Objective To evaluate the ambient dose equivalent rates of photons and neutrons inside and outside the door of a 10 MV accelerator room, and to report the shielding effect of boron-containing polyethylene as maze wall lining. Methods The ambient dose equivalent rates of photons and neutrons inside and outside the door of an accelerator room were taken as the research subject. The Kersey, Falcão, and modified Kersey methods were used to calculate the ambient dose equivalent rates of neutrons and neutron capture gamma rays inside and outside the door of the room before and after renovation. Measurements were made using an X-ray/γ-ray dose rate instrument and a neutron ambient dose equivalent rate meter. Calculated and measured results were compared. Results Before renovation, the measured neutron dose rate inside the door was 409 μSv/h, while the calculated values were 323 μSv/h (Kersey method), 428 μSv/h (Falcão method), and 219 μSv/h (modified Kersey method). The Falcão method yielded a value closest to the measured value, while the Kersey and the modified Kersey methods underestimated the value by 21% and 46%, respectively. After the installation of boron-containing polyethylene plates, the measured neutron dose rate inside the door was 190 μSv/h, with a 54% reduction. The neutron and photon ambient dose equivalent rates outside the door were 5.8 μSv/h and 6.0 μSv/h, respectively, before renovation, and 0.14 μSv/h and 1.6 μSv/h, respectively, after renovation. Conclusion For a 10 MV accelerator room, neutron shielding and protection measurements are necessary, especially for rooms with short mazes. The Falcão method provides the best estimate of neutron dose rates inside and outside the door. Using boron-containing polyethylene plates as maze wall lining is an economical and effective shielding method.

Objective To analyze the layout and shielding effectiveness of medical accelerator vaults, and to provide a reference for the layout, shielding design, and optimization of protection of medical accelerator vaults. Methods Four medical accelerator radiotherapy vaults were selected. The layouts of these vaults were compared with the layout requirements in the radiation therapy protection standards. For each vault, the dose rates at four points of interest outside the shielding were calculated, including the primary shielding area, secondary shielding area, maze outer wall, and lateral shielding area. These values were then compared with the actual measurements obtained using a dose rate meter. Results All four vaults were located on the ground floor of the building and included a maze, with the auxiliary rooms all placed outside the treatment rooms. However, one vault was not located at one end of the building, and in another vault, the control room was exposed to direct irradiation of the useful beam. The calculated dose rates outside the primary shielding area ranged from 0.04 μSv/h to 0.62 μSv/h, while the measured values ranged from 0.10 μSv/h to 0.66 μSv/h, with the measured values being higher than the calculated ones. The calculated dose rates outside the secondary shielding area ranged from 0.0005 μSv/h to 0.12 μSv/h, those outside the maze outer wall ranged from 0.06 μSv/h to 0.18 μSv/h, and those outside the lateral shielding area ranged from 0.009 μSv/h to 0.15 μSv/h; the measured values were all below the detection limit. Conclusion Inadequate layouts were observed in some of the accelerator vaults. The calculated and measured dose rates at points of interest outside the vaults were both significantly lower than the shielding protection requirements in standards, indicating that the shielding designs were overly conservative. Construction units should follow the principle of optimization of radiation protection to design the layout and shielding reasonably and pay attention to the underestimation of dose rates outside the primary shielding caused by the tenth value layer.

