Masanoni Akira, Kenji Morinaga,

MD MD

#{149} Satoru

Yamamoto, Higashihara,

#{149} Tokuro

Asbestosis: Correlation

(n (n

H

curvilinear

shadows

IGH-RESOLUTION

computed

to-

4),

asbestos-exposed

4),

showed radiographic profusion of 0 or 1, and concluded that subpbeural isolated dotlike or branching structunes connected with the most penipheral branch of the pulmonary amtery are the earliest diagnostic HRCT findings in asbestosis. Yoshimura et al (7) performed HRCT in 19 asbestos-exposed pa-

terms:

Asbestosis,

60.1211

(CT), #{149} Lung,

Radiology

60.773

diseases,

1990:

.

Lung,

who

I From

the

have

been

correlation documented pathologic

CT,

60.773

176:389-394

Departments

Kinki

pan; the partment 1989;

Department of Radiology, revision

reprint RSNA,

Chuo

examined

of Radiology Hospital

(MA.),

Chest

of Radiology, Kansai Osaka University

requested

requests 1990

for

January

to MA.

30,

Pathology

Diseases,

1 180

Rosai Medical 1990;

who

demonstrated

small,

imreg-

The authors suggested that the shadow might be related to early pulmonary fibrosis. Although CT findings in asbestosis

fixed,

National

patients

ular opacities on standard radiographs. They noted a subpleural curvibinear shadow parallel to the inner chest wall in the lungs of 15 of the patients. Radiobogic-pathologic comelation was available for one postmortem lung, and the curvilinear shadow corresponded to penibronchiolar fibrotic thickening with anthracosis, combined with flattening and coblapse of the alveoli due to fibrosis.

Computed

.

high-resolution

tients

Hospital. School,

revision

described,

(S.Y.),

HRCT

air-dried

and

Nagasone-cho,

March

seven

inflated,

postmortem

Medicine Sakai

Amagasaki, Osaka, Japan received

CT-pathologic

has not been extensively (8). To determine the basis for CT findings, we with

and

#{149} Nobuhiko

Kita,

MD

CT-Pathologic

=

tomography

C

MD MD

=

Index

dress

Yokoyama, Kozuka,

#{149} Takahiro

mography (HRCT) findings in asbestosis have been well documented (1-7). Findings include thickened interlobular septal lines and intrabobubar core structures, pamenchymal fibrous bands, honeycomb patterns, and subpleural opacities and curvilinear lines that persist in the prone position (1-3). We previously examined paired senab HRCT scans of 23 occupational

ground-glass appearance traction bronchiectasis (n 4), and honeycombing (n = 2). The thickened intralobular lines were shown histologically to be due to penibronchiolar fibrosis. Thickened interlobular lines were due mainly to interlobular fibrotic thickening in four lungs and edema in three. The peribronchiolar fibrosis was most severe in the subpleural lung regions, creating curvilinear line shadows and pleural-based areas of opacity. Some subpleural fibrosis extended proximally along the bronchovascular sheath to create bandlike lesions. Areas of groundglass appearance on HRCT scans were shown to be the result of mild alveolar wall and interlobular septal thickening due to fibrosis or edema. Postmortem HRCT findings were similar to premortem HRCT findings and correlated well with the pathologic findings of asbestosis.

20,

#{149} Kunihiko

MD

High-Resolution

High-resolution computed tomography (HRCT) was performed in seven inflated and fixed postmortem lungs from seven asbestos-exposed patients with pathologically proved asbestosis. The parenchymal abnormalities seen at in vitro HRCT included thickened intralobular lines (n = 7), thickened interlobular lines (n = 7), pleural-based opacities (n 7), parenchymal fibrous bands (n 5), subpleural

MD

(KY., City,

lung

N.K.,

Osaka

Japan (T.H.); and (T.K.). Received 26; accepted

April

KM.), 591,

Ja-

the DeDecember 19.

specimens from seven asbestos-exposed patients with pathologically proved asbestosis, and correlated

HRCT ing

findings

with

histologic

AND

Seven lungs seven patients The

METHODS

excised at autopsy from with asbestosis were stud-

histologic

criteria

(9) were used bestosis. The specimens right and four left lungs. at

five

death

men

by

described

Craighead

were

the

correspond-

findings.

