IMAGING APPROACH OF

ADRENAL MASSES

DR S CHAKRABORTYRESIDENT RADIODIAGNOSIS

ANATOMY

BLOOD SUPLY

PHYSIOLOGY

ADRENAL CORTEX zona glomerulosa-

glucocorticoids zona fasciculata and the

zona reticularis- cortisols and androgens

zona fasciculata contains the large, clear lipid-laden cells- RAD IMG IMP

ADRENAL MEDULLA- derived from

neuroectodermal tissue and contains catecholamine-producing cells - chromaffin cells

Norepinephrine and epinephrine

ADRENAL MASSES

NEOPLASTIC1. CORTEX2. MEDULLA3. STROMA4. METS

NON-NEOPLASTIC1. GRANULOMAS2. B/L HYPERPLASIA3. CYST4. HMG

STRUCTURES SIMULATE ADRENAL MASS

I. Renal cysts or tumours2. Spleen and accessory spleen3. Pancreatic cyst or tumour4. Liver mass5. Para-aortic glands6. Retroperitoneal tumour7. Stomach mass.

PLAIN X RAY AND IVU

CALCIFICATION IN ADRENAL

MASS IN SUPRARENAL REGION

DISPLACEMENT OF KIDNEY

ADRENAL CALCIFICATION

IDIOPATHIC NEOPLASM GRANULOMA CYST OLD HMG WOLMAN’S DS

USS

Primarily reserved for use in the paediatric population

RT > LT Loco regional N/

Pathological structures Routine screening

ADRENAL VENOUS SAMPLING

Measurement of the endocrine function of the adrenal glands - Primary hyperaldosteronism

No apparent adrenal gland abnormalities on either CT or MRI

Each adrenal vein is cannulated with a catheter via either a transfemoral or a transjugular approach- measure aldosterone

RADIONUCLIDE IMG

To demonstrate the functional status of adrenal nodules or masses shown on anatomical imaging

To assess function in the contra lateral adrenal To confirm bilateral disease in pituitary-driven

syndromes To detect extra-adrenal or ectopic sites of

hormone production To detect functioning metastases in patients with

primary malignant adrenal tumours To detect recurrences after surgery

ADRENAL CORTEX

Seleno-nor –cholesterol scintigraphy

After day 3-5, posterior view is taken

DMSA scintigraphy used to confirm anatomical location

Conn- unilateral uptake Cushing- B/L symmetrical

uptake

CONN'S SYNDROME

Primary hyperaldosteronism most common cause is a unilateral aldosterone-

secreting adrenal adenoma (60%). Adrenal hyperplasia (40%) and, very rarely, functioning adrenocortical carcinomas

Adrenal vein sampling may be performed in equivocal cases of CT or MRI to localize disease process

CUSHING'S SYNDROME

Chronic excess of circulating glucocorticoids ACTH-dependent Cushing's syndrome is

secondary to Cushing's disease (pituitary hypersecretion of ACTH) or ectopic ACTH secretion by peripheral tumors

ACTH independent etiologies of Cushing's syndrome include adrenal adenoma and adrenocortical carcinoma

CUSHING'S SYNDROME

Initial imaging evaluation- of pituitary Adrenal adenoma- 2-4 cm low density mass Adrenocortical carcinomas-large mixed-density

masses (10 to 15 cm) Thickness of the unaffected limbs of the adrenal

gland – cortisol cause atrophy

ADRENOGENITAL SYNDROME

Excessive secretion of sex hormones and causes virilization, feminization, or precocious puberty

MC- congenital adrenal hyperplasia secondary to an enzymatic deficiency in adrenal steroid synthesis

IMG- uniformly enlarged adrenal glands Both benign adrenal adenomas and adrenocortical

carcinomas may be the cause

ADRENAL INSUUFICIENCY

ADRENAL MEDULLA

Scintigraphy with MIBG is highly accurate in localisation of pheochromocytoma and neuroblastoma

Images after 4 and 24 hr of injection

Staging, response to Rx and to find recurrence

CHARACTERIZATION OF AN ADRENAL MASS

Hormonal Functionality Benignity versus Malignancy1. Size (> 4 cm) and shape2. Lipid content3. Enhancement pattern

BASIC WORK UP- CT

NCCT   HU < 10, benign; no

further workup If HU > 10, go on to either

contrast-enhanced CT study or chemical shift MRI

CECT: Obtain delayed (10- to 15-minute) images

If HU< 24 on 15-minute delay scan, probably benign

If RPW < 40% or APW < 60 % perform percutaneous biopsy or PET imaging

If RPW > 40% or APW> 60 % benign; no further workup

BASIC WORK UP- MRI

If discovered incidentally on chemical shift MRI If signal dropout occurs on opposed-phase

images, benign; no further workup If no signal dropout occurs on opposed-phase

images, consider contrast-enhanced study or, especially if known malignancy, consider PET or percutaneous biopsy.

ROLE OF CT

Benign lesions contain a significant amount of intracellular cytoplasmic lipid

Adenomas, whether lipid rich or lipid poor