AJR 2004; 183:1333-1338
© American Roentgen Ray Society
Hepatic Nodular Lesions Associated with Abnormal Development of the Portal Vein
Tonsok Kim1,
Takamichi Murakami1,
Eiji Sugihara1,
Masatoshi Hori1,
Kenji Wakasa2 and
Hironobu Nakamura1
1 Department of Radiology, Osaka University Graduate School of Medicine, D1, 2-2
Yamadaoka, Suita City, Osaka 565-0871, Japan.
2 Department of Pathology, Osaka City University Medical School, 1-4-3
Asahimachi, Abenoku, Osaka City 545-8585, Japan.
Received October 4, 2002;
accepted after revision February 21, 2004.
Address correspondence to T. Kim
(kim{at}radiol.med.osaka-u.ac.jp).
Abstract
OBJECTIVE. We reviewed the medical records including pathologic
descriptions, CT images, MR images, and digital subtraction angiograms of
three patients with hepatic lesions that were associated with abnormal
development of the portal vein—patent ductus venosus or congenital
absence of the portal vein—to clarify the imaging characteristics of
these abnormalities.
CONCLUSION. Two-phase helical CT and MRI, including MR angiography
and dynamic studies, are useful for the diagnosis of patent ductus venosus and
congenital absence of the portal vein. MRI may more effectively reveal hepatic
lesions than two-phase helical CT under such abnormal conditions in which the
liver has only the arterial but not the portal blood supply.
Introduction
Both patent ductus venosus and congenital absence of the portal vein
are rare abnormalities of the portal vein
[1,
2]. Focal hepatic lesions have
been frequently reported to be associated with these abnormalities
[2-5].
We examined three patients with hepatic nodular lesions associated with patent
ductus venosus or congenital absence of the portal vein. We reviewed the
medical records, including pathologic descriptions, CT images, MR images, and
digital subtraction angiograms of these patients, to clarify the imaging
characteristics of these abnormalities.
Subjects and Methods
Three patients with focal hepatic lesions associated with patent ductus
venosus or congenital absence of the portal vein were diagnosed in our
hospital between 1994 and 2000. Patient 1 had patent ductus venosus; this
patient was an 18-year-old man who had visited another hospital for
epigastralgia and was endoscopically determined to have a gastric ulcer.
Patient 2 was a 6-year-old boy who had visited another hospital because of
symptoms of heart failure, including dyspnea and cyanosis; he also had patent
ductus venosus. Patient 3 had congenital absence of the portal vein; this
patient was an 8-year-old boy who had multiple malformations including
polydactylism, polysplenia, and azygos continuation and had been followed up
after surgery for endocardial cushion defect of congenital heart disease. In
all patients, hepatic dysfunction was identified on the basis of laboratory
data, and hepatic focal lesions were found during sonography screening for
hepatic dysfunction. The three patients were referred to our hospital for
further examination. Laboratory data showed hyper-ammonemia in all three
patients.
All three patients underwent CT and MRI. Unenhanced and two-phase
contrast-enhanced CT images were obtained using a helical CT scanner (HiSpeed
Advantage, GE Healthcare). Early phase helical CT was performed just after the
completion of an IV bolus injection of 2 mL/kg of nonionic contrast material
(Omnipaque [iohexol], Daiichi Pharmaceutical) of 300 mg I/mL, and then late
phase helical CT was performed 1 min after the start of the injection. The
scanning delay for the early phase scan was approximately 30 sec for all
patients.
MR examinations were performed using a 1.5-T superconducting unit (Signa
Advantage, GE Healthcare). T1-weighted spin-echo MRI (TR/TE, 600/10; number of
excitations, 2) was performed in all three patients. Patient 1 also underwent
T2-weighted spin-echo MRI (2,000/80; number of excitations, 2), and patients 2
and 3 also underwent fast spin-echo MRI (4,000/80; number of excitations, 3).
Time-of-flight MR angiography was performed with a 2D Fourier transformation
fast spoiled gradient-recalled acquisition in the steady-state (SPGR) sequence
(40/11; number of excitations, 1; flip angle, 60°). For dynamic MRI, 2D
Fourier transformation fast SPGR (150/2.2; number of excitations, 1; flip
angle, 60°) images were obtained before, just after, 1 min after, and 2
min after the IV bolus injection of 0.1 mmol/kg of gadopentetate dimeglumine
(Magnevist, Nihon Schering). Finally, contrast-enhanced T1-weighted imaging
was performed with the same sequence as unenhanced T1-weighted imaging
approximately 1 min after the dynamic sequence.
Conventional digital subtraction angiography was performed in all three
patients with patients 2 and 3 under general anesthesia. Celiac arteriography
and superior mesenteric-arterial portography were performed in all
patients.
