approach to adrenal lesions

1. Imaging of
adrenal masses
DR. DEVKANT LAKHERA

2. Topics
Anatomy
Imaging modalities
Adrenal masses
Approach
Characteristic imaging appearance

3. Anatomy
Endocrine gland – Inverted Y
configuration
Body and two limbs (medial and
lateral)
Right - pyramidal Left - crescent
The cortex is subdivided into three zones
zona glomerulosa
zona fasciculata
zona reticularis
The medulla
Size
Length 3-5 cm
Width 2-3 cm
Thickness 5 mm
Enclosed in perirenal fascia/ mesoderm/ neural crest// produces catecholamines (adrenaline, noradrenaline) as well as
dopamine //

4. Blood supply
Arterial supply - three adrenal arteries
superior - inferior phrenic artery
middle - abdominal aorta
inferior - from renal artery
Adrenal veins
left adrenal - left renal vein
right adrenal - IVC

5. Imaging modalities
USG limited
CT and MRI mainstay – structural changes
Scintigraphy – functional assessment of gland
CT primary imaging modality of choice, other play a
complimentary role

6. Scanning and CT appearance
No special preparation
Pheochromocytoma
inverted Y or V shape on CT
and is seen as an
anteromedial ridge with two
posterior limbs, medial limb
being shorter than the lateral
limb and limbs have normally
straight or concave outline //
criteria for enlargement of
adrenal are taken as length
more than 4.0 cm,
anteroposterior diameter of
more than 3.0 cm and limb
thickness of more than 6.0
mm body 10 mm //
hypertensive crisis

7. Adrenal pathologies
Adrenal masses
Adrenal hyperplasia
Adrenal cysts
Adrenal haemorrhage
Adrenal infection
Adenoma
Adreno-cortical
carcinoma
Pheochromocytoma
Adrenal metastasis
Adrenal
myelolipoma

8. Most (95-98%) of adrenal lesions are benign
Even in patients with a known malignancy - usually non-functioning
adenomas.
differentiate these benign adenomas from malignant adrenal masses.
Adrenal masses

9. Approach to adrenal masses
◦ Morphology
Size, shape, contour and attenuation
◦ Enhancement characteristics
Enhancement pattern and washout
◦ Clinical presentation
Functioning and non functioning
◦ Biopsy

10. Morphology Hyperplasia –
Hyperfunctioning
and insufficiency
Smooth / nodular
Malignant
larger > 6cm
Shape
lesion / hyperplasia
Homogeneity
homogenous/ heterogenous
Size
(<3, 3-6, >6)
Contour
smooth /irregular
Attenuation
Larger lesions are usually carcinoma exception of myelolipoma

11. ADENOMA – 2 distinct properties
70% high fat content
Rapid contrast washout
Unenhanced CT
Density </= 10 HU diagnostic of adenoma
HU - equal to or below 10 HU the lesion is considered to be an adenoma and no further workup is
necessary // High intracellular fat / lipid rich adenoma //30% are lipid poor – do not have intracellular
lipid for density <10 HU / Cannot be differentiated with malignant lesions

12. CT algorithm
Benign and malignant - not possible
on the initial enhanced CT (at 60sec)
Density - more than 10 HU then wash out
should be calculated

13. 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.

14. Enhancement pattern
Initial phase (60 sec) – most adenomas show mild
enhancement
Malignant lesions and pheochromocytoma show strong
enhancement
Overlap in attenuation values
Differentiation is possible with calculation of rate of
washout of contrast
60 sec and 15 min mcly used is the absolute washout//
Absolute enhancement wash out > 60% = adenomaRelative
enhancement wash out > 40% = adenoma

15. CT – adrenal adenoma
Incidentally detected adrenal lesion // washout of more than
60% - Diagnostic for lipid rich ROI<1/2

16. Adrenal mass identified during staging
for lung carcinoma.
On an enhanced CT at 60 sec the
attenuation value was 22HU.
Next day - dedicated adrenal CT.
unenhanced CT the attenuation
value was -19HU -presence of a lipid-
rich adenoma.
No further work up was needed
Smooth well defined homogenous lesion with post contrast
attenuation value – 22 hu

17. Nephrectomy for RCC
Adrenal nodule
with HU = - 5HU
In a patient with primary and lesion should be considered as secondary unless proven
otherwise .. With exception for appearance in adenoma

18. Confident diagnosis - criteria
Density <10 HU
Normal enhancement in 60 sec scan with significant washout on 10 min scan
Signal washout on and out of phase T1 MRI scan

19. MRI in characterization
Adrenal carcinoma, some metastasis and pheochromocytoma– appear bright on T2 – due to
fluid content and necrosis
OVERLAP – in T1 and T2 appearances in adenoma and some metastasis

20. MRI – Chemical shift imaging
Basis- Different resonant frequency rates of proton in fat and
water
Echo time
In phase – 4.2 -4.5
Out phase – 2.2 – 2.7
Signal intensity in phase – fat + water
Out of phase – cancel out Use of in-phase and out-of-phase gradient-
echo (GRE) techniques for adenoma vs
metastasis distinction.Two different T1 weighted images are taken with diff echo
times// first short echo time when fat and water and out of
phase// Contrast enhanced T1 fatsat