MATERIALS

ied.

the

to diagnose ascomprised three The subjects

and two women whose from 56 to 77 years

ranged

age

(mean, 67.6 years). Their mean duration of exposure to asbestos was 20.6 years ± 7.8 (range, 10-34 years), and the interval from years

first exposure ± 6.5 (range,

subjects

had

were smokers, smoking for

to death was 20-42 years).

30.9 Three

never

smoked.

one more

of whom had stopped than 1 year at time of

Four

subjects

death. The

lungs

described

Each

were fixed Markarian first distended

by the method and Dailey (10). through a main

by

was

bronchus

with

polyethylene hol, 40%

fixative

fluid

400,

glycol formalin,

and

containing

95% ethyl

plain

portions of 10:5:2:3, fixative for 2 days. then air dried and

and immersed The fixed lung cut into sagittal

or transaxial radiograph

(n

slices of each

with

a fine-grain

kyo)

at 20 kVp

source-film mens

slice

film and

distance were

=

pro-

in the was

(n

5)

A

mAs,

Fuji,

To-

with

of 60 cm. scanned

then

in

2) 0.5 cm thick. was obtained

(Softex;

250

alco-

water

with

scanner (GE Medical Systems, kee), with 1.5-mm-thick sections geted reconstruction (by means volution filter) of the bone-detail

a

The

speci-

a GE

8800

Milwauand tarof a conalgo-

rithm, with a field of view of 16-25 cm, depending on the size of the lung. In vitro HRCT scans were graded by two observers (MA., T.H.), and their consensual grade kind

was recorded. of abnormality

point mal),

scale for + (slight,

25%-50%),

and

The was

severity scored

on

of each a 4-

each lung slice: (nor50%).

AdAbbreviation: puted

HRCT

=

high-resolution

com-

tomographs.

389

a.

b.

d.

e.

Figure had

C.

1.

never

Images

from

smoked.

woman

(a) Chest

who

died

radiograph

f. at the

obtained

age

of 75 years

1 month

before

after

31 years

death

shows

in the

asbestos

diffuse,

small,

textile

industry

irregular

and

opacities

25 years

(coarse

of exposure.

reticular

She

pattern;

profusion, 2/3). This patient also had primary squamous cell carcinoma in the right lower lobe. Postmortem low-kilovoltage radiograph (b) and HRCT scan (c) of the inflated and fixed left lung show honeycombing in the lower two-thirds of the lung. In the subpleunal zones, dotlike lesions (arrowheads), confluence of dots, and a pleural-based, wedge-shaped opacity (arrow) are seen. (d) Magnified view of box in b. Nodular opacities can be seen a few millimeters from the pleural surface and are joined with adjacent nodular opacities and the visceral pleural surface by linear opacities (arrows). (e) Photomicrograph of lung specimen obtained from box I in c. Peribronchiolar nodular fibrosis (arrowheads) is seen along the pleural surface. Part of lesion is attached to the visceral pleura. Arrow indicates the bronchiole (hematoxylineosin stain; original magnification, X2.5). (f) Photomicnograph of lung specimen obtained from box 2 in c. Subpleunal fibrosis and penibronchiolar fibrosis are joined (hematoxylin-eosin stain; original magnification, X2.5).

The

final

scone

normality

the lung

390

calculated

and

multiplication

percentage slice

for each

was

#{149} Radiology

parenchymal by

ab-

assessment

of involvement

in each by

a factor

of

to correct for differences among the slices. Areas

in volumes of low attenua-

tion suggestive of emphysema and bullae were not evaluated. Tissue blocks for his-

tologic

examination

were

basis of the CT images. findings were correlated

the

corresponding

selected In vitro with

histologic

on the

HRCT findings

in

sections.

August

1990

Table 1 Frequency

and Degree

of Parenchymal

Thickened

Thickened

Intralobular

Interlobular

Case

Lines

Abnormalities

on Postmortem .

Pleural-based

.

.

