Calcium is a barrier to the penetration of ultrasound signal and causes characteristic '
acoustic shadowing'.
17.) They may have posterior
acoustic shadowing or no change in the echogenic appearance of the tissue posterior to the tumor.
Case 2: USG: Hyperechogenic image with posterior
acoustic shadowing S/O-Foreign Body in Abdominal Cavity.
US shows marked posterior
acoustic shadowing from an irregular, hypo-echoic density.
Whilst atelectatic lung does have areas of homogeneous echogenicity, it also has highly echogenic regions with distal
acoustic shadowing (due to the presence of air) (Figure 3).
Criteria Benign Appearance Shape Round, well-defined Margins Smooth, sharp, well-defined edges Echogenicity Isoechoic or slightly hypoechoic Internal echo pattern Homogeneous
Acoustic shadowing None demonstrated Calcifications Macrocalcifications Compressibility Compressible Criteria Malignant Appearance Shape Irregular, lobulated Margins Irregular, indistinct edges Echogenicity Markedly hypoechoic or black Internal echo pattern Heterogeneous
Acoustic shadowing Demonstrated Calcifications Microcalcifications Compressibility Noncompressible Shape
(1-3) Sonographic findings include single or multiple cysts, dilated ducts and highly echogenic foci with posterior
acoustic shadowing, representing fibrous tissue (Figure 4).
Ultrasound appearance of ascaris is reported in various studies as presence of long echogenic structure (linear or curved, single or multiple) with or without a central anechoic tube, mostly without
acoustic shadowing. (5,6,7) Varied appearances like "winding highway" or "parallel lines", "railway track"sign, "3 line" or "4 line" sign on longitudinal scan and doughnut or target sign, ring sign, bull's eye appearance on transverse scan had been reported in cases of ascariasis.
This configuration causes
acoustic shadowing and has a characteristic "laminated" sonographic appearance with parallel lines (FIGURE 2).
1c) revealed a right lower quadrant inflammatory mass with posterior
acoustic shadowing and surrounding loculated fluid collection.
A targeted left breast ultrasound at 11 o'clock, 5 cm from the nipple, underlying the area of a palpable abnormality, demonstrates an ill-defined hypoechoic mass with posterior
acoustic shadowing measuring 1.2 x 1.3 x 0.7 cm (Figure 3).
Sonography shows single or multiple poorly marginated hyopechoic lesions with or without distal
acoustic shadowing [6].
