Effect of B-mode optimization techniques on fetal bowel echogenicity using computerized image analysis

The purpose of this study was to provide and compare measurable parameters for normal fetal bowel echogenicity under predefined B-mode scanning presets.

Forty healthy fetuses underwent 14- to 17-week ultrasound scans, and 40 underwent 21- to 25-week scans. Sagittal, coronal, and axial fetal abdominal images were tested using predefined B-mode presets. The presets differed from fundamental imaging by isolated activation of harmonic imaging, compound resolution imaging, speckle reduction imaging, focus and frequency composite imaging, and coded excitation imaging features. A transabdominal probe was used in all fetuses, and transvaginal images were added for the 14- to 17-week scans. The images were studied with custom-developed software, which provided a grayscale analysis of the pixels in the region of interest within the image. The mean brightness of the pixels from the fetal bowel area was calculated.

The 14- to 17-week transabdominal scans showed significantly higher mean brightness on harmonic imaging compared to fundamental imaging (P < .01). Activation of coded excitation and compound resolution imaging in these scans resulted in a significant decrease in the mean brightness compared to fundamental imaging. Mean bowel brightness values on the 21- to 25-week transabdominal scans did not differ significantly with the use of the different imaging presets compared to fundamental imaging.

Transabdominal harmonic imaging in the early second trimester may significantly increase the mean brightness of the fetal bowel tissue. Contrarily, compound resolution imaging and coded excitation imaging produce the opposite effect on bowel echogenicity.