Automatic dynamic range optimization for 3D medical ultrasound imaging

In ultrasound B-mode imaging, dynamic range (DR) is typically given with a fixed value, and operators should manually adjust it. However, in 3D ultrasound imaging, it is difficult to adjust DR during 3D data acquisition, leading to low image quality. In this paper, the automatic DR adjustment (ADRA) method was applied to optimize the DR value in 3D ultrasound imaging. In ADRA, the log average of a reference image is computed and the distance ratio from its log average to each extreme value is obtained. The distance ratio is used for adjusting the DR value of an input image to have similar contrast. When the ADRA method is applied to 3D ultrasound imaging, its first frame can be used as a reference image so that consecutive frames during 3D data acquisition can have comparable contrast. To evaluate the performance of the ADRA method, 70 frames of complex baseband in vivo abdominal data were acquired with a commercial ultrasound system by moving a 3.5-MHz convex array probe from the left lobe of the liver to the right kidney of a volunteer. The proposed ADRA method provides more uniform contrast in the c-plane image over the fixed DR method that suffers from dark lines. The consistent results were obtained with the measured correlation coefficient (CC) values. The proposed ADRA method provided the CC value of 0.9669 ± 0.0199 vs. 0.9611 ± 0.0308 and 0.6768 ± 0.3594, compared to the fixed DR and histogram matching methods, respectively. These results indicate that the proposed ADRA method can automatically adjust DR of the consecutive frames during 3D data acquisition to get uniform contrast, leading to the improvement in image quality of 3D ultrasound imaging.