Abdominal Mark

S. Peterson, MD #{149}Richard H. Oliver III, MD #{149}William William L. Campbell, MD #{149}John

James

L. Baron,

Miller, K. Sammon,

were

malignant,

only

defects

aid

are

and

for

ualion

hepalic

chyma.

Pittsburgh. April 15; of Pittsburgh

Surgery

From revision

artery

circulation

and

previously

MATERIALS

shown

re-

(M.S.P.,

a recent

J. Zajko, M. Bron,

Albert Klaus

#{149}

#{149}

MD MD

lular carcinoma noma metastases

rhosis

(n

=

(n

without

colorectal

31), =

(n

(n

=

card-

end-stage

16),

malignancy

cholangiocarcinoma

dr-

=

10),

and

2),

pancre-

atic neuroendocrine tumor metastases (n = 1). The median time from CTAP to surgery was 38 days. At our institution, patients with perfusion defects identified with portography are not denied surgery on the basis of portography findings alone. All potential lesions identified with portography

that

if they

were

biopsy. patient

This

would

predude

malignant

limits population.

surgery

are subjected

a selection

bias

to in our

CTAP was performed with incremental dynamic scanning of the liver performed in a caudal-to-cranial direction with 5-mm section

coffimation

and

8- or 10-mm

increments on GE 9800 computed raphy (CT) scanners (GE Medical Milwaukee).

20-25

CT images

seconds

catheter

after

(5-F)

injection

material nostics, New trast

were

superior

obtained

of a trans-

mesenteric mL

table

tomogSystems,

the initiation

of 120-iSO

16-month

period

(Medrad, (Au-

gust 1990 to November

1991) 183 patients

were

at our

referred

for CTAP

institution.

definitive

surgery

(transplan-

39J; segmentectomy, or trisegmentectomy [n [n

lobec20]; and

=

open

surgical

tients

who

dude

patients

R.L.B., G.D.D.,

May 12; accepted

by Balfe (pp 18-19)

METHODS

biopsy

[n

=

1J).

did not undergo awaiting

=

The

123 pa-

surgery

in-

transplantation

and patients who, subsequent to portography, had biopsy-proved unresectable tumor in other hepatic lobes. The 60 patients who underwent definitive surgery included 33 with and 27 without cirrhosis.

received

Presbyterian

AND

Of these 183 patients, 60 (36 men and 24 women; mean age, 55 years) subsequently

University of Pittsburgh RSNA scientific assembly.

PA 15261. C RSNA, 1992 See also the editorial

Radiology

artery

of iopamidol

(Isovue-300; Brunswick,

con-

Squibb DiagNJ). Contrast ma-

terial was injected at a rate of 1.2-1.5 sec with an automated power injector

During

may

of Radiology

Center,

eval-

four

(B.I.C.), the 1991

Medical

radiologic

(3,4). Most hepatic predominantly

Although

Pathologic

and

arterial portograbecome increasingly

defects.

185:149-155

From the Departments

com-

to be the most sensitive imaging technique for the detection of hepalic tumors (5-9), CTAP is often less specific, frequently depicting benign or falsely positive perfusion defects (10,11). We undertook this study to determine whether specific characteristics of perfusion defects detected with CTAP might allow prospective differenliation of benign from malignant

Index terms: Liver, cirrhosis, 761.794 #{149} Liver neoplasms, CT, 761.1212, 761.31, 761.321, 761.33 #{149} Liver neoplasms, diagnosis, 761.31, 761.321, 761.33 #{149} Portography, 761.33, 952.1242

I

(1,2),

are typically depicted with CTAP as parenchymal perfusion defects relalive to normal enhanced liver paren-

tation tomy,

J.K.S.)

liver

preoperative

underwent

1992;

of the

of the liver are perfused

tumors by the

biopsy.

Radiology

advances in surgical of primary and met-

tumors

used

in differentia-

nonspecific

recent treatment

puted tomographic phy (CTAP) has

tion of benign from malignant processes, all other types of perfusion defects quire

D. Dodd III, MD I. Carr, MD, PhD

#{149}

ITH

astalic

(6%) of 68 intermediate-attenuation defects were malignant. Although these characteristics of parenchymal perfusion

Gerald Brian

#{149}

MD MD

Gastrointestinal

Perfusion with CTAP: Correlation’

W

To determine whether characteristics of focal hepatic parenchymal perfusion defects detected with computed tomographic arterial portography (CrAP) correlate with underlying pathologic processes, 245 perfusion defects detected with CTAP in 60 patients who subsequently underwent definitive hepatic surgery were characterized by shape, location within the liver, and relative attenuation value and were prospectively correlated with sectioned pathologic speclinens. Of 177 round perfusion defeds, 102 (58%) were malignant and 75 (42%) were benign. Only one (2%) of 53 peripheral wedge-shaped defects was malignant All 15 peripheral flat defects were benign. Defects in characteristic locations anterior to the porta hepatis (n = 15) and adjacent to the intersegmental fissure (n = 7) were uniformly benign. While 83 (56%) of 147 soft-tissue attenuation defects

MD

J.