Scans

Curvilinear

Panenchymal

Opacities

Lines

HRCT

of Lungs

with

Bands

Traction

Shadows

Ground-Glass Appearance

Bronchiectasis

Honeycombing

1

++

++

+

+++

+

++

2 3

+++ +++

+++ ++

++ ++

+ +

+ +

-

4 5 6

++ ++ ++-l-

-

+

-

-

-

-

++ +

+

-

-

+ +

+

++

+ ++ +++ +

-

7

++ + + +

-

-

Total

7

7

7

5

4

4

Note.--

not

=

found;

Table 2 HRCT-Pathologic

+

slight,

=

50%.

glass

Sign

+

-

++ ++ +

-

Correlation

HRCT

the

Asbestosis

Subpleural

then

anthracosis,

com-

of the seen

radioon

process of asbestosis penibmonchiolar areas progresses

of

to involve

alveoli, showing the classic of asbestosis (interstitial fi(9).

Asbestosis

is usually

more

severe in the lower subpbeural zones (9). Animal experiments have mdicated that the initial sites of asbestos fiber

deposition

are

the

respiratory

bronchioles and alveolar ducts (11) and that, with time, asbestos fibers tend to concentrate under the pleura (12). that

Our preliminary data the early panenchymal

seen on HRCT isolated dotlike

showed changes

scans are subpleural structures connected

to the most peripheral branch of the pulmonary artery, and that these dots increase in number to create a neticubonodular appearance on serial HRCT scans. In all seven inflated and

Radiology

#{149} 391

a.

b.

e.

d.

Figure 2. Images from man had undergone a right lower 1 month

before

low-kilovoltage

death

fixed postmortem similar subpleurab abnormal

of carcinoma of the stomach at the age of 68 years after 10 years in the asbestos textile industry. He lobectomy due to bronchogenic carcinoma in the right lower lobe 8 years before. (a) Chest radiograph obtained small round opacities (fine nodular pattern; profusion, 1 I 1) as well as small, irregular opacities. Postmortem (b) and HRCT scan (c) of the inflated and fixed left lung show intralobular and interlobular thickenings, suband areas with a ground-glass appearance (box 2). (d) Photomicrograph of lung specimen obtained from box

shows

(arrowheads),

fibrosis of lung specimen obtained stain; original magnification,

in less

who

radiograph

pleural opacities I in c. Subpleural

and penibronchiolar from box 2 in X10).

lungs, dotlike areas

died

fibrosis .

we observed structures

of in vitro

scans, and these dots comesponded to penibronchiolam nodular fibrosis with subsequent involvement of the alveolar ducts histobogically. In all lungs, although penibronchiolar fibrosis was seen from site to site histologically, the penibronchioHRCT

392

C.

#{149} Radiology

The

thickenings

are seen

(hematoxylin-eosin

of interlobular

septa

stain; and

original

alveolar

lam fibrosis in the subpleural portion was of a degree that could be recognized as a dotlike structure at HRCT. Penibronchiolar fibrosis obliterated surrounding alveoli, extending outward from the bronchiole and joining adjacent peribronchiobam fibrosis and the visceral pleura. It was thought that the subpleural dots amranged along the inner chest wall

magnification,

walls

by edema

X2.5). are

seen

(e) Photomicrograph (hematoxylin-eosin

created

a subpleural

shadow.

The confluence dots was thought

pleural

a lamelbar pulmonary

structure

curvilinear

tients malities

subin

of subpbeumal

fibrosis.

We previously observed nab-based wedge-shaped HRCT

of these to result

the pleuopacity on

scans of asbestos-exposed with early parenchymal (6). The same opacities

August

paabnorseen

1990

a.

b.

e.

d.

Figure

3.

Images

radiograph ening

from

obtained

(profusion,

man

fixed

heads).

Subpleural

opacity

(arrows).

who

1 month 3+).

ed and

left lung

(e)

The

died

before night

show

at the

death

shows

intenlobar

diffuse

nodular opacities Photomicrognaph

f. age

pleural

of 56 years

after

a predominantly

fissure

is thickened.

thickening

are also seen (arrows). (d) of lung specimen obtained

on in vitro HRCT scans corresponded to subpbeural pulmonary fibrosis histobogicalby. These opacities were seen in all the lungs, despite differences in degree.

Some

extended

proximally

along the bronchovascular sheath to show bandlike lesions. Parenchymal fibrous bands coursed almost along the bronchovascular sheath or interlobular septa, even though their dinections appeared to be incompatible with those of blood vessels. Some ameas of opacity due to subpleural pul176

#{149} Number

2

monary

42 years

in the

basal

involvement,

Postmortem Magnified from X2.5).

fibrosis

opacities

textile

industry

“shaggy” extending

heart, radiograph

along

and

and (b)

22 years

extensive and

HRCT

the bronchovasculan

of exposure.

