This document provides an overview of adrenal gland imaging and differentiation of benign and malignant adrenal masses. It discusses normal adrenal gland anatomy and histology. Common imaging modalities for adrenal masses are CT, MRI, ultrasound, and PET. Benign adrenal adenomas typically appear homogeneous with rapid contrast washout on CT. Malignant masses tend to be heterogeneous with delayed washout. Specific adrenal tumors discussed include adenomas, metastases, myelolipomas, and lymphoma. Features on various imaging modalities that help characterize each tumor are presented.

1. IMAGING OF ADRENAL MASSES
Dr.Abduljelil .MD,RRII
Oct.03, 2020 GC

2. Objective
1. Overview of adrenal gland .
2. Imaging modalities.
3. Current concept of differentiating a benign from malignant
adrenal mass.
4. Specific Adrenal tumors

3. Normal Anatomy
• Paired endocrine glands
• Enclosed in the perirenal fascia
and each have a body and two
limbs -medial and lateral
• Gross anatomy- the right is
triangular (pyramid), and the left is
semilunar and larger
• Characteristic inverted Y, V, or T
shape
• Boundary

4. Histology
v ADRENAL CORTEX-90% of adrenal three zones
1. Zona glomerulosa-outer most –10-15% Secretes mineralocorticoids
(aldosterone)
2. Zona fasciculata-80% - secretes cortisol
3. Zona reticulata-5-10% - secretes androgens
v ADRENAL MEDULLA- 10% of adrenal made up of chromaffin cells,
• secretes-EPINEPHRINE or NOREPINEPHRINE
• Part of sympathetic autonomic nervous system.

5. Vasculalr suuply and lymphatic dreanage
• Arterial supply :
ü Inferior phrenic artery superiorly.
ü aorta medially .
ü renal artery inferiorlly
• Venous drainage :
Ø Right side: drain to IVC .
Ø Left side : drain to left renal vein or
directly to IVC.
• Lymphatics :
v Para-aortic and paracaval lymph nodes

6. Imaging modallities -US
• Primarily reserved for use in pediatric population
• Helpful for the screening of masses in the suprarenal region.
• Nevertheless, its findings have to be verifed by CT or MRI.
Normal right adrenal gland in a 1-
day-old girl.

7. Imaging modalities -CT
• Imaging modality (golden standard) of choice for evaluating adrenal
glands morphology and masses
• HRCT of upper abdomen, using 1-3mm thick slices to reduce the volume
averaging, is most accurate technique for indentifying adrenal lesions.
• Routine CT protocol for adrenal imaging
1. NCCT abdomen
2. CECT abdomen (70 secs delay) -(60sec Assistant/Grainger)
– 100-150ml of contrast is injected at a rate of 3ml/sec
3. Delayed scan (after 15 minutes)

8. CT Measurements
• Normal
Ø Length - 4-6cm
Ø Width -2-3cm .
Ø Each limb normally measures ≤
5mm in width and the body should
measure ≤ 8-10mm in width
• Criteria for Enlargement:
ü Length >6cm
ü AP diameter > 3cm
ü Limb thickness > 6mm
ü Thickness more than adjacent
crus

9. Imaging modallities -MRI
• Modality of choice for further characterization
of adrenal lesions.
• MR parameters should include T1-and T2-
weighted sequences along with chemical shift
imaging.
• T1 weighted signal show normal adrenal as
low signal against high signal fat.
T1W TSE image
T2 W MR image

11. Differentiating benign from malignant
• The most common tumor in the adrenal gland (Even in
patients with a known malignancy) is the adenoma.
– 70% of adrenal masses in cancer patients are benign
• Differentiation is essential in determining treatment and
prognosis.
• Benign- no further treatment.
• Metastasis – indicates advanced disease , not amenable
to surgical resection.

12. CT-Examination
• Adrenal adenomas have two properties that differentiate
them from non-adenomas.
1. 70% of adenomas contain high intracellular fat (lipid-rich adenomas) and
will be of low attenuation on unenhanced CT .
2. Adenomas rapidly wash out contrast.
• Unenhanced CT,Using a safe threshold value of 10HU on
a native CT scan results in a sensitivity of 70% and a high
specificity of 98% for the diagnosis of an adenoma.