Hepatic Parenchymal Defects Detected Imaging-Pathologic

and

Medical

Received May 15. Address

University

in this issue.

Hospital,

diagnoses

included

hepatocel-

A.J.Z.,J.H.O.,

W.J.M.,

K.M.B., W.L.C.,

Center,

Montefiore University Hospital, March 3, 1992; revision requested reprint requests to R.L.B., University Desoto and O’Hara Sts, Pittsburgh,

Pittsburgh).

giography was CTAP. Contrast

mL/

Conventional

an-

not performed before material administered

fore CT scanning

was limited

be-

to 5-10 mL

injected by hand to visualize any aberrant vessels and to facilitate proper catheter placement.

CTAP med

images

for focal

were hepatic

prospectively

exam-

parenchymal

perfu-

sion defects. Segmental, subsegmental, and lobar perfusion defects secondary readily

mors readily

identifiable

were

centrally

excluded

explainable

had five or more lar appearance, ered to have

from analysis (12). When

perfusion

the patient five perfusion

these

characteristics.

used

in consideration

to

located

tu-

as

one

defects

patient

of simi-

was considdefects with

This criterion was of the inherent difficulties in accurately correlating with pathologic specimens excessive numbers of lesions imaged in the same liver and to prevent

one

Abbreviation: phy.

patient

CTAP

(with

=

CT

numerous

arterial

cir-

portogra-

149

rhotic

nodules, cantly biasing was encountered

multiple

for example) from signifithe results. This situation in seven patients with

cirrhotic

nodules

and seven

pa-

tients with multifocal hepatocellular carcinoma. Focal perfusion defects identified at CTAP were characterized by shape, localion within the liver, and relative attenualion value. Perfusion defects were categorized by shape as round, wedge-shaped,

or flat. Wedge-shaped

perfusion

defects

were generally triangular, with one edge extending along the capsular surface of the liver. To be categorized as wedgeshaped, perfusion defects were required on all images to have relatively straight margins that meet at a centrally directed apex (Fig 1). Relative attenuation values of individual perfusion defects were assessed by

means

described

of visual

inspection

as low,

soft-tissue,

and

than

that of adjacent

enhanced

normal liver parenchyma were considered to be of high attenuation (Fig 5). Before surgery, ClAP results were reviewed with the referring surgeon. After surgery, CTAP images were directly correlated with surgical pathology specimens by

one

of the

radiology

present at the time Pathology specimens

transaxial son

plane

of CTAP

pathologic Of the

investigators

of specimen sectioning. were sectioned in a

to allow

perfusion

direct defects

CTAP

perfusion

defects

pathology

specimens. and

An addisubcapsular

perfusion defects that were not resected were included for evaluation. All of the unresected perfusion defects that were

included

in the study

were

evaluated

at

the time of surgery with intraoperative US and surgical palpation and visualization, often combined with intraoperative biopsy. We believed that inclusion of these unresected perfusion defects was important, as several types of benign processes with characteristic appearances at CTAP were seen repeatedly but were not resected and would not otherwise have been included in this study.

RESULTS A total

of 245

perfusion

defects

focal were

parenchymal identified

at

portography

and met criteria for inclusion in our study. Pathology specimens included 222 (91%) of the 245 characterized perfusion defects. Negalive

150

findings

Radiology

#{149}

of intraoperative

image

heads)

shows

perfusion

in a 52-year-old

tal carcinoma.

The round

lion,

defect, normal

defect

hepatic

peripheral

(ar-

vein

was

wedge-shaped

of intermediate liver

colorec-

intraparenchymal

to the middle The

was

with

perfusion

adjacent

perfusion

(arrow-

woman

soft-tissue-attenuation

row)

a peripheral

defect

attenua-

Figure 2. old woman.

tissue.

US

Colorectal CTAP

carcinoma image shows

in a 61-yeara peripheral,

round, low-attenuation perfusion row) in the right lobe of the liver, and

surgical

as proof ripheral,

palpation

were

of benignity predominantly

perfusion tissue not mens.

