An Enhanced Multi-frequency Distorted Born Iterative Method for Ultrasound Tomography based on Fundamental Tone and Overtones

Conventional Distorted Born Iterative Method (DBIM) using single frequency has low resolution and is prone to creating images with high-contrast subjects. We propose a productive frequency combination method to better result in tomographic ultrasound imaging based on the multi-frequency technique. This study uses the natural mechanism of emitting oscillators' frequencies and uses these frequencies for imaging in iterations. We use a fundamental tone (i.e., the starting frequency f0) for the first iteration in DBIM, then consecutively use its overtones for the next ones. The digital simulation scenarios are tested with other multi-frequency approaches to prove our method's feasibility. We performed 57 different simulation scenarios on the use of multi-frequency information for the DBIM method. As a result, the proposed method for the smallest normalization error (RRE = 0.757). The proposed method's imaging time is not significantly longer than the way of using single frequency information.

Four-Dimensional Introital Ultrasound in Assessing Perioperative Pelvic Floor Muscle Functions of Women with Cystoceles

Purpose Research on the use of ultrasound to explore the pelvic floor in women is rarely done with introital ultrasound. This study aimed to investigate the performance of four-dimensional (4D) introital ultrasound in the perioperative assessment of pelvic floor muscle (PFM) function in women with cystocele. Materials and Methods The reliability and agreement of ultrasound measurements were determined by intraclass correlation coefficients (ICC) with 95 % confidence interval and Bland-Altman analysis in 20 women. The validity of ultrasound parameters was assessed by correlating squeezing ultrasound measurements with the modified Oxford scale (MOS) in 317 women. 4D introital ultrasound data of 241 women with (n = 29) and without (n = 212) postoperative cystocele at the 12-month postoperative assessment were retrospectively analyzed. Levator avulsion was diagnosed using tomographic ultrasound imaging. Involuntary and voluntary PFM functions were explored by dynamic changes in the bladder neck and genital hiatus, respectively, upon coughing and squeezing on 4D introital ultrasound. Results The ICC for the reliability of all tested ultrasound parameters was good to very good. The changes and change ratios of most ultrasound measurements from resting to squeezing were fairly correlated with MOS. Women with postoperative cystocele demonstrated more rates of complete levator avulsion [41.3 % vs. 4.7 %, P < 0.001, odds ratio (OR) 14.26, 95 % confidence interval (CI) 4.88–42.42] and fewer rates of capable voluntary PFM contraction (65.5 % vs. 92.5 %, P < 0.001, OR 0.16, 95 % CI 0.06–0.43) than those without postoperative cystocele postoperatively. Conclusion 4D introital ultrasound is feasible to assess perioperative PFM function in women with cystocele.