Evaluation of left and right ventricular systolic function by cardiac MR compressed sensing ultrafast cine sequence / 中华放射学杂志

Objective:To explore the clinical value of cardiac MR (CMR) compression sensing (CS) ultrafast cine sequence in evaluating left and right ventricular systolic function by comparing with traditional segmented acquisition cine sequence (Seg).Methods:Twenty-seven patients with various heart disease were prospectively included. Seg, breath holding CS (bhCS) and free breathing CS (fbCS) covering the left and right ventricles using multi slices in short axis were performed in random order. Friedman test was used to evaluate the overall image quality (grade 1-5 score), blood pool myocardial signal ratio (BMC) and edge sharpness under different methods. Biventricular end diastolic volume (EDV), end systolic volume (ESV), stroke volume (SV), ejection fraction (EF) and left ventricular myocardial mass (Mass) were measured for all three methods. The agreements of the functional measurements between bhCS and Seg (gold standard), and between fbCS and Seg were analyzed by Bland-Altman, and the correlation test was performed.Results:Twenty-four patients with diagnostic images(overall image quality score≥2) for all three methods were included in further analysis. The total imaging time of Seg, bhCS and fbCS decreased successively[375.0 (332.0, 405.6) vs. 50.0 (47.8, 53.7) vs. 20.0 (17.8, 23.7) s, χ 2=48.00, P<0.001]. The overall image quality of fbCS was slightly lower than that of Seg ( Z=-2.67, P=0.023), and there was no difference between Seg and bhCS ( Z=-1.44, P=0.447), bhCS and fbCS ( Z=1.23, P=0.660). There were no differences in edge sharpness (χ 2=1.08, P=0.582) and BMC (χ 2=0.58, P=0.747) for three methods. Bland-Altman polts showed good agreement for biventricular functional measurements between bhCS and Seg, and between fbCS and Seg. All functional measurements of bhCS and fbCS were highly correlated with that of seg ( r>0.96, P<0.001). Conclusions:Compared with traditional sequences, CS ultrafast cine sequences can save scanning time and provide similar image quality. No matter whether breath holding or not, the cardiac functional results of CS sequence and traditional cine sequence have good agreement and high correlation.

Protein Kinase C Controls the Excitability of Cortical Pyramidal Neurons by Regulating Kv2.2 Channel Activity / 神经科学通报·英文版

The family of voltage-gated potassium Kv2 channels consists of the Kv2.1 and Kv2.2 subtypes. Kv2.1 is constitutively highly phosphorylated in neurons and its function relies on its phosphorylation state. Whether the function of Kv2.2 is also dependent on its phosphorylation state remains unknown. Here, we investigated whether Kv2.2 channels can be phosphorylated by protein kinase C (PKC) and examined the effects of PKC-induced phosphorylation on their activity and function. Activation of PKC inhibited Kv2.2 currents and altered their steady-state activation in HEK293 cells. Point mutations and specific antibodies against phosphorylated S481 or S488 demonstrated the importance of these residues for the PKC-dependent modulation of Kv2.2. In layer II pyramidal neurons in cortical slices, activation of PKC similarly regulated native Kv2.2 channels and simultaneously reduced the frequency of action potentials. In conclusion, this study provides the first evidence to our knowledge that PKC-induced phosphorylation of the Kv2.2 channel controls the excitability of cortical pyramidal neurons.

Quantitative study of cardiac MR T 1 mapping/iECV in patients with aortic insufficiency / 中华放射学杂志

Objective:To explore the clinical value of T 1 mapping/indexed extracellular volume fraction (iECV) quantified with cardiac MR (CMR) parameters, and its correlation with traditional indicators of myocardial dysfunction in aortic insufficiency (AI) patients. Methods:A total of 36 patients clinically and radiologically diagnosed with chronic AI in our hospital between May 2012 and February 2016 were retrospectively selected. All AI patients underwent conventional CMR protocol, native and post T 1 mapping. CMR parameters, such as aortic regurgitant fraction (RF), late gadolinium enhancement (LGE) mass fraction, myocardial extracellular volume fraction (ECV) and iECV. Based on the values of aortic RF, AI patients were divided into mild AI group (9 cases), moderate AI group (14 cases) and severe AI group (13 cases). The clinical characteristics were teased from the patients′ electronic medical records. Univariate analysis of variance was used to compare the measurement data of native T 1 mapping, post-contrast T 1 mapping, ECV, and iECV. LSD test was used for pair wise comparison between the mild AI, moderate AI and severe AI groups. Data about cardiovascular history, New York Heart Association (NYHA) heart function classification, and LGE were compared by chi-square test or Fisher exact test. The correlation between left ventricle ejection fraction (LVEF) and iECV was evaluated by Spearman correlation analysis. Results:There was no difference in age, sex, cardiovascular history among the three groups. Comparison of patients with different severity of AI in the three groups: (1) There was statistically significant difference in the LGE positive rate among the three groups ( P=0.023), while the myocardial replacement of fibrosis increased with the grade of aortic regurgitation. (2) There was no statistically significant difference in the measurement data of native T 1 mapping, post-contrast T 1 mapping, ECV among the three groups ( H=1.815, 0.929, 2.496, all P values>0.05), while the diffuse myocardial fibrosis tended to increase with the degree of aortic regurgitation. There was statistically significant difference in iECV among the three groups ( H=16.725, P<0.001). The measurement data of iECV in the severe AI group was significantly higher than those in the other two groups ( P<0.05). LVEF value was inversely correlated with iECV ( r=-0.649, P<0.001). Conclusions:Quantitative T 1 mapping/iECV can serve as a parameter to noninvasively identify diffuse myocardial fibrosis in AI patients of different severities. It changes with LVEF and can manifest the reversible stage of left ventricular decompensation.