Download Evaluation of the portal venous system: complementary roles of

Evaluation
of the Portal
Venous
System:
Complementary
Roles
of Invasive
Imaging
and
Noninvasive
1
Phi14
C. Pieters,
MD
Williamj
Miller, MD
Jonathan
H. DeMeo,
MD
Evaluation
of the portal
venous
system
is required
in several
clinical
circumstances,
including
before
and after liver transplantation,
before
creation of a transjugular
intrahepatic
portosystemic
shunt,
in the clinical
setting
of bowel
ischemia,
or to evaluate
varices.
Several
noninvasive
modalities
(magnetic
resonance
[MR] imaging
and MR angiography,
computed
tomography
[CT] and ultrasound
[US]) are available
for
evaluation
of the portal
venous
system
in addition
to the invasive
angiographic
methods.
In most clinical
circumstances,
either
CT or MR imaging and MR angiography
in combination
with US of the liver vasculature
will allow complete
evaluation
of the portal
venous
system.
Invasive
evaluation
of the portal
venous
system
is necessary
when
results
of the
noninvasive
tests disagree
or are inconclusive.
Angiography
may also be
indicated
whenever
noninvasive
tests indicate
occlusion
of the portal
venous
system,
as this is often a crucial
clinical
question
and false-positive results
can occur
with the noninvasive
tests.
,
U INTRODUCTION
Portal
hypertension
and the life-threatening
common
entities
that account
for more
United
States.
Historically,
its location
sively.
between
Angiographic
venous
Recent
(CT),
Abbreviation:
TIPS
terms:
Portal
RadioGraphics
1997;
‘From
the Department
Marshall
Sts, Richmond,
tific
assembly.
1 . Address
RSNA,
Received
reprint
portal
capillary
and
=
vein.
(US)
intrahepatic
957.1291
have
portosystemic
Portalvein,
#{149}
complications
of variceal
1 5,000 hospital
admissions
system
the
has
inability
invasive,
in magnetic
ultrasound
CT,
and
although
advances
transjugular
venous
beds
techniques,
system.
mography
Index
the
two
than
MR,
difficult
to access
allow
resonance
allowed
been
hemorrhage
per year
reliable
(MR)
to image
this
region
imaging
imaging,
noninvasive
are
in the
due
of the
portal
to-
computed
evaluation.
to
noninva-
Although
shunt
957.1294
Portal
#{149}
vein,
tJS,
957.1298
Portography,
#{149}
957.124
17:879-895
of Radiology,
Medical
College
of Virginia
and Virginia
Commonwealth
VA 23298.0615.
Recipient
ofa Gum Laude
award
for a scientific
September
requests
6, 1996;
revision
requested
October
2 and
received
exhibit
October
University.
at the
1 2th and
1995 RSNA
3 1 : accepted
scicn
November
to P.C.P.
1997
879
Figures
1, 1
(1) Gastroesophageal
varices.
Portal
venogram
shows
a large coronary
vein arising
from the partially
thrombosed
portal
vein (curved
arrow)
and shunting
blood
to large esophageal
varices (straight
arrows).
The imaging
procedure
was performed
through
a thrombosed
TIPS. (2) Paraumbilical
vein. US scan shows
a paraumbilical
vein (arrow)
that originates
from the left portal
vein and
courses
through
the falciform
ligament.
Note the shrunken,
nodular
liver with surrounding
ascites.
Color Doppler
flow imaging
demonstrated
patency
and defmed
the direction
of flow in the paraumbilical
vein.
the
noninvasive
is desirable,
aspect
of the
angiography
latter
remains
complications
procedures
the
standard
of reference
for evaluation
of the portal
venous
system,
and the various
invasive
and noninvasive techniques
should
be considered
comple-
mentary.
In this
article,
we
review
the
various
invasive
and noninvasive
methods
of evaluating
the
tal venous
system
and discuss
the advantages
and disadvantages
of each modality.
THAT
U SITUATIONS
por-
NECESSITATE
OF THE
PORTAL
VENOUS
SYSTEM
Imaging
of the portal
venous
system
is crucial
in the evaluation
of candidates
for liver transplantation
and in evaluations
after liver transplantation.
Preoperative
detection
of recipient
vessel
thrombosis
and characterization
of existing extrahepatic
shunts
is critical
for surgical
planning
and minimizing
dissection
time (1).
EVALUATION
Quantifying
diseased
liver
volume
and
identify-
ing the sequelae
of portal
hypertension
are also
objectives
of the pretransplantation
work-up.
Finally,
a search
for an occult
tumor
(found
in
as many
as 4.5% of liver transplantation
candidates)
is important.
After liver transplantation,
prompt
diagnosis
and treatment
of vascular
portosystemic
(because
Scientific
Exhibit
procedure-including
he-
the
patency
(which
system
by a neoplasm,
patency
of surgical
of the
commonly,
in
portal
venous
sys-
TIPS creation),
of the portal
venous
and
shunts
U PORTAL
HYPERTENSION
Portal
hypertension
results
obstruction
is important
management
of chronic
liver
before
creation
of a transportosystemic
shunt
(TIPS)
tem is critical
for successful
evaluation
of involvement
or, less
U
shunts
the diagnosis
and
disease),
evaluation
jugular
intrahepatic
solute
880
of the
patic artery
and portal
vein thrombosis-are
crucial
for liver allograft
and patient
survival.
Evaluation
of the portal
venous
system
is
important
in the clinical
setting
of bowel
ischemia.