Objective:To explore the value of cardiac magnetic resonance imaging (CMR) derived left ventricular late gadolinium enhancement (LV LGE) for the primary prevention of malignant ventricular arrhythmias in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients.Methods:This was a single-center retrospective study. Consecutive ARVC patients who underwent CMR at Fuwai Hospital between January 2016 and September 2020, with no history of malignant ventricular arrhythmias at diagnosis, were enrolled. Clinical data and CMR characteristics were collected. The primary endpoint was defined as new-onset malignant ventricular arrhythmias related events, including sustained ventricular tachycardia, ventricular fibrillation/flutter, sudden cardiac death, cardiac arrest, and appropriate implantable cardioverter-defibrillator discharge. Follow-up via telephone interviews and medical records was conducted to confirm endpoint occurrences, and patients were categorized into event-free and event groups based on endpoint status. Univariable and multivariable Cox regression analysis were performed to identify independent risk factors for malignant ventricular arrhythmias in ARVC patients. Subgroup analyses were conducted based on the ARVC 5-year risk score (cutoff: 25%) and the median value of LV LGE percentage (cutoff: 13%). Kaplan-Meier curves were plotted, and log-rank tests were used to compare the difference in the incidence of primary endpoint events between subgroups. Receiver operating characteristic curves and likelihood ratio test were used to evaluate the incremental prognostic value of LV LGE percentage beyond the ARVC 5-year risk score.Results:A total of 172 ARVC patients were enrolled, aged (39.0±16.6) years, including 73 females (42.4%). During a follow-up of 53.1 (25.4, 76.9) months, 51 patients (29.7%) experienced malignant ventricular arrhythmias related events, including 3 cases of sudden cardiac death, 1 cardiac arrest, 33 sustained ventricular tachycardia and 14 appropriate implantable cardioverter-defibrillator discharges. Multivariable Cox regression analysis indicated that the ARVC 5-year risk score ( HR=1.028, 95% CI 1.015-1.041, P<0.001) and LV LGE percentage ( HR=1.059, 95% CI 1.032-1.087, P<0.001) were independent risk factors of the primary endpoint events. Kaplan-Meier analysis using composite stratification (ARVC 5-year risk score cutoff: 25%; LV LGE percentage cutoff: 13%) demonstrated that patients with both high risk scores (≥25%) and extensive LV LGE (≥13%) had the highest risk of primary endpoint events. Notably, among patients with ARVC 5-year risk scores <25%, those with LV LGE≥13% had a higher incidence of primary endpoint events than those without (log-rank P=0.037). The composite prediction model combining the 5-year risk score and left ventricular LGE percentage demonstrated significantly improved predictive performance (area under the curve ( AUC)=0.82, 95% CI 0.75-0.90; likelihood ratio test all P<0.001) compared to single-variable models (left ventricular LGE percentage alone: AUC=0.71, 95% CI 0.63-0.82, P=0.01; 5-year risk score alone: AUC=0.71, 95% CI 0.62-0.81, P=0.02). Conclusion:LV LGE percentage independently predict new-onset malignant ventricular arrhythmias in ARVC patients and provided incremental prognostic value based on the existing ARVC 5-year risk score.

To verify whether chaperones can promote the soluble expression of PlpE in Escherichia coli and whether the expressed protein is active,prokaryotic expression and Western blot detection were performed.The results showed that:The PlpE prokaryotic expression vector pET-32a(+)-plpE was expressed as inclusion body,and the expression form was not changed by changing the concentration of inducer,induction time and temperature.The companion proteins pG-KJE8,pGro7,pKJE7 and pG-Tf2 were co-expressed with pET-32a(+)-plpE in Eschierichia coli expres-sion system,respectively.When the final concentration of IPTG of 0.5 mmol/L,L-arabinose of 0.5 g/L or tetracycline of 5.0 μg/L were added as inducers and induced at 37 ℃ for 8 h,the results showed that the molecular companion pGro7 could change the expression of rp-PlpE from inclu-sion body to soluble expression.pG-KJE8,pKJE7 and pG-Tf2 had no effect on the expression of rp-PlpE.The soluble rp-PlpE can react specifically with the positive serum of Mannheimia haemolyti-ca.Therefore,the study showed that the co-expression of the chaperone protein pGro7 can make the rp-PlpE protein express in a soluble form,and the purified protein exhibits reactogenicity.These findings lay the foundation for the establishment of a subunit vaccine and serological diagno-sis methods for Mannheimia haemolytica.