13. NCCT DENSITY
• <18 H.U.—considered adenoma
• <10 H.U.—96% specific , 79%sensitive
• <0 H.U.—100% specific, 47%sensitive
• At 10 HU specificity approaches 100% if size , shape and
change in lesion size is considered
• Lesions on unenhanced CT with an attenuation greater
than 10 HU require further evaluation with either:-
– Contrast “washout” on CT
– Chemical Shift on MRI

14. ROI
v ROI at least 1/2 (two-thirds) of the lesion and excluding
calcifications and the periphery of the lesion to avoid volume
averaging and adjacent periadrenal fat.

15. q Absolute enhancement wash out > 60% OR Relative enhancement wash
out > 40% = adenoma
ü Lesions that demonstrate RPW < 40% (or APW < 60%) on a 15-minute
delayed scan are almost always malignant.-Radiology 2008;249:756-775
v The most commonly used formula is the 'enhancement wash
out' formula (sometimes called absolute wash out)

16. Fact/pitfall
• If >120 HU on the portal venous phase, the washout value
should be ignored
– as the lesion is most likely a hypervascular metastasis or
pheochromocytoma rather than a lipid-poor adenoma
• Be aware that HCC and RCC may contain intracellular fat
and, therefore, their metastasis may mimic adenoma
• Lesions with attenuation values grater than 20-30HU on
non-contrast CT are unlikely to be shown as adenomas on
chemical shift MRI and may rather benefit from a dynamic
contrast CT study

17. Morphologic features
• Adenomas are generally small, homogeneous and well-defined lesions
with clear margins.
– Although the presence of these features are non-specific the absence
strongly suggests a nonadenoma.
• In a retrospective study Gufler et al combined morphologic criteria with
the density measurements on unenhanced CT and found a high
accuracy in differentiating adrenal adenomas from metastases in
patients with a known malignancy
In patients with a known
extra-adrenal
malignancy a total score
> 7 points was highly
accurate for the
diagnosis metastasis.

18. • The discriminating parameters on CT based on attenuation
values only apply to homogenous lesions.
• Metastases may have a relative low HU due to central necrosis.
• Adenoma on the right is homogeneously of low density.
Metastasis on the left is inhomogeneous and centrally of low
attenuation due to necrosis.

19. MRI-Examination
• Generally metastasis and carcinomas contain large
amount of fluid – bright on T2.
– Significant overlap in T1 and T2 intensity between adenoma
and metastasis ; thus not reliably used to distinguish.
• Adenomas contain lot of fat so bright on T1.
• Enhancement patterns are similar to CT : adenomas
rapidly enhance and show rapid washout; metastasis
enhance rapidly but exhibit delayed washout.

20. Chemical shift imaging
• Relies on the different resonance frequency rates of protons in fat
and water molecules
Ø IN PHASE—signal of water and fat protons add
Ø OUT OF PHASE---signal of water and lipid protons cancel out each other.
• Tissues containing lipid and water have signal loss (ie, appear
darker) on out-of phase images
– Amount of signal loss depends on amount of lipid in tissue.
• Thus, on out-of phase images, adenomas appear darker than on in-
phase images,
• Metastases or carcinoma (because of lack of lipid and presence of
water) appear bright on both in-phase and out-of-phase images.

21. • The loss of signal can be assessed virtually using spleen
as the internal reference
• Liver should not be used -as it may also show signal loss
on opposed phase image when there is fatty infiltration of
liver
An ASR(adrenal-lesion-to-spleen ratio ) of 70 or less has been shown to
be 100% specific for adenomas but only 78% sensitive

22. Signal intensity indices(SII)
v Have been shown to discriminate between adenomas and
metastases with an accuracy of 100%.
v SI INDEX : > 16.5 is suggestive of benign adrenal lesion
v Adenomas characteristically have signal intensity indices
greater than 5%, whilst metastases have indices lower than 5%

23. (A) out-of-phase and (B) in-phase images of a large left-sided
adenoma seen with visual signal dropout on the out-of-phase
images. ASR of the mass is 33% and SII is greater than 50%-
confirming an adenoma

24. CS-MRI vs DCE-CT
• CS-MRI is superior to DCE-CT only in those cases where the
unenhanced attenuation value of the adrenal lesion is < 80
HU .
– If a hyperattenuating tumor presents, DCE-CT achieves higher
sensitivity than CS-MRI.
• MRI cannot be used to definitively characterize lipid-poor
adenomas
– However, MRI is appropriate in pregnant patients or those with
iodine hypersensitivity and reduced renal function.