It is estimated
that 5%- 1 5% of cases of
mesenteric
ischemia
are caused
by occlusion
of
the mesenteric
vein (2). Mortality
is estimated
at 20% (3). Many reports
have emphasized
the
difficulty
of making
a preoperative
diagnosis
of
mesenteric
vein occlusion
because
of the protean clinical
manifestations,
the diverse
causes
of the disorder,
and the nonspecific
laboratory
and plain radiographic
findings.
Other
clinical
circumstances
in which
imaging of the portal
venous
system
is needed
inelude
evaluation
of varices
and spontaneous
determination
and
from
of the
splanchnic
from
increased
Volume
of the
TIPS.
a relative
or ab-
blood
portal
17
flow
blood
Number
4
3, 4#{149}(3) Retroperitoneal
collateral
vessels. Arterial portogram
(venous
phase of a superior
injection)
(a) and coronal
MR angiogram
(repetition
time msec/echo
time msec =
50/10,
30#{176}
flip angle,
one signal acquired)
(b) show large retroperitoneal
collateral
vessels (arrowheads) that empty into the gonadal
vein and subsequently
into the left renal vein and inferior vena
cava. The small but patent portal vein is seen on the MR angiogram
but not on the conventional
angioFigures
mesenteric
gram
due
CT scan
CT scan
artery
to steal
shows
shows
by the
shunt.
a large gastric
the confluence
(4)
Spontaneous
splenorenal
varix (arrow)
comparable
of the splenorenal
shunt
flow.
Portal
shunt.
(a)
Contrast
material-enhanced
in size with the aorta. (b) Contrast-enhanced
with the left renal vein (arrow).
Normal
portal
pressure
is 5- 10 mm Hg.
hypertension
is defined
as a wedged
hepatic vein pressure
or direct
portal
vein pressure more
than 5 mm Hg greater
than the infenor vena caval pressure
(ie, a portosystemic
gradient
greater
than 5 mm Hg) or a splenic
vein pressure
greater
than 1 5 mm Hg (4). The
obstruction
of hepatopetal
flow leads to devel-
temic
esophageal
veins)
(Fig 1), paraumbilical
veins (from
the left portal
vein to the paraumbiical
veins to the systemic
epigastric
veins)
(Fig 2), retroperitoneal
region
(from
veins of
the duodenum,
ascending
and descending
colon, and liver to the systemic
lumbar,
phrenic,
gonadal,
and renal veins)
(Fig 3), splenorenal
opment
splenic
veins to the systemic
left renal vein)
(Fig 4), and hemorrhoidal
veins (from
the superior hemorrhoidal
vein to the systemic
middle
and inferior
hemorrhoidal
veins)
(Fig 5).
of numerous
collateral
pathways
from
the high-pressure
portal
system
to the low-pressure systemic
circulation.
Major sites of portosystemic
collateralization
include
the gastroesophageal
junction
(from
the coronary
and short
gastric
veins to the sys-
July-August
1997
region
(from
the
coronary,
Pleters
short
et al
gastric,
U
and
RadioGraphics
U
881
Figure
5.
Hemorrhoidal
collateral
vessels.
(a), early venous
phase
(b),
and late venous
phase
(c) inferior
mesenteric arteriograms
show emptying
of the inferior
mesenteric
vein (arrow
in b), but late
hepatofugal
flow into the systemic
middle
and inferior
hemorrhoidal
veins is demonstrated
(arrowheads
in C).
Arterial-phase
Pathophysiologically,
can be caused
in the Table.
U MR
PHY
portal
by a variety
IMAGING
AND
hypertension
of entities,
as shown
MR ANGIOGRAC.
.
Technique
Conventional
MR
with
Ti-weighted
short
repetition
imaging
of the
sequences
(eg,
time/echo
lion-prepared
gradient
sequences
(eg,
time/echo
time,
time,
echo)
conventional
fast
spin
and
long
echo).
liver
begins
conventional
magnetiza-
T2-weighted
se-
quences
(eg, gadolinium-enhanced
Ti-weighted
imaging,
heavily
T2-weighted
imaging
with extended
echo times
such as 1 20 msec)
can be
performed
as necessary.
882
U
Scientific
Exhibit
sequential
two-dimenmethods
(two-dimensional
fast
[30-35/8,
low-angle
shot
40#{176}-50#{176}
flip
angle])
exploit
the signal enhancement
effects
of flowing
blood
so that vessels
are highlighted.
repetition
Additional
In MR angiography,
sional time-of-flight
Gradient-echo
series
planes.
sequences
of overlapping
Each
section
are
sections
is obtained
used
to acquire
in the
during
a
desired
a single
breath
hold (lasting
6-9 seconds).
The singlesection
data are postprocessed
with a maximum-intensity
projection
algorithm
to generate
three-dimensional
angiograms.
The projection
angiograms
may be rotated
in space
to define
the optimum
viewing
angle (Fig 6) (5,6).
Volume
17
Number
4
a.
b.
Figure
6.
MR angiography
giogram
(34/3,
40#{176}
flip
rial portogram
(venous
to the MR angiogram.
Causes
of Portal
versus
angle,
phase
conventional
one signal
of a splenic
angiography
acquired)
artery
shows
injection)
Increased
portal
resistance
Presinusoidal
Extrahepatic
(cavernous
transformation
the portal
vein)
Pediatric
onset
Umbilical
vein catheterization
Omphalitis
Neonatal
sepsis
Adult
onset
Trauma
Sepsis
Pancreatitis
Hypercoagulable
states
Intrahepatic
Congenital
hepatic
fibrosis
cirrhosis
(eg, from
venous
of the splenic
confirmation
system.
methotrexate)
over
dient-echo
bolus
Postnecrotic
cirrhosis
from
Extrahepatic
Budd-Chiari
syndrome
Congestive
heart
failure
Hyperkinetic
(arterioportal
fistula)
Traumatic
Penetrating
abdominal
wound
Surgery
Percutaneous
bihiary procedure
black
and
MR an-
veins.
