Spectrum of abdominal findings by Multidetector computed

Transcripción

Abdomen
Update
Spectrum of abdominal findings by
Multidetector computed tomography in
hereditary hemorrhagic telangiectasia
Romina Aun, Florencia Biagiotti, Ezequiel Levy Yeyati, Ernestina Gentile, Marcelo Serra, Ricardo García Mónaco
Resumen
Abstract
Objetivos de aprendizaje. Demostrar la utilidad de la
tomografía computada multidetector (TCMD) en la
realización de un protocolo de estudio específico en el
diagnóstico, caracterización y diferenciación de las distintas lesiones vasculares abdominales halladas en la
telangiectasia hemorrágica hereditaria (THH).
Revisión del tema. La telangiectasia hemorrágica hereditaria o síndrome de Rendu-Osler-Weber es una alteración
vascular multisistémica, caracterizada por la formación
de lesiones angiodisplásicas, en la que existe una comunicación directa entre las arterias y venas, sin una red
capilar entre ambas. Es transmitida como un rasgo autosómico dominante, con una prevalencia de 1 a 2 casos
cada 10.000 personas. Clínicamente se caracteriza por la
presencia de telangiectasias mucocutáneas con hemorragias gastrointestinales y epistaxis recurrentes, así como
también por la conformación de shunts que, dependiendo
del órgano afectado, pueden causar complicaciones,
como hipoxemia, stroke, abscesos cerebrales o falla cardíaca. El diagnóstico se basa en una combinación entre la
clínica, el examen físico y los métodos diagnósticos.
Hallazgos en imágenes. El papel de la tomografía computada multidetector en el diagnóstico de la telangiectasia hemorrágica hereditaria adquiere cada vez mayor
relevancia, ya que permite obtener imágenes de alta
resolución espacial y temporal con un protocolo multifásico específico. Éste consiste en la realización de una fase
arterial precoz, una fase arterial tardía (a los 20 segundos
de la anterior) y una fase venosa (a los 40 segundos de la
primera). De acuerdo con su comportamiento en las
diferentes fases, podemos identificar lesiones como
telangiectasias, masas vasculares confluentes, trastornos
de la perfusión hepática, shunts arteriovenosos, arterioportales, porto-venosos y aneurismas arteriales.
Conclusión. La tomografía computada multidetector,
debido a su alta resolución témporo-espacial y a un protocolo específico multifásico, permite el reconocimiento
y caracterización de las lesiones típicas de esta patología
en los órganos abdominales (principalmente el hígado),
ayudando a arribar al diagnóstico de la enfermedad.
Palabras clave. Telangiectasia hemorrágica hereditaria. Tomografía computada multidetector. RenduOsler-Weber. Telangiectasias. Derivaciones.
Spectrum of abdominal findings by multidetector
computed tomography in hereditary hemorrhagic
telangiectasia.
Learning objectives. To demonstrate the utility of multidetector computed tomography (MDCT) in conducting a specific study protocol for the diagnosis, characterization and
differentiation of various abdominal vascular lesions found
in hereditary hemorrhagic telangiectasia (HHT).
Topic review. Hereditary hemorrhagic telangiectasia or
Rendu-Osler-Weber syndrome is a multisystemic vascular
disorder characterized by the development of angiodisplasic
lesions, with direct communication between arteries and
veins without a capillary network in between. It is transmitted as an autosomal dominant feature with a prevalence of 12 cases per 10,000 people. Clinically, it is characterized by
the presence of mucocutaneous telangiectasias with recurrent epistaxis and gastrointestinal bleeding, as well as development of shunts, which depending on the affected organ,
can cause hypoxemia, stroke, heart failure or brain abscesses. Diagnosis is based on a combination of clinical history,
physical examination and diagnostic methods.
Imaging findings. The role of multidetector computed
tomography in the diagnosis of hereditary hemorrhagic
telangiectasia is becoming increasingly important, as it
allows to obtain high resolution images with a spatial and
temporal specific multiphase protocol. Such protocol consists in an early arterial phase, a late arterial phase within
20 seconds to the previous one and a venous phase 40 seconds after the first one. According to their behavior in the
different phases, we can identify lesions such as telangiectasias, confluent vascular masses, hepatic perfusion disorders, arteriovenous, arterioportal or portal venous shunts
and arterial aneurysms.