Perfusion

defects included

be a simple trasonography

accepted

1)

0.4 cm to 12 cm. Of 177

perfusion

defects,

102

(58%)

were found to represent malignancies (Fig 4) (hepatocellular carcinoma [n = 74]; colorectal carcinoma metastases [n = 23]; cholangiocarcinoma [n = 3]; and pancreatic neuroendocrime tumor metastases [n = 2]). Of 75 round perfusion defects of benign pathogenesis, 65 were contained within

the

pathology

specimens.

diagnoses

for benign

Pathologic round

perfusion

rholic

nodules

ul-

focal perfuCTAP were

characterized by shape as round (n = 177 [72%]), wedge-shaped (n = 53 [22%]), or flat (n = 15 [6%

round

at intraoperative

Shape

Two hundred forty-five sion defects detected with

from

(arto

in regions of liver in resected speci-

Defect

diameter

hepatic cyst (US).

defect proved

for 23 (9%) pesubcapsular

Round.-Round perfusion defects were identified both centrally (Fig 1) and peripherally (Fig 2) within all segments of the liver and ranged in

tissue

sectioned

peripheral

CTAP

wedge-shaped

with

in this study, 222 (91%) were by means of correlation with

23 (9%)

1.

::.;-

(Table).

evaluated confirmed tional

Figure

:1

compari-

findings. 245

‘i a metastasis.

were

intermediate, or high. Low-attenuation perfusion defects were of lower attenuation than skeletal muscle (Figs 2, 3). Soft-tissue-attenualion perfusion defects were of attenuation similar to that of skeletal muscle (Fig 1). Intermediate-attenuation perfusion defects were of attenuation greater than that of skeletal muscle, but not quite equal to that of normal enhanced liver tissue (Figs 1, 4). Lesions of attenuation equal to or

greater

;:

defects included cir(n = 40) (Fig 4), normal liver tissue without identifiable pathologic condition (n = 15), cysts (n = 4), hemangiomas (n = 2) (Fig 6), focal nodular hyperplasia (n = 1), focal fibrosis (n = 1), focal fatty change (n = 1), and nonspecific regenerative change with an inflammatory exudate (n = 1). Intraoperalive US confirmed two round defects as hepalic cysts

(Fig 2), and negative findings of intraoperative US and surgical evaluation

Figure

3.

cinoma

CTAP

image

in a 49-year-old

shows

A round,

defect

of low

parenchymal

perfusion

ation

in the medial

(arrow)

cholangiocar-

man.

segment

intraattenu-

of the

liver represents the cholangiocarcinoma. though it is oflow attenuation (similar attenuation of ascitic fluid), the tumor

Alto the is in-

homogeneous.

were

accepted

as proof

eight peripheral perfusion defects.

of benignity

or subcapsular

of

round

Wedge-shaped.-Wedge-shaped perfusion defects were found only in the periphery of all segments of the liver and ranged in maximal length from

0.5 to 8 cm. Of a total of 53 wedgeshaped perfusion defects, 46 were contained within pathology specimens. Pathologic diagnoses included normal liver tissue with no identifiable pathologic condition (n = 33) (Figs 1, 7), focal fibrosis (n = 8) (Fig 8), focal fatty change (n = 3), a cirrhotic nodule (n = 1), and a colon cancer metastasis (n = 1). Negative findings of intraoperative US and surgical evaluation were accepted as proof of benignity

for

seven

peripheral,

October

1992

I Figure 4. (a) (b) pathologic

CT arterial portogram and specimen from a 48-year-old man with cirrhosis and hepatocellular carcinoma. (a) CTAP image shows innumerable round intraparenchymal cirrhotic nodules of intermediate

attenuation

and

the

soft-tissue-

attenuation hepatocellular carcinoma (arrow) adjacent to the inferior vena cava. The flat perfusion defect of soft-tissue attenuation (arrowhead) anterior to the porta hepatis had no corresponding pathologic condition.

(b)

Axial gross demonstrates

.

atocellular

pathologic cirrhotic

specimen nodules and

carcinoma

section the hep-

(arrows).

-

a.

b. Flat-Flat

Hepatic

Parenchymal

Perfusion

Defects

Cirrhotic

Detected

with

CTAP

Patients

Noncirrhotic

Malignant

Shape Round Wedge Flat Attenuation Low Soft-tissue

Normal Liver

Benign

Malignant

cm

found

in the

56 0 0

44

8

46

8

15

8 1

21 4

1 0

4 2

19 8

1 50

3 17

5 18

7

5

1

33

5

24

Intermediate

3

33

10

1

4

17

High

2

0

0

6

0

0

peripheral

1

.4

. #{149}

q

defects were immediately

all located posteriorly, anterior to the porta

.

I ‘

Figures

5, 6.

noma. arterial

(5) CT arterial

portogram

obtained

superior

mesenteric

artery.

