CT & MRI EVALUATION OF ADRENAL GLAND

TUMOURS

PRESENTED BY: :

DR. BHISHM PRATAP SEVENDRASEEN BY :DR. KANCHANA PACHHIGAR

Anatomy

Each adrenal gland have a body and two limbs -medial and lateral.

The right adrenal gland is pyramidal in shape while the left adrenal gland is crescenteric .

 Each adrenal gland is enclosed in the perirenal fascia .

Each limb normally measures <5mm in width and the body should measure <10mm in width . 

The adrenal size is larger in neonates and infants, being almost one-third of the size of the kidney . 

Right adrenal gland 

Right adrenal is seen directly superior to the upper pole of the right kidney, with its most caudal portion just anterior to the upper pole.

CT: linear, V-shape or comma-shape .

Relations

medial -  right crus of the diaphragm, right inferior phrenic nerve.

lateral - right lobe (bare area) of the liver anterior - IVC posterior - right kidney

Right crus of diaphragm

IVC

Right adrenal gland

Right lobe of liver

Left adrenal gland

The left adrenal may be seen at the same level as the right, but often it is slightly more caudal.

It is antero-medial to the upper pole of the left kidney.

CT: in the same slice as the left kidney & appears as a triangular or Y-shape .

Relations

Medial - left crus of the diaphragm, left inferior phrenic nerve.

Antero-medial – diaphragm. Anterior - less sac, stomach, splenic artery,

pancreas. Posterior & laterally- left kidney

Left adrenal gland

Left crus of diaphragm

Left kidney

stomach

Splenic artery

pancreas

Tumours of the adrenal gland Adrenal adenoma Adrenal carcinoma Pheochromocytoma Neuroblastoma Adrenal metastases Adrenal myelolipoma

Adrenal adenoma

Commonest adrenal mass lesion.

Often found incidentally termed “incidentaloma”.

Incidence: increase in frequency with age.

Majority: non-functioning (asymptomatic). In all cases, but especially in the setting of known

current or previous malignancy, adrenal adenomas need to be distinguished from adrenal metastasis or other adrenal malignancies.

CT two properties that differentiate them from non-

adenomas.

1. 70% of adenomas : lipid-rich(HU<10).

2. Adenomas rapidly wash out contrast.

30% of adenomas: lipid-poor (HU >10), and cannot be differentiated from malignant masses on an unenhanced CT .

CT-Algorithm benign versus malignant

Enhanced and Delayed scan

On the initial enhanced CT (at 60 sec):

Most adenomas : mild enhancement.

Malignant tumors and pheochromocytoma : strong enhancement.

but there is too much overlap in attenuation values to allow differentiation between malignant and benign.

A number of these adenomas however can be differentiated from malignant masses on the basis of their fast wash-out of contrast.

The wash-out can be calculated by comparing the attenuation value at 60 sec with the attenuation value on a delayed scan at 15 minutes.

Absolute enhancement wash out > 60% = adenoma. Relative enhancement wash out > 40% = adenoma.

dedicated adrenal protocol in a patient with an adrenal mass.

On the unenhanced CT : well defined small homogeneous mass HU=9.which is characteristic of a lipid-rich adenoma.

i.v. contrast was given to determine the washout.

The enhancement washout = (43 - 22) : (43 - 9) = 62% indicating a fast washout characteristic of an adenoma.

Typical nonenhanced CT findings of an adrenal adenoma in a 64-year-old man with no known malignancy. The left adrenal adenoma has smooth margins, is well defined, and has a attenuation of 5 HU, all findings characteristic of an adenoma.

MRI

Chemical shift imaging: is the most reliable for diagnosis especially when CT findings are equivocal.

It has high sensitivity to minute amounts of intravoxel fat.

On opposed-phase:  a drop in signal intensity of greater than 20% is considered diagnostic for an adenoma .

Signal intensity index=SI on in phase-SI on opposed phase x100 SI on in phase

Rather than measuring the signal, one can compare the adenoma in and out of phase, with images windowed similarly (using the spleen or muscle as a reference )

Do not use the liver as it can change signal on in phase and out of phase imaging depending on presence of  hepatic steatosis) .

right adrenal lesion in T1 in phase image appears iso-intense to liver

Signal drop in right adrenal lesion in T1 out phase image

Adrenal cortical carcinoma

A primary adrenal cortical carcinoma is a highly malignant but rare neoplasm.

It may present as a hormonally active or inactive tumour.

CT

A large inhomogeneous mass with heterogeneous enhancement.