25. Nuclear medicine imaging
qFuorine-18-fludeoxyglucose (18F-FDG) PET.
• Even though PET/CT demonstrates high accuracy, it is still inferior to
DCE-CT
• Highly accurate in differentiating malignant from benign adrenal
masses.
qSensitivity : 94.4%-100%
qSpecificity : 80-100%
• Increased metabolic activity is characteristic of
malignant masses.
Ø Malignancy : activity in adrenal mass is more intense than that of liver

26. Right adrenal adenoma.
(a) Contrast-enhanced CT scan demonstrates a smooth-margin,
low-attenuation
(b) FDG PET scan shows normal activity in the kidneys (arrows)
but no increasing activity in the right adrenal gland.

27. Right adrenal metastasis in a patient with lung carcinoma.
(a) Nonenhanced CT scan demonstrates a right adrenal mass
(arrow).
(b) FDG-PET SPECT scan obtained at the same level shows
increased activity in the right adrenal gland (arrow), a finding
diagnostic of a metastasis

28. BENIGN vs MALIGNANT
• BENIGN
1. Size
Small
No change
2. Smooth margin
3. Homogenous
4. NCCT : HU < 10
5. CECT-----
– Mild & rapid enhancement
– Quick wash-out
• MALIGNANT
1. Size
– >4cm
– Change in size
2. Irregular shape
3. Heterogenous
4. NCCT : HU > 10
5. CECT-----
• Heterogenous & vigorous enhancement
• Prolonged wash-out

29. Criteria to diagnose adenoma and malignancy
v Adenoma
• CECT delayed :
– HU <24 on 15 min delayed or
– HU < 30 on 10 min delayed.
• RPW > 40%
• APW > 60%
• CSI : signal loss
v Malignancy
• CECT delayed :
– HU >24 on 15 min delayed or
– HU >30 on 10 min delayed.
• RPW < 40%
• APW < 60%
• CSI : no signal loss

30. INDICATORS SUGGESTING POSSIBILITY OF
MALIGNANCY
1. Masses > 4cm size tends to be metastasis or primary
adrenocortical carcinoma.
2. Irregular shape.
3. Heterogenous appearance.
4. Growth of adrenal mass over time

31. Specific Adrenal tumors

32. GROUP I : ADRENAL DISEASE
WITH NORMAL FUNCTION
• Most of these are incidentally detected as adrenal masses.
• Include :-
Ø Non-functional adrenal adenoma or carcinoma,
Ø Metastasis ,
Ø Lymphoma ,
Ø Myelolipoma ,
Ø Adrenal cyst.

33. Adrenal Adenoma
• Most common incidental finding.
• Prevalence of adrenal adenoma is age related.
• 0.14% for patients aged 20–29 years and
• 7% in those older than 70 years.
• Benign, with no malignant potential and mostly
nonfunctional-no need for intervention
v Although CT does not allow differentiation of functioning from
nonfunctioning masses, the presence of contralateral adrenal
atrophy suggests that a lesion may be functioning
Ø because pituitary adrenocorticotropic hormone secretion is suppressed
by elevated cortisol levels

34. US
v Appear as homogeneous, solid masses that are usually
similar in echogenicity to the liver

35. CT
• Round & homogenous
• < 4 cm, unilateral
• low unenhanced CT
attenuate values (<10HU)
• Rapid contrast washout
• Absolute contrast washout
>60%
The NECT attenuation value of the mass is
–13 HU, consistent with a lipid-rich adenoma

36. MRI
• Isointensity with liver on both
T-1 & T-2 (MRI)
• Chemical shift : lipid on MRI
so loss of signal intensity
(C) in-phase and (D) out-of-phase
images-drop significant visual signal
intensity:typical lipid-rich adenomas

37. 3.5 cm left adrenal lesion which shows reduction in signal
intensity between the in-phase and out of phase T1-weighted
images

38. Left adrenal mass with loss of signal
on out-of-phase imaging
Left adrenal mass with < 10 HU:
consistent with an adrenal adenoma.