(6) CTAP

image

obtained

woman

with

colorectal

of the metastasis was due right hepatic artery arising

pathology

Only defect

with

specimens.

one was

tumor

wedge-shaped found

rounded central the typical sharp 185

associated

in a 54-year-old

woman

could be wedge-shaped the presence

Number

#{149}

this

differentiperfuof a

contour rather apex present 1

other wedge-shaped fects. The rounded was due to a small

noma tal,

(Fig 9). In retrospect,

perfusion defect ated from other sion defects by

Volume

perfusion

to be

than in

with

from the colorectal

metastasis

perfusion decentral contour colorectal cara-

that

wedge-shaped,

produced posttumoral

a disper-

fusion defect. Delayed CT performed with a high dose (60 g) of iodinated contrast material 4 hours after the CTAP examination allowed confirmation of the presence of a small intra-

parenchymal

Perfusion

Defect

were

found

to be

tumor.

tumor

(Fig 9).

Location

immediately anterior to the porta hepalis (n = 15) or adjacent to the intersegmental fissure (n = 7). Anterior to the porta hepatis.-Flat (n = 12) and wedge-shaped (n = 3) perfusion defects identified in a char-

to hepatic

carcinoma. The peripheral, round, low-attenuation perfusion defect (arrow) within the lateral tip of the lateral segment of the left hepatic lobe represents a hemangioma. The peripheral, wedge-shaped, soft-tissue-attenuation perfusion defect anterior to the porta hepatis (arrowheads) was found to be normal liver tissue at intraoperative US and surgical evaluation.

wedge-shaped perfusion defects that were not contained within resected

with

card-

-

#‘kh

in a 68-year-old

High attenuation of the periphery (arrowheads) circulation of contrast material from a replaced

defects

associated

in flat

In the evaluation of perfusion defect locations, we identified two typical locations where perfusion defects were found to be universally benign. These locations were exclusively within the left lobe of the liver, either

6.

5.

perfusion

not contained specimens. No

,

#{231}1i,

q

.

he-

patis. Of 15 flat perfusion defects identified, 10 were contained within resected pathology specimens and were proved to be normal liver tissue (n = 7) or focal fatty change (n = 3). Negative findings of intraoperalive US and surgical evaluation were accepted as proof of benignity for five

f /

always

subcapsular

.



,

.

were

and were identified (Figs 4, 6, 10) or

flat perfusion defects resected pathology t_

perfusion

in length

lateral segments of the left lobe of the liver. Medial-segment flat perfusion

Normal Liver

Benign

1-3

region of the liver only in the medial

Patients

Characteristic

of Perfusion Defect

or elongated

defects

acterislic location in the posterior peripheral aspect of the medial segment, immediately anterior to the porta hepatis, were always benign (Figs 4, 6, 10), as mentioned above. All six flat defects contained within resected pathology specimens were found to be normal liver tissue. Of two wedgeshaped

perfusion

defects

included

within resected specimens, one was found to be focal fatty change and one represented normal liver tissue. For six flat defects and one wedge defect not contained within resected Radiology

151

#{149}

specimens,

negative

findings

of intra-

brosis

one round, one the anteromedial

fects sected

segment,

were

contained

matory

US and

surgical

were accepted two perfusion

eral

segments

sentative

were

of focal

found fatty

exudate

that were surgical

53 were nodules

benign, (n

Defect

of

Two one !at-

to be repre-

change.

(Table

focal perfuCTAP were

1).

Low attenuation-A total of 22 lowattenuation perfusion defects were identified. Of 20 low-attenuation perfusion defects contained in resected

pathology sented noma

specimens,

eight

repre-

tumor [n =

(hepatocel!ular carci41; colorecta! carcinoma metastases [n = 3]; and cholangiocarcinoma [n = 1] [Fig 3]) and 12 represented benign processes (normal liver

without lion [n

identifiable =

giomas

pathologic

=

perfusion contained pathology

de-

of high

with

and

catheter. without

Cirrhosis

Of the patients included in our study, 23 of 31 with hepatocellular carcinoma had underlying cirrhosis and 10 additional patients had endstage cirrhosis without complicating hepatoce!lular carcinoma. Al! 33 of these patients with cirrhosis underwent transplantation; thus all 142 perfusion defects identified on their CTAP studies were correlated with

of

T

or foci of

high attenuation within defects of predominantly

tissue-,

angiographic

le-

hepatic

attenuation

12). Peenhance-

when a replaced right hepatic was directly perfused with iocontrast material from a mal-

specimens.

attenuation-Focal

(1) (Fig

of colorectal carcinoma metasta= 3) (Fig 5) also occurred in one

Patients

representing cirrhotic 29) (Fig 4), norma! liver

resected

examination high-attenuation

positioned

within respecimens,

were accepted as proof of benignity 1 1 intermediate-attenuation perfusion defects that were not contained

sions

characterized from relative attenualion as low (n = 22 [9%]), soft-tissue (n = 147 [60%]), intermediate (n = 68 [28%]), or high attenuation (n = 8 [3%])

ses (n patient artery dinated

cellular carcinomas and a colorectal carcinoma metastasis) were of intermediate attenuation. Negative intraoperative US and surgical evaluation