Retrograde venography of the patent ductus venosus with the balloon
occlusion technique through a catheter inserted via the inferior vena cava and
right atrium was performed in patient 2. Patient 1 underwent sonographically
guided percutaneous biopsy of the hepatic nodular lesion using an 18-gauge
needle; patient 2, open biopsy of the liver parenchyma; and patient 3, open
biopsy of both the hepatic nodular lesion and the liver parenchyma. The open
biopsy in patient 2 was performed during the surgical ligation of the patent
ductus venosus to reduce the massive portosystemic shunt flow running into the
right atrium because this patient had heart failure due to the massive shunt
flow.
Results
CT and MRI showed multiple hepatic nodular lesions in patients 1 and 3, but
a solitary hepatic nodular lesion was seen in patient 2 (Figs.
1A,
1B,
1C,
1D,
1E,
2A,
2B,
2C,
3A,
3B,
3C,
3D,
3E). A large hepatic nodular
lesion over 5 cm in diameter was found in all patients. The hepatic nodular
lesions appeared slightly hypo- or isoattenuated on unenhanced CT images, and
they appeared heterogeneously isoattenuated or slightly hypoattenuated on
early phase CT images. In all patients, the hepatic nodular lesions became
more conspicuous as hypoattenuated lesions on late phase images than on early
phase images (Figs. 1A,
1B,
1C,
1D,
1E and
3A,
3B,
3C,
3D,
3E). Contrast-enhanced CT
images revealed an enlarged shunt vein connecting the main portal trunk in the
hepatic hilum to the inferior vena cava in patient 1 and to the right atrium
in patient 2. In patient 3, contrast-enhanced CT images showed the dilated
hepatic artery (Figs. 3A and
3C), but not the portal vein,
in the hepatic hilum (Fig. 3C)
and revealed a connection between the superior mesenteric vein and the left
renal vein (Fig. 3B). In all
patients, no intrahepatic portal branches were identified.
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Fig. 1A. —18-year-old man (patient 1) with hepatic masses associated
with patent ductus venosus. Early phase contrast-enhanced helical CT image
shows heterogeneous enhancement of right lobe of liver.
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Fig. 1B. —18-year-old man (patient 1) with hepatic masses associated
with patent ductus venosus. Late phase CT image shows mass (thick
arrows) with hypoattenuation. Enlarged abnormal shunt vein
(arrowhead) connecting main portal trunk to inferior vena cava is
seen, but no intrahepatic portal branches are observed. Left and middle
hepatic veins (thin arrows) are visible.
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Fig. 1C. —18-year-old man (patient 1) with hepatic masses associated
with patent ductus venosus. T2-weighted spin-echo MR image (TR/TE, 2,000/80)
more conspicuously shows greater number of hepatic masses (arrows)
with high signal intensity than do CT images. Linear high-signal-intensity
area (arrowhead) indicating central scar within mass is seen.
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Fig. 1D. —18-year-old man (patient 1) with hepatic masses associated
with patent ductus venosus. Arterial portogram shows venous shunt flow
(arrow) from main portal trunk to right atrium, but no visible
intrahepatic portal branches.
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Fig. 1E. —18-year-old man (patient 1) with hepatic masses associated
with patent ductus venosus. Microscopic image of hepatic mass obtained by
percutaneous needle biopsy shows hyperplasia of hepatocytes and led to
diagnosis of focal nodular hyperplasia. (H and E, x50)
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Fig. 2A. —6-year-old boy (patient 2) with hepatic mass associated with
patent ductus venosus. Maximum-intensity-projection image from 2D
time-of-flight MR angiography shows abnormal shunt vein (arrow)
running from main portal trunk toward right atrium, but no intrahepatic
branches. Inferior vena cava is also shown.
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Fig. 2B. —6-year-old boy (patient 2) with hepatic mass associated with
patent ductus venosus. Retrograde venogram of abnormal shunt vein
(arrow) through catheter inserted via right atrium reveals
hypoplastic intrahepatic portal branch (arrowhead).
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Fig. 2C. —6-year-old boy (patient 2) with hepatic mass associated with
patent ductus venosus. T2-weighted spin-echo MR image (TR/TE, 1,800/80) shows
large hepatic mass (arrow) of mild high signal intensity in right
lobe of liver.
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Fig. 3A. —8-year-old boy (patient 3) with hepatic masses associated
with congenital absence of portal vein. Early phase contrast-enhanced helical
CT image obtained at level of hepatic hilum shows hepatic artery
(arrow).
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Fig. 3B. —8-year-old boy (patient 3) with hepatic masses associated
with congenital absence of portal vein. Early phase CT image obtained at more
caudal level than A shows superior mesenteric vein (arrow)
connected with left renal vein (arrowhead).
