Mode Decomposition Based Cepstrum Measurement of Scatterer Spacing with Ultrasonic Scattering

Bone loss is closely related to the mean scatter spacing (MSS) changes of quasi-periodic trabecular, and ultra-sonic backscattering is an effective method to measure these changes. This paper presented the method of Mode Decomposition Based Cepstrum Spacing Measurement (MDCM) which improves the performance of the bone scatterer measurement. Compared with other techniques, MDCM approach is adaptive, empirical and takes advantage of the Intrinsic Mode Functions (IMFs) which have specific physical meanings. This technique was validated by backscattering data obtained from simulations based on two different methods, Faran cylinder model and Finite Element Method (FEM), where scatterers were defined to be equally and quasi-periodically spaced. Both the simulation results show that the first mode (IMF1) decomposed by Empirical Mode Decomposition (EMD) preserves the intrinsic feature of original data and clearly demonstrates the scatterer spacing of 0.41 mm and 0.5 mm. Then the Ensemble EMD (EEMD) based cepstrum technique was used and it shows that the interference peaks are suppressed. Besides, in addition to IMF 1, the IMF 2 also shows valuable information for MSS measurement.