Computed

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MELVYN

Tomography KOROBK1N,”2

in the Diagnosis

of Adrenal

ERIC A. WHITE,’ HERBERT Y. KRESSEL,”3 AND JEAN-PHILL1PE MONTAGNE”4

Disease

ALBERT

A. MOSS,’

A series of 63 patients with suspected adrenal disease was evaluated by computed tomography (CT). In 15 additional patients CT diagnosed unsuspected adrenal disease. The CT results were correlated with surgical, postmortem, or compelling clinical data. In those patients with adequate visualization of both adrenals, CT correctly identified all adrenal masses subsequently proven at surgery or postmortem examination. CT accurately predicted the presence or absence of a unilateral adrenal neoplasm in patients with Cushing’s syndrome and primary aldosteronism. Unsuspected primary or metastatic neoplasms of the adrenals were occasionally detected in patients scanned for other reasons. CT is a safe and accurate method of evaluating patients with suspected adrenal disease.

the EMI 5000 or a production model of the EMI 5005 (both with an 18 sec scan time, 13 mm slice thickness, and 160 x 160 matrix) or a prototype or production model of the GE CT/T body scanner (4.8 sec scan time, 10 mm slice thickness, and 320 x 320 matrix). in patients scanned for suspected adrenal disease, contiguous slices were obtained at 1 cm intervals through the expected region of both adrenals [3]. Patients studied for suspected disease in other organs had scans obtained at 1 or 2 cm intervals. An adrenal gland was interpreted as normal if it met the previously described size and shape criteria [3]. An occasional gland was interpreted as abnormally enlarged if it appeared disproportionately thickened relative to the surrounding organs and tissues, even if it did not clearly exceed the upper size limit sometimes seen in normal patients. The size of an adrenal mass

initial reports describing application of computed tomography (CT) in extracranial portions of the body did not emphasize its major role in evaluating adrenal disease. Subsequent reports [1 2] described the CT findings in a small number of patients with adrenal masses, but a comprehensive report of the CT findings in patients with known or suspected adrenal disease is not yet available. We [3] and others [4] recently described the CT appearance of the normal adrenal glands (fig. 1). Reported here are CT findings in 78 consecutive patients being evaluated for known or suspected adrenal disease, or in whom unsuspected adrenal abnormalities were discovered while being scanned for other reasons.

was determined

,

Materials From

June

1976 to June

and 1978,

by measuring

its major

and minor

axes on the

slice in which it appeared largest, and estimating its cephalocaudal dimension by observing the number of contiguous slices on which it was visible. However, in tabulating the results for this

report,

we

have

listed

only

the

maximum

diameter

for

each

adrenal mass. Size of the normal and abnormal gland was determined by correcting measurements made on the hard copy recording medium routinely used to true size by multiplying by the minification factor determined for each scanner and its recording device. Most patients ingested 480-720 ml of a 2%-3% solution of sodium diatrizoate to allow identification of bowel loops. Most patients

were

Occasionally, especially

scanned

without

the

was

scan

if a paucity

identify

the

inferior

difficult

to distinguish

of

intravenous

repeated

after

retroperitoneal

cava

vena from

the

fat

or if the adjacent

contrast

material.

contrast

injection,

made

it difficult

adrenal vessels

to

glands

were

upper

pole

or

of the kidneys.

Methods 63 patients

were

referred

for

Results

CT scanning of the adrenal glands because clinical evidence suggested adrenal disease. The suspected clinical disorder, the results of CT evaluation, and the final clinical diagnosis for each patient are reported. An additional 15 patients are included in whom an abnormality was discovered in one or both adrenal glands, although the CT examination had been requested for suspected disease in other organs. We made no attempt to determine how many patients with suspected or subsequently proven adrenal disease during the same period were not referred for CT evaluation. Moreover, we did not systematically evaluate how many patients undergoing upper abdominal CT evaluation for other reasons had adrenal disease that was not detected by CT. All CT scans were performed on either a prototype model of