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Fig. 3C. —8-year-old boy (patient 3) with hepatic masses associated
with congenital absence of portal vein. Late phase CT image shows dilated
hepatic artery (arrow) and also shows portal vein is absent.
Hypoattenuated mass (arrowheads) is seen in left lobe of liver.
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Fig. 3D. —8-year-old boy (patient 3) with hepatic masses associated
with congenital absence of portal vein. T1-weighted spin-echo MR image (TR/TE,
600/10) more conspicuously shows greater number of hepatic masses
(arrows) of increased signal intensity than do CT images.
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Fig. 3E. —8-year-old boy (patient 3) with hepatic masses associated
with congenital absence of portal vein. Arterial portogram depicts venous flow
from superior mesenteric vein (arrow) to inferior vena cava
(arrowhead).
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T1- and T2-weighted MRI showed the nodular hepatic lesions more
conspicuously than did two-phase CT in all patients. Moreover, these sequences
showed more hepatic lesions than CT in patients 1 and 3 (Figs.
1A,
1B,
1C,
1D,
1E and
3A,
3B,
3C,
3D,
3E). In all patients, the
nodular hepatic lesions showed increased signal intensity on T1-weighted
images (Fig. 3D) but a variety
of signal intensities from high to low on T2-weighted images
(Fig. 1C). The hepatic nodular
lesions in patient 1 showed a linear inner structure of low signal intensity
on T1-weighted images and of high signal intensity on T2-weighted images,
indicating a central scar within the lesions.
MR angiography and dynamic MRI also revealed abnormal portosystemic shunt
veins in all three patients; these findings were confirmed by CT. Dynamic MRI
showed the hepatic nodular lesions exhibited the same degree of enhancement as
the hepatic parenchyma in all three patients.
Hepatic arteriography showed dilated hepatic arteries through the liver
during the vascular phase in all patients; during the parenchymal phase, the
whole liver was heterogeneously enhanced, but the hepatic nodular lesions were
not clearly demarcated. Digital subtraction arterial portography clearly
depicted the prominent portosystemic shunt flow of contrast material from the
main portal vein to the right atrium in patients 1 and 2 and from the superior
mesenteric vein to the inferior vena cava in patient 3 (Figs.
1A,
1B,
1C,
1D,
1E,
2A,
2B,
2C,
3A,
3B,
3C,
3D,
3E). Arterial portography did
not show any intrahepatic portal branches in all three patients. Retrograde
venography of the shunt vein via the right atrium with the balloon occlusion
technique was performed only for patient 2, and it revealed the presence of
hypoplastic intrahepatic portal branches that were not seen on CT or MR
images. In patients 1 and 2, the diagnosis was patent ductus venosus, and in
patient 3, the diagnosis was congenital absence of the portal vein.
Histologic examination of the hepatic lesions in patients 1 and 3
established a diagnosis of focal nodular hyperplasia. Histologic examination
of the liver parenchyma in patients 2 and 3 revealed hyperplasia of the
hepatocytes in both patients, whereas portal venules were seen in patient 2,
but not in patient 3.
All patients have undergone MRI follow-up every year for more than 2 years.
The hepatic nodular lesions have shown no signs of malignancy, such as distant
metastasis, lymph adenopathy, or rapid growth. None of the imaging features of
the hepatic nodular lesions has changed in any of the patients.
Discussion
Ductus venosus is the continuation of the umbilical vein; it originates
from the left portal vein and ends in the region of the hepatic vein at the
point of confluence with the inferior vena cava
[1,
6]. During fetal life, the
ductus venosus allows blood returning through the umbilical vein to bypass the
portal venous system. The ductus venosus closes within 2 weeks after birth and
finally is transformed into the ligamentum venosus
[1,
6]. Patent ductus venosus is an
extremely rare abnormality [1].
It can be found in association with symptoms of portosystemic encephalopathy
or malformations, including congenital heart disease and minor anomalies, or
it can be found incidentally during abdominal sonography
[5]. Hepatic nodular lesions,
such as focal nodular hyperplasia, have been reported to develop in patients
with patent ductus venosus
[5].
The development of the portal vein occurs between the fourth and 10th weeks
of gestation. The portal vein originates from the right and left vitelline
veins and their median anastomosis
[3]. The congenital absence of
the portal vein is also a rare congenital abnormality and is thought to be
associated with the presence of an anastomosis between the splanchnic and
systemic circulations [7].
