Assessment of Vascular Complications of Renal, Hepatic, and Pancreatic Transplantation1 DavidE. Finlay, MD Janis Gissel Letourneau, Deborah G. Longley, MD

The

assessment

plex;

current

of the

MD

vasculature

is on

emphasis

of the

utilization

transplant

recipient

of noninvasive

is corn-

techniques,

particularly conventional and color duplex sonography. These exarninations reduce the need for diagnostic angiography, and their findings provide crucial information with regard to vascular complications seen after transplantation, such as arterial or venous stenosis or occlusion, arteriovenous fistulas, and pseudoaneurysrns. However, the complexity of the clinical settings of these vascular complications often

makes

necessary. plantations,

other

noninvasive

Some but

complications some, such

plantation,

predominate

imaging

is also

tation.

In addition,

be

provided

with

NC

=

inferior

access

1

From

nesota RSNA

1992;

the

Department

Hospital scientific

of transtrans-

of transplant. for

radiologic

angiographic

Use

liver

of

transplan-

intervention

can

procedures.

transplantations are being demand for knowledgeable grafts. Arterial and venous

81.4551, 761.1298.

81.4552. 770.1298,

81.4557 81.1298

performed with increasing evaluation of vascular stenoses and occlusions,

#{149} Liver,

transplantation.

761458

#{149} Pancreas.

trans.

12:981-996 of Radiology,

University

of Minnesota

and Clinic, Minneapolis, MN 55455. Recipient assembly. Received February 13. 1992; revision

reprint

13. Address c RSNA,

type candidates

for therapeutic

as angiography,

to all three types in pancreatic

cava

Index terms: Kidney, transplantation. plantation, 770.458 #{149} Ultrasound (US), RadioGraphics

particular

in identifying

diagnostic

vena

as well

are common as graft thrombosis

in one

important

U INTRODUCTION Renal, hepatic, and pancreatic frequency, leading to a greater complications involving these

Abbreviation:

examinations,

requests

Hospital, ofa Cum requested

420

Delaware

St SE. Box

292,

University

Laude award for a scientific exhibit at the March 10 and received May 1 1; accepted

of Mm1991 May

to D.E.F.

1992

981

b. Figure

1.

demonstrates

The external the external

Figure

2.

color image

change obtained

Normal renal artery transplant. (a) the usual end-to-side anastomosis

Longitudinal of the main

iliac vein courses adjacent to the external iliac artery ( IA ) and the external iliac vein

Renal

artery

transplant

stenosis.

(a) Color

(straight LLQ

arrow), =

left

lower

consistent quadrant,

pseudoaneurysms, and arteriovenous fistulas occur in all of these transplants. Diagnostic techniques established first in kidney transplantations have been successfully used for parallel complications in liver and pancreatic transplantations. Noninvasive studies, includ-

U

RadioGrapbics

U

Finlay

et a!

Doppler artery ART

=

image of the right lower quadrant (M.R4) with the external iliac artery. artery. (b) Transverse view shows

(IV).

image

at the anastomosis (ANAST) of the main renal at the renal artery anastomosis (R4 ANAST)

approximately 260 cm/sec confirmed with angiography.

982

color renal iliac artery.

demonstrates artery

(MRA

an area

offocal

) to the iliac artery

narrowing and (b) Doppler systolic velocity of stenosis. This was (IA).

(curved arrow) reveals a peak with a hemodynamically significant LONG = longitudinal, 7X = transplantation.

ing

duplex

sonography,

computed

tomogra-

phy (CT), and magnetic resonance (MR) imaging, reduce the need for diagnostic angiography and serve to direct angiographic and surgical intervention. This article presents some of the current methods of vascular assessment of kidney, liver, and pancreatic transplantation, emphasizing the role of conventional duplex and color Doppler ultrasonography (US).

Volume

12

Number

5

Figure

4.

anuric.

Color

be detected artifactual.