Most

patients

referred

for

CT evaluation

of the

adrenal

glands had strong clinical suspicion of Cushing’s syndrome, pheochromocytoma, on primary aldosteronism (table 1). A small number were scanned for several other adrenal diseases (grouped here under miscellaneous adrenal disorders). Because some patients were scanned only with and others

only

material,

we

without did

intravenous not

attempt

injection to define

attenuation values for each type out intravenous contrast material, from

values

similar

to adjacent

of the

contrast

spectrum

of adrenal lesion. adrenal masses liver

to values

of

Withvaried

similar

to

Received July 14, 1978.; accepted after revision November 9, 1978. M. Korobkin was recipient of National Institutes of Health Research Career Development Award GM 00055 from the National Institute of General Medical Sciences. Work by E. A. White was supported in part by National Institutes of Health Training Grant GM 01272 from the National Institute of General Medical Sciences. ‘ Department of Radiology, M-380, University of California School of Medicine, San Francisco, California 94143. Address reprint requests to A. A. Moss. 2 3 4

Present address: Present address: Present address:

AJR 132:231-238, © 1979 American

Department

of Radiology,

Duke University

Department

of Radiology,

University

Radiologie,

H#{243}pital Rousseau,

February Roentgen

1979 Ray Society

Medical

Hospital,

Center,

University

Durham,

North Carolina

of Pennsylvania,

Philadelphia,

27710. Pennsylvania

19174.

75012, Paris, France.

231

0361-8o3x/79/1322-o231

$0.00

232

KOROBKIN

ET AL.

February

AJA:132,

TABLE Final

1979

2

Diagnoses cT Findings

Final

Diagnoses and No. Grouped Referring Diagnosis

by Unilateral

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Mass

Normal

Cushing’s Adrenal

syndrome adenoma

(19): (2)

2

.

.

.

.

.

Adrenal

carcinoma

(1)

1

.

.

.

.

.

.

.

.

3*

Bilateral hyperplasia* (3) Pituitary adenoma* (10) After bilateral adrenalectomy

Fig.

1 -Normal

Cushing’s inferior

adrenal

syndrome. vena

diaphragm. anteromedial

cava

(v)

glands

in

patient

Curvilinear

right

adrenal

between

right

lobe

with

(black of

ACTH-dependent

arrow)

liver

and

Left adrenal (white arrow) has inverted to upper pole of left kidney (k).

posterior right crus

“Y”

to of

6

(2) lndeterminate(i) Suspected pheochromocytoma (10): Adrenal pheochromocytoma (4) Bilateral adrenal pheochromocytoma(i) Extra-adrenal pheochromocytoma(1) No pheochromocytoma (4)

Suspected

appearance

primary

1$

adrenal

Indication

Suspected adrenal Cushing’ssyndrome

No. Patients

disease: 19

Pheochromocytoma Primary aldosteronism Miscellaneous adrenal

disorders

Other indications Total

(5)

10 24 10

Adrenal

pheochromocytoma

15 78

(1) Pancreatic

tail neoplasm

Indeterminate .

Bilateral

diffuse

Bilateral

diffuse

.

.

.

.

.

.

lii

.

.

.

.

.

.

.

4

.

.

.

.

.

.

.

1**

.

.

.

211**

7 2

(1)

(1)

.

.

1

1

4 211 1

.

.

.

.

.

2

.

.

.

.

.

.

.

Stt

.

.

.

.

.

1

.

.

.

.

.

1

.

.

.

.

.

1ff

.

.

.

.

.

.

enlargement.

enlargement (3); diffuse bilateral in each gland (1). t In expected position of adrenal. § Neither gland identified. I Only one gland identified. # Tumor site correctly identified in bladder dome. ‘. Neither gland visualized. tt Bilateral masses. U Suspected myelolipoma.

enlargement

with

single

or less than water. Pheochnomocytomas and metastases, especially after intravenous contrast nial, often had a mottled appearance apparently senting zones of hemorrhage or necrosis. Cushing’s

.

