Electrocardiogram (ECG) signals are susceptible to be disturbed by 50 Hz power line interference (PLI) in the process of acquisition and conversion. This paper, therefore, proposes a novel PLI removal algorithm based on morphological component analysis (MCA) and ensemble empirical mode decomposition (EEMD). Firstly, according to the morphological differences in ECG waveform characteristics, the noisy ECG signal was decomposed into the mutated component, the smooth component and the residual component by MCA. Secondly, intrinsic mode functions (IMF) of PLI was filtered. The noise suppression rate (NSR) and the signal distortion ratio (SDR) were used to evaluate the effect of de-noising algorithm. Finally, the ECG signals were re-constructed. Based on the experimental comparison, it was concluded that the proposed algorithm had better filtering functions than the improved Levkov algorithm, because it could not only effectively filter the PLI, but also have smaller SDR value.
Algorithms ; Electrocardiography ; Humans

Objective To investigate the diagnostic value of one-stop liver magnetic resonance dynamic enhanced MRA for esophageal and gastric varces.Methods 82 patients with liver cirrhosis portal hypertension who were diagnosed by clinical and laboratory detect were taken,conducting liver horizontal scanning and multitemporal three dimensional dynamic enhanced scanning using Philips Achieva 1.5T MRI scanner,and then make maximum intensity projection(MIP) at work station to draw up portal vein image,observing the form and distribution of portal vein and its branches,meanwhile refer to cross sectional image to carefully observe whether there was cirsoid vein in esophagus and stomach,and further the source,degree and depth of cirsoid vein were compared,and whether there was cirsoid vein in other parts,and the pathological situation of liver.Compared with the result of gastroscope inspection,whether there is cirsoid vein in esophagus and stomach.Results The trunk and class-Ⅲ branches of portal vein of all patients had been clearly shown.In this team,there were esophageal and gastric varces in 78 patients,specifically including varices of fundus of stomach & esophageal varices in 27 patients,and varices of fundus of stomach and varices of body of stomach in 19 patients.Meanwhile,it diagnose 6 patients with liver cirrhosis and liver cancer and indicate 8 patients with liver cirrhosis nodule cancerization.The endoscope found out esophageal varices and varices of fundus of stomach in 68 patients,specifically including gastric varicesa and esophageal varices in 25 patients,sole gastric varicesa in 8 patients,and sole esophageal varices in 35 patients.Conclusion The one-stop liver three dimensional dynamic enhanced MRA is with great value in diagnosing the location and degree of esophageal varices and varices of fundus of stomach of patients with portal hypertension.The overall effect is better than endoscope.