39. Metastases
• Most common malignant lesions involving the adrenal gland.
– Statistically most non-adenomas are metastases
• Fourth most common site of metastases
v Are found in 27% of postmortem studies in patients with malignant
neoplasms.
• usually bilateral
– Unilateral involvement is more prevalent on the left side (ratio of
1.5:1)
• Lung ca ,breast ca and melanoma are the most common
primary tumors.
– A diagnosis of adrenal metastasis is important in examining
patients with cancer because the metastasis indicates inoperable
stage IV disease (except in ipsilateral renal cancer).

40. US
• On sonography, metastases are often indistinguishable
from adenomas, although metastases are usually larger
and are often heterogeneous
solid, lobulated hypoechoic mass
large, slightly heterogeneous
hyperechoic mass with scattered cystic
areas (cursors)

41. CT/MRI -Practical points
• On CT, metastases usually demonstrate less than 50%
washout
– If intense enhancement of more than 120 HU is identified in
the portal venous phase, washout should be ignored, and a
hypervascular lesion such as renal cell carcinoma or
hepatocellular carcinoma metastasis should be considered as
a primary
• MRI: no signal loss on out-of-phase images
– Isointensity or slightly less intense than liver T-1 , high to
intermediate intensity T-2 MRI (represent water increase)

42. CT scan 62/M shows a mass in the
upper right pulmonary lobe that
invades the mediastinum. On the
images extended to the superior
abdome -a masses in both adrenal
glands

43. Myelolipoma
• Benign tumors and most are hormonally inactive.
• Age=5th to 6th decade,M=F
• Usually small (<5 cm), solitary and is composed of
haematopoietic precursor cells and mature adipose tissue
– Usually they are easy to recognize on CT or MR because they contain
areas of fat.
• Often have a recognisable capsule,may have areas of
fibromyxoid degeneration, haemorrhage, necrosis
– Calcifications are seen in 20/30% of cases

44. US
• Appearance reflects the amount of fat in the tumor.
– Usually hyperechoic and may attenuate the sound and produce
partial shadowing
– When myeloid elements are dominant the lesion will be less
echogenic
– Heterogenous----h’ge
large, solid, hyperechoic right adrenal mass with fat attenuation

45. US cont..
• Posterior displacement of the diaphragm (arrows) is due to
speed propagation artifact -slower speed of sound in fat

46. CT
• The key to CT diagnosis is a focal area of fat in the adrenal mass.
Ø In nearly all myelolipomas, some regions with attenuation values less than –30
HU can be identified
• Although an adrenal adenoma may have lowattenuation values due to a
large amount of intracellular lipid, this is usually not less than –20 HU
• Enhancement in soft-tissue component.
• Calification in 30% ,often punctate
adrenal mass containing islands of fat
large predominantly fatty mass

48. MRI
T1
T1-weighted with fat saturation
out-of-phaselarge right-sided adrenal mass
with multiple foci of high T1 signal
intensity . These areas of high T1
signal -lose signal on fat
saturation sequences, and on out-
of-phase

49. Lymphoma
• Non-Hodgkin’s lymphomatous involvement of the
adrenals is not uncommon and usually is due to direct
invasion from retroperitoneal disease.
• Bilateral in almost 50% of cases
– Often difficult to use bilaterality to differentiate primary versus
secondary
• Primary adrenal lymphoma is very uncommon, but it does
occur (Bilateral in 70% of cases)
• Most common presentation is diffuse bilateral
enlargement of adrenal glands

50. US
• As with lymphoma elsewhere, adrenal lymphoma is
typically a solid, hypoechoic mass
Diffuse enlargement bilaterally.CT scan confrms uniform adrenal
enlargement bilaterally

51. CT
• Usually of soft tissue attenuation (40-60 HU) with mild
progressive enhancement
Large bilateral soft-tissue density adrenal lesions. No internal fat
or calcification-Size > 4cm is concerning for malignancy, including
metastases or bilateral adrenal cortical carcinomas

52. Adrenal Cysts
• True adrenal cysts are rare. Most simple adrenal cysts are liquefed
hematomas with a fibrous capsule
• Cysts in most instances are unilateral.
• Large cysts may be complicated by hemorrhage and consequent onset of
acute symptoms.
• Most importantly lesions show a thin wall and no enhancement after
intravenous contast material.