4

4

t

1

.

adenoma

Indeterminate (4) Unsuspected adrenal disease (15): Unilateral metastasis (4) Bilateral metastasis (7) Adrenaladenoma(1)

for CT

.

1# 4

(6)

Indications

.

1

Adrenal hyperplasia (7) Essential hypertension (2)

1

4t

hyperaldos-

teronism (24): Proven adrenal adenoma

Suspected TABLE

Other

Glands

nodule

adrenal materepre-

Syndrome

A unilateral adrenal mass (fig. 2) was identified by CT in three patients from this group (table 2). At surgery two had an adrenal adenoma and the other an adrenal carcinoma. Two of the patients had a normal-appearing contralatenal adrenal gland; in the other, the contralateral gland could not be identified. Six

Fig.

2.-Cushing’s

cm left adrenal

syndrome

mass

(arrow)

with

adenoma

anteromedial

of

left

adrenal

to left kidney (k).

gland;

3

patients

had

diffuse

enlargement

of

both

glands, but the normal shape and configuration adrenals were preserved (fig. 3). In an additional with bilaterally enlarged adrenals, a single smaller than 1 cm was superimposed on each

adrenal

of the patient nodule gland.

AJR:132,

February

CT

1979

OF

ADRENAL

DISEASE

Final

clinical

izing

syndrome

sia. Two

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233

for

the

secondary

patients

bilateral visualized left

diagnosis

had

recurrent

gland,

patient

but

mass

right

viril-

hyperpla-

syndrome

one, neither CT showed

a 1 cm

expected position of the fused further surgery.

was

adrenal

Cushing’s

adrenalectomy. in by CT. In the other,

adrenal

seventh

to bilateral

after

adrenal absence

was

adrenal;

was of the

found

this

in

the

patient

re-

Pheochromocytoma In five

patients,

CT identified

a unilateral

adrenal

mass

(fig. 4) with normal contralateral gland; in each case, an adrenal pheochromocytoma was surgically removed, with complete resolution of the patient’s hypertension. In the patient with bilateral adrenal pheochromocytomas, a right adrenal mass was seen on CT, but the left gland was not clearly identified. One patient with normal adrenal

Four of the six patients had surgical, autopsy, or compelling clinical evidence of bilateral adrenal hyperplasia secondary to a pituitary adenoma; one had a final clinical diagnosis of adrenogenitai syndrome with bilateral adrenal hyperplasia. Length, width, and thickness of each resected adrenal gland in the patient undergoing bilateral adrenalectomy were virtually identical to those predicted from the CT scan. In seven of the patients both adrenal glands appeared normal on CT examination. In six of these a final clinical diagnosis of bilateral adrenal hyperpiasia secondary to tumor or other abnormality of the pituitary gland was made; one had surgical resection of a pituitary adenoma, three underwent pituitary irradiation, and the other two had compelling clinical evidence of a pituitary lesion but have not yet received therapy. The four patients who underwent pituirary ablation had clinical evidence of regression of their Cushing’s syndrome after therapy.

perfusion

specimen.

(arrow)

evident

after intravenous

contrast

material.

glands CT

had

wall

on

scans

was the

surgically hypertension.

an of

oval the

removed, In

mass

abutting

pelvis; with

four

the

bladder

a pheochromocytoma

subsequent patients, CT

resolution showed

of both

adrenals to be normal; angiography and/or repeat chemical studies failed to substantiate a diagnosis pheochromocytoma in any of these patients. Primary

bioof

Aldosteronism

In nine

patients,

adrenal resected

CT

interpretation

was

a mass

in one

(fig. 5). An adrenal adenoma in four of these patients; surgical

was surgically exploration is

planned

in three

others.

and

medical

diseases

preclude

Advanced

age

surgery

in the

associated

other

two

pa-

tients. Both

adrenal

of the

patients

these had of bilateral with

Cystic and hemorrhagic

glands with

compelling adrenal

spironolactone.

zones

within

were

interpreted

suspected

biochemical hyperpiasia Surgery

tumor

found

as normal

aldosteronism.

in 10

Seven

of

and clinical evidence and are being treated is

at pathologic

not

planned

examination

for

this

of surgica’

KOROBKIN

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234

Fig. ing);

5.-Primary aldosteronism 1 .5 cm left adrenal mass

group. cluded Final

vena

adrenal

adenoma

(surgery pendtail (p) and

(arrow) between pancreatic crus. Normal right adrenal (arrowhead)

left diaphragmatic inferior

with

posterior

to

cava.

repeat biochemical impression of primary

diagnosis

is uncertain

studies that aldosteronism.

in the

tenth

ex-

patient.

