CT Detection

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VICTOR

of Demyelinated

M. HAUGHTON,’

KHANG-CHENG

Plaques HO,2 ALAN

CT images and anatomic slices of two brains containing numerous demyelinated plaques were correlated. Demyelinated plaques smaller than 0.7 cm were not detected by CT. Some larger plaques were misinterpreted as normal structures. These and other considerations suggest that chronic cerebral demyelination cannot be excluded by negative nonenhanced CT scan.

too

the radiologist factors

affect

correlated cadavers

for

resolution,

reviewing

the images.

CT detection

53226.

of Radiology, Address

To determine

reprint

College

requests

2Department

of Pathology, February

1979

Medical

Roentgen

Ray Society

November of Wisconsin

brains

multiple

of

0.

and

were

removed

and

container

or container

filled

with

holder

of

a clinical immediately

physiologic

was extracted

head

ELDEVIK’

Methods with

the brain

the

PETTER

cadavers

polyethylene in

Sclerosis

two

sclerosis

placed

a

saline.

diagnosis placed Air

(12] and the container General

scanner. Consecutive CT sections were parallel to the base of the brain. Technical mm cut thickness, 9.6 sec scan time, 600 radiologists studied the display console and tried to identify the location and size

Electric

CT/T

of in a within

was 8800

made at 5 mm intervals factors included a 5 mA, and 120 Ky. Three and hard copy images, of any low attenuation

abnormality.

The brains were subsequently fixed and sectioned with an electric slicer into 5 mm thick axial sections parallel to the base of the brain. The pathologist then identified the location and size of each demyelinated plaque visible on the surface of the sections and the pathologically identified lesions were correlated with those identified radiographically. To compare these

what we

from

AND

Materials

by

plaques,

in brains

after revision

Medical

AJR 132:213-215,

1979 American

recognized

of demyeiinated

July 25, 1978; accepted

‘Department

©

or not

CT and anatomic findings with multiple sclerosis.

Received Wisconsin

small

L. WILLIAMS,’

The

Computed tomography (CT) demonstrates focal abnormalities in one-third of patients with clinically diagnosed multiple sclerosis [1-11]. in two-thirds of these patients, cerebral demyelinated plaques are either not present, isodense,

in Multiple

two

6, 1978. and

Milwaukee

County

Medical

Complex,

8700

West

Wisconsin

Avenue,

Milwaukee,

to V. M. Haughton.

College

of Wisconsin

and Milwaukee

County

213

Medical

Complex,

Milwaukee,

Wisconsin

53226.

o361-8o3x/79/i322-o213

$0.00

214

HAUGHTON TABLE CT-Detected Lesion

Brain

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TABLE Attenuation

Plaques

Location

Detection

Paraventricular

2.1 xO.7 1.5x0.9

3.0 x 0.8 1.2x0.6

3.2xi.6 2.1 xO.5 1.7x0.6 1 .6 x 1 .1

i.2x0.4 i.2x0.2

.

2 (of 39 lesions): x 0.7 x 0.3 x 0.6

Number

plaques

of

detected

observations

AJR:132,

1979

2

in Brain

No. 1

Attenuation No.

-

February

SD

Area (cm’)

27.2 23.6

2.4 2.8

0.30 0.44

43.8 45.0

3.8 2.6

0.43 0.39

34.8 35.8

2.4 2.4

1.68 1.47

31 lesions):

2.8 x 0.6

Brain 0.6 0.7 1 .4

AL.

1

Demyelinated

Size (cm)

1 (of

ET

radiologists

Epiventricular Paraventricular Subcortical (of

retrospectively

with

three)

who

detected

3 3

Lesion: Area 1

3 2 2 A A A A A A

Area2

Gray matter: Areal Area2 White matter: Areai Area2

3

2 demyelinated

plaques

or

to

(R)

in vivo

imaging,

demyeiinated plaques in the patients with presumed multiple a region-of-interest cursor.

attenuation

cadaver sclerosis

brain were

numbers

images

of the

and

measured

in

with

Results in the first brain, 31 demyeiinated plaques were found (table 1). Five of these plaques, all larger than 1.0 cm, were initially detected by one or more of the radiologists. Six additional lesions 1 .6-3.2 cm in greatest diameter and located immediately adjacent to the ventricle, were detected only after the anatomic specimens and the CT images were compared (fig. 1). The remaining 20 lesions, 0.2-1 .6 cm in greatest diameter, were not detected prospectively or retrospectively. All lesions in this brain were paraventniculan (near the ventricle) or epiventnicuiar coven the ventricle). In the second brain, 39 demyeiinated found on pathologic examination. Only plaques, 0.6-1 .4 cm in greatest in the CT images (table 1). The

diameter,

Fig. 2.-Two white matter, in

were

contrast

coefficients

were

mea-

detected

Fig.

3.-Attenuation

in periventricular

lesions (arrows) measured 16-23 units presumed disseminated sclerosis.

CT-detected abnormalities in multiple sclerosis patients include: (1) nonspecific findings such as atrophy [1, 3, 9]; (2) transient focal contrast-enhancing or lowdensity lesions [2, 5, 6, 8-10]; and (3) chronic low without

attenuation

plaques were three of these

Discussion

lesions

average

sured.

other 36 lesions, all less than 1 cm in diameter, were missed by CT scanning both prospectively and retrospectively. Of the 39 plaques in brain 2, 36 were panaventnicu Ian. Pathologic examination showed the plaques in both brains to be old, except for two plaques that were undergoing organization. The two largest demyeIinated plaques in the first brain had average attenuation numbers of 27.2 and 23.6 units (table 2, fig. 2). A living patient with multiple sclerosis (fig. 3) had plaques measuning 16-25 units. Attenuation of white matter in cadaver brains averaged 35.3 units compared to 32.6 units in the living patient with multiple sclerosis.

attenuation

which

regions of gray matter, two regions of and two regions of demyelinated plaque

enhancement

[3,

5,

11].

The

third

abnormality,

presumably

low

density

in patient

an

with

organized

demyelinated plaque, is the subject of this study. The Resolving capacity of the scanner affects detection of small low-contrast lesions, such as demyelinated

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AJR:132,

February

CT

1979

OF

PLAQUES

IN MULTIPLE

plaques. A 3 mm diameter cylindrical phantom differing by 5 units from the surrounding substance may be detected in a CT/T 8800 tomognaphic slice obtained perpendicular to the cylinder [13]. However, a 3 mm chronic demyelinated plaque differing from cerebral white matter by 5 units is not distinguished in the same scanner. in fact, plaques smaller than 7 mm were not detected in vitro. These undetected demyelinated plaques are probably hypodense (since their pathologic and histologic appearance is identical to the larger hypodense plaques), yet presumably they are not detected by CT because of irregular, rounded margins that result in partial volume averaging. Whether xenon contrast enhancement of cerebral white matter permits more accurate detection of these plaques is under investigation

[14,

15]).

Plaques larger than 7 mm are sometimes disregarded on a CT scan if they simulate normal structures. Paraventnicular plaques in the occipital lobe may simulate occipital horn, and plaques in the corpus callosum may simulate lateral ventricle; confluent paraventnicular iesions may appear as enlargement of the ventricle; subcortical

lesions

may

simulate

sulci

or

fissures,

or

when

detected as an abnormality on CT may suggest infarct rather than a demyelinating process. The study would have been more valuable if the brains had also been scanned when living. However, differences in CT appearance between cadaver and living brains are mainly related to the cortex. The attenuation numbers of cadaver white matter and demyelinated plaques agree well with in vivo measurements by the same scanner and with published data [1 6] We conclude that the minimum size of chronic cerebral demyelinated plaques detectable with the CT techniques we used is 7 mm, and that plaques larger than 7 mm may be missed

computerized transaxial tomograms. Neurology (Minneap) 27:890-891, 1977 3. Gyldensted C: Computer tomography of the brain in multipie sclerosis. A radiologic study of 110 patients with special reference to demonstration of cerebral plaques. Acta Neurol Scand 53 : 386-389, 1976 4. Jacobs L, Kinkel WA: Computerized axial tomography in multiple sclerosis (abstr). Neurology (Minneap) 26:390391,

they

simulate

a normal

bral involvement cannot presumed demyelination, negative.

structure.

be ruled out even though

Therefore,

cere-

in a patient with the CT scan is

1 Cala IA, Mastaglia FL: Computerized axial tomography multiple sclerosis. Lancet 1 :689, 1976 2. Cole M, Ross RH: Plaques of multiple sclerosis seen .

rosis.

Paper

presented

Society

RJ, Rothner

computed

DA, Duchesneau

tomography

at the annual

of North America,

PM,

in multiple

meeting

Chicago,

scle-

of the Radio-

November,

1977

6. Aita JF, Bennett DA, Anderson RE, Ziter F: Cranial appearance of acute multiple sclerosis. Neurology (Minneap) 28: 251-255, 1978 7. Robertson WC, Gomez MR, Reese EF, Okazaki H: Comput-

erized

tomography in demyeiinating disease of the young. (Minneap), 27 : 837-842, 1977 8. Aita JF, Bennett D, Anderson R, Ziter F: Cranial CT appearance of multiple sclerosis. Neurology (Minneap) 28:251Neurology

255, 1978 9. Campbell BA, Pedley TA: Computerized tomography in cerebral diseases of white matter. Neurology (Minneap) 28: 534-544, 1978 1 0. Aita JF: Cranial CT and multiple sclerosis: contrast enhancing lesions (letter). Arch Neurol 35 : 183, 1978 ii. Eyerman DL, Archer CR. Mayer B Jr: Multiple sclerosis in

brain and optic nerves seen by standard and high resolution CT (abstr). Neuroradiology 1 2 : 52, 1976 12. Binder GA, Haughton VM, Ho DC: Computed tomography

13.

of anatomic specimens. 508, 1978 Di Bianca FA, Edelheit

J Comput LS, Eisner

Assist AL, Glover

Tomogr

ida, March

16. Radue

T, DiChiro

G, Brooks

differentiation Tomogr

RA,

in computed

1 :437-442,

EW, Kendall

computed roradiology

GS:

of CT image Symposium Beach, Fior-

1978

14. Haughton V. Harrington G, Schmidt contrast enhancement for computed in multiple sclerosis (abstr). J Comput 1977 Arimitsu

2:506-

GH, Keyes

The contrast-detail-dose diagram as a measure quality. Paper presented at the International and Course on Computed Tomography, Miami

Assist

on

D: Cranial

logical

matter in

MN, Lederman

Norman

15.

REFERENCES

1976

5. Weinstein

.

when

215

SCLEROSIS

Assist Smith

G: Xenon scanning

Tomogr PB:

tomography.

1 :271,

White-gray J Comput

1977

BE: Iodine

tomography 15:153-158,

J, Scanlon tomography

and xenon

(CT) in multiple 1978

enhancement

sclerosis

(MS).

of Neu-

CT detection of demyelinated plaques in multiple sclerosis.

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