Conclusion. Multidetector computed tomography, with its
high spatial and temporal resolution and a specific multiphase protocol, allows recognition and characterization of
typical lesions of this pathology in abdominal organs (mainly the liver), contributing to the diagnosis of this disease.
Keywords. Hereditary hemorrhagic telangiectasia.
Multidetector computed tomography. Rendu-Osler-Weber
Rendu. Shunts. Telangiectasias.
Hospital Italiano de Bueno Aires, Buenos Aires, Argentina.
Corresponding author: Dra. Florencia [email protected]
RAR - Volumen 77 - Número 2 - 2013
Recibido: diciembre 2012; aceptado: marzo 2013
Received: december 2012; accepted: march 2013
©SAR
doi: 10.7811/rarv77n2a09
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Hereditary hemorrhagic telangiectasia
INTRODUCTION
Hereditary hemorrhagic telangiectasia (HHT) or
Rendu-Osler-Weber disease was first described in
1876. HHT is a multisystem vascular dysplasia with
the presence of a direct communication between arteries and veins of varying sizes without an intervening
capillary network (1). This disorder is transmitted as an
autosomal dominant feature, with an estimated prevalence of 1 to 2 cases per 10,000 people (2,3).
HHT occurs equally in both genders, more commonly manifesting at puberty or in adulthood (between the third and fourth decades of life), although it
may also occur in pediatric patients (3).
It is characterized by the presence of skin and mucosal telangiectasias, mainly in the cheeks, lips, tongue,
ears, fingers, and less frequently, in the eyes (involvement of the palpebral conjunctiva, the bulbar conjunctiva, the retina and the macula).
Lesions are detected during the early years of life
and recurrent epistaxis is common at childhood. By the
age of 10, about 50% of patients have experienced gastrointestinal bleeding, which is generally not serious
before the age of 40.
Among the described complications it is mentioned: persistent headache, seizures, hemiparesis,
hemianopsia, epilepsy or mild focal neurological deficit (that may occur as a result of cerebral vascular malformation or septic or aseptic emboli resulting from
the interruption of the filtering action of the lung at
the site of malformation). Additionally, postprandial
abdominal pain, cirrhosis, ascites, bleeding esophageal veins, hepatic encephalopathy, pulmonary hypertension or right heart failure may also manifest as a
result of hepatic involvement (4).
Two genes are implicated in the pathogenesis of
this condition: HHT1 and HHT2, which determine
two different forms of a same disease. Mutations in the
endoglin (ENG), located on the long arm of chromosome 9 gene originates the HHT1 variant, while the HHT
variant is caused by mutations in the ALK1 gene, located on the long arm of chromosome 12 (1).
Patients must meet at least 3 of the 4 criteria
shown in Table 1 in order to establish the diagnosis.
According to these criteria, diagnosis of HHT is
based on medical history, physical examination and
imaging findings. The role of computed tomography
(CT) has become increasingly important over the
years, even more with the advent of MDCT, which
allows for detection of lesions difficult to be diagnosed in the past.
The natural evolution of hepatic vascular malformations is the development of intrahepatic vascular
shunts. Telangiectasias are usually asymptomatic and
infrequently may cause pain or elevated enzyme
levels. Arterioportal shunt may rarely induce portal
hypertension, ascites, encephalopathy and hematemesis. Arteriovenous shunts may, in rare occasion, be
responsible for high-output heart failure and necrotizing cholangitis by arterial flow steal. For this reason,
hepatic vascular malformations are usually not treated. Treatment of these conditions is extremely complex and includes embolization, hepatic resection and
even liver transplantation in more advanced cases.
For gastrointestinal bleeding, endoscopic laser coagulation, electrocoagulation and systemic treatment
with hormones (estrogens and progesterone) have
been successfully used.
The aim of this study is to demonstrate the usefulness of MDCT in the development of a specific protocol for HHT and to report the various abdominal
lesions found, their characterization and differentiation using a data base of 170 patients from the HHT
Unit at Hospital Italiano de Buenos Aires.
