboloid model was applied to measure WSS value at common carotid artery. Results The mean/peak WSS was (0.75±0.41)N/m2 for the common carotid artery; The mean (range) velocity was (23.4± 12.0) cm/s; The mean (range) luminal vessel area was (32.2±2.9) mm2; The blood flow rate was (7.8±4. 6) ml/s; Conclusion WSS's magnitude, distribution and changes can be determined by MR imaging combining with the three-dimensional paraboloid method.

Objective To study the effect of age on the hemodynamics of common carotid artery. Methods 47 healthy volunteers werestudied. Wall shear stress (WSS) values localized at common carotid artery 2 cm below the bifurcation were calculated with cine phase-contrastMR imaging combined three-dimensional paraboloid (3DP) model. On the spatial distribution, common carotid artery wall was dividedinto 24 equal parts. Calculate the mean WSS in a cardiac cycle on each part, and choose the minimal WSS value. Then the effects of age onthe average WSS and minimal WSS were observed. Results Total 94 common carotid arteries of 47 health volunteers were examined, inwhich 9 carotid arteries in 9 volunteers were excluded because of uninterpretable high-resolution MRI findings or volunteer's intolerance forthe detection. In the remaining 85 common carotid arteries, the average WSS and the minimal WSS during a cardiac cycle on the spatial distributionwere (7.45±2.12) dyne/cm2 and (5.98±1.93) dyne/cm2 respectively. Both average WSS and minimal WSS were negative correlatedwith age (P<0.05). Conclusion With the age increased, mean WSS and minimal WSS on the spatial distribution of common carotid arterydecreased.

English training is important for young doctors＇ career development in general hospital.The stagewise English training mode of Beijing Tiantan Hospital of Capital Medical University was introduced.By summarizing the experience of five years trial,viewpoints were brought forward that hospital English training in radiological department of general hospital should adopt a stagewise mode,create an English communication atmosphere,show the special feature of department and combine with clinical daily work.

time (r = 0. 070, -0.003, -0. 195,0. 177,P 0.05). Conclusions Compared with omnivore's, the shear stiffness of brain parenehyma was lower in vegetarians. The shear stiffness of brain parenchyma may be affected by the diet.

Objective To investigate the diagnostic value of CTP-SI in acute stroke less than 9 hours.Methods In present study."one-stop shop"CT examination were performed in 34 patients with symptoms of acute stroke in le88 than 9 hours.We divided patients into two groups according to with and without delayed perfusion on CTP-SI.and compared ASPECTS (Alberta Stroke Program Early CT Score Study)scores on non-contrast CT(NCCT),arterial phase CTP-SI,venous phase CTP-SI with follow-up imaging.The ASPECTS were analyzed on arterial phase CTP-SI and veIlous phase CTP-SI using Wilcoxon rank-sum test.then compared with the follow up imaging ASPECTS using multiple linear regression.Results The median(min-max)scores of ASPECTS on NCCT,arterial phase CTP-SI,venous phase CTP-SI and follow-up imaging were 9.0(6.0-10.0),6.5(1.0-8.0),8.0(3.0-10.0)and 7.0(0-10.0)in group with delayed perfusion,respectively,and 9.0(1.0-10.0),8.5(1.0-10.0),8.5(1.0-10.0)and 8.0 (0～10.0)in group without delayed perfusion respectively.ASPECTs scores measured on arterial phase CTP-SI did not differ from venous phase CTP-SI in group without delayed perfusion ( Z = - 1.00, P =0.317), while there was significant difference in group with delayed perfusion (Z = -3.08, P = 0.002 ).There were significant correlation with ASPECTS scores measured on NCCT, arterial phase CTP-SI and venous phase CTP-SI to follow-up imaging ASPECTS (r =0.899,0.926,0.928,P ＜0.01 ) in group without delayed perfusion; ASPECTS measured in venous phase CTP-SI showed the best correlation to follow-up imaging ASPECTS (r = 0.762, P = 0.004) in group with delayed perfusion.Multiple linear regression showed that the correlation in only venous phase CTP-SI with foUow-up imaging ASPECTS was statistically significant:in group without delayed perfusion, Beta = 0.966, P ＜ 0.001 ; in group with delayed perfusion,Beta = 0.765, P = 0.004. Conclusion Presence of delayed porfusion in CTP-SI is quite important in identifying ischemic penumbra, which plays a critical role in imaging-guided thrombolytie therapy.