53. T2 FSE
T1 Fat sat +C
The lesions demonstrate the
expected imaging characteristics of
cysts
Fluid attenuation on CT, no
enhancement following contrast
medium administration, anechois on
ultrasound and low T1 and high T2
signal characteristics on MRI

54. Haemorrhagic Cyst (Pseudocyst)
• The presence of solid components, thickened walls and septae
increase the likelihood of a necrotic mass or infective cyst
rather than a benign cyst
• Fig:right adrenal cystic lesion with a mural based isodense
nodule suggestive of a complex adrenal cyst
• patho:fibrotic wall with no epithelial or endothelial lining. The
cyst contains only blood with no malignancy detected.

55. Hydatid cysts
• AHC disease constitutes for less than 1% of all hydatid cyst
cases
• Are the main parasitic cysts involving the adrenal glands
• unilateral in 90% of cases

56. (6-7%)

57. GROUP II : HYPERFUNCTIONING
ADRENAL NEOPLASM
• Adrenal medullary neoplasm:-
q Pheochromocytoma,
q Neuroblastoma.
• Adrenal cortical neoplasm:-
• Cushing syndrome , Hyperaldosteronism , Conn sydrome ,
Hyperandrogenism

58. Pheochromocytoma
• Paragangliomas arising from the adrenal medulla.
• Peak age : 40-50yrs
• Hormonally active in 90% of cases.
• 10% tumor
– 10% risk of malignancy
• The combination of abnormal biochemical laboratory
studies and a visible mass on imaging is usually
diagnostic

59. Radiographic features
• Large at presentation, average size of ≈ 5 cm.
• Are typically large, vascular, and heterogeneous tumors
– They may occasionally be predominantly cystic
• Not possible to distinguish malignant from benign
pheochromocytoma merely on the direct appearance of
the mass.
– Distinction is made on :evidence of direct tumour invasion
/presence of metastases

60. US -Pheochromocytoma in different patients
heterogeneous mass homogeneous, hyperechoic
mass
complex, predominantly cystic
mass

61. CT/MRI
Phaeochromocytoma (adrenal paraganglioma) on CT and MRI.
There is strong enhancement on enhanced CT and very high
signal intensity on T2-weighten MRI

62. MRI
• Most sensitive .
– particularly useful in cases of extra-adrenal location.
• T1- slightly hypointense .
• T2- markedly hyperintense .
• T1 C+ (Gd)-heterogenous enhancement
» enhancement is prolonged.

63. (A) In-phase and (B) out-of-phase images of a right adrenal
mass. On visual inspection no significant signal dropout is seen
in the mass. The SII of 3%, consistent with a
phaeochromocytoma- surgically confirmed

64. Neuroblastoma
• The most common extracranial solid childhood
malignancies and
– the third commonest childhood tumor after leukemia and brain
malignancies
– younger age group (< 2 years of age)
• MRI-T1 - heterogeneous and iso to hypointense
• T2 -heterogeneous and hyper intense. C+ (Gd) - variable and
heterogeneous enhancement

65. CT
• Calcification ( 90%)
• Encases vascular structures but does
not invade them
• Poorly marginated
• More common to have extension into
chest
• Elevates the aorta away from the
vertebral column
• Adjacent organs are usually displaced,
although in more aggressive tumours direct
invasion of the psoas muscle or kidney can
be seen

66. Primary Adrenocortical carcinoma
• Rare and often diagnosed at an advanced stage (tend to
be large at diagnosis)
• Patients present with abdominal pain (mass effect),
palpable mass or Cushing's syndrome (50%).
– Functioning tumours are more common in women and children with
resultant Cushing’s syndrome or virilisation
• Has a bimodal peak (1st and 4th decades)
– however, this tumor is often identified earlier in children
because it tends to be hormonally active .
• Female-to-male ratio -2.5–3 : 1
– Male patients tend to be older and have a worse overall
prognosis
• Approximately 75% of children are younger than 5 years

67. US
• large solid or complex Lobulated, irreg.margins,
heterogenous,calcification (30%-patchy/irreg/nodular)
• Echogenic rim
• Hemorrhage/necrosis
• Spread—LN/liver mets/IVC invasion

68. US cont..
• Longitudinal view shows a right adrenal mass that deviates
IVC anteriorly-tumor thrombus
• D large right adrenal mass that directly invades the liver