Patients with congenital absence of the portal vein commonly have congenital
anomalies including cardiovascular, skeletal, and visceral anomalies
[2] and occasionally have
encephalopathy [8]. The
reported cardiovascular abnormalities include congenital heart diseases such
as dextrocardia, patent ductus arteriosus, patent foramen ovale, ventricular
septal defect, and atrial septal defect and inferior vena cava anomalies such
as azygos or hemiazygos continuation and left inferior vena cava
[2]. The reported skeletal
abnormalities are scoliosis with hemivertebra and oculoauriculovertebral
dysplasia or Goldenhar's syndrome, thoracic hemivertebrae, right maxillary
hypoplasia, mild micrognathia, and short fifth fingers
[2]. Focal hepatic masses have
also been reported to be frequently found in patients with congenital absence
of the portal vein [2,
3].
Although the mechanisms of patent ductus venosus and congenital absence of
the portal vein are considered to be different, as mentioned earlier, the
clinical manifestations of these two abnormalities are similar. In some cases,
patients need to undergo liver transplantation for congenital absence of the
portal vein and surgical ligation for patent ductus venosus, so correct
diagnosis is important.
Two-phase helical CT and MRI, including MR angiography and dynamic studies,
clearly showed the presence and location of portosystemic shunt in our
patients and led to the correct diagnosis of patent ductus venosus or
congenital absence of the portal vein. Conventional angiography, which is more
invasive, was once performed for the diagnosis of these abnormalities.
However, conventional angiography, which requires general anesthesia in
children, is thought to be unnecessary when the diagnosis can be established
on CT and MR examinations. Surgical ligation of the shunt may be performed to
manage the symptoms of patent ductus venosus such as encephalopathy and heart
failure, as observed in patient 2, due to marked portosystemic shunt
[9]. Confirming the presence of
intrahepatic portal branches for preoperative assessment of surgical ligation
of the shunt is considered important because this procedure can lead to edema
and engorgement of the bowel due to overflow of the portal vein
[10]. Conventional angiography
is considered essential for determination of the presence of the intrahepatic
portal branches before surgical ligation of the shunt, because in our case 2
these branches, which were not visualized on CT or MRI, could be visualized
only by means of retrograde venography of the shunt vein using balloon
occlusion.
Both patent ductus venosus and congenital absence of the portal vein are
known to be frequently associated with focal hepatic lesions
[2-5,
7]. The possibility of these
abnormalities should therefore be considered in infants and young patients
with focal hepatic lesions. Both malignant hepatic lesions including
hepatoblastoma and hepatocellular carcinoma and benign lesions including
adenoma, focal nodular hyperplasia, and nodular regenerative hyperplasia are
associated with patent ductus venosus and congenital absence of the portal
vein. Moreover, Morse et al.
[11] reported a case of
congenital absence of the portal vein in which hepatoblastoma was found after
the diagnosis of focal nodular hyperplasia based on biopsy findings.
Therefore, histologic examination of the hepatic lesions by biopsy, strict
follow-up observation of the hepatic lesions, or both should be performed for
patients with patent ductus venosus or congenital absence of the portal vein
because malignant hepatic lesions have also been reported to occur in such
patients. The diagnosis of focal nodular hyperplasia could be established in
two of our three patients.
Many researchers believe that focal nodular hyperplasia arises as a
hyperplastic response of the liver parenchyma to differential blood flow
caused by a preexisting arterial malformation
[10]. Focal hepatic lesions
associated with patent ductus venosus and congenital absence of the portal
vein might be caused by an abnormal response of liver cells to the lack of
portal flow [3].
Two-phase (arterial and portal venous phases) contrast-enhanced helical CT
has been used for the evaluation of patients with hepatic disease and the
characterization of hepatic focal lesions. To our knowledge, however, no
reports of two-phase helical CT for the evaluation of patients with patent
ductus venosus or congenital absence of the portal vein have been published. A
diagnosis of focal nodular hyperplasia was established in two of our patients.
Focal nodular hyperplasia is an uncommon benign tumorlike lesion of
well-circumscribed hyperplastic liver parenchyma, often with a central
stellate scar. These lesions are thought to be hypervascular and to be
supplied exclusively with arterial blood
[10]. Because they are
hypervascular, these lesions typically appear hyperenhanced relative to the
surrounding liver parenchyma on arterial phase helical CT images
[12]. The lesions of focal
nodular hyperplasia in our patients showed atypical appearances on two-phase
helical CT images: they appeared isoattenuated or slightly hypoattenuated on
the arterial phase CT images.
The normal liver is supplied by the hepatic artery and portal vein, whereas
the liver in patients with patent ductus venosus or congenital absence of the
portal vein is supplied only by the hepatic artery in the absence of the
portal vein. Under such abnormal conditions, the normal liver and focal
nodular hyperplasia lesions are highly enhanced on the arterial phase CT
images. In our patients, hepatic nodular lesions were seen more conspicuously
and a greater number of hepatic lesions were depicted on MRI than on CT. We,
therefore, conclude that unenhanced MRI may result in more effective
visualization of focal hepatic lesions under such abnormal vascular
conditions.
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Abstract
Introduction
