Diagnostic ultrasound ( PDFDrive )

296 PART II Abdominal and Pelvic Sonography
FIG. 8.46 Intussusception in Two Patients (A) Sonogram shows
multiple concentric rings representative of the invaginating intussuscipiens
and the intussusceptum. Submucosal metastatic nodule
as lead point. (B) Sonogram of the right lower quadrant shows a
highly echogenic lead point related to a lipoma (arrow). The invaginating
fat in the mesentery is also echogenic. (C) Conirmatory CT scan
for image B. (B and C with permission from Wilson SR. The bowel
wall looks thickened: what does that mean? In: Cooperberg PL,
editor. RSNA categorical course syllabus. Chicago: RSNA; 2002. pp.
219-228. 1 )
A
B
C
AIDS Patients
Today, efective antiviral medications for HIV infection have
drastically changed the outlook for those living with AIDS in
the Western world. Nonetheless, patients with AIDS are at
increased risk for development of both GI tract neoplasia,
especially lymphoma (see Fig. 8.10C and D), and unusual
opportunistic infections, most oten Candida esophagitis and
CMV colitis 65,66 (see Fig. 8.36).
Pseudomembranous Colitis
Pseudomembranous colitis is a necrotizing inlammatory bowel
condition that may occur as a response to a heterogeneous group
of insults. At present, antibiotic therapy with efects from the
toxin of Clostridium diicile, a normal inhabitant of the GI tract,
is most oten implicated. Watery diarrhea is the most common
symptom and usually occurs during antibiotic therapy but may
be quite remotely associated, occurring up to 6 weeks later.
Endoscopic demonstration of pseudomembranous exudative
plaques on the mucosal surface of the gut and culture of the
enterotoxin of C. diicile are diagnostic. Supericial ulceration
of the mucosa is associated with inlammatory iniltration of the
lamina propria and the submucosa, which may be thickened to
many times the normal size. 86
Sonography is frequently performed before pseudomembranous
colitis is diagnosed, oten based on a history of fever,
abdominal pain, and watery diarrhea. Sonographic features
have only rarely been described 87,88 but are suggestive of pseudomembranous
colitis. Usually the entire colon is involved in
a process that may produce striking thickening of the colon
wall. Exaggerated haustral markings and a nonhomogeneous
thickened submucosa, with virtual apposition of the mucosal
surfaces of the thickened walls, are characteristic 63 (Fig. 8.48).