The development of a specific protocol allows for
identification and characterization of typical vascular
Table 1: Curaçao diagnostic criteria (4).
1. Spontaneous recurrent epistaxis.
2. Multiple telangiectasias in typical locations (fingers, lips,
oral cavity, nose, subungual areas).
3. Visceral lesions including:
a. Gastrointestinal telangiectasias
b. Lung AVM
c. Liver AVM
d. Brain AVM
e. Spine AVM
4. First-degree family member with HHT
Diagnosis: definite HHT: 3 or more criteria are met; possible HHT; 2 criteria
are met; unlikely: < 2 criteria. AVM: arteriovenous malformation.
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Fig. 1: Hepatic telangiectasias in a 59-year-old female patient with a
diagnosis of HHT. Axial plane showing the presence of nodular hepatic lesions less than 10 mm in size in the arterial phase (arrows).
Romina Aun et al.
a
b
Fig. 2: Hepatic telangiectasias in a 24-year-old female patient with a diagnosis of HHT. Abdominal CT angiography showing a markedly
heterogeneous liver parenchyma in the arterial phase, at the expense of multiple IV contrast-enhanced rounded images, consistent with
diffuse telangiectasias.
a
b
Fig. 3: On the left, large confluent vascular masses in a 59-year old female patient with a diagnosis of HHT. Abdominal CT axial view in the arterial
phase showing, at the level of the left hepatic lobe and in segment 8, two large areas of enhancement, persisting in the venous phase (arrows). On the
right, and for the sake of comparison, note the absence of enhancement in a normal liver in the arterial phase.
lesions of this condition, differentiating their potential
etiology, based on different behaviors and enhancement with intravenous (IV) contrast administration.
Images are obtained in an early arterial phase,
beginning when the ROI placed in the abdominal
aorta reaches 180 HU, a late arterial phase, beginning
within 20 seconds of the previous one, and a venous
phase 40 seconds after the first one.
ABDOMINAL MANIFESTATIONS
Hepatic lesions
Fig. 4: Abdominal CT angiography in a 41-year-old male patient
with a diagnosis of HHT. Axial slice showing multiple nodular images less than 10 mm in diameter with diffuse distribution, consistent
with telangectasias. There is a trend towards confluence in some
areas, mainly in the subcapsular region of the right hepatic lobe, forming confluent vascular masses (arrow).
Telangiectasias
Telangiectasias are the most common findings in
this disease. They are dilated small vessels (capilla-
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a
b
Fig. 5: Hepatic perfusion abnormality in a 41-year-old male patient with a diagnosis of HHT. Abdominal CT angiography axial (a) and reconstruction (b) images show markedly heterogeneous and hyperdense liver parenchyma upon contrast administration, as a result of diffuse impairment of liver perfusion.
Fig. 6: Coronal view of an abdominal CT angiography in a 23-yearold female patient with a diagnosis of HHT showing heterogeneous
parenchyma at the expense of perfusion defects (arrow).
a
ries, venules or arterioles), appearing as small hypervascular nodules, generally a few millimeters in diameter (< 10 mm). They appear as focal or diffuse
lesions, hyperdense in the early and late arterial phases, often becoming isointense with the hepatic
parenchyma in the venous phase (Figs. 1 and 2) (5).
Maximum intensity projection (MIP) reconstruction is
particularly useful in this case, as it allows for perception of attenuation differences with the hepatic
parenchyma, enhancing higher density structures,
even those 1 or 2 mm in size (which makes this technique more sensitive than plain spiral CT for the
detection of lesions). This allows for recognition of
small hepatic lesions and improvement of diagnosis
and at the same time permits differentiation from normal intrahepatic vessels. MIP reconstruction, through
display of vascular structures and 3D volume rendering allows for the evaluation of small- and mediumcaliber blood vessels, thus differentiating tubular vascular structures from malformations of nodular and
small nodule appearance, which are characteristic of
HHT.
b
Fig. 7: Arteriovenous fistula in a 45-year-old female patient with a diagnosis of HHT. Axial (a) and coronal (b) MIP images in the arterial phase
of abdominal CT angiography show early enhancement of the left suprahepatic vein, consistent with arteriovenous fistula with the left hepatic vein
(arrows).