High

Attenuation

Two hundred forty-five sion defects detected with

ment

tissue (n = 16), focal fatty change (n = 4), focal fibrosis (n = 3) (Fig 8), and focal nodular hyperplasia (n = 1). Four resected tumors (three hepato-

within Perfusion

of nonspecific with an inflam(n = 1). Negative US and surgical eva!-

termediate-attenualion

evaluation

resected. round, resected

CTAP ripheral

uation were accepted as proof of benignity for 10 soft-tissue--attenuation perfusion defects that were not contamed in resected specimens. Intermediate attenuation-Of 57 in-

within

as proof of benignity defects in the medial

segment that were not perfusion defects (one wedge-shaped) within

fi-

an area change

intraoperative

resected pathology specimens and were representative of focal fatty change (Fig 11) or normal liver tissue (Fig 9). Negative findings of intraoperative

(n

(n = 3), and regenerative

flat) identified within aspect of the medial

three

nodules (n = 12), focal = 6), focal fatty change

cirrhotic

operative US and surgical evaluation were accepted as proof of benignity. Adjacent to the intersegmentalfissure-Wedge-shaped (n = 4), flat (n = 1), and round (n = 2) perfusion defects identified immediately adjacent to the intersegmental fissure within the medial (n = 5) and lateral (n = 2) segments of the liver were a!ways benign (Figs 9, 11). Of five perfusion defects (three wedge-shaped,

perfusion low-, soft-

or intermediate-attenuation

were

encountered

(eight

lesions)

ciated

with

in six patients

and

were

always

malignancies.

The

assohigh

attenuation was due to calcification within colorectal carcinoma metastases (n = 2), to previously administered

Lipiodol

(iodized sous-Bois,

contrast

material Figure year-old

oil; Andre France)

Guerbet, Aulnaywithin hepatocellular carcinomas (n = 2), or to enhancement of a malignancy from recircu!alion of iodinated contrast material

when

imaging

late

7.

CTAP woman

image obtained with colorectal

The peripheral,

soft-tissue-attenuation,

wedge-shaped perfusion defect within the medial aspect of the the right hepatic lobe represented liver at pathologic examination.

in the

in a 61carcinoma. (arrow) inferior tip of normal

condi-

6], cysts [n = 41, and hemanEn = 2] [Fig 6]). Two low-at-

tenuation perfusion defects that were not contained in resected pathology specimens

were

intraoperative

proved

to be

cysts

at

US (Fig 2).

Soft-tissue

attenuation-So

ft-tissue

attenuation was identified in 147 focal perfusion defects. Of 137 perfusion defects contained in resected patho!ogy specimens, 83 represented malignancies (hepatocellular carcinoma [n = 65] [Fig 4]; colorecta! carcinoma metastases [n = 14] [Fig 1]; cholangiocarcinoma [n = 2]; and pancreatic

neuroendocrine [n = 21). Benign for 54 perfusion contained included

152

tumor defects

in resected norma! liver

Radiology

#{149}

metastases

processes

accounted

that

Figure year-old merable fibrosis

and =

a.

eral,

were

specimens tissue (n

.

32),

...‘

S

#{149} S

#{149}

b. 8.

(a) CT arterial portogram and (b) corresponding pathologic specimen from a 49woman with cirrhosis and hepatocellular carcinoma. (a) CTAP image shows innuintraparenchymal, round, soft-tissue-attenuation cirrhotic nodules and two periph-

wedge-shaped, at pathologic

strates the cirrhotic ond area of fibrosis

soft-tissue-attenuation examination.

nodules present

perfusion

defects

(b) Axial section from gross two peripheral wedge-shaped

and in pathology

specimen

was

excluded

(arrows) pathology

that

represented

specimen

focal demon-

areas of fibrosis (arrow) from the photograph).

(sec-

October1992

resected cirrhotic

pathology patient

specimens. population,

intraoperative

In our 56(52%)

ation.

of 108 round perfusion defects were found to represent malignant lesions and 52 (48%) were benign processes.

46 (67%)

Of 85 perfusion defects with soft-tissue attenuation, 50 (59%) were malignancies. In contrast, of 46 intermedi-

tastases

ate-attenuation only three

patients 103

without

defects studies

cirrhosis.

perfusion

defects,

proved

benign

by

means

de-

con-

and

of negative

defects, tumor sis).

only one (co!orectal

me-

DISCUSSION

23];

=

Of 62 perfusion

(5%) represented carcinoma metasta-

ma-

While

CTAP

has

been

shown

to be

the most sensitive imaging technique for the detection of hepatic tumors (5-9), perfusion defects detected with

defects

of

soft-tissue attenuation, 33 (53%) were tumors (colorectal carcinoma metastases [n = 14]; hepatocellular carcinoma [n = 15]; cho!angiocarcinoma [n = 2]; and pancreatic neuroendocrine tumor metastases [n = 21). Conversely, of 22 intermediate-attenuation perfusion

of 27

tamed within resected specimens 23 were accepted as having been

perfusion

hepatocellular carcinoma [n = 18J; cholangiocarcinoma [n = 3]; and pancreatic neuroendocrine tumor metastases [n = 2]), and 23 (33%) were benign