To verify whether chaperones can promote the soluble expression of PlpE in Escherichia coli and whether the expressed protein is active,prokaryotic expression and Western blot detection were performed.The results showed that:The PlpE prokaryotic expression vector pET-32a(+)-plpE was expressed as inclusion body,and the expression form was not changed by changing the concentration of inducer,induction time and temperature.The companion proteins pG-KJE8,pGro7,pKJE7 and pG-Tf2 were co-expressed with pET-32a(+)-plpE in Eschierichia coli expres-sion system,respectively.When the final concentration of IPTG of 0.5 mmol/L,L-arabinose of 0.5 g/L or tetracycline of 5.0 μg/L were added as inducers and induced at 37 ℃ for 8 h,the results showed that the molecular companion pGro7 could change the expression of rp-PlpE from inclu-sion body to soluble expression.pG-KJE8,pKJE7 and pG-Tf2 had no effect on the expression of rp-PlpE.The soluble rp-PlpE can react specifically with the positive serum of Mannheimia haemolyti-ca.Therefore,the study showed that the co-expression of the chaperone protein pGro7 can make the rp-PlpE protein express in a soluble form,and the purified protein exhibits reactogenicity.These findings lay the foundation for the establishment of a subunit vaccine and serological diagno-sis methods for Mannheimia haemolytica.

Objective:To explore the value of cardiac magnetic resonance imaging (CMR) derived left ventricular late gadolinium enhancement (LV LGE) for the primary prevention of malignant ventricular arrhythmias in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients.Methods:This was a single-center retrospective study. Consecutive ARVC patients who underwent CMR at Fuwai Hospital between January 2016 and September 2020, with no history of malignant ventricular arrhythmias at diagnosis, were enrolled. Clinical data and CMR characteristics were collected. The primary endpoint was defined as new-onset malignant ventricular arrhythmias related events, including sustained ventricular tachycardia, ventricular fibrillation/flutter, sudden cardiac death, cardiac arrest, and appropriate implantable cardioverter-defibrillator discharge. Follow-up via telephone interviews and medical records was conducted to confirm endpoint occurrences, and patients were categorized into event-free and event groups based on endpoint status. Univariable and multivariable Cox regression analysis were performed to identify independent risk factors for malignant ventricular arrhythmias in ARVC patients. Subgroup analyses were conducted based on the ARVC 5-year risk score (cutoff: 25%) and the median value of LV LGE percentage (cutoff: 13%). Kaplan-Meier curves were plotted, and log-rank tests were used to compare the difference in the incidence of primary endpoint events between subgroups. Receiver operating characteristic curves and likelihood ratio test were used to evaluate the incremental prognostic value of LV LGE percentage beyond the ARVC 5-year risk score.Results:A total of 172 ARVC patients were enrolled, aged (39.0±16.6) years, including 73 females (42.4%). During a follow-up of 53.1 (25.4, 76.9) months, 51 patients (29.7%) experienced malignant ventricular arrhythmias related events, including 3 cases of sudden cardiac death, 1 cardiac arrest, 33 sustained ventricular tachycardia and 14 appropriate implantable cardioverter-defibrillator discharges. Multivariable Cox regression analysis indicated that the ARVC 5-year risk score ( HR=1.028, 95% CI 1.015-1.041, P<0.001) and LV LGE percentage ( HR=1.059, 95% CI 1.032-1.087, P<0.001) were independent risk factors of the primary endpoint events. Kaplan-Meier analysis using composite stratification (ARVC 5-year risk score cutoff: 25%; LV LGE percentage cutoff: 13%) demonstrated that patients with both high risk scores (≥25%) and extensive LV LGE (≥13%) had the highest risk of primary endpoint events. Notably, among patients with ARVC 5-year risk scores <25%, those with LV LGE≥13% had a higher incidence of primary endpoint events than those without (log-rank P=0.037). The composite prediction model combining the 5-year risk score and left ventricular LGE percentage demonstrated significantly improved predictive performance (area under the curve ( AUC)=0.82, 95% CI 0.75-0.90; likelihood ratio test all P<0.001) compared to single-variable models (left ventricular LGE percentage alone: AUC=0.71, 95% CI 0.63-0.82, P=0.01; 5-year risk score alone: AUC=0.71, 95% CI 0.62-0.81, P=0.02). Conclusion:LV LGE percentage independently predict new-onset malignant ventricular arrhythmias in ARVC patients and provided incremental prognostic value based on the existing ARVC 5-year risk score.