(a) Renal

artery

Doppler

(K4 ) transplant

US image

failed

thrombosis.

to definitively

Soon show

after

the

renal

renal

transplantation,

artery.

became

(arrows); its source was uncertain, was present within the main renal farction of the graft. (b) Arcuate artery (ARCART) waveform in severe acute rejection of renal transplant. The waveform from an interpolar arcuate artery has a spikelike configuration (arrow). Systolic velocity is diminished,

and

LONG

=

.

on Doppler examination At surgery, fresh thrombus

the patient

Only a faint signal intensity could but it was thought to be possibly artery and there was complete in-

diastolic

flow

longitudinal,

Renal

In this case, follow-up sonograms lower quadrant. (Reprinted, with

Thrombosis

Artery

Thrombosis

is absent. = right

RLQ

of the

transplanted

renal

artery

is

lan rejection

a thrombosed

diastolic

waveform ings

can

vascular cesses

984

U

The most void within

rare, usually occurring immediately after transplantation (2) The absence of documentab!e flow within the renal artery and graft with conventional and colon Doppler US is compatible with, but not diagnostic of, renal artery thrombosis (Fig 4a) (9). Proximal to .

RadioGrapbics

vessel,

may also

be demonstrated. be

caused

impedance (6).

U

a “spiked,” by markedly

from

various

preocclusive

These

ies

and

renal serial

common a transplant with

retrograde

absent,

of normal reference

occlusion

of the

thrombosis

When may

arter-

main

this occurs, show dimin-

diastolic

absence

small

of the

on reversed

to complete

waveforms. 9.)

cause of arterial signal is severe acute vascu-

artery (Fig 4b) (6). Doppler evaluation

ished, ing

return from

flow

of both

systolic

evolvand

flow.

find-

increased

disease

showed the permission,

pro-

.

Renal

As is the

Vein case

Thrombosis with

the

renal

artery,

anatomic

and hemodynamic information regarding the renal vein transplant and its iliac anastomosis can be obtained with both conventional and color Doppler US (Fig 5). Thrombosis of the

Finlay

et a!

Volume

12

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5

Figure 7. Renal transplant and giant pseudoaneurysm after a biopsy. (a) Color sonogram depicts an intrarenal pseudoaneurysm identified 2 weeks after the renal transplant biopsy. Note the characteristic whirling blood flow within the pseudoaneurysm (arrow). TRANS = transplantation. (b) Doppler waveform at the neck of the pseudoaneurysm (curved arrow) shows a typical ‘to-and-fro’ waveform, with antegrade systolic flow (straight arrow) and retrograde diastolic flow (arrowhead). LONG = longitudinal, PSA = pseudoaneurysm, ‘

RLQ

.

Renal

After

occur (Figs

right

=

lower

quadrant.

Transplant

at vascular or

with

permission,

Pseudoaneurysm

transplantation, 7, 8),

(Reprinted,

pseudoaneunysms anastomoses,

in association

at biopsy with

U

RadioGraphics

U

Finlayeta!

from

reference

9.)

can

High velocity to-and-fro within the neck of the

sites

which

infection

(9, 1 1). Their importance lies in their potential for rupture and infection (1 1). Duplex criteria include disorganized, pulsati!e flow within a hypoechoic on variably complex penivascular mass (12). Color Doppler sonography demonstrates a multidirectional whirling flow within the nonthrombosed portion of the lumen.

986

‘

is best

identified

flow is identified pseudoaneunysm, with

color

imaging

(Fig 7b) (9,12). This diagnosis should always be considered when a hypoechoic or complex mass is seen near the vascular anastomoses or within a graft after biopsy.