(b) Artethe similarity
blood
tech-
presaturation
slab
main
sequences.
magnitude
The
direction
of the
displacement
of blood
flow,
displacement
of the
and
the
at designated
intervals
can be used to calculate
velocity
(5,6).
Flow direction
in the portal
vein (but not yelocity)
can also be evaluated
with a standard
black blood
technique.
A coronal
two-dimensional
fast low-angle
shot time-of-flight
Sequence
(128/18,
25#{176}
flip angle)
is performed
with a 10-mm
presaturation
band and acquisition time of 27 seconds,
allowing
three
6-mm
rated
rection
La#{235}nneccirrhosis
the
is in the
ascending
Postsinusoidal
Intrahepatic
portal
Note
portal
vein, thus labeling
a volume
of blood.
The radio-frequency
pulse is
approximately
2.5 msec
in duration
and is oriented
at a 45#{176}
angle, which
is perpendicular
to
the main portal vein. The displacement
of the
labeled
slab is studied
by performing
several
grais placed
of
(a) Coronal
and main
of patency.
In the bolus tracking
mque,
a thin radio-frequency
Hypertension
Schistosomiasis
Primary
biliary
Toxic
fibrosis
Sarcoidosis
of the portal
patency
allows
sections.
blood
The
in the
of flow
(Fig
portal
movement
vein
of the
indicates
the
satudi-
7).
hepatitis
Congenital
Atherosclerotic
July-August
1997
Pieters
et a!
U
RadioGraphics
U
883
a.
b.
Figure
7.
Black
placed
perpendicular
petal displacement
vein (arrow).
.
blood
technique.
to the main
of the trailing
(a) Coronal
MR image
portal
vein (arrow).
(b)
edge of the presaturation
Advantages
MR imaging
noninvasive.
of the portal
venous
system
is
Use of iodinated
contrast
material
is unnecessary;
thus,
trast material
and
avoided.
Although
US,
MR
to iodinated
portal
can
than
venous
when
procedures.
be performed
con-
be
CT or
system
compared
with
In addition,
MR examinain a relatively
short time
minutes).
Convenient
excellent
and
safe,
MR imaging
also allows
and portal
(Figs 6, 8). The three-dimengenerated
with MR angiography
in a visually
appealing
format
that
evaluation
venous
system
sional
images
are presented
is readily
of the liver
comprehensible
surgeon
vide
of the
inexpensive
invasive
tion can
(<60
reactions
renal toxic effects
more expensive
evaluation
is relatively
(Fig 6) (5).
anatomic
to the
Spin-echo
information
transplantation
MR
images
comparable
prowith
that provided
by CT and allow better
characterization
of some hepatic
masses
than CT (1). Imaging in multiple
planes
is useful
in the evaluation
of surgically
(5) and
(Figs
created
is sensitive
a high
sonography
allows
Finally,
7)
bolus
of peak
to values
(6).
shunts
detection
the
calculation
correlation
(Fig
portosystemic
in the
3, 9) (7-10).
technique
with
(35/8)
shows
a thin presaturation
slab
Coronal
MR image (128/18)
shows
hepatoband with loss of signal in the main portal
Figure
8#{149}
Thrombus
at the portal
confluence.
Axial MR angiogram
(35/8,
50#{176}
flip angle,
one signal
acquired)
shows
a thrombus
at the confluence
of the
splenic
vein and superior
mesenteric
vein. The lack
of signal in the aorta is secondary
to placement
of a
presaturation
band over the heart.
.
Disadvantages
of varices
Limitations
tracking
venous
velocities
obtained
with
of MR
system
evaluation
include
of the
several
portal
contraindications
that apply
to the use of MR imaging
in general.
These
contraindications
include
severe
claustrophobia,
metal fragments
in the eyes, an aneurysm
clip
in the
head,
or surgical
clips
in the
abdomen.
Other
limitations
of MR imaging
in
general
include
evaluation
of children,
uncooperative
patients,
and patients
in unstable
condition who are unable
to suspend
respiration,
884
U
Scientific
Exhibit
Volume
17
Number
4
Figures
10, 11.
(10) Motion
artifact
in a patient
with a large amount
of ascites.
Axial MR image
two signals
acquired)
shows
artifact
secondary
to motion
of the ascites.
(11) Flow artifact.
Coronal
gram (34/8,
40#{176}
flip angle,
one signal acquired)
shows
flow artifact
from turbulent
flow mimicking
tal vein thrombus.
MR images
secondary
10). In patients
with
sion,
MR
(3,200/90,
MR angioa main por-
to motion
artifact
(Fig
severe
portal
hyperten-
angiography
of the
portal
venous
sys-
tern can be difficult
when
stagnant
or “to-andfro” flow is present
in the portal
vein. Such
stagnant
flow may produce
low or no signal in
a vessel
that is actually
patent,
leading
to a falsepositive
fmding
of nonobstructive
thrombus
or
occlusion
(Fig 1 1) (7,9). Surgical
clips produce
artifacts
on MR images
that may obscure
the
portal
venous
system.
Clip artifacts
may be especially
troublesome
in patients
with liver
transplants
or surgically
created
portosystemic
shunts.
Figure
9.
