The ultrasound Doppler fetal heart rate measurement is the gold standard of fetal heart rate counting. However, the existing fetal heart rate extraction algorithms are not designed specifically to suppress the high maternal interference during the second stage of labor, and false detection occurrences are common during labor. With this background, a method combining time-frequency frame template library optimal selecting and non-linear template matching is proposed. The method contributes a template library, and the optimal template can be selected to match the signal frame. After the short-time Fourier transform of the signal, the difference between the signal and the template is optimized by leaky rectified linear unit (LReLU) function frame by frame. The heart rate was calculated from the peak of the matching curve and the heart rate was calculated. By comparing the proposed method with the autocorrelation method, the results show that the detection accuracy of the proposed method is improved by 20% on average, and the non-linear template matching of 23% samples is at least 50% higher than the autocorrelation method. This paper designs the algorithm by analyzing the characteristics of the interference and signal mixing. We hope that this paper will provide a new idea for fetal heart rate extraction which not only focuses on the original signal.
Objective To investigate the effectiveness of arthroscopic anterior cruciate ligament (ACL) reconstruction via transtibial (TT) and transportal (TP) techniques after 10 years follow-up. Methods A clinical data of 103 patients who underwent arthroscopic ACL reconstruction with a single bundle of autologous hamstring tendon between March 2006 and March 2009 was retrospectively analyzed, among which 57 patients were reconstructed with TT technique (TT group) and 46 patients were reconstructed with TP technique (TP group). There was no significant difference in gender, age, cause of injury, interval between injury and operation, preoperative pivot shift test, preoperative International Knee Documentation Committee (IKDC) score, Lysholm score, and KT-2000 side-to-side difference (SSD) between the two groups (P>0.05). At 10 years after operation, Lachman test was used to evaluate the forward joint stability and pivot shift test to evaluate the rotational stability of the knee; KT-2000 SSD was used to measure tibial anterior displacement; IKDC score and Lysholm score were used to evaluate knee function; MRI examination was performed to observe graft healing and measure coronal inclination angles of the tibia and femoral tunnels. The rate of return to sports was also calculated. Results The incisions healed by first intention in the two groups, and no early complication occurred after operation. All patients were followed up 10-13 years, with an average of 11.5 years. During the follow-up period, there was no limitation of knee extension and flexion, no discomfort of donor site or graft failure in either group. MRI examination showed that the graft healed well. The IKDC score, Lysholm score, and KT-2000 SSD in the two groups were significantly improved after 10 years (P<0.05), and there was no significant difference between the two groups at 10 years after operation (P>0.05). There were significant differences in coronal inclination angles of femoral tunnel and tibial tunnel between the two groups (P<0.05). There was no significant difference in Lachman test and pivot shift test between the two groups (P>0.05). The rate of return to sports of patients was 61.40% (35/57) in TT group and 63.04% (29/46) in TP group, showing no significant difference between the two groups (χ2=0.29, P=0.87). Conclusion TT and TP techniques can both achieve good effectiveness in ACL reconstruction.