Objective To evaluate the shear stiffness of brain by MR elastography (MRE) in healthy Chinese volunteers and to assess the association between the cerebral shear stiffness and age. Methods Brain MRE studies were performed on 105 healthy volunteers. The shear stiffness of brain parencham was measured by local frequency estimation (LFE) algorithm. The differences of the shear stiffness between white matter(WM) and grey matter(GM) were analyzed by independent sample t test; the differences of brain parenchyma shear stiffness between male and female were estimated by independent sample t test. Spearman test was used to analyze the correlation between age and the shear stiffness of parenchyma; the volunteers were divided into two groups (age ≤ 40 and age > 40) and the correlation between age and shear stiffness of parencbyma in each group were analyzed separately. Results The shear stiffness of whiter matter [(23.1±5.7) kPa] was higher than that of grey matter[(11.3±2.6) kPa], and the difference was significant (t = 19.34, P < 0.01). In male, the shear stiffness of WM and GM was (23.4±5.8) kPa and (11.4±2.8) kPa respectively; while in female, it was (22.8±5.6) kPa and (11.1±2.5) kPa respectively. No sex differences were found in the stiffness of white matter or gray matter (t = - 0.534, - 0.606, P > 0.05). An age-dependent trend was observed in the stiffness of grey matter(r =0.315, P < 0.01),while not in whiter matter (r = 0.183, P > 0.05). When the shear stiffness of subjects no more than 40 years old was analysed, the age-dependent trend of shear stiffness was found both in white matter and gray matter(r = 0.251,0.235, P < 0.05); While in subjects over 40 years old, the age-dependent rend of shear stiffness was not found in white matter or gray matter(r = 0.181, - 0.001, P > 0.05). Conclusions The shear stiffness of WM is significantly higher than that of GM. No obvious sex difference was found in the stiffness of brain parenchyma. The shear stiffness of GM increases with age; the age-related increase of shear stiffness of WM was only found in subjects under 40 years old.

OBJECTIVETo assess the value of detecting the compositional features of carotid atherosclerotic plaques by 3.0T high resolution magnetic resonance imaging (MRI) in patients with coronary artery disease (CAD).

METHODSConsecutive 104 patients with coronary atherosclerosis confirmed by coronary angiography were prospectively recruited from January 2013 to January 2015 in Tiantan hospital. All patients were imaged with 3.0T high resolution MRI system. After exclusion patients with poor image quality, 97 patients were divided into 3 groups according to the degree of coronary artery stenosis: coronary atherosclerosis group (coronary stenosis between 1%-49%, n=16); single-vessel lesion group (single vessel lesion with stenosis between 50%-100%, n=48); multi-vessel lesion group (two or three vessel lesions with stenosis between 50%-100% or left main stem disease, n=33). The prevalence of total carotid plaque, calcified plaque, lipid-rich necrotic core, intra-plaque hemorrhage, plaque ulcer and rupture were compared among 3 groups.

RESULTSThe prevalence of total carotid plaque (81.3%(13/16), 72.9%(35/48), and 93.9%(31/33)) and calcified plaque (50.0%(8/16), 35.4%(17/48), and 42.4%(14/33)) were similar among the 3 groups (both P>0.05). The prevalence of carotid lipid-rich necrotic core in coronary atherosclerosis group was significantly lower than in single-vessel lesion group (18.8%(3/16) vs. 64.6%(31/48), P<0.01) and multi-vessel lesion group(18.8%(3/16) vs. 69.7%(23/33), P<0.01), but there was no significant difference between single-vessel lesion group and multi-vessel lesion group(P>0.05). Intra-plaque hemorrhage was detected in 2 patients of multi-vessel lesion group. There was no plaque ulcer or rupture in this cohort.

CONCLUSIONCarotid plaque features are associated with the severity of coronary atherosclerosis in CAD patients.

Objective To investigate the distribution characteristics and risk factors of intracranial and extracranial aterial lesions in Chinese patients with ischemic stroke . Methods In this multi‐center study ,2 310 continuously inpatients with ischemic stroke diagnosed in 20 stroke screening and prevention project base hospitals from June 2015 to M ay 2016 were enrolled . Carotid ultrasonography and transcranial color‐coded sonography or transcranial Doppler were performed in all patients to confirm the presence of cerebral artery stenosis or occlusion . According to the distribution of lesions ,the subjects were divided into 2 groups :the simple intracranial artery stenosis group and the simple extracranial artery stenosis group . T he difference of risk factors between the two groups was compared . Results Of the 2 310 patients with ischemic stroke ,1 516 ( 65 .6% ) had simple intracranial artery stenosis and 794 ( 34 .4% ) had simple extracranial artery stenosis . T he incidence of anterior circulation artery stenosis was higher in the group of intracranial artery stenosis than that in the extracranial artery stenosis group ( 68 .1% vs 48 .7% , P ＜0 .001) . Posterior circulation artery stenosis and combined anterior with posterior circulation artery stenosis were more common in patients with extracranial artery stenosis group than those in intracranial artery stenosis group ( 36 .4% vs 22 .1% ,14 .9% vs 9 .8% ;all P ＜0 .001) . Univariate analysis of risk factors for stroke showed that patients with intracranial arterial stenosis had a higher prevelence of hypertension , diabetes ,obesity ,and family history of stroke ,and their systolic blood pressure ,diastolic blood pressure , body mass index ( BM I) ,fasting blood‐glucose ,glycosylated hemoglobin ,triacylglycerol ,total cholesterol , and low‐density lipoprotein cholesterol were significantly higher than those in the extracranial arterial stenosis group ( all P ＜ 0 .05 ) . T he proportion of elderly ( ≥ 65 years old ) ,male and smokers in the extracranial arterial stenosis group was significantly higher than that in the intracranial arterial stenosis group ( all P ＜0 .05) . Multivariate logistic regression analysis showed that elderly ( ≥65 years old) ,male , and smoking history were independent risk factors for extracranial arterial stenosis ( OR＝ 2 .012 ,1 .637 , 1 .325 ,respectively ;all P ＜0 .05) . While hypertension ,diabetes ,less physical activity ,and high BM I levels were independent risk factors for simple intracranial arterial disease ( OR ＝ 1 .301 ,1 .252 ,1 .248 ,1 .030 , respectively ;all P ＜0 .05) . Conclusions There are significant differences in the distribution characteristics and risk factors of intracranial and extracranial aterial lesions in patients with ischemic stroke in China .

