Backscatter difference techniques for bone assessment using an ultrasonic imaging system

Abstract

Background: Backscatter difference techniques are being developed to detect changes in bone caused by osteoporosis. Backscatter difference techniques compare the power in one portion of an ultrasonic backscatter signal to the power in a different portion of the same signal. Goal: Evaluate the feasibility of using an ultrasonic imaging system to perform backscatter difference measurements of bone. Procedure: Ultrasonic signals and images were acquired from 24 specimens of bone using an ultrasonic imaging system (Terason) with a 5 MHz linear array transducer. The signals were analyzed to determine the normalized mean backscatter difference (nMBD) between two gated portions of each signal. The images were analyzed to determine the normalized pixel value difference (nPVD) between regions of interest (ROIs) positioned at two different depths. Results: nMBD demonstrated strong linear correlations with bone mineral density that ranged from 0.83 to 0.87. nPVD performed less well, yielding correlations that ranged from 0.42 to 0.81, depending on ROI separation. Conclusions: It is feasible to apply the backscatter difference technique to ultrasonic imaging systems for the purpose of bone assessment. Better results are obtained by analyzing the signals rather than the images.