In three patients, either one or both adrenals were not identified because of a marked paucity of retropenitoneal fat. In one of these patients, a 2 cm adenoma was found at surgery (fig. 6); surgery is pending in one and is not planned in the other. In two patients, previous unilateral adrenalectomy for a presumed adenoma did not cure the hypertension

Fig.

or reduce

the

elevated

urinary

aldosterone

Adrenal

Disorders

Three patients had biochemical evidence of hypoadrenalism or had suspected adrenal atrophy (table 3). Both adrenal glands appeared normal by CT in two of these patients, one on long-term steroid therapy after renal transplantation and the other with clinical evidence of hypoadrenalism after pituitary irradiation. CT in a patient with intravascular coagulation and acute hypoadrenalism showed bilateral adrenal masses (fig. 7), thought to represent adrenal hemorrhage. Three patients had CT evaluation of a suspected adrenal mass diagnosed by excretory urography. An adrenal mass, subsequently proven to be a pheochromocytoma, was seen in one of these patients, but a normal adrenal adjacent to an upper pole renal cyst was diagnosed by CT in the other two. A normal adrenal gland was seen in one patient with a previous venographic diagnosis of an enlarged gland. In one patient, CT confirmed a previously diagnosed adrenal carcinoma. In another, angiographic evidence suggested recurrence of a previously resected carcinoma

the

of the

posterior

right

adrenal

segment

gland.

of the

right

CT

showed

lobe

of the

a mass

liver,

in

but

aldosteronism

fat prevented

site of 2 cm adenoma

no evidence

Unsuspected

Either abnormal

of a tumor

with

left adrenal

clear delineation found

at surgery

recurrence

adenoma.

of either (arrow).

in the

bed

1979

Paucity

of

adrenal

gland;

of the

right

adrenal

Adrenal

Disease

one or both adrenal by CT in 15 patients abnormalities.

glands were interpreted as not specifically examined Most

of

these

patients

had

metastatic carcinoma, and CT was used to search for possible primary neoplasm in the pancreas. In two patients, CT was requested to search for abdominal metastases; in one to evaluate a retrogastric mass found on

Miscellaneous

6.-Primary

February

adrenal. Postmortem examination confirmed both findings. in the final patient, a 2 cm left adrenal mass was seen on CT after biopsy diagnosis of neurobiastoma metastatic to the orbit.

for

levels to normal. Results of biochemical studies after surgery were more consistent with bilateral hyperplasia rather than adenoma. A normal adrenal, contralateral to the resected gland, was identified on CT in both cases.

AJR:132,

retroperitoneal possible

Two had the initial clinical

ET AL.

upper

gastrointestinal

series;

in

one

to

evaluate

lateral displacement of the left kidney at urography; and in two to evaluate unexplained abdominal pain. In five patients, CT showed both adrenal glands were enlarged by a spherical or irregular mass (fig. 8). One had bilateral adrenal metastases documented at autopsy and the other four died with widespread metastatic disease but had no postmortem examination. In eight patients, CT showed a unilateral adrenal mass with a normal-appearing contralateral gland: a unilateral adenoma was surgically resected in one and a unilateral

pheochromocytoma

in another.