. Renal Fistula

Transplant

Arteriovenous

Renal graft arteniovenous fistulas are rare and usually occur after graft biopsy but may also occur secondary to vessel ligation during graft harvesting or secondary to interventional an-

Volume

12

Number

5

r t \. -

JfV

V

V

V

\

V V

V’

C-

Figure

9. Renal transplant and arteriovenous fistula after a biopsy. (a) Color sonogram of the lower pole markedly increased color saturation secondary to tissue vibration artifact surrounding an arteriofistula. A draining vein can be seen exiting the fistula (arrow). Biopsy of the lower pole of the renal transplant was performed 2 days before the examination. LONG = longitudinal, 7X = transplantation. (b) Diastolic flow in the lower pole arcuate arteries is increased (arrow), indicating a loss of normal vascular impedance secondary to the fistula. A = artery. (C) Enlarged vein exiting the lower pole (arrowhead) demonstrates increased pulsatiity (arrows). V = vein. (d) Subselective angiogram demonstrates early opacification of three draining veins (arrows). The most caudal of these is the vein shown in a and c.

shows venous

sib!e

(Fig

10).

Patency

ily with color Doppler definite flow is detected or if there is cavernous portal vein or numerous lateral vessels, precise

can

be

established

eas-

US (15); however, if no within the portal vein transformation of the portal systemic colidentification of the

portal

vein

MR imaging

can

be difficult.

may then

Angiography

be necessary

or

to define

the

status of the portal veins (16,17). Conventional Doppler US often demonstrates compensatory increased hepatic artena!

flow

in portal

hypertension

on portal

vein

thrombosis (18). A new aspect of candidacy evaluation is surfacing with the development of the transjugular intrahepatic portosystemic

988

U

RadioGrapbics

U

Finlay

et a!

Volume

12

Number

5

I..

Figure 12. Diagram of hepatic transplant vascular anastomoses. Straight arrows = P/C anastomosis, curved arrow = portal vein anastomosis, arrowhead

=

hepatic

(Reprinted, erence 22.)

arterial

with

anastomosis.

permission,

from

ref.

Figure 13. Transplant portal vein thrombosis. MR image demonstrates increased signal intensity within

the

branches, sis

(arrow).

and

its main

consistent

portal

vein

with

thrombo-

Normal

signal

void

is

seen in the IVC and aorta (arrowheads). (Reprinted, with permission,

from

reference

23.)

. Vascular Occlusion Duplex sonography is used

routinely

for fo!-

low-up in liven transplantation Hepatic artery thrombosis thrombosis are each seen

10% ofliver (23).

NC

transplant thrombosis

(Fig 12) (22). and portal vein in approximately recipients (Figs 13, 14)

is seen

in approximately

5% ofrecipients initial method intrinsic

to the

duplex

and

problem

U

RadioGraphics

U

Finlay

et a!

the

of conventional

Doppler

technologies

of flow

as the

is the

principal

finding.

In the

portal

is supported

luminal thrombus bus with dynamic

990

limitations

color

of absence

diagnostic nosis

(24). Duplex US is usually used for diagnosis. However,

vein

and by

the

in the

NC,

finding

this

diag-

of echogenic

or visualization of thromCT or MR imaging (Figs 13,

Volume

12

Number

5

a. Figure the

15.

Hepatic transplant anastomosis

infrahepatic

the anastomosis. significant.

Figure portal

There

ANAST

16. vein

=

and normal NC of the NC (arrow).

is no elevation anastomosis,

Hepatic transplant at the anastomosis

mosis demonstrates normal the anastomotic narrowing (approximately vein, RT = right,

1.0 m/sec) TRANS

=

anastomosis. (b) Duplex

of flow velocity,

LONG

=

longitudinal,

and portal vein stenosis. (straight arrow). Doppler

992

U

RadioGrapbic’s

aids

(straight arrow), transplantation.

in identifying

U

Finlay

indicating that RT = right.

the narrowing

(a) Sonogram interrogation

demonstrates of the portal

indicating

stenotic

et a!