Central necrosis is common.

Calcification is seen in 20-30% of cases.

A 68-year-old woman with a large right upper quadrant primary adrenocortical carcinoma with curvilinear calcification. Low-attenuation regions anteriorly are consistent with necrosis

MRI Useful to determine hepatic invasion if CT is

inconclusive. Heterogeneous mass is seen that is of high signal

on T2 sequences. Heterogeneous enhancement is seen with

administration of gadolinium.

Adrenal metastases

Most common malignant lesions.

 Metastases are usually bilateral but may also be unilateral.

Morphologic criteria with the density measurements on unenhanced CT.

high accuracy in differentiating adrenal adenomas from metastases in patients with a known malignancy.

scoring system :

In patients with a known extra-adrenal malignancy a total score > 7 points was highly accurate for the diagnosis metastasis.

CT

variable appearances .

Usually demonstrates less than 50% washout.

MRI Exact signal characteristics depend on the type of

tumour.

T1 - low signal intensity. T2 -  high signal intensity. C+ (Gd) - usually has progressive enhancement

after administration of contrast material . 

An important diagnostic feature is the lack of signal loss on out-of-phase images (in contradistinction to that seen with adrenal adenoma)

T1-weighted MRI demonstrates left adrenal metastasis in a patient with previous resection of the right liver lobe for metastasis.

Pheochromocytoma Uncommon tumour of the adrenal gland, with

characteristic clinical, and to a lesser degree, imaging features.

The tumours follow a 10% rule:  ~ 10% are extra-adrenal ~ 10% are bilateral ~ 10% are malignant ~ 10% are found in children ~ 10% are familial ~ 10 % are not associated with hypertension

Radiographic features.

large at presentation, average size of ≈ 5 cm.

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 . 

CT  Large heterogeneous masses with areas of

necrosis and cystic change. 

Up to 7% demonstrate areas of calcification . 

Contrast may be contraindicated as it could precipitate a hypertensive crisis.

MRI

most sensitive . particularly useful in cases of extra-adrenal location.

T1slightly hypointense .

T2markedly hyperintense .

T1 C+ (Gd)heterogenous enhancementenhancement is prolonged.

Pheochromocytoma on CT and MRI. There is strong enhancement on enhanced CT and very high signal intensity on T2-weighten MRI.

Neuroblastoma

The most common extracranial solid childhood malignancies and the third commonest childhood tumor after leukemia and brain malignancies. 

CT CT: heterogeneous with calcifications.

The morphology of is often most helpful, with the mass seen insinuating itself beneath the aorta and lifting it off the vertebral column. It tends to encase vessels and may lead to compression.

Adjacent organs are usually displaced, although in more aggressive tumours direct invasion of the psoas muscle or kidney can be seen.

MRI

T1 - heterogeneous and iso to hypointense T2 -

heterogeneous and hyper intense.

C+ (Gd) - variable and heterogeneous enhancement

Neuroblastoma

calcification ( 90%) encases vascular structures but does not invade

them younger age group (< 2 years of age) poorly marginated more common to have extension into chest elevates the aorta away from the vertebral column

Wilms tumour

calcification :(10 - 15%) displaces adjacent structures with out

insinuating between them. well circumscribed slightly older age group : peak 3 - 4

years of age extension into IVC / renal vein

neuroblastoma Wilms tumour

Adrenal myelolipoma

Adrenal myelolipomas are rare benign tumours of the adrenal gland.

CT

Well circumscribed mass with fat-containing components.

calcifications may be seen.

MRI

T1 - hyper intense. T1 (FS) - shows fat suppression. T2 - intermediate to hyper intense. T1 C+ (Gd) - shows striking enhancement.

in and out of phase - demonstrate signal loss as the macroscopic fat cells usually have little intracellular water .

Bilateral myelolipoma in a 79-year-old man. Nonenhanced CT scan shows an exophytic mass of fat attenuation (straight arrow) in the right adrenal gland. The left adrenal gland has a soft-tissue mass containing calcifications and a central area of fat attenuation (curved arrow).

LEFT: adrenal mass containing islands of fat specific for the diagnosis myelolipoma. RIGHT: different case with high SI on T1WI indicating fat in myelolipoma.

Adrenal hyperplasia Adrenal hyperplasia refers to non malignant

growth (enlargement) of the adrenal glands.

cause of 70% of the cases of Cushing's syndrome and 20% of the cases of Conn syndrome.

In diffuse hyperplasia, the limbs of the adrenal glands exceed 5mm thickness. 

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