1. PORTAL VEIN THROMBOSIS
63 yr male with multiple well defined round
to oval shaped lesions with variable sizes
studding the Rt lobe of the liver ( especially MERCURY IMAGING
the segment 6 and 7 of the liver ) . INSTITUTE
The echo pattern of these lesions is
heterogeneous – primarily Hyperechoic at SCO 172-173 SEC 9C
places. The largest of all the lesions CHANDIGARH
measures 53mmx 48mmx 56mm in size (
seen in the segment 6/7 of the liver ) . Note MERCURY IMAGING CENTRE
is made of prominent main portal vein with SCO 16-17 SEC 20D
intraluminal thrombus in the main portal
vein extending to the left and Rt branches CHANDIGARH
also . Periportal collaterals are appreciated
on color Doppler.

2. Dilated main portal vein with intraluminal thrmobus
with intermediate to hyperechoic echopattern suggestive of
subacute stage thrombus .

3. Serpigenous tracts along the periphery of
the intraluminal thrombus – ? Partially patent lumen / recanallization..

4. Thrombus extending to the left main branch and more
vertically oriented left lobe branches .

5. Serpigenous tracts along the periphery of
the intraluminal thrombus – ? Partially patent lumen / recanallization..

6. PORTAL VEIN THROMBOSIS
ETIOLOGY : BRIEF ANATOMY :
• Reduced portal blood flow caused • Generally, the portal vein enters
by hepatic parenchymal disease the porta hepatis and divides into
and abdominal sepsis the right and left main branches.
(ie, infectious or ascending The right main branch divides
thrombophlebitis) are the major into anterior and posterior
causes. branches that supply the anterior
• Transient PVT is also being and posterior segments of the
recognized with abdominal right lobe. The left main branch
inflammation such as appendicitis courses horizontally to the left
• Hypercoagulable syndromes can before turning vertically to form
lead to portomesenteric and the medial and lateral segmental
splenic vein thrombosis. branches.

7. Points to remember................
• Tumor in the portal vein may • In children, the portal vein may
have an appearance identical to recanalize with the development
that of thrombosis, but this of multiple, small, collateral
appearance is far less common channels. These channels are seen
than others. Tumor in the portal as a partly echogenic band of small
vein is most frequently related to vessels extending to the porta
HCC.The thrombus may be partial hepatis (cavernous
or complete. It may be mixed transformation). These have a
with bland thrombus as well. reduced flow velocity of 2-7 cm/s.
• Adults who have acute PVT Nonvisualization of the portal vein
secondary to abdominal sepsis is strongly suggestive of occlusion.
may completely recover, and the The portal vein may then be seen
vessel may recanalize with as a band of high-level echoes at
successful treatment of the the porta hepatis.
underlying sepsis.

8. RADIOGRAPH
• Hepatosplenomegaly
CONVENTIONAL
RADIOGRAPHS CAN • Enlarged azygos vein.
HELP TO ASSESS THE
FOLLOWING • Para spinal varices .
OBSERVATIONS …….

9. USG
• PVT eliminates the usual venous flow signal
from the lumen of the portal vein during
either pulsed or color flow Doppler imaging.
• On sonograms, echogenic lesions Color flow Doppler images can show flow
may be present in the portal vein. around a thrombus that partially blocks the
Clot with variable echogenicity may vein. However, if flow is sluggish, the Doppler
be depicted. The clot usually has signal may not be detected. Color flow may
be present in other small collateral vessels.
moderate echogenicity, but if it is • Incomplete occlusion may occur. This is
recently formed, it may be common with neoplastic invasion.
hypoechoic. Patent vessels may Alternatively, thrombolytic recanalization
have increased intraluminal may occur. The two cannot be differentiated
on sonograms. Cavernous malformation,
echogenicity because of spontaneous shunts, and splenorenal and
erythrocyte rouleaux formation, portosystemic collaterals may be seen. The
which makes slow-flowing blood underlying cause (eg, hepatocellular
slightly echogenic. Increased or carcinoma, metastases, cirrhosis, pancreatic
neoplasms) may be evident. The incidence of
decreased echogenicity may be PVT is reported to be low in portal
observed in the lumen of the portal hypertension.
vein. In isolation, this finding is not • The string sign—that is, thickening of the
sufficient to diagnose or exclude portal vein with narrowing of its lumen—is
PVT. assumed to be caused by portal phlebitis.
This is considered a precursor of PVT in
patients with acute pancreatitis. The portal
vein thrombus may be calcified. The
diameter of the portal vein is larger than 15
mm in 38% of the cases of PVT.

10. CT
• On contrast-enhanced CT scans, PVT may be • The portal vein supplies 75% of the
depicted as a low-attenuating center in the blood flow to the liver. Therefore,
portal vein surrounded by peripheral peak liver contrast enhancement
enhancement. Portal vein attenuation is 20- occurs during the portal venous
30 HU less than that of the aorta. phase, about 60 seconds after the
• CT angiography (CTA) is an application of start of a bolus injection of contrast
helical CT. The rapidity of helical CT allows the material.With helical CT, a liver
maintenance of a higher concentration of examination requires about 20
intravenous contrast medium, particularly seconds to complete; images can
through the arterial enhancement phase, and
it has the capability of 3-dimensional (3D) usually be acquired in one breath
reconstruction. Both peripheral intravenous hold.[18]
injections of contrast agent and CT arterial • This technique can be extended to
portography have been used as with CTA. CTA acquire a dual-phase contrast-
has shown great promise in the evaluation of enhanced CT scan in which the liver
hepatic vessels before liver resection. It is imaged twice with a single
provides preoperative surgical information contrast agent bolus, first during
about the segmental location of liver tumors,
the segmental venous anatomy, and the the arterial phase and then through
presence of significant arterial anomalies. The portal venous phase. Dual-phase CT
value of CTA in the evaluation of portal is indicated in some cases involving
hypertension is unclear, but CTA is likely to be benign or malignant lesions in
useful because it may delineate the collateral which vascular characteristics
vessels, varices, and other findings in patients suggest the correct diagnosis (see
with portal hypertension. the images below).

11. MRI
• The vascular anatomy of the liver may be • MRCP coupled with dynamic 3D
outlined by using spin-echo and gradient- gradient-echo imaging can not
recalled-echo (GRE) techniques, but these only detect portal vein occlusion,
techniques cannot demonstrate the
direction of portal flow. Time-of-flight MRI cavernous transformation, and
with bolus tracking has been successful in gallbladder varices but also depict
the assessment of portal hypertension and bile duct abnormalities associated
its squeal. Phase-contrast sequences can with portal biliopathy.
also be used to evaluate the portal
vein, and phase-contrast cine MRA can
show the direction of portal venous flow
and the presence of portal vein thrombus.
Magnetic resonance evaluation of the
portal venous system accurately
demonstrates thrombosis and the
collateral circulation. Gadolinium
enhancement is useful in this application
(see the images below).