Paraumbilical
vein. Coronal
MR angiogram (34/8,
40#{176}
flip angle,
one signal acquired)
shows
a paraumbihical
vein (straight
arrow).
Curved
arrow = portal vein.
causing
respiratory
motion
that will degrade
images (5). Use of MR imaging
is also limited
in
patients
who require
intense
nursing
care or
medical
equipment
that cannot
be placed
in
proximity
to the MR unit. MR-compatible
respirators
and intravenous
pumps
are expensive,
and their availability
is limited.
Other
disadvantages
are more
specific
to MR
evaluation
of the portal
venous
system.
Ascites
is common
sion,
and
July-August
in patients
movement
1997
with
portal
of the
ascites
Finally,
are usually
missed
splenic
detected
in a pre-liver
with MR imaging.
source
of morbidity
plantation.
U
COMPUTED
.
Technique
artery
with
aneurysms,
angiography,
transplantation
These
and
100-
1 50 mL
be
work-up
aneurysms
mortality
can be a
after trans-
TOMOGRAPHY
Evaluation
of the portal
venous
system
with CT is performed
after intravenous
jection
of iodinated
contrast
material.
is injected
which
may
of 60%
with
iodinated
a mechanical
contrast
injector
and liver
bolus
inTypically,
material
at a rate
hypertenmay
degrade
Pleters
et al
U
RadioGraphics
U
885
12.
13L
Figures
12, 13.
(12)
Large esophageal
varices
in a patient
with
portal
hypertension.
CT scan shows
a thickened
esophagus
(arrow)
and large vascular
structures
around
the distal esophagus
(arrowheads).
(13) Mesenteric
varices.
(a) CT scan shows
mesenteric
Varices in the region
of the right renal vein. The varices
appeared
to
drain into the right gonadal
vein. Arrowheads
=
nondilated
ureters.
(b) Comparison
arterial
portogram
shows
the mesenteric
varices
(straight
arrows).
Curved
arrow
=
inferior
vena cava.
of 2-3
placed
mljsec
in the
between
the
of scanning
through
antecubital
start
varies
of the
with
an i8-gauge
fossa. The
injection
the
catheter
delay time
and
time
the
needed
onset
to scan
the liver (10). The predicted
time of peak enhancement
of the liver is 70-98
seconds
for
low-flow
monophasic
injection
(1 1). Dynamic
incremental
CT of the liver, which
typically
requires
a scanning
cessitates
time
that
45 seconds
scanning
after
of 90be
initiation
i 20 seconds,
initiated
of the
ne-
early
(20-
injection)
to
ensure
hepatic
imaging
in the portal
venous
phase
of contrast
enhancement.
Spiral CT of
the liver requires
30-60
seconds,
and a longer
delay (60-80
seconds)
is used to scan during
peak enhancement,
yielding
greater
overall
enhancement
(i,i2).
.
Advantages
Advantages
of CT evaluation
of the portal
venous
system
include
the noninvasive
nature
of the procedure,
the availability
of CT scanners,
the
relatively
and
the
short
30
minutes).
low
procedure
Furthermore,
cost
of the
time
CT
procedure,
(usually
is not
less
operator
than
dependent
and can be performed
cal facility,
large or small.
The global
abdominal
survey
is valuable
U
Scientific
Exhibit
provided
circumstances.
CT
mediby CT
an-
swers
many of the clinical
questions
in the
evaluation
of liver transplant
candidates,
including the patency
of recipient
vessels,
the presence of extrahepatic
shunts
(Figs 4, 1 2, 13)
(10,13),
and the diseased
liver volume.
After
liver transplantation,
CT is valuable
in detecting
many
of the
possible
complications
of surgery,
including
portal
vein thrombosis,
liver infarction (Fig 14), and fluid collections.
The global
abdominal
survey
provided
by CT is also valuable in patients
who present
with abdominal
pain and possible
bowel
ischemia.
Splanchnic
venous
thrombosis
may be present
in this setting,
886
in several
at any
often
unexpectedly
(Figs
Volume
1 5, 16) (2,15).
17
Number
4
Figures
heads)
15, 16.
(15)
Portal
and
enlarged
vein thrombosis.
portal
vein (straight
arrow)
and contain
hypoattenuating
are demonstrated
in the splenic
CT scan of the upper
abdomen
thrombosis
(14).
CT scan
shows
occlusion
of the splenic
bed (curved
arrow).
shows
a hyperattenuating
(16)
Acute
portal
vein thrombosis.
thrombus
in the portal
vein,
CT
is also
valuable
the
portal
and
In fact,
many
prefer
CT
evaluation
for
the
before
of
cre-
radiologists
before
TIPS
creation
comprehensible
format
of the
relationship
patic
veins
portal
vein
to the
patency
TIPS
interventional
visualization
al-
of the
he-
branches.
Disadvantages
terial
injection
tal venous
toxic
with
As in MR
and
the
CT.
Unlike
in MR
US,
there
is no
venous
imaging,
imaging
with
and
artifacts
poor
images
sources
means
CT
renal
from
(pos-
or inability
(bolus
quantitative
flow
por-
possible
reactions
are
ma-
of the
inherent
motion
to cooperate)
contrast
evaluation
technically
to respiratory
the patient
portal
CT
of allergyhike
clips
due
for
system
effects.
surgical
sibly
of iodinated
is necessary
complications
July-August
the
veins
readily
Intravenous
Figure
14.
Complication
of liver transplantation.
Enhanced
CT scan shows
a peripheral
region
of low
attenuation
consistent
with infarction
of the liver allograft.
The portal
vein is patent.