Of these

80 were

evalu-

population,

found to represent (colorectal carcinoma [n

processes.

malignant lesions. A total of 103 perfusion were identified on CTAP

surgical

noncirrhotic

of 69 round

fects were lignancies

perfusion defects, were secondary to

(7%)

US and

In this

CTAP

are

(10,11). ever,

not

This that

specific

study

there

for

has are

tumor

shown,

specific

howcharacter-

istics of certain perfusion defects detected with CTAP that allow more accurate interpretation of CTAP results. Perfusion

defects

related

to malig-

nant lesions ranged in diameter from 3 mm to more than 10 cm. Malignant lesions were identified in both the central and peripheral regions of a!! segments

of the

always round. fects, however, malignancies, occupying

were

nearly

Round perfusion are not specific as any spherical

liver

defor space-

process

round shape hemangiomas, nodular

and

can

assume

on CTAP cirrhotic

hyperplasia,

change

were

a

images. Cysts, nodules, focal and

all causes

focal

fatty

of round

per-

fusion defects and illustrate the specificity of the round perfusion

a.

b.

peripheral,

9.

Colorectal carcinoma metastasis in a 62-year-old wedge-shaped, soft-tissue-attenuation perfusion

the posterior is rounded

aspect of the medial (arrowhead), secondary

Figure

the pathology arrow)

specimen.

adjacent

segment

segment of the left to a 1-cm metastasis

The round,

to the

intersegmental

of the left hepatic

lobe

peripheral,

(a) CTAP image shows a (solid black arrow) within

hepatic lobe. The anterior found at surgery and

soft-tissue-attenuation

fissure

represented

woman. defect

within

the

normal

liver

wedge confirmed

perfusion

anteromedial

aspect

at pathologic

margin in

defect of the

(open

medial

evaluation.

The small,

round, peripheral, soft-tissue-attenuation perfusion defect (white arrow) in the posterior aspect of the lateral segment was a metastasis. (b) Delayed CT image obtained with a high dose (60 g) of iodinated contrast material 4 hours after CTAP shows a round lesion of decreased attenuation (arrow) within the posterior aspect of the medial segment. It corresponds to the

location sion

of the metastasis

defect

identified

confirmed

adjacent

to the

at pathologic

examination.

intersegmental

fissure

The region is isoattenuated

of the CTAP to normal

perfuliver.

fect. Normal liver also be associated sion defects. The identified in our

attenuation pected

perfusion at intraoperative

woman

defect US and

Volume

segments

185

represented

Number

#{149}

metastases.

I

hemangiomas were of low

dal vascular perfused cu!ation.

tumors

channels

be ex-

with

sinusoi-

preferentially

by the hepatic artery Cysts may potentially

discriminated

from

cirbe

low-attenuation

tumors by recognition of the homogeneous low attenuation of the cyst fluid, as compared with the slight in-

homogeneity Wedge-shaped

of low-attenuation perfusion

tumors. defects

were

peripheral

were

always

and

uniformly benign. The one of a peripheral wedge-shaped

in-

defect found peripheral co!orecta! carcinoma

to a small metastasis (Fig

represented a variant enon of a peripheral secondary to central

of the phenomperfusion defect tumor tissue. Al-

some defects

peripheral wedgewere associated

9)

with

with

colorectal

focal fibrosis (Fig 8) or fatty change at pathologic examination, in most instances either normal or cirrhotic liver parenchyma without focal abnormal-

(arrow)

immedi-

ity

surgical

evalua-

lion. (11) CT arterial portogram obtained in a 60-year-old man with colorectal carcinoma. The peripheral, round, soft-tissue-attenuation perfusion defect (arrowhead) adjacent to the intersegmental fissure within the medial segment of the left hepatic lobe represented focal fatty change. The round, soft-tissue-attenuation perfusion defects (arrows) within the anterior and lateral

can perfu-

(Fig 6), as might

though shaped

in a 52-year-old

two study

of benign

nearly stance

Figures 10, 11. (10) CT arterial portogram obtained carcinoma. The peripheral, flat, intermediate-attenuation ately anterior to the porta hepatis was normal liver

parenchyma with round

nonde-

was

tion.