69. CT
Ø Large inhomogeneous mass with heterogeneous
enhancement(NECT (>20HU),Delayed contrast washout
(10 min),Absolute contrast washout < 60 %)
Ø An adrenal carcinoma is not likely to be less than 5 cm in
diameter, unilateral
Ø Central necrosis is common.
Ø Calcification is seen in 20-30% of cases
Ø Invasion of the IVC is a well-known complication of
adrenocortical carcinoma

70. large size,irregular margins
anteriorly, speckled calcification,
heterogeneous enhancement
Invasion of the IVC

71. Primary Adrenocortical carcinoma cont..
• Most tumours spread by both the haematogenous (lung
(45–97%), liver(48–96%) and bone(11–33%)) and the
lymphogenous route(25–46%).
• Liver metastases tend to be hypervascular
• As in renal cell carcinoma tumour tends to spread early by direct
invasion of surrounding structures.
– some series finding renal vein involvement in up to 40% of
patients

72. MRI
• Can be useful to determine hepatic invasion if CT is
inconclusive.
• Heterogeneous mass is seen that is of high signal on T2
• Hemorrhage may result in variable signal intensity dependent
on the age of the hemorrhage.
• Heterogeneous enhancement
Axial T2-weighted MR
Axial T1 hemorrhage

73. Large inhomogeneous mass with central calcification typical of
an adrenal carcinoma

74. Adrenal hyperplasia
• Refers to non malignant growth (enlargement) of the
adrenal glands.
• In diffuse hyperplasia, the limbs of the adrenal glands
exceed 5mm thickness
• cause of 70% of the cases of Cushing's syndrome
and 20% of the cases of Conn syndrome.

75. GROUP III : ADRENAL HYPOFUNCTION
• May be due to adrenal destruction or inadequate pituitary
stimulation.
• CAUSES :
vautoimmune disorders
vAdrenal hemorrhage
vInfections – fungal and TB
vSarcoidosis
vDrugs: inhibit cortisol synthesis(ketoconazole , etomidate) ,
or increase cortisol clearane (barbiturates and phenytoin.)

76. Adrenal Hemorrhage
• Extensive adrenal hemorrhage may occur at any age and
under various circumstances such as:-
– severe stress as in surgery, sepsis, burns, hypotension, trauma,
hemorrhagic diathesis and underlying conditions such as
adenoma, cyst and tumour.
• Traumatic and non-traumatic causes.
• When unilateral, it is often clinically silent.
– In contrast, bilateral adrenal hemorrhage(20%) can lead to
catastrophic adrenal insufficiency
• imaging apperance depends on its age hematoma

77. US
1. Solid with diffuse or inhomogeneous echogenicity
2. Mixed echogenicity with a central hypoechoic region
3. Completely anechoic and
4. Cyst-like walls calcification- early as 1-2 weeks after onset
and gradually compact as the blood is absorbed
Neonatal hemorrage

78. CT
NECT
Ø Characteristically appear round or oval, often with
surrounding stranding of the periadrenal fat.
Ø The attenuation value depends on its age-
q decrease in size and attenuation over time

79. Adrenal tuberculosis
• Rare and are usually bilateral
• one of the most common causes of adrenal insufciency
worldwide
– When >90% of the cortex has been destroyed-Addisonian crisis
• Chest radiographs and sputum cultures may be negative

80. Bilateral adrenal diffuse enlargement
(larger and mass like on the left side)
showing calcfications
ØCT-mainstay of evaluation
Ø early-stage “adrenalitis” includes bilateral adrenal
enlargement with a central necrotic area of hypoattenuation
and a peripheral enhancing rim.
Ø In the healing stage of the disease, the adrenal glands
become calcified and atrophic (adrenal calcification).

81. summary

82. An algorithmic approach and current recommendations
for imaging of adrenal masses
surgical
resection
≥ 1cm over 6month-1yr

83. REFERENCES
• Grainger & Allison's Diagnostic Radiology, 6th ed © 2015
• Adrenal Mass Imaging with Multidetector CT: Pathologic
Conditions, Pearls, and Pitfalls ,RSNA © 2009
• Ultrasound - The Requisites 3rd ed © 2016
• Radiology Assistant-Adrenals :Differentiating benign from
malignant,Theo Falke and Robin Smithuis,September 26,
2005

84. THANK YOU