OBJECTIVE: To assess the practical and health economical values of non-invasive prenatal test (NIPT) in Changsha Municipal Public Welfare Program. METHODS: A retrospective analysis was carried out on 149 165 women undergoing NIPT test from April 9, 2018 to December 31, 2019. For pregnant women with high risks, invasive prenatal diagnosis and follow-up of pregnancy outcome were conducted. The cost-benefit of NIPT for Down syndrome was analyzed. RESULTS: NIPT was carried out for 149 165 pregnant women and succeeded in 148 749 cases (99.72%), for which outcome were available in 148 538 (99.86%). 90% of pregnant women from the region accepted the screening with NIPT. 415 (0.27%) were diagnosed as high risk. Among these, 381 (91.81%) accepted amniocentesis, which led to the diagnosis of 212 cases of trisomy 21 (PPV=85.14%), 41 cases with trisomy 18 (PPV=48.81%) and 10 cases with trisomy 13 (PPV=20.83%). The sensitivity and specificity of NIPT for trisomy 21, trisomy 18 and trisomy 13 were (97.70%, 99.98%), (97.62%, 9.97%) and (100%, 99.97%), respectively. In addition, 213 and 30 cases were diagnosed with sex chromosomal aneuploidies (PPV=46.2%) and other autosomal anomalies (PPV=16.57%), respectively. For Down syndrome screening, the cost and benefit of the project was 120.79 million yuan and 1,056.95 million yuan, respectively. The cost-benefit ratio was 1: 8.75, and safety index was 0.0035. CONCLUSION NIPT is a highly accurate screening test for trisomy 21, which was followed by trisomy 18 and sex chromosomal aneuploidies, while it was less accurate for other autosomal aneuploidies. The application of NIPT screening has a high health economical value.
Aneuploidy ; Cost-Benefit Analysis ; Female ; Humans ; Noninvasive Prenatal Testing ; Pregnancy ; Retrospective Studies ; Trisomy 18 Syndrome/genetics*

Objective:To investigate the hemodynamic characteristics of the lenticulostriate artery (LSA) in cerebral small vessel disease (CSVD) patients with recent small subcortical infarcts (RSSI) using 7.0 T two-dimensional phase-contrast MRI (2D PC-MRI).Methods:A total of 16 CSVD patients with deep RSSI and 18 age-and sex-matched healthy controls (HC group) meeting the inclusion criteria were prospectively recruited from July 2021 to June 2022 at Beijing Tiantan Hospital, Capital Medical University. All participants underwent 7.0 T 2D PC-MRI with imaging plane localized at the level of the basal ganglia. A self-developed software (Flow analyze V1.0) was used to analyze the hemodynamic status of bilateral LSAs. The hemodynamic parameters including the maximum velocity (V max), average velocity (V avg), pulsatility index (PI), and resistance index (RI) of LSAs were calculated and recorded. As for the CSVD cases, the symptomatic side was defined as the ipsilateral side to the RSSI (CSVD symptomatic-side group), and the contralateral side was defined as the asymptomatic side (CSVD asymptomatic-side group). ANOVA or Mann-Whitney U test was used to compare hemodynamic parameters among the three groups. Results:Significant differences in V max, V avg and PI were observed among the CSVD symptomatic-side group, CSVD asymptomatic-side group, and HC group ( F=5.22, P=0.006; F=3.47, P=0.033; F=4.37, P=0.014). Specifically, CSVD symptomatic-side group showed significantly reduced V max ( P=0.004) and V avg ( P=0.017), and increased PI ( P=0.007) compared to the HC group. The CSVD asymptomatic-side group showed decreased V max ( P=0.026) and increased PI ( P=0.039) compared to the HC group. Conclusions:Hemodynamic assessment based on 7.0 T 2D PC-MRI reveal that CSVD patients with RSSI decrease blood flow velocity and increase arterial PI of LSAs. These findings suggest potential corresponding hemodynamic mechanisms associated with CSVD with RSSI lesions.