21. Relatively enhancing lesuion // signal drop in T1 out of phase

22. Signal drop on out of
phase T1 imaging
Spleen used to compare

23. Ratio
SI index- >16.5 %
Adrenal to spleen ratio <0.71
ADENOMA/ BENIGN LESION

24. Dynamic MRI
Similar enhancement pattern to CT
Adenoma -washout
Malignant lesions showing retention of contrast

25. Criteria for suspicion of malignancy
Size- larger lesions (>6 cm)
Heterogenous appearance / enhancement
Delayed washout

26. Percutaneous
biopsy
Adrenal biopsies can be performed via a
posterior approach with the patient in the
prone position.
CT guided FNA of the left adrenal gland via a posterior
approach. The black dot at the end of the needle (green arrow)
indicates that the tip of the needle is seen in this image.// on-
specific adrenal mass in a patient with lung cancer, who was a
possible candidate for curative surgery. Transhepatic CT-guided
FNA proved the presence of metastatic disease.

27. Based on clinical history
Group I : Adrenal hyperfunctional diseases.
Group II : Adrenal insufficiency.
Group III : Adrenal diseases with normal function.
Functioning
Adenoma
(Conn’s and Cushing’s)

28. Clinical history
◦ Obesity, striae, weakness, osteoporosis  Cushing syndrome
◦ Hypertension  +/- hypokalemia  Conn’s syndrome / pheochromocytoma
◦ Androgenital syndrome

29. Cushing’s disease
Bulky left adrenal
Prominent intra-abdominal fat
Hepatic steatosis

30. ACTH dependant – Hyperplasia /single
/multiple small nodules
Adrenocortical Adenoma
Larger than those in Conn
bilateral adrenal hyperplasia. Post contrast T1W coronal image
of MRI sella of the same patient reveals
a microadenoma on left side of anterior pituitary

31. Conn’s
Excessive mineralocorticoid
Hypertension and hypokalemia
Polyuria and polydipsia and hypokalemia
Cortical scintigraphy
NP-59 Normally kidneys visualized on 5th day

32. Androgenital syndrome
Precious puberty virilization
>2 cm with nodular hyperplasia of gland

33. Adrenal hyperplasia
Due to overstimulation by ACTH produced by
pituitary adenoma
Appear bulky with normal configuration
Physiological
◦ Ageing
◦ Stress

34. D/d
◦ Adenoma
◦ Haemorrhage
◦ Stress induced hyperplasia
◦ Ageing

35. Adrenal hyperplasia
Adrenal hyperplasia
Smooth
Functioning Clinical
symptoms
Conn
Hypertension and
hypokalemia
Cushing
Obesity, striae
Non functioning
Physiological
Ageing
Stress
Hemorrhage
Calcification –TB / histo
Nodular Androgenital
syndromes

36. Pheochromocytoma
4-6th decade
Adrenal medulla -
Hypertension / palpitation
Elevated urinary catecholamines
Marked heterogenous enhancement
10 % rule
Bilateral
Malignant
Children
Extra-adrenal
Familial
No Hypertension

37. Marked heterogenous enhancement in a patient with hypertension, confirmed to be
pheochromocytoma with urine VMA

38. Hypointense on t1, hyperintense on t2 , axial t1 pc with fat sat
– heterogenous enhancmeent

39. Out of phase images do not show loss of signal

40. Light bulb sign
Pheochromocytoma
Shows hyperintense signal on t2
weighted images
Neither sensitive nor specific

41. Extra-adrenal pheochromocytoma
MIBG scintigraphy
To be correlated with CT and MRI

42. Adrenal insufficiency
Earliest presenting feature is
hypovolemic shock
Causes
◦ Atrophy
◦ TB – Hyperplasia with
calcification
◦ Histoplasmosis - Hyperplasia

43. Adrenal haemorrhage
Uncommon
Non enhancing lesion
Adrenal hemorrhage is usually associated with
anticoagulant therapy or with stress caused by
surgery, sepsis or hypotension.
low attenuating left adrenal
mass with blood-fluid level suggestive of adrenal
hemorrhage

44. Adrenal-cortical carcinoma
Arise form cortex
Larger lesions - > 6cm
Heterogenous enhancement with calcification
Can invade adjacent organs

45. Large heterogenous mass in
left suprarenal region
invading into upper pole of
left kidney
Metastatic deposit in liver
Diagnosed with surety with clinical presentation of metastasis
or biopsy

46. Axial T1, T2 and T1 fat supressed enhanced MR images
Larger masses
Hypertension and weight loss
Large heterogenous left adrenal mass woth areas of necrosis
and haemorrhage (t1 bright foci)

47. Differentials
◦ Metastasis – typically smaller
◦ Pheochromocytoma – symptomatic
◦ Renal cell carcinoma – bulk of the lesion

48. Adrenal myelolipoma
Large masses
Usually non functioning
Characteristic CT appearance – due to fat
content
Calcfication and haemorrhage can be seen
Biopsy

49. Neuroblastoma
Arise anywhere in sympathetic chain
Most common adrenal
Infants and young children (major differentiating factor)
Heterogenous appearance with calcification and necrosis

50. Thank you

51. Differentials for lipid rich adenoma
Metastasis
Adrenocortical carcinoma
Pheochromocytoma
Granulomatous adrenal disease