Ultrasonography is the imaging exam of choice; classical features of intussusceptions comprise a target sign in transverse view and a pseudokidney sign
in longitudinal view .
The sonographic feature of acute diverticulitis is the so-called pseudokidney sign
, in which a section of the intestinal tract involved in inflammation acquires a kidney-shaped appearance.Therefore, the intestine presents a peripheral hypoechoic border that mimics the renal cortex surrounding a hyperechoic center, which instead resembles the renal medulla.
On ultrasonography multiple, concentric, target like appearance of wall layers of invaginated segments (Target sign) on axial scan, as well as pseudokidney sign
(sandwich sign) on longitudinal scans were accepted as diagnostic criteria for intussusception.
The ultrasound revealed a targetoid appearance (Figure 1) in the bowel and a pseudokidney sign
(Figure 2) consistent with intussusception.
Solid lesions and neoplastic masses can produce a characteristic sonographic pattern, known as the target or pseudokidney sign
. While gas-filled loops of the small bowel cannot be imaged with sonography, fluid-filled, distended loops can be visualized and may be useful in confirming small bowel obstruction.
CT will show a pseudokidney sign
and a target sign, with edema of Kerckring's folds in the intussusceptum of the small bowel.
Sandwich sign, hayfork sign, pseudokidney sign
can be seen on longitudinal scan.