In one

patient,

a unilateral adrenal metastasis was found at postmortem examination. In one there was clinical evidence of widespread metastatic disease from a lung carcinoma. One patient with metastatic disease from an unknown primary was lost to clinical follow-up. One had a bladder carcinoma with liver metastases. One had CT evidence of an adrenal myelolipoma, but was lost to follow-up. One patient had surgical evidence of a neoplasm of the pancreatic tail rather than a left adrenal mass. In two

patients,

the

gland

contralateral

to an

adrenal

mass was not identified by CT due to technical factors or a paucity of retropenitoneal fat: one had bilateral adrenal

AJA:132,

February

1979

CT

OF

ADRENAL

TABLE

Results

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case No.

of CT Scans in 10 Patients

Suspected

Adrenal

Hypoadrenalism

2

Adrenal

3

Acute

4

? Right adrenal mass excretory urography ? Right adrenal mass

S 6

Both Both

atrophy

on on

? Right adrenal mass excretory urography

7

? Enlarged left venography

8

Known

9

cinoma Prior resection right nal carcinoma;

pected 10

clinical

on

adrenal

Right

cal evidence

at autopsy

of metastatic

Hypoadrenalism* Long-term

at

caradresus-

recurrence meta-

adredensity

mass

steroid

(8 cm)

right

adrenal

mal Both adrenals

hemor-

pheochro-

(8 cm)t renal

Right right

adrenal

cystt;

normalt

Cyst right kidney*; adrenal normal*

nor-

normal

adrenal

adre-

adrenal

Right adrenal mocytoma

Normal

Right adrenal mass (9 cm); left adrenal normal Sequential enlargement of liver mass; posterior segment right lobe Left adrenal mass (2 cm); right

thor-

normal-sized

Acute rhage*

pole right kidadrenal normal pole right kid-

Right

left

right

adrenal*

adrenal

Large

carcinomat

hepatic

metastasis;

no recurrent adrenal neopIasm Left adrenal neurobiastoma’; patient died with metastatic neuroblastoma

normal

evidence.

Fig.

identified

Disorders Final Diagnosis

8.-Bilateral

enlarged

metastases

Adrenal

normal normal

adrenal

Cyst upper ney; right Cyst upper ney;

adrenal

Neurobiastoma, static to orbit

. Compelling t 5urgery. Autopsy.

adrenals adrenals

Bilaterally enlarged nals with low centers

urography

right

with Miscellaneous

apy; nals

hypoadrenalism

excretory

3

CT Findings

Disease

1

235

DISEASE

and the

osteogenic

other

had clini-

sarcoma.

Discussion The large number of imaging techniques advocated for diagnosing suspected adrenal disorders reflects the limitations of each method. Adrenal calcification may be seen on plain abdominal radiographs in patients with carcinoma or neuroblastoma, but is unusual in pheochromocytoma, rare in adenoma, and not seen with hyperpiasia [5]. Conventional urography will show downward displacement of the ipsilateral kidney only if a large

adrenal

adrenals

probably

metastases.

represents

Mottled

appearance of both or hemorrhage.

zones of necrosis

adrenal mass is present. The use of intravenous contrast material, combined mography, detect’ng still

not

greatly

tumors,

be identified

Angiography [7-10], addition

increases

adrenal

but to

of

lesions

less

doses linear

of to-

urography than

2 cm

in will

[6].

is useful the the

accuracy but

large with

in detecting

well known risks technical difficulties

adrenal of

arteriography, and potential

masses in risk

of adrenal infarction using adrenal venography [11], are significant limitations. Adrenal scintigraphy, using isotopically labeled iodocholesteroi [12], can be useful in lateralizing adrenal adenomas, but a delay of 4-15 days

KOROBKIN

236

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after injection of the isotope is usually required. Recent reports suggest that gray scale ultrasonography may be useful in detecting adrenal masses [13-15], especially those larger than 2-3 cm. The major limitation of ultrasonography is the high degree of technical expertise needed to both obtain and interpret the images. CT

offers

several

important

advantages

suspected adrenal disorders. Most quire a vascular injection of contrast of

angiography,

The

resolution

ing

data

and

during

identification 75%

of

rather

ing

of normal

than of

The

of

bilateral

the

first

be

avoided.