lesions,

as

a hemodynamically

increased sampling

significant

colon may

at

is not hemodynamically

vein

antegrade flow (curved arrow). (b) However, waveforms (curved arrow) demonstrate a markedly increased velocity

graphic imaging frequently demonstrates narrowing at the anastomoses of the portal vein and NC, which is usually not hemodynamically significant, as indicated by an absence of elevated velocities through these regions (Fig 15) (26). Colon Doppler sonography frequently

(a) Sonogram demonstrates mild narrowing sonogram demonstrates normal flow through

focal narrowing caudal to the

obtained of portal stenosis.

saturation

is seen;

subsequently

be

of the anasto-

at the level of venous flow PV = portal

velocity

performed

in

these suspicious areas (Fig 16). Hepatic artery stenosis is usually more difficult to demonstrate than portal vein stenosis because of the small size of the vessel. Initial diagnosis is generally made with thorough Doppler sampling in the perianastomotic region, where findings include abruptly elevated velocity, with dampening of the systolic

Volume

12

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Figures

19, 20. (19) Pancreatic transplant artery thrombosis. Transverse color Doppler sonogram shows flow only in the most proximal portion of the artery (white arrow). The remainder of the artery is thrombosed (black arrow) secondary to severe acute rejection.

(Reprinted,

9.) (20)

with

permission,

from

reference

Pancreatic

transplant artery thrombosis. (a) Pancreatic transplant artery flow shows an abnorma! high-resistance waveform with reversal of flow in diastole (arrow) . Pancreatic arterial waveforms were normal 3 days earlier. ART = artery. (b) After another

4 days,

flow is undetectable

plying ANAST

the

graft. Venous anastomosis,

=

atic artery, PANC 1X = right. (Reprinted,

RT ence

in the major

artery

sup-

flow

=

was also unidentifiable. OBL = oblique, PA = pancrepancreatic transplantation,

with

permission,

from

FVV

refer-

22.)

19.

In the

past,

scintigraphy

has

been

the

pri-

means of assessing intrapancreatic flow (29,30) However, numerous false-positive and false-negative findings have been reported. Duplex US evaluation of a normal pancreatic transplant usually demonstrates intrapancreatic arterial and venous flow. However, duplex US diagnosis of graft thrommary

.

bosis

is limited

by dependence

on

one

fea-

tune: Doppler signal void. Increased confidence in this finding is afforded by the setting of serial changes in the arterial waveform, suggesting progressively increasing vascular impedance (Fig 20).

U RFJECTION Recently, there has been investigation into potential for quantification of graft arterial flow as a means of noninvasively demonstrating

acute

studies measure

rejection

Pancreatic

Transplant

eurysms and Pseudoaneurysms also

occur

Arteriovenous and arteniovenous

in association

transplants, within the

either transplant

Diagnostic

criteria

scnibed

PseudoanFistulas

for renal

with

are

similar

transplants.

pancreatic

to those

U

RadioGrapbics

U

Finlay

et a!

and

obstructive

(34-

hydronephnosis

or (1 1). de-

Both retrospective and prospective studies have shown a lack of correlation between loss of arterial diastolic flow and histopathologic evidence of acute rejection in hepatic trans. plants (38). However, quantification of flow within

the

graft

may

cneatic transplants transplants because causes

994

early

index, a flow within

37).

fistulas

at vascular anastomoses itself (Figs 2 1, 22)

Although

the resistive to arterial

the graft, was valuable in diagnosing acute vascular rejection within the renal grafts (3136), it has been subsequently shown that increases in the resistive index can be seen in various other conditions, including acute 1ii bular necrosis, renal vein thrombosis, graft infection, compressive perinephric fluid co!lections,

.

(31-36).

suggested that of impedance

the

of pancreatic

be

more

useful

for

pan-

than for renal or hepatic of the fewer apparent graft dysfunction (39).

Volume

12

Number

5

9.

Letourneau

JG,

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170:557-558. Tobben PJ, ZajkoAB,

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