42
can be seen in other inflammatory conditions affecting the intestines, e.g., CMV
infection and enterocolitis. Moreover, in GVHD, it can be present in varying
degrees, but as compared to small bowel follow through contrast radiographic stud-
ies, CT has the advantage of a better image of luminal and extra luminal disease and
does not necessitate the use of oral contrast, which may be difficult to tolerate in
some of the patients in the pediatric population [ 1 ]. The bowel wall itself may mani-
fest in a radiologic sign that is known as the “halo sign”, which is due to hyperemic
granulation tissue surrounded by lower-attenuation outer bowel wall layers [ 3 ].
An additional finding that may be present is the “comb sign” which is due to
engorged blood vessels (Fig. 3.6) [ 4 ].
Liver abnormalities and complications are common in post-HSCT patients. One
unfortunately too frequent hepatic complication in the peri-transplant period is
veno-occlusive disease. Multidetector CT will demonstrate diffuse, hypoattenuating
liver parenchyma, ascites, periportal and gallbladder wall edema, and possibly nar-
rowed hepatic veins, therefore being useful for excluding other causes of the symp-
toms. Hepatic fungal or bacterial abscesses are also seen in patients post HSCT. A
contrast-enhanced CT or MRI may be superior to ultrasonography, specifically for
detection of fungal lesions (Fig. 3.7). CT findings include small hypoattenuating
lesions with peripheral ring enhancement, and detection of these lesions is improved
when CT imaging is collected during both the arterial phase and venous phase [ 4 ].
Genitourinary complications can include hemorrhagic cystitis, renal abscesses, and
renal parenchymal loss. Hemorrhagic cystitis can be seen after treatment with
Fig. 3.6 Coronal post
contrast CT from a case
with proven graft versus
host disease (GVHD).
Patient presented with abd
pain, diarrhea and bloating
post transplant for
NHL. Notice the thickened
large bowel loops with
hyperemia (arrows) in
mesenteric vessels (Coomb
sign). Also seen is the Halo
sign (box) around a loop of
inflamed colon
M. Atiq et al.