The low attenuation around
the portal
vein branches
may be secondary to periportal
ischemia
or lymphedema.
US findings suggested
occlusion
of the hepatic
artery,
which
was confirmed
with hepatic
arteriography
Unenhanced
indicating
acute
lows
.
not
(arrow-
in confirming
hepatic
ation.
because
(images
vein
as a complication
of splenectomy.
The thrombosed
veins are
clot with enhancement
of the portal
vein wall. Surgical
changes
(10).
of
of error
tracking)
in
and
of estimating
Splenic
artery
shown).
1997
Pleters
et a!
U
RadioGraphics
U
887
Figures
shows
17-19.
(17) Portal
vein thrombosis.
US scan obtained
before
liver transplantation
a thrombosed
main portal
vein (arrow).
This finding
was confirmed
angiographicahly.
(18) Large main portal vein. Duplex
US image shows
the direction
and velocity
of flow in the
right main portal
vein (RTMPV).
(19) Paraumbiical
vein. US scan shows
a large paraumbilical vein (curved
arrow)
arising
from the left portal
vein. A TIPS (straight
arrows)
extends
from the left portal
vein through
the liver parenchyma
into the inferior
vena cava (arrowheads).
aneurysms
may
be
liver transplant
the
section
missed
in CT
candidates
on
(see
disadvantages
evaluation
of
discussion
of MR
in
imaging
and
MR angiography).
Small
branches
superior
of peripheral
and inferior
titi vein
branches
are
portions
of the
mesenteric
veins
not
as well
shown
and
por-
with
CT and other noninvasive
modalities
as with angiography.
Finally,
misdiagnosis
of portal
vein
thrombosis
ported
can
may
be
ducts
occur
with
16% of patients
in
difficult
from
CT
and
in one
to differentiate
segmentally
occluded
was
re-
series
(16).
dilated
bile
veins.
It
No
large, prospective
study evaluating
the diagnostic efficacy of CT in detection
of portal
vein
thrombosis
has
been
performed,
to our
knowl-
of fasting.
edge.
patic
ated
SONOGRAPHY
U
Flow
artery,
Technique
Sonographic
system
evaluation
is performed
color
Doppler
sonographic
and
imaging
disease
and
real-time
supine
is helpful
position,
and
consists
transducer
with
capability.
Color
in the
time.
venous
of a 3-
are
after
the
portal
be
kept
survey
of the
.
Doppler
of
hours
in
system
tively
like
Scientific
Exhibit
abdomen
and
peak
the
the
ye-
be-
ultrasound
as possible.
beam
A general
is required
of portal
flow
angle
for
detecting
hypertension
and
col-
vessels.
Advantages
is not
U
vein
heis evalu-
of flow
and
accuracy,
as acute
signs
Sonographic
dalities
888
the direction
maintain
should
veins,
system
both
evaluated
several
To
tween
lateral
hepatic
venous
vs hepatofugah)
secondary
identification
Patients
usually
duplex
Standard
usually
real-time
saves
portal
techniques.
phased-array
Doppler
flow
with
flow
equipment
or 5-MHz
the
of the
the
portal
by determining
(hepatopetal
locities.
.
within
and
evaluation
of the
is noninvasive,
fast,
and
the
discussed.
required,
reactions
readily
least
expensive
Intravenous
eliminating
and
renal
portal
venous
available,
contrast
the
toxic
Volume
rela-
of the
risk
momaterial
of allergy-
effects.
Owing
17
Number
to
4
Figure
20.
False-negative
US results.
(a) Duplex
US image
obtained
before
TIPS creation
to
confirm
patency
of the portal
vein shows
venous
flow in the region
of the main portal
vein.
Therefore,
the portal
vein was thought
to be patent.
However,
note that no “color”
is seen
within
the portal
vein on the Doppler
flow image.
In retrospect,
US showed
the portal
vein
to be thrombosed.
The venous
flow that was detected
was most likely from a collateral
yessel. Multiple
attempts
were
made to cannulate
the portal
vein for TIPS creation.
(b) Arterial
portogram
(venous
phase
of a superior
mesenteric
artery
injection)
obtained
after attempted
TIPS creation
shows
occlusion
of the main portal
vein and large collateral
vessels
(arrows).
the lack of radiation
venous
contrast
exposure,
material,
the lack of intra-
and
the
nature
of the procedure,
serial
sonographic
aminations
can be performed
after liver
plantation
(17).
In this
graphic
evaluation
venous
system,
and
ate angiography
confirm
CT
(18).
any
age
may
and
critically
the
(Fig
18)
US can
cially
patent
and
be
of
is the
the noninvasive
modalities
reproducibility
of sonographic
problem.
Medical
gists
US images
when
frnd
highly
July-August
trained
1997
personnel
difficult
personnel
vein.
bowel
may
with
sluggish
thrombus
determined
results
to be
can
occur
patent
are
at
tected
in a collateral
vessel
vessel
is erroneously
thought
in
splanchnic
(Fig
vein,
which
(ie,
falsely
occluded).
when
of
accurate
when
flow
vein
negative
direction,
occur
may
is wrongly
False-
flow
and
that
is de-
the
collateral
to be
a named
is actually
thrombosed
20).
flow
U ANGIOGRAPHIC
detec-
vessels,
espe-
(Figs
2, 19)
.
dependent
discussed,
of
and the
findings
other
by
flow
Wedged
With
operator
or splenic
obscured
results
to contain
in
(24).
most
gas
portal
be so stagnant
in the portal
venous
system
detection
is not possible
with
US and the
need
Disadvantages
Sonography
bowel
main
vein,
commonly
veins
use
proach,
.
