Age is negatively correlated with arterial diameter in the circle of Willis [7], which causes that the smallest arteries may not be visualized unless the image resolution is accordingly increased.
In perforated appendicitis, a phlegmon or abscess may be seen, while the appendix may appear decompressed or may not be visualized [35, 36]. 4.
CT provides details concerning distant structures such as underlying bone, muscle and organs that may not be visualized during sonographic imaging due to the limited depth imaged by ultrasound.
Specific differences in gene expression, however, are identified after normalizing for global differences in the level of gene expression, thus, global differences may not be visualized in these analyses.
It is likely that only a limited number of similar RIFIN variants are detected, making it difficult to draw general conclusions on RIFIN expression patterns during gametocytogenesis, as relevant proteins may not be visualized and assignment of the variant is difficult.
A small, focal or loculated pericardial effusion may not be visualized nor easily 'tapped'tapped
Cancers may not be visualized because of overlying dense breast tissue [ 10– 10].
However, this multilayered pattern may not be visualized in all cases and not in all parts of the stomach.
Normally the gallbladder wall is 3 mm or less in thickness and carcinomas that are confined to the mucosa or slightly raised lesions may not be visualized sonographically.
Given the frequency of hepatic abscesses as a complication of pylephlebitis, and since they may not be visualized in a CT scan (with or without drainage), a minimum of 6 weeks antibiotic therapy seems prudent [ 13, 14].