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Romina Aun et al.
a
b
Fig. 8 (a) Coronal CT angiography in a 27-year-old female patient with a diagnosis of HHT showing an arteriovenous fistula associated with an
area of impaired perfusion in the segment IVb (arrow). (b) Coronal CT angiography in a 60-year-old female patient with a diagnosis of HHT showing in the arterial phase a faint early enhancement of the suprahepatic branch for segment IVb, suggestive of the presence of AV fistula/microfistula (arrow).
Figs. 9 and 10: CT angiography Axial and Coronal MIP reconstruction images in a 59-year-old patient with a diagnosis of HHT showing arterioportal fistula located between the right hepatic artery and the right branch of the portal vein (arrow).
a
b
Fig. 11: Coronal (a) and 3D (b) MIP reconstructed images of abdominal CT angiography in a 45-year-old female patient with a diagnosis of HHT
showing a portovenous fistula at the level of the hepatic dome with an approximately 7-mmm nidus (arrow).
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Fig. 14: Pancreatic telangiectasias in a 74-year-old male patient
with a diagnosis of HHT. Abdominal CT angiography axial image
obtained in the arterial phase shows multiple focal opacification,
consistent with telangiectasias, mainly in the head and tail of the
pancreas (arrow).
Fig. 12: CT angiography coronal MIP reconstruction image in a
74-year-old patient with a diagnosis of HHT showing portovenous
fistula at the level of hepatic segment IV (arrow).
a
b
Fig. 13: Forty-one year-old male patient with pancreatic telangiectasias. Abdominal CT angiography axial images show nodular enhancement
structure of approximately 8 mm (a), consistent with telangiectasia in the body of the pancreas. Other punctiform structures, which might have a
similar origin, appear to be observed at the level of the pancreatic isthmus.
a
b
Fig. 15: (a) Axial and (b) 3D images of abdominal CT angiography, obtained in the arterial phase, show pancreatic arteriovenous fistulas in a 74year-old male patient with a diagnosis of HHT (arrows).
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Romina Aun et al.
a
b
Fig. 16: 3D reconstruction in abdominal CT angiography in a 74-year-old female patient shows saccular aneurysms of mesenteric vessels of the
gastroduodenal arcade (a) and of the splenic artery (b) and vascular dilations (arrows).
Large confluent vascular masses
Shunts
Large confluent vascular masses are areas of telangiectasias that coalesce, forming nodules with a diameter more than 10 mm (Figs. 3 and 4). They usually
demonstrate enhancement in the early arterial phase,
with enhancement persisting in the venous phase.
Because of the CT appearance of these lesions, differential diagnosis with hemangiomas is required.
Large vascular masses have a heterogeneous or homogeneous enhancement pattern, but without the characteristic globular enhancement pattern seen in hemangiomas, progressive and centripetal, persisting in the
late and portal phases (5).
There are three types of hepatic vascular shunts or
fistulas in HHT:
Hepatic perfusion abnormalities
Hepatic perfusion abnormalities are identified as
lesions of ill-defined borders, which appear hyperdense relative to the hepatic parenchyma following
the administration of intravenous contrast. Like telangiectasias and large confluent vascular masses, these
abnormalities are best seen during the early arterial
and late arterial phases, often becoming homogeneous as the hepatic parenchyma during the venous
phase (Figs. 5 and 6) (5).
As differential diagnosis, perfusion abnormalities
that are seen in patients with cirrhosis are usually
more focal and occur more frequently in peripheral
areas. They can be related to focal areas of occlusion of
small hepatic venules, small arterioportal shunts,
hepatocellular carcinoma, or idiopathic causes.
1. Arteriovenous shunt: from the hepatic artery to the
hepatic vein. These shunts are the most frequently
observed and are seen in the arterial phase. Because
hepatic veins normally fill with contrast material
during the venous phase, opacification of the hepatic veins during the early arterial phase indicates
arteriovenous fistula (Figs. 7 and 8) (8).