In recent years,cardiovascular MRI(CMRI)technology has made significant advances,and multimodal CMRI imaging has been useful to display anatomical structure of the valves,to assess the severity of valvular disease,and to quantify the volume of cardiac chambers and myocardial fibrosis,as well as led to progress in judging mitral stenosis,mitral valve closure insufficiency,and risk stratification.Hence they have been widely used in the assessment of mitral valve lesions.The research progresses of CMRI for assessing mitral valve lesions were reviewed in this article.

Objective:To investigate the clinical and cardiac magnetic resonance (CMR) characteristics of heart involvement in patients with Fabry disease (AFD).Methods:From January 2018 to March 2021, eight AFD patients [3 males and 5 females, mean age (50±11) years old, range 26-60 years old] confirmed by genetic testing or pathology in Fuwai Hospital were retrospectively included in this study. At the same time, sixteen patients with hypertrophic cardiomyopathy (HCM) [6 males and 10 females, mean age (46±15) years old] and 16 healthy individuals [6 males and 10 females, mean age (51±11) years old] were included as controls. The clinical baseline data and CMR data of the patients were collected and analyzed. The CMR data were analyzed using the software CVI42, with the corresponding parameters automatically generated. One-way ANOVA or Kruskal-Wallis test was used to compare the differences in the parameters among the three groups. Independent-samples t test, Fisher precise test or Mann-Whitney U test were used for the comparison between each two groups. Results:Statistically significant difference was found in renal insufficiency between the HCM group and the AFD group; No other significant difference was found in other clinical factors and ECG results (all P>0.05). CMR results showed that in the AFD group, there were 5 cases with symmetric or roughly symmetric hypertrophy, and 3 with asymmetric hypertrophy. The late gadolinium enhancement (LGE) showed myocardial enhancement in 5 patients, mainly presenting as multiple intermural enhancement, and partially as local subendocardial enhancement. In the HCM group, fourteen cases suffered mainly asymmetric ventricular septal thickening, with or without thickening of other parts of left ventricular wall; and 2 cases had thickening of middle and distal part of the left ventricle. The LGE showed myocardial enhancement in 14 patients, which manifested as focal or patchy enhancement in hypertrophic myocardium, including focal enhancement in the right ventricular insertion of ventricular septum (more common) and subendocardial enhancement in the middle and far segments of left ventricle. Statistically significant difference was found in the differences between the left atrial anterior posterior diameter, the maximum wall thickness of left ventricular, the left ventricular myocardial mass index (LVMI) and the native T 1 value among the three groups (all P<0.001). However, there was no statistically significant difference in the left atrial anterior posterior diameter and the maximum wall thickness of left ventricular between AFD group and HCM group ( P>0.05). The LVMI in AFD group was higher than that in healthy group and HCM group (all P<0.05). Significant difference was found in the native T 1 value among the three groups, with the native T 1 value of the AFD group [(1 177.4±46.0) ms] was significantly lower than that of the healthy group [(1 244.5±34.3) ms] and the HCM group [(1 278.8±41.6) ms], with ( F=13.10, P<0.001). Conclusions:The clinical characteristics of AFD and HCM are quite similar. When AFD is suspected, CMR imaging should be the first choice for imaging examination. Especially, T 1 mapping imaging can provide important information for the diagnosis of AFD.

