DOI:10.2214/AJR.05.0327
AJR 2006; 187:1199-1203
© American Roentgen Ray Society
Abdominal Manifestations of Cystic Fibrosis in Older Children and Adults
Tanya M. Fields1,
Steven J. Michel1,2,
Carina L. Butler1,
Vesna M. Kriss1 and
Sheri L. Albers1
1 Department of Diagnostic Radiology, University of Kentucky, 800 Rose St.,
HX-311, Lexington, KY 40536.
2 Present address: Northwest Radiologists, Inc., Bellingham, WA 98225.
Received February 25, 2005;
accepted after revision July 25, 2005.
Address correspondence to T. M. Fields.
CME
This article is available for CME credit. See
www.arrs.org
for more information.
Abstract
OBJECTIVE. Cystic fibrosis (CF) is a disorder of exocrine gland
function of which the gene mutation has been existing for thousands of years.
With recent medical advances, neonates presently affected have a life
expectancy of 40 years. The common gastrointestinal presentations of CF
patients, including pancreatic, hepatobiliary, and bowel manifestations, are
thus important to recognize.
CONCLUSION. Gastrointestinal manifestations of CF are varied yet
common and thus increasingly important to recognize. The sonographic, CT, and
MRI abdominal findings in older children and adults with CF are presented.
Keywords: abdominal imaging • cystic fibrosis
Introduction
Cystic fibrosis (CF), an autosomal recessive disorder of exocrine gland
function, is caused by a defective transmembrane conductance regulator located
on chromosome 7. CF involves multiple organ systems and has pulmonary
manifestations in 90% of patients. Affected neonates presently have a life
expectancy of 40 years, which exemplifies the importance of understanding
abdominal manifestations [1].
This article illustrates the sonographic, CT, and MRI abdominal imaging
findings in older children and adults with CF.
Pancreatic Manifestations
Eighty-five to ninety percent of CF patients have clinically apparent
pancreatic disease, which is most commonly manifested as exocrine
insufficiency, with endocrine insufficiency in only 30-50% of patients
[2,
3]. Severity and prevalence
increase as patients age. Complete pancreatic fatty replacement is the most
common pancreatic abnormality seen on CT or MRI
[3,
4]. Studies have shown diffuse
fatty replacement in 56-93% of CF patients, with the mean age for fatty
replacement being 17 years [2,
3]
(Fig. 1). Pancreatic
abnormalities are seen sonographically in 70-100% of CF patients. Pancreatic
fibrosis is identified on CT, and pancreatic lipomatosis and fibrosis are
considered characteristic in pediatric CF patients
[1,
3]. MRI appearances vary
according to the amount of fat or fibrosis. Increased fatty changes appear
more intense on T1-weighted images, and fibrosis appears decreased on T1- and
T2-weighted images (Fig.
2).
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Fig. 1 —24-year-old woman with cystic fibrosis. Abdominal
contrast-enhanced CT scan reveals marked pancreatic glandular atrophy, which
is nearly replaced by fat (arrows). Also note hepatomegaly (H).
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Fig. 2 —18-year-old woman with cystic fibrosis. Axial T1-weighted
image without fat saturation through abdomen shows markedly increased signal
in region of pancreas (arrows), which is consistent with
near-complete fatty replacement.
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Pancreatic duct calcifications are another manifestation of CF, with a
reported prevalence of up to 8%
[1]. CT findings include
increased density in dilated pancreatic ducts, which vary in size and
morphology (Fig. 3).
Microscopic or small pancreatic cysts are commonly seen in CF patients. These
vary from 1 to 3 mm in diameter
[1,
4]. Rarely, an extreme form of
cystic change, pancreatic cystosis, occurs in which the pancreas is completely
replaced by cysts. CT, MRI, and sonography reveal near-total replacement of
the pancreas by cysts of varying sizes that have diameters ranging from less
than 1 to 12 cm (Fig. 4).
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Fig. 3 —20-year-old woman with cystic fibrosis. Contrast-enhanced CT
scan of abdomen reveals discrete high-density foci in pancreas
(arrow) that are consistent with multiple tiny pancreatic
calcifications.
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Fig. 4 —19-year-old woman with cystic fibrosis. Contrast-enhanced
abdominal CT scan, including magnification view, shows near-complete
replacement of pancreas by multiple low-attenuation masses (long thin
arrows), which is consistent with pancreatic cystosis. Incidentally noted
are pancreatic calcifications (short thin arrow) and colonic wall
thickening (thick arrow).
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Hepatobiliary Manifestations
Hepatic manifestations of CF include steatosis, hepatomegaly, and focal
biliary cirrhosis, which can lead to frank cirrhosis and portal hypertension.
The incidence of hepatic involvement is 20-50%. Development of cirrhosis is
uncommon, seen in fewer than 5% of CF patients
[1]. Fatty liver changes are
commonly asymptomatic, occurring 30% of the time
[4,
5]. Steatosis may become severe
and cause hepatomegaly. Sonographically, increased echogenicity of hepatic
parenchyma is seen (Fig. 5).
Focal fat deposition in centrilobular and periportal regions can occur,
creating difficulty discerning portal triads
[1]. The liver may appear
normal on CT or have decreased attenuation, which creates an apparent vascular
prominence [4,
5]. MRI findings include
hepatic hyperintensity on T1-weighted images that suppresses with
fat-saturation sequences. T1-weighted images with in- and out-of-phase
sequences are also used [3,
4].
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Fig. 5 —19-year-old woman with cystic fibrosis. Transverse sonogram
through abdomen identifies increased echogenicity of hepatic parenchyma (L)
compared with kidney (K), which is consistent with fatty liver infiltration.
