Real-time signal quality assessment for ECGs collected using mobile phones

Considering that the uncertainty noise produced the decline in the quality of ECGs, this paper proposed a real-time signal quality assessment method for ECGs collected using mobile phones. The method defines four “flags” to denote different type problems duo to the poor quality of ECGs: using flag1 to detect if there is a misplaced electrode; using flag2 to detect if there is a huge impulse; using flag3 to denote if there is a strong Gauss noise; and using flag4 to denote if there is a detector error of R-wave peaks by the template matching method. Then based on the values of four ”flags”, we calculate the single signal quality index (SSQI) for each ECG and the integrative signal quality index (ISQI) for twelve-lead ECGs. The range of ISQI is between 0 and 12 inclusively. High value of ISQI means good quality of the ECGs. Each ECG record would be assigned to two groups according to ISQI, acceptable and unacceptable group. We define two indices, Sensitivity and Specificity, to evaluate the validity of this paper's method and the results are 90.67% and 89.78% respectively.