glands

properties,

adrenal

a real

technical

im-

provements, such as 5 mm collimators, should improve the already promising application of CT in imaging small organs, such as the adrenal glands. It is essential

to differentiate

those

occasionally

inconclusive

these

or anomalous

biochemical results,

hyperplasia

had

CT

evidence

of

Cushing’s

syndrome

show

that

on by

of suppres[16]. How-

in these

yielded patients

bilaterally

normal

‘

some

patients

have

ad-

renais that are grossly and histologically normal [18]. Therefore, it is not surprising that many of our patients had a CT appearance of bilaterally normal adrenal glands. Although there may be some uncertainty in any individual case about the borderland between normal and hyperpiastic adrenal glands in patients with Cushing’s

syndrome,

our

study

indicates

that

CT

injection

of contrast

material

into

assessment

of 10 patients

with

known

or

pheochnomocytoma. All five patients with adrenal tumors were identified, although one with bilateral adrenal tumors had insufficient visualization of the left adrenal gland to identify or exclude a neoplasm on that side. The role of angiognaphy with respect to CT is unclear from this small group of patients because all the

adrenal

tumors

an ectopic can detect visualized complications

were

large

(4-8

cm)

and

origin. It is unknown whether an abdominal pheochromocytoma by CT. However, it is clear of an iatnogenic hypertensive

only

one

had

angiognaphy that is not that potential crisis can be

Primary aidostenonism is a rare syndrome characterized by hypertension, hypokalemia, increased aldosterone production, and absent or subnormal plasma renin activity [21 22] Between 65% and 75% of cases are associated with a unilateral adrenal adenoma, while most of the remaining patients have idiopathic” aidos-

adrenais or bilaterally enlarged adrenais that maintained their normal shape. One of the latter patients had a solitary nodule superimposed on each enlarged gland, probably representing the ‘nodular’ form of bilateral adrenocortical hyperplasia [17]. Pathologic studies of the adrenal glands in patients with ACTH-dependent ‘

after

avoided

a simple and accurate method of imaging the adrenal glands can be vital. Even in patients with unequivocal biochemical evidence of Cushing’s syndrome due to an adrenal neopiasm, adrenal imaging is essential to localize the side of the tumor before surgery. Our study suggests that CT can accurately differentiate ACTH-dependent Cushing’s syndrome from that due to a unilateral neoplasm. The three patients with a unilateral neoplasm were easily identified, and all 13 patients with clinical and therapeutic evidence of bilateral adrenocortical

pressure

those

studies and

diagnosis

Cush-

bilateral adrenocortical hyperpiasia dependent production. This distinction can often be made plasma ACTH levels and the effect with high doses of dexamethasone

the

with

with

ever,

neoplasm

in confirming

from

syndrome

measuring sion tests

to an adrenal

patients

ing’s

ACTH

due

useful

a blood vessel feeding the tumor can be considered either a deleterious effect of the procedure or a valuable provocative test [20]. In our study, CT proved to be highly suspected

the large

1979

the site or sites of a pheochromocytoma. for patients to undergo a marked increase

in the

hyperpiasia

Additional

proven

clinically

present in many patients, syndrome, makes imag-

time.

have

accurate

anatomic,

and

raphy,

and detecting The tendency

allows in at least

on

February

seldom seen, but dramatic, syndrome of variable hypertension and episodic attacks of tachycardia, diaphoresis, and anxiety [19]. Urography, and especially arteriog-

of record-

respiration

depend

adrenal

retroperitoneal fat those with Cushing’s for

can

adrenal

scans

do not reso the risks

capable

patient sized

[3].

functional,

diagnosis

possibility

urography,

on scanners

suspended

patients

amount especially

even

available

AJA:132,

in blood

in evaluating

patients media,

ET AL.

can

accu-

rately differentiate tumorous and nontumorous forms of this disease. Pheochromocytoma is a tumor that secretes abnormal amounts of catechoiamines, and is associated with a

with CT.

,

.