and
of the
mesenteric
also
determined
performed
in the
veins
varices
splanchnic
to
the
venous
useful
collateral
paraumbilical
rectal
used
convenience
of portal
also
of portosystemic
(23)
be
are
False-positive
obvi-
consideration
can
of ascites
visualization
gas.
in patients
to the
presence
superior
Varices
at low cost.
without
the
prevent
vein,
portal
may
be
duplex
US is highly
the presence
(Fig 17),
velocity
tion
condition
In addition
(6,19-22).
also
performed
ill patients-and
the procedure,
determining
cava
fmdings
important
bedside.
and
be
in any
sedation-an
US can
ex-
trans-
artery,
vena
imaging
may
sono-
hepatic
inferior
or MR
Sonography
for
circumstance,
of the
cedure,
noninvasive
than
to interpret.
perform
can
be
radiolo-
a
Hepatic
Venography
of a jugular
a hepatic
eter
is advanced
small
venule).
or femoral
vein
into
The
sure
can
be
with
the
portal
tion
PROCEDURES
wedged
closely
pressure.
by injecting
the
position
hepatic
and
venous
ap-
and
a wedged
measured
is confirmed
venous
is selected
cath(in
vein
a
pres-
correlates
Catheter
a small
amount
posiof
Even
the
pro-
Pieters
et al
U
RadioGraphics
U
889
b.
a.
Figure
patic
21
venule
Wedged
hepatic
venography.
and contrast
material
injected
(a) Venogram
obtained
with the catheter
shows
opacification
of the surrounding
normal
appearance
of the opacified
venules
and
venogram
of a cirrhotic
liver shows
an irregular,
ture by fibrosis
and regenerating
nodules.
sinusoids
pruned
is a delicate,
leaflike
pattern.
appearance
due to distortion
a.
Figure
wedged
into a small
venules
and sinusoids.
(b) Wedged
of the vascular
heThe
hepatic
architec-
b.
22.
Portal
vein patency
confirmed
with
wedged
hepatic
venography.
(a) Coronal
MR
angiogram
(35/8,
50#{176}
flip angle, one signal
acquired)
shows
no signal in a portion
of the main
portal
vein. Duplex
US (images
not shown)
could
not demonstrate
patency
of the main portal
vein.
(b) Wedged
hepatic
venogram
obtained
with carbon dioxide
shows
retrograde
filling of the patent
main portal
vein as well as splenic
vein (arrowhead),
superior
mesenteric
vein (open
arrows),
and inferior
mesenteric
vein (curved
arrow).
A
patent
paraumbilical
vein is also seen (straight
solid arrows).
(C) Wedged
hepatic
venogram
of
the left lobe of the liver shows
filling of a collateral vessel,
which
empties
into a splenorenal
shunt.
C-
890
U
Scientific
Exhibit
Volume
17
Number
4
23#{149}
24.
Figures
23, 24.
(23) Cavernous
transformation.
Wedged
hepatic
venogram
shows
reflux
of contrast
material
into small collateral
vessels.
The main portal
vein is not opacified,
mdieating
cavernous
transformation
of the portal
vein. (24) Subcapsular
injection.
Wedged
hepatic venogram
shows
dissection
of contrast
material
through
the parenchyma
into the subcapsular
space.
Such dissection
may result
from forceful
injection.
Although
temporarily
painful,
this complication
is rarely
significant.
a.
b.
Figure
25.
Pseudothrombus.
(a) Arterial
portogram
(venous
phase
of a
tion) shows
opacification
of the splenic
and portal
veins (straight
arrow)
coronary
vein. An apparent
filling defect
at the confluence
(curved
arrow)
for a thrombus
but actually
represents
mixing
of unopacified
blood
from
teric vein with opacified
blood
from the splenic
vein. (b) Arterial
portogram
of a superior
mesenteric
artery
injection)
allows
confirmation
of patency
contrast
material,
parenchymal
trast
30
material
mL)
trast
agent
venous
tion
flow,
(6-
10 mL)
hepatic
branches
is forceful
the
splenic
troesophageal
July-August
main
vein,
2 i
).
enough
portal
superior
varices
1997
demonstrate
or carbon
sinusoids
dioxide
or if there
and
mesenteric
may
be
(20-
The
into
If the
vein,
visualized
Carbon
agent
because
its low
rapid
flow
through
the
.
the
por-
injec-
dioxide
may
Arterial
be the
preferred
viscosity
con-
allows
sinusoids.
Portography
Evaluation
of the
frequently
performed
portal
mesenteric
the
(Figs
1 3b,
or gas-
inferior
(Fig
may
3a,
6b,
mesenteric
be
selected.
venous
with
the superior
is hepatofugal
possibly
23).
trast
con-
fashion
and
2 1 -24).
vein
con-
by hand.
in a retrograde
(Figs
a
Water-soluble
injected
is forced
the
should
(Fig
is forcefully
through
tal
which
stain
splenic
artery
injecas well as a large
could
be mistaken
the superior
mesen(venous
phase
at the confluence.
20b,
artery
25).
artery
Less
or left
Pharmacologic
Pieters
system
selective
is most
injection
or splenic
commonly,
gastric
of
artery
the
artery
enhancement
et al
U
RadioGraphics
U
891
a.
b.
Figure
26.
Thrombus
and ostomy
varices
in a patient
with Crohn
disease
and primary
bihiary cirrhosis
who
presented
with bleeding
from a colostomy.