The

ripheral

represent tam. We represent

found

at pathologic

pathogenesis perfusion

normal hypothesize

variations

examina-

of these defects

liver

pe-

found

tissue that

in the

to

is uncerthey

may

normal

Radiology

#{149} 153

portal perfusion of the microvasculature of the peripheral subcapsular liver parenchyma. When using the wedge shape of a perfusion defect as a criterion of benignity, one must be certain that the perfusion defect is wedge-shaped on all images, for superior or inferior margins of large round tumors may appear wedgeshaped on single images due to associated

posttumoral

perfusion

Radiology

#{149}

!:‘

‘!

defects.

We have observed that peripheral, flat or wedge-shaped perfusion defects are nearly always benign. In addilion, peripheral perfusion defects in two characteristic locations in the left lobe of the liver were, in our series, always benign. A possible coincidental neop!asm in either location, however, is theoretically possible. One of these characteristic locations is adjacent to the intersegmental fissure (Figs 9, 11), typically within the anteromedial aspect of the media! segment. This is a recognized location of occurrence of focal fatty change (13). A second characteristic location of benign perfusion defects is within the posterior, peripheral aspect of the media! segment of the liver, immediately anterior to the porta hepatis (Figs 4,6, 10). A benign perfusion defect in this location was recently reported to have been found in seven of 50(14%) patients who underwent CTAP examination (11). This region of the medial segment is known to be focally spared from fatty change (14-16). We support the hypothesis suggested by Fernandez and Bernardino (11) that this region of the medial segment of the liver may receive collateral circulalion. Since CTAP directly reflects portal perfusion, benign perfusion defects unrelated to tumor may well reflect normal variations in the portal perfusion of the liver microvasculature. In support of this hypothesis, in several patients with complete portal vein thrombosis and only collateral portal venous circulation to the liver seen at CTAP, we observed the phenomenon of marked enhancement of this region of the medial segment (Fig 13), confirming the collateral circulalion to this region. Cirrhotic nodules pose a particular problem in the radiologic assessment of the patient with cirrhosis and at risk for hepatocellular carcinoma. Although cirrhotic nodules were found to be of both soft-tissue and intermediate attenuation, most intermediateattenuation defects were found to be benign. This information may be helpful in differentiating most intermediate-attenuation perfusion defects in cirrhotic patients from the more 154

S

.‘-.

\LMk 13.

12. Figures

12, 13.

woman.

CTAP

(12) High-attenuation image shows high

to contrast enhancement of the examination. The

tamed

in a 60-year-old

from aorta

man

colorectal

attenuation

systemic is opacified

with

carcinoma

circulation by contrast

cirrhosis,

hepatocellular

show

(arrow),

immediately

anterior

to the porta

lesions may be explained by a previous report describing preferential

fusion

carcinoma,

and

due

the late portogram

portal

vein

phase ob-

throm-

portal vein (P) and the periportal colthroughout the porta hepatis. Marked in the posterior aspect of the medial

hepatis,

perfusion of cirrhotic nodules preferential hepalic artery perof hepatocellular carcinomas

may

the only

region

of the liver

to

islics

Tumors of high attenuation are generally not problematic. Small calcifications related to round perfusion defects should be considered suspicious for malignancy, particularly in colorectal carcinoma patients. When scanning is prolonged, resultant hepatic arterial circulation of contrast material may allow peripheral enhancement of malignancies (Fig 12). This phenomenon may occur late in the CTAP examination, after enough time has elapsed to allow systemic circulation of contrast material. This process may be most evident in pa-

sion

with

large

livers

that

require

longer scanning times. Systemic circulation of contrast material may also allow enhancing lesions to become isointense with adjacent liver parenchyma. This phenomenon has been observed as a cause of a false-negative CTAP result in a patient with fatty infiltration of the liver (18). With the advent of faster scanners capable of scanning an entire liver in 30 seconds, enhancement of malignancies from late systemic circulation of contrast material will become less of a problem. Periphera! enhancement of malignancies

also

be

observed

when

contrast

material perfuses the liver via a replaced right hepatic artery (Fig 5). The patient population of our study included both cirrhotic and noncirrhotic patients with and without severa! types of tumor. As no significant differences were identified between these subpopulalions in the character-

(17).

tients

of the metastasis

material during (13) CT arterial

enhancement.

common soft-tissue attenuation of hepatocellular carcinomas (Fig 4). These relative differences in attenualion between benign and malignant

portal versus

in a 60-year-old

(arrows)

of contrast material.

bosis. Note the lack of enhancement of the thrombosed lateral circulation appearing as small enhancing vessels contrast enhancement of the liver parenchyma is noted

segment

metastasis

of the periphery

of malignant

and

benign

perfu-

defects, we believe that our resu!ts are app!icable to interpretation of CTAP studies in most patients, irrespective of the underlying pathologic condition of the liver. In conclusion, we have shown that recognition of certain characteristics of focal perfusion defect appearances and locations can aid in differenlialing malignant from benign processes

detected

with

CTAP.