Note portal triads are difficult to discern.
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Focal biliary cirrhosis occurs in up to 40% of CF patients
[4,
5]. One percent of patients
progress to portal hypertension and end-stage liver disease
[1,
5]. Focal biliary cirrhosis
appears sonographically as regions of increased echogenicity in periportal
areas. Sonographically, cirrhotic livers have a nodular appearance with a
coarsened echotexture. Right lobe atrophy and hypertrophy of the caudate and
lateral segments of the left lobe are seen. Splenomegaly, portosystemic
shunts, portal vein enlargement, hepatofugal flow, and ascites can be seen
with portal hypertension (Fig.
6). Regenerative nodules in cirrhotic livers can be seen on CT and
MRI. They appear iso- to hyperintense on T1-weighted images with fat
saturation, are separated by hypointense fibrotic bands, and do not enhance
with administration of contrast material
[4]. Biliary manifestations
include abnormalities of intra- and extrahepatic bile ducts, gallbladder
thickening and contraction, microgallbladder, and cholelithiasis
[3]. Biliary abnormalities are
evident in 5-33% of CF patients
[4].
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Fig. 6 —15-year-old girl with cystic fibrosis. Contrast-enhanced
abdominal CT scan identifies atrophied, cirrhotic liver (L), splenomegaly (S),
abundant ascites (thick arrow), and venous collaterals (thin
arrows). These findings are consistent with portal hypertension.
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Fig. 7 —29-year-old woman with cystic fibrosis. Transverse
sonographic view of gallbladder reveals multiple echogenic structures in
gallbladder and posterior wall shadowing (arrows), which is
consistent with cholelithiasis.
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King et al. [4] revealed
gallbladder abnormalities in up to 50% of CF patients. Gall-stones, seen in
12-24% of these patients, consist mostly of cholesterol stones
(Fig. 7). Cholelithiasis can be
detected on CT; however, CT is not routinely used in this manner. MR
cholangiopancreatography (MRCP) has become an excellent noninvasive procedure
to reveal stones and intra- and extrahepatic biliary disorders
[4].
An autopsy series found microgallbladders in 25% of CF patients (Figs.
8 and
9). Atretic or stenotic cystic
ducts secondary to inspissated mucus have been postulated to create a
microgallbladder [1,
5]. Dietrich et al.
[2] revealed pathologic bile
duct abnormalities in 49% of CF patients. Intra- and extrahepatic biliary
abnormalities are described that vary from tapering of distal intrahepatic
bile ducts to focal dilatation of larger bile ducts
(Fig. 10).
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Fig. 9 —17-year-old girl with cystic fibrosis. Coronal T2-weighted MR
cholangiopancreatograms reveal microgallbladder (thin arrows). Two
fluid collections are noted in region of pancreas (thick arrows) and
represent pancreatic pseudocysts. Arrowhead indicates cystic duct.
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Fig. 10 —15-year-old boy with cystic fibrosis. Contrast-enhanced
abdominal CT scan identifies focal biliary dilatation in right lobe of liver
(arrows). Also of note is cirrhotic liver (L) with associated ascites
(A).
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Bowel Manifestations
Meconium ileus or plug, meconium ileus equivalent, intussusception,
appendicitis, rectal prolapse, gastroesophageal reflux, an increased incidence
of Crohn's disease, and fibrosing colonopathy are all reported
gastrointestinal manifestations of CF
[6].
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Fig. 11 —18-year-old woman with cystic fibrosis. Contrast-enhanced
abdominal CT scan identifies multiple loops of dilated small bowel
(arrows), which is consistent with distal intestinal obstruction
syndrome.
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Fig. 12 —29-year-old woman with cystic fibrosis. Contrast-enhanced
abdominal CT image reveals cecal wall thickening (arrow) and
pericolonic fat stranding (arrowhead), which are consistent with
additional manifestation of distal intestinal obstruction syndrome.
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Generally, all infants presenting with meconium ileus are later diagnosed
with CF [5,
6]. Older children and adults
present instead with the equivalent of meconium ileus, now called distal
intestinal obstruction syndrome (DIOS), which occurs in 10-15% of CF patients
(Fig. 11). A high prevalence
is seen in the second and third decades of life
[6]. CT findings include
colonic wall thickening, mural striation, mesenteric soft-tissue infiltration,
and increased pericolonic fat. Findings are predominately seen in the right
colon (Fig. 12).
Fibrosing colonopathy is more common in children younger than 10 years old
and has not been reported in adults
[6,
7]. It is often seen in
patients treated with pancreatic enzyme replacement
[5-7].
Radiographic findings include nodular thickening of the colon, the loss of
normal haustral folds, strictures, and colonic shortening
[5]. The appendix of CF
patients is routinely enlarged (> 6 mm) in the absence of appendicitis
resulting from mucoid impaction (Fig.
13). Using secondary signs to diagnose appendicitis is critical.
The prevalence of appendicitis is reportedly lower in CF patients (1-2%) than
in the general population (7%)
[5].
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Fig. 13 —18-year-old woman with cystic fibrosis. Axial unenhanced
pelvic CT scan with coronal reformatted image (inset) shows enlarged
appendix (arrow). Note increased attenuation of appendix as result of
mucous inspissation.
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Ileocolic intussusception is a known complication of CF and is seen more
commonly in older children, with an average presenting age of 10 years. When
idiopathic, ileocolic intussusception presents in patients younger than 2
years old. The lead point is often enlarged lymphoid follicles at the terminal
ileum or an enlarged appendix (Fig.
14).
Gastrointestinal manifestations of CF patients are varied yet common and
are increasingly important to recognize.
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Abstract
Introduction