(a) Transjugular
portogram
shows
a nonobstructing
thrombus
(arrows)
in the main portal
vein. (b) Portal
venogram
of the lower
abdomen
shows
hepatofugal
flow in the supenor mesenteric
vein (arrow)
with filling of large ostomy
varices
(arrowheads).
These
varices
shunted
to the systemic
common
femoral
vein.
with
25-50
30-60
mg
mg
into
the
superior
immediately
jection
vasodilates
decreases
This
tense
opacification
tal of 30-50
5 mL/sec
mL
for
splenic
artery
nomegaly
seconds
phase.
may
.#{149}d,
mefor
a to-
injection
be
.
with
superior
mL.
):
should
mL/sec
artery
of 25-30
,I
for
In gen-
imaging
5-6
at
in-
system.
at 4-
A larger
needed
if sple-
Portography
hepatic
vein
approach.
Bloomington,
and
so that
more
Figure
hepatic
puncture
27.
Patent
portal
portogram
obtained
of the left portal
vein. Percutaneous
transwith percutaneous
vein under
sonographic
guidance
and contrast
material
injection
small dilator
shows
patency
of the left
through
a
portal
vein.
is present.
right
jugular
30-45
material:
injection
Transjugular
The
and
protocols
or splenic
a total
capillary
subtraction
injection
and
venous
venous
contrast
artery
portal
injection
digital
iodinated
senteric
the
earlier
over
portal
in-
arteries
through
extend
for
material
splanchnic
of the
the following
or splenic
contrast
allows
of the
suitable
60%
vein
time
should
eral,
.
the
maneuver
evaluation
or
injected
artery
before
transit
beds.
Imaging
hydrochloride
hydrochloride
mesenteric
artery
be
of tolazohine
of papaverine
A Colapinto
Ind)
passed
the
portal
manner
is cannulated
needle
is advanced
through
vein
the
with
into
liver
is cannulated
a
(Cook,
the
wire
hepatic
same
the
portal
measurements
may
can
tal of 20-30
(Fig
26).
elusively
creation.
a catheter
into
material
parenchyma
in the
as in TIPS
technique,
venous
be
injected
mL
to perform
performed
the
Seldinger
over
system.
obtained,
be
Transjugular
With
is advanced
a guide
Pressure
and
contrast
at 8- 10 mL/sec
portal
portography
as a prelude
for
a to-
venography
is almost
to TIPS
ex-
cre-
ation.
892
U
Scientific
Exhibit
Volume
17
Number
4
a.
b.
Figure
28.
Cavernous
transformation
in a 10-year-old
boy with splenomegaly.
Patency
of the portal
vein could
not be clearly
established
with CT and US. MR imaging
could
not be performed
secondary
to the patient’s
inability to cooperate.
(a) Arterial
portogram
(venous
phase
of a splenic
artery
injection)
shows
short gastric
‘arices but does not adequately
demonstrate
the portal
vein. (b) Splenoportogram
shows
multiple
collateral
yessels (arrows)
in the region
of the main portal
vein, a finding
that indicates
the diagnosis
of cavernous
transformation
of the main portal
vein.
.
Percutaneous
Transhepatic
sures.
Portography
Catheterization
branch
of an intrahepatic
is performed
subxiphoid
of the
can
left
sonographic
portal
can
be
ner as in percutaneous
(ie,
cannulated
(Fig
the
Seldinger
27).
with
The
needle
gelatin
sponge
Kalamazoo,
duct).
the
portal
tract
can
after
is
is used
images
are
obtained
should
be
embohized
sponge
pledgets
.
for
tween
posterior
the
eighth
diaphragm
spleen.
and
The
pulp
amount
pressures
an accurate
July-August
estimate
1997
ribs.
detection
splenic
or superior
in combination
(25,26).
3-4
the
cm
position
into
of contrast
can
be
essary
venous
is in-
mally
invasive
of the
venous
and
needle
including
injec-
dient
venography
pressure
portoghepatic
fail
to provide
transhepatic
may
hepatic
rarely
results
and
wedged
are
requiring
and
can
a
of
performed,
portosystemic
of the
he-
mini-
a wealth
properly
of the
demonstration
only
provide
when
be nec(25,29).
measurement
procedures,
an estimate
and
arterial
question,
definitive
(8).
require
wedged
provides
(28).
in the
shunts
techniques
clinical
information
system
imaging
generally
with
puncture,
valuable
of reference
collateral
portography
and
Wedged
the
MR
will
If these
patic
be-
of the
of blood
is com-
venous
mesentenic
to the
or transjugular
dome
tract
gelatin
standard
and
evaluation
venography.
guid-
the
of extrahepatic
raphy
A needle
toward
by aspiration
of a small
Splenic
ninth
and
needle
procedure
portal
to CT
Upjohn,
usually
The
several
the
of the
A complete
embolized
line,
advanced
intrasplenic
is confirmed
vide
and
at a 45#{176}
angle
troduced
tion
axillary
28).
with
remains
evaluation
It is equivalent
to ad-
. Percutaneous
Splenoportography
The spleen is localized
under sonographic
ance. Percutaneous
puncture
is performed
the
is performed,
Advantages
an answer
along
(Fig
when
at 6- 1 0 mL/
material
mL
(25,27).
system
(Gelfoam;
the procedure
of 30-40
Angiography
either
venous
be
pledgets
Mich)
vein
With
of contrast
a total
inman-
cholangiogportal
for
plete
a right
technique
into
a
direct
in a similar
right
of a bile
a catheter
to puncture
under
used
of the
instead
approach,
vance
used
transhepatic
a branch
vein
The
Alternatively,
approach
raphy
be
vein
guidance.
tercostal
portal
percutaneously.
approach
branch
Injection
sec
gra-
intrahepatic
material.
obtained
of portal
venous
and
propres-
Pieters
et al
U
RadioGraphics
U
893
portal
veins,
the
main
splenic
vein
and
portions
ferior
mesenteric
of flow
Indirect
(wedged
cannulation
portal
of the
portal
portal
pressure
of stenoses
procedures
creased
risk-in
stant
shunts.
can
be
for
these
tiple
in-
evaluation
with
sive.
ral arterial
and
tion
con-
nursing
at-
punctures
(ie,
raphy,
aneurysm,
hemorrhage.
dures
should
answer
the
be
reserved
procedures
patic
require
with
the
renal
toxic
tions.