(a) Chest

bilateral

pleural thickscan (C) of the inflatsheath (arrow-

view of box in b. The bronchus is seen in the area of increased box 1 in C. Pleural fibrosis and fibrosis along the bronchovascular (f) Photomicnograph of lung specimen obtained from box 2 in

Arrows

were

asbestos

low-kilovoltage

and pleural-based

sheath are seen (hematoxylin-eosin stain; original magnification, Subpleural fibrosis and peribronchiolan nodular fibrosis are joined. nification, X2.5).

Volume

C.

indicate

the

the bronchioles

lamellam

structures lining the pleura surface, which attached to pleural fibrosis to create the thickenings of the axillary pleural line and intembobar area that could be recognized on madiographs. Thickening of the axillamy pleural line was due to pleural thickening or subpleural pulmonary fibrosis or both. Subpleumal pulmonary fibrosis could not easily be differentiated from pleural thickening. Prominent irregularity of the pleural surface

(hematoxylin-eosin

stain;

suggested that the thickening due to subpleural fibrosis. Alveolar walls thickened sis

on edema

and

C.

original

mag-

was by fibmo-

intenbobular

septal

thickenings that were not prominent enough to be recognized as short lines at HRCT, in addition to aeration of alveolar spaces, may have created the ground-glass appearance. Mild thickening of the alveolar walls, especially when lung architecture was preserved, was seen as normab-appeaning lung at HRCT. Radiology

#{149} 393

In the lungs we examined, predeath agonal events may have occurred and modified the pathologic findings. Evidence of interstitial edema seen in case 3 (Table 1) was considered as due to a complicating agonal event. In conclusion, our study of the HRCT-pathobogic correlation in asbestosis showed that HRCT findings correlated well with the pathologic findings of asbestosis and that HRCT is useful

chymal

in the

changes

evaluation

in asbestosis.

2.

3,

1.

aging

1989; 4:61-67.

DR. Gamsu CT of benign

eases:

clinical AJR

#{149} Radiology

CS,

9.

Feuerstein

G, Ray CS.

AC,

Asbestos-related bestosis: diography. 5,

SB,

a comparison AJR 1988;

Lynch DA, Asbestos-related

dis-

can

correla-

Fisher

pleura!

Gamsu

MS,

disease of CT and 150:269-275.

chest

Ray CS, Aberle

G, focal

lung

10.

asra-

DR.

masses:

1 1.

mani-

on conventional and high-resolulion CT scans. Radiology 1988; 169:603-607. Akira M, Yokoyama K, Higashihara I, et festations

6

Early

asbestosis:

evaluation

high-resolution

CT.

Yoshimura

H, Hatakeyama

al.

Pulmonary

curvilinear

Radiology

asbestosis: shadow.

Radiology

(in

press).

M, Otsuji CT

study

H, et of

1986;

158:653-658.

8.

Pathologists

McLoud T. The use of CT in the examination of asbestos-exposed persons. Radiolo-

Markarian

and

proposed

report of the of the College

Pneumocoof Amen-

and

Institute

National

Safety and Health. Med 1982; 106:544-596. B, Dailey

epithelium

phages. 12.

of asbestosand pleural

ET.

for

Arch

Preparation

of in-

flated lung specimens. In: Heitzman ER, ed. The lung: radiologic-pathologic correlations. 2nd ed. St Louis: Mosby, 1984; 4-12. Brody AR, Hill LH, Adkins B, et a!. Chrysotile asbestos inhalation in rats: deposition pattern and reaction of a!veolar

with

criteria

schema: Committee

Occupational Pathol Lab

et al. and

JE. The pathology disease of the lungs

cavities-diagnostic

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Craighead associated grading niosis

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asbestos-related

and radiographic

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Friedman

gy 1988;

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G, Ray

lution tion. 4.

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Gamsu, G, Aberle DR, Lynch D. Computed tomography in the diagnosis of asbestos-related thoracic disease. J Thorac Im-

Gamsu

Aberle

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August

1990