The Accuracy of the Assessment of Normal Fetal Intestinal Echogenicity – Electro-Optical Densitometry versus the Ultrasonographer’s Eye

Abstract

Ten plates of normal fetal ultrasonography (at 16-20 weeks’ gestation) showing fluid, liver, lung, bone and intestine were submitted to electro-optical transmission surface densitometry. A distinct echogenic gradient has been found and used as an ‘internal standard’ to evaluate intestinal echogenicity. Intestine had significantly different echogenic properties from bone, liver and fluid but similar to that of lung. Using this echogenicity scale for fetal bowel, observers were correct in 46%, overscored in 32.6% and underscored in 21.4%. These poor results may be due to the significant inconsistency in the interpretation of each plate compared to other plates (about 65%). Although the densitometry-derived grading scale seems valid at these gestational ages, interobserver variation is too large and precludes a simple ultrasonic diagnosis of the hyperechogenic fetal intestine. Densitometric evaluation may be indicated in suspected cases when fetal bowel seems to have increased echogenicity.

Quantitative assessment of sonographic image echogenicity by transmission densitometry: fetal liver model

“…Our group evaluated fetal bowel echogenicity using a comparison to an "internal standard" of five fetal tissues. 7 Densitometry again clearly established the inability of the sonographer to assess qualitatively the true density of the sonographic image.…”

“…7 The purpose of the current study is to establish a mathe-matical transformation that may allow quantitative densitometry of sonographic images.…”

Computed Sonography: Requiem to Echogenicity Assessment?

“…All the above were performed in 7 patients. In 10 patients, images were created at three low-contrast 2-D postprocessing curves (2,3,4) and at three high-contrast 2-D postprocessing curves (5,6,7) while all other parameters were kept constant. A hard copy of each image was produced by the AGFA matrix mini daylight processor (Mortsel, Belgium).…”

“…The fetal liver area was measured ten times at random locations through a 3-mm hole, and a mean den sity was calculated. Although the entire surface density of the fetal liver was not measured, several random densitometries through a large measuring hole adeqately represent the mean surface transmis sion density [2].…”

“…An observer's interpretation of tissue echogenicity is dependent, among other things, on image density [1], Sig nificant interobserver variations in echogenicity assess ment are expected due to the inability of the naked human eye to accurately assess differences in image density [2][3][4], In contrast to human vision, objective densitometry, by measuring image density, can accurately differentiate subtle differences in tissue echogenicity [3][4].…”