Therefore,
fore
existing
and
use
to
dioxsuch
material
procedures
may
reac-
be limited
other
disadvantages
of the
and
the
required
age
angiographic
angiography).
invasive
expertise.
evaluation
that
twice
noninvasive
As emphasized
procedures
experience
are
and
expertise.
(eg,
cuhar
complication
modality
(MR
reliant
False-positive
on
not
test
abscess,
also
these
not
clinically
opera-
derlying
(often
sis to be
detected
intention
intervention
performed
as the
Use
unsuspected)
with
a less
of per-
if possible.
bowel
because
suspected.
collecIf a vas-
angiography
the
is regarded
not
complifluid
biloma).
with
is
sur-
vascular
but
ischemic
CT
abdominal
only
ahlogi-aft
be
sonog-
Abdominal
is suggested,
for
can
serial
cost.
percutaneous
agnostic
to answer
a global
undertaken
often
in-
low
liver
Angiography
as
disshould
transplantation
with
hematoma,
be
forming
results
procedure
demonstrates
tions
portal
as expensive
repeatedly,
highly
aver-
the
angiography
providing
in the
should
can
US in combination
When
liver
at a relatively
vey
cost
of
limited.
transplantation
imaging.
after
in pa-
are
The
of the
is at least
expensive
system
apphi-
evaluation
with
CT
are
in this
to be
liver
sensiand
modalities
Sonographic
noninvasively
valuable,
of angiographic
venous
operator
system
most
portal
the
question.
performed
cations
followfor
these
as the definitive
also
or co-
the
angiography,
inconclusive,
clinical
be-
insufficiency
preced-
disadvantages,
demonstrated
appears
or MR
or are
raphy
expertise
of the
as angiogi-aphy
before
Evaluation
as
coagulopathy.
Two
the
inva-
recommended
MR
performed
CT
local
basis
of varices;
10,30).
reliably
be used
he-
have
vessels
agree
carbon
contrast
(5,8,
with
wedged
of morbidity
renal
be
in-
and
procedures,
are
imaging,
Evaluation
proce-
factors
advantages,
as accurate
collateral
angio-
of these
coexisting
evaluation
venous
evaluation
of iodi-
for
with
risk
transplantation
with
in the
intraperito-
injection
performed
inherent
effects
liver
tients
portog-
resorts
(except
studies
of MR
cation
Selec-
situations:
tivities
at least
the
various
for
system.
and
On
work-ups
clinical
Muh-
accuracy,
procedure
of the
is re-
available
venous
of the
Several
from
latter
All of the
material
venography
ide)
or
as last
questions.
contrast
given
now
is multifactorial;
discussion
femo-
system
are
procedure.
costs
pseudo-
the
such
circumstances.
availability,
of the
imaging
or intra-
fistula,
Therefore,
of
prevent
venous
portal
cost,
the
ing
splenography)
of intrahepatic
wrongly
(8,9).
modalities
proce-
intraparenchymal
specific
graphic
tor
risks
opacify
Performance
should
portal
of a modality
elude
and
frequently,
invasive
be
3a).
ar-
not
in conjunction
clinical
of the
inva-
from
portography,
arterial-portal
neal
are
transhepatic
hemorrhage,
nated
less
more
percutaneous
the added
splenic
they
occur
and,
The
transjuguhar
have
described
is that
mortality
punctures.
dures
of the
procedures
Morbidity
venous
the
of the
imaging
ing
disadvantage
may
(Fig
venography
in several
inva-
Disadvantages
greatest
may
interpretations
siveness
angiographic
portal
mesenteric
which
portography
Evaluation
with
The
vein,
is flow
in the
injection
occluded
hepatic
quired
tention.
.
portal
arterial
if flow
a superior
artery
to be
wedged
thus,
of the
method
U CONCLUSIONS
detection
and
or splenic
27);
because
The
TIPS
and
ill patients
is hepatofugal,
tery
false-positive
performed-with
monitoring
(Fig
main
occur
expertise.
vein
with
created
Finally,
critically
hemodynamic
of
in diagnos-
reliable
frequently
of operator
the
venography
allow
lack
judged
procedure
Portal
of these
mea-
portal
of surgically
terpretations
dependent
measurement
definitive
measurement
di-
system).
is invaluable
shunts.
in-
measure-
vein)
evaluation
portosystemic
the
pressure
In addition,
is the
and
the
and
or transjugular
pressures
evaluation
venous
pressure
hypertension.
venography
sive
pulp
often
on
venous
(transhepatic
venous
ing
portal
hepatic
or direct
and
superior
(depending
in the
or splenic
ment)
vein,
of the
veins
rection
surement
portal
definitive
disease
the
dibut
is
diagnosis
is
allows
un-
of CT
venous
thrombo-
invasive
method.
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