2. Arterioportal shunt: from the hepatic artery to the
portal vein. Visualization occurs through filling of
the portal vein and its branches in the early arterial phase (Figs. 9 and 10).
3. Portovenous shunt: from the portal vein to the
hepatic vein. These shunts are rarely seen in HHT.
These shunts are seen in the portal phase, with a
dilated portal vein branch communicating with
some of the suprahepatic veins, also larger than
usual (Figs. 11 and 12) (8).
Pancreatic lesions
Pancreatic lesions have been reported in approximately 10-30% of patients with HHT and occur more frequently in patients with ALK1 gene mutation (9).
They rarely cause any symptoms and the may be
the only manifestation of disease in the absence of any
other findings. This is a highly important fact if we
take into account that one of the diagnostic criteria is
the presence of visceral lesions. Thus, identification of
pancreatic lesions may confirm diagnosis of disease in
the absence of other types of lesions.
These lesions are characteristically seen in the arterial phase, and may not be always be evident during
the venous phase (5,9,10).
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Fig. 17: Coronal MIP reconstruction in abdominal CT angiography in a 46-year-old patient with a diagnosis of HHT showing
a small saccular aneurysm in the distal area of the splenic artery,
5.7 mm in size (measured on the image).
Fig. 19: Axial MIP reconstruction in CT angiography in a 41-yearold patient with a diagnosis of HHT shows, at the level of the cecum,
small images of pseudonodular appearance enhanced by IV contrast
relative to afferent vessels from the ileocolic artery. These lesions are
associated with a slightly earlier filling of the ileocolic vein, consistent with small AVM (arrow).
Telangiectasias
Telangiectasias are seen during the arterial phase
and have the same appearance as those seen in the
liver: hypervascular small nodular focal lesions not
larger than 10 mm in diameter (Figs. 13 and 14).
Because of the behavior of these lesions after intravenous contrast administration, differential diagnosis
must include neuroendocrine tumors and hypervascular metastases, which also demonstrate early
enhancement.
Fig. 18: Coronal 3D reconstruction in abdominal CT angiography
in a 75-year-old patient with a diagnosis of HHT. Fusiform dilatation of proximal third of the splenic artery and saccular aneurysm
of 13.4 mm in the distal third of the splenic artery, in the hilum of
spleen.
Fig. 20: Axial MIP reconstruction in abdominal CT angiography
in a 21-year-old patient with a diagnosis of HHT shows, at the level
of the rectum, a prominence of vascular structures on the left posterolateral wall, which may be associated with the arteriovenous
malformation (arrow).
Arterial vessels abnormalities: aneurysms and
arterial dilations
Aneurysms are abnormal dilations of blood vessels (more commonly of arterial blood vessels). They
may appear as fusiform tortuous dilations, when dilation is circumferential, or as saccular dilations when
they appear as evagination of one arterial wall (Figs.
16, 17 and 18). 3D volume rendering has become a
very helpful technique in the evaluation of vascular
structures for detecting anatomic variants and the presence of aneurysmal dilation of vessels, very commonly found in patients with HHT.
Arteriovenous fistulas
Arteriovenous fistulas usually occur between the
pancreatic artery and the splenic or superior mesenteric vein. Features include arteriovenous dilatation,
presence of nidus and early opacification of drainage
(Fig. 15).
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Other lesions
On MDCT, extrahepatic vascular lesions of HHT
were observed in approximately 6% of patients. In
addition, hypervascular lesions (such as telangiecta-
Romina Aun et al.
sias) were also seen in the spleen and cecal AVM as
well as bowel or gastric telangiectasias were observed
within the bowel and stomach (Figs. 19 and 20) (5).
CONCLUSION
The role of MDCT in the diagnosis of HHT is becoming increasingly important, as this technique makes
it possible to obtain high resolution images in short
acquisition times (an essential feature considering that
most lesions are seen in the early arterial phases). MIP
and 3D reconstructions are particularly helpful, as
they increase the likelihood of recognizing visceral
lesions that failed to be identified, especially in
asymptomatic patients, allowing for diagnosis and, if
needed, timely treatment.
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The authors declare no conflicts of interest.
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Spectrum of abdominal findings by Multidetector computed

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