OBJECTIVE: Segmented cardiac cine magnetic resonance imaging (MRI) is the gold standard for cardiac ventricular volumetric assessment. In patients with difficulty in breath-holding or arrhythmia, this technique may generate images with inadequate quality for diagnosis. Real-time cardiac cine MRI has been developed to address this limitation. We aimed to assess the performance of retrospective electrocardiography-gated real-time cine MRI at 3T for left ventricular (LV) volume and mass measurement. MATERIALS AND METHODS: Fifty-one patients were consecutively enrolled. A series of short-axis cine images covering the entire left ventricle using both segmented and real-time balanced steady-state free precession cardiac cine MRI were obtained. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), and LV mass were measured. The agreement and correlation of the parameters were assessed. Additionally, image quality was evaluated using European CMR Registry (Euro-CMR) score and structure visibility rating. RESULTS: In patients without difficulty in breath-holding or arrhythmia, no significant difference was found in Euro-CMR score between the two techniques (0.3 ± 0.7 vs. 0.3 ± 0.5, p > 0.05). Good agreements and correlations were found between the techniques for measuring EDV, ESV, EF, SV, and LV mass. In patients with difficulty in breath-holding or arrhythmia, segmented cine MRI had a significant higher Euro-CMR score (2.3 ± 1.2 vs. 0.4 ± 0.5, p < 0.001). CONCLUSION: Real-time cine MRI at 3T allowed the assessment of LV volume with high accuracy and showed a significantly better image quality compared to that of segmented cine MRI in patients with difficulty in breath-holding and arrhythmia.
Arrhythmias, Cardiac ; Diagnosis ; Heart Ventricles ; Humans ; Magnetic Resonance Imaging ; Magnetic Resonance Imaging, Cine* ; Retrospective Studies* ; Stroke Volume

Objective: To compare the imaging characteristics and long-term prognosis in hypertrophic cardiomyopathy(HCM) patients with or without left ventricular apical aneurysm(LVAA). Methods: Retrospectively analyzed the clinical data from 18 patients diagnosed as HCM complicating with LVAA(HCM-LVAA group), hospitalized and underwent cardiac magentic resonance (CMR) examination in Fuwai Hospital between December 2012 and December 2016. Eighteen age and gender matched patients with HCM diagnosed by CMR served as control(HCM group). Outpatient and in-hospital clinical data as well as follow up results were compared. The major adverse cardiovascular events were defined as malignant arrhythmia events (including sudden cardiac death, ventricular flutter/ventricular fibrillation) and heart failure events (including heart transplantation, progressive heart failure). Results: Compared with HCM group, patients in HCM-LVAA group had a more positive family history of HCM(P=0.04), higher incidence of ST-T segment changes and abnormal Q wave in electrocardiograms (both P<0.01), the CMR derived left ventricular end-diastolic transverse diameter and end-diastolic volume index were also significantly higher (both P<0.05), and delayed enhancement was more significant ((25.26±10.60)% vs. (15.78±7.33)%, t=3.12, P=0.004) in HCM-LVAA group. Moreover, the left ventricular ejection fraction ((54.4±10.6)% vs. (67.5±7.6)%, t=-4.28, P<0.000 1) and the thickness of the apical wall ((3.11±1.05) mm vs. (5.46±1.94) mm, t=-4.49, P<0.000 1) were significantly lower in HCM-LVAA group than in HCM group. The mean follow-up duration was (3.46±1.64) years, 4 patients in HCM-LVAA group (22.2%) developed 4 cardiovascular events, including 1 sudden cardiac death, 3 progressive heart failures. One patient in HCM group developed progressive heart failure. Conclusion The prognosis of the HCM complicating with LVAA patients is worse than that of HCM patients without LVAA, and the amount of late gadolinium enhancement is higher than that of HCM patients without LVAA.