To be

spe-

cific, peripheral wedge-shaped and flat perfusion defects were rarely due to tumor. Perfusion defects in two characteristic locations within the left lobe of the liver were, in our series, always benign. High-attenuation lesions were, in our series, always malignant. Of 245 perfusion defects in our patient population, 76 (31%) were included in these categories that could be classified as benign or malignant with high probability. Intermediate-attenuation perfusion defects, of attenuation approaching that of norma! enhanced liver, were uncommonly due to tumor. Perfusion defects

with

other

features

do

not

allow

differentiation of benign from malignant processes and require biopsy for accurate characterization. U October

1992

examination

References 1.

Hughes

al.

2.

3.

4.

KS, Simon

Resection

R, Songhorabodi

of the liver for colorectal

carcinoma metastases: a multi-institutional study of indications for resection. Surgery 1988; 103:278-288. Hughes KS, Rosenstein RB, Songhorabodi 5, et al. Resection of the liver for colorectal carcinoma metastases: a multi-institutional study of long-term survivors. Dis Colon Rectum 1988; 31:1-4. Sugarbaker PH, Nelson RC, Murray DR,

Chezmar JL, Bernardino ME. A segmental approach to computerized tomographic portography for hepatic resection. Surg Gynecol Obstet 1990; 171:189-195. Nelson RC, Chezmar JL, Sugarbaker PH, Murray DR. Bernardino ME. Preoperative localization

of focal

liver

lesions

Matsui

0, Kadoya

M, Suzuki

M, et al.

8.

Matsui

Dynamic arterial

Volume

0, Takashima

T, Kadoya

computed

tomography

portography:

185

#{149} Number

the

1

most

M, et al.

during sensitive

carci-

1985;

13.

9:19-

Nelson RC, Chezrnar JL, Sugarbaker PH, Bernardino ME. Hepatic tumors: comparison of CT during arterial portography, delayed CT, and MR imaging for preoperative evaluation. Radiology 1989; 172:27-34. Heiken

JP, Weyman

tection

of focal hepatic

PJ, Lee JKT,

et al.

masses:

prospective

14.

9.

10.

11.

12.

diology 1989; 171:47-51. Matsui 0, Takashima T, Kadoya M, et aL Liver metastases from colorectal cancers: detection with CT during arterial portography. Radiology 1987; 165:65-69. Miller DL, Simmons JT, Chang R, et al. Hepatic metastasis detection: comparison of three CT contrast enhancement methods. Radiology 1987; 165:785-790. Fernandez MdP, Bernardino ME. Hepatic pseudolesion: appearance of focal low attenuation in the medial segment of the left lobe at CT arterial portography. Radiology 1991; 181:809-812. Tyrrel Straight

RT, Kaufman line sign:

SL, Bernardino appearance and

cance during CT portography. 1989; 173:635-637.

ME. signifi-

J, Matsui 0, Takashima T, et al. Focal fatty change of the liver adjacent to the falciform ligament: CT and sonographic findings in five surgically confirmed cases. AJR 1987; 149:491-494. Sauerbrei EE, Lopez M. Pseudotumor of the quadrate lobe in hepatic sonography: a Yoshikawa

sign of generalized 1986; 147:923-927.

De15.

evaluation with CT, delayed CT, CT during arterial portography, and MR imaging. Ra-

Work in progress: dynamic sequential cornputed tomography during arterial portography in the detection of hepatic neoplasms. Radiology 1983; 146:721-727. 6.

for small hepatocellular Assist Tomogr

Comput

24. 7.

to specific

liver segments: utility of CT during arterial portography. Radiology 1990; 176:89-94. 5.

nornas.J

S, et

16.

fatty

infiltration.

AJR

White EM, Simeone JF, Mueller PR, Grant EG, Choyke PL, Zeman RK. Focal penportal sparing in hepatic fatty infiltration: a cause of hepatic pseudomass on US. Radiology 1987; 162:57-59. Arai K, Matsui 0, Takashima T, Ida M, Nishida Y. Focal spared areas in fatty liver caused by regional decreased portal flow. AJR 1988; 151:300-302.

17.

Matsui

18.

Benign and malignant nodules in cirrhotic livers: distinction based on blood supply. Radiology 1991; 178:493-497. Llaugerj, Perez C, Coscojuela P. Sanchis E, Traid C. Hepatic metastases: false-negative CT portography in cases of fatty infiltration. J Comput Assist Tomogr 1991; 15:

0, Kadoya

M, Kameyama

T, et al.

320-322.

Radiology

Radiology

#{149} 155

Hepatic parenchymal perfusion defects detected with CTAP: imaging-pathologic correlation.

To determine whether characteristics of focal hepatic parenchymal perfusion defects detected with computed tomographic arterial portography (CTAP) cor...
2MB Sizes 0 Downloads 0 Views