“

teronism,

often called

“bilateral adrenocortical

hyperpla-

sia” [21], and glands of normal size [17]. For unknown reasons, adrenal surgery, even total adrenalectomy, is unlikely to cure patients with bilateral hyperpiasia [21], but unilateral adrenalectomy usually cures the hypertensive patient with a solitary adenoma. An absolute distinction between bilateral hyperplasia and unilateral adenoma cannot be made on biochemical features

alone

[23].

Bilateral adrenal venography and adrenal venous sampling [24-26] have been reported to successfully identify unilateral adenomas and bilateral hyperplasia. However, difficulty in routinely catheterizing the right adrenal vein and reports of adrenal infarction after adrenal venognaphy have prevented widespread use of these techniques. Adrenal imaging with 13’l-19-iodocholesteroi [271, especially when used after dexamethasone suppression [28], may localize a unilateral adenoma in about 80% of patients. The necessity of repeating scintiscans from 419 days

after

injection

of the

isotope

is a drawback

not

present with a newer agent, 311-6B-iodomethyi-1 9-norcholesterol [29]. Unfortunately, these drugs remain available only as investigational agents and have been limited to a few

medical

centers.

The results of our study suggest that CT is an easy and accurate method of differentiating unilateral adenoma from bilateral hyperplasia in patients with primary aldosteronism. A unilateral adrenal mass was demonstrated in all nine patients having biochemical evidence favoring a unilateral adenoma in whom both adrenal glands were

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AJA:132,

February

CT

1979

OF

ADRENAL

visible on the CT scan. Four have been confirmed at surgery, and an additional three patients will be operated on in the near future. All seven patients with biochemical evidence favoring diagnosis of idiopathic aldosteronism in whom both adrenais were visualized had CT appearance of bilaterally normal glands. Confirmation of the absence of a unilateral adenoma has led to a medical rather than surgical approach in these patients. The limitation of CT in patients with a sparsity of retropenitoneal fat is illustrated by the patient in our series in whom a unilateral adenoma was found surgically in a gland not delineated by CT. Isotopic adrenal scanning was performed in some of these patients with primary aldosteronism as part of prospective study, and a complete description and analysis of that study will be part of a separate

report.

Three factors limit firm conclusions regarding CT scanning in primary aidosteronism: (1) surgical results in the four patients to be operated on are necessary to confirm the accuracy of a CT diagnosis of a small aldosterone producing adenoma; (2) the clinical evidence against diagnosis of a unilateral adenoma in those patients whose CT examinations showed normal adrenals bilaterally means that surgical confirmation of idiopathic aldosteronism will not be available; and (3) it is unknown whether CT will be able to identify adenomas smaller than

1 cm

because

none

of the

tumors

in our

series

were

as small as some described in previous reports. When a mass was seen in the region of the adrenal gland during excretory urography, CT was useful in determining whether the lesion was renal or adrenal in origin. This distinction should be easy in patients with an upper pole renal cyst, where a normal adrenal gland is usually well seen, but may be difficult if a solid renal mass invades the adrenal compartment. It was somewhat surprising to see normal-appearing adrenal glands in CT evaluations of poadnenalism from pituitary irradiation roid therapy.

Factors

that may

account

patients with or long-term

hyste-

mass was seen in another patient evaluated placed contralateral kidney seen at urography. that the capacity of CT to image both adrenal lead to occasional discovery of asymptomatic disease. Because

of the

inconsistent

use

for a disIt is clear glands will adrenal

or availability

of other

imaging procedures in the patients described in our study, we were unable to systematically compare CT with other methods. However, our study clearly suggests an important role for CT in the evaluation of adrenal disease. The vast majority of adrenal masses proven by surgery were detected by CT, and none were missed in those glands clearly delineated. CT was able to differentiate tumorous from nontumorous forms of adrenal disease in patients with Cushing’s syndrome and primary aidosteronism. Unsuspected primary and metastatic neoplasms of the adrenais were occasionally detected in patients scanned for other reasons. CT seems to be a simple and accurate method to assess the adrenal glands in patients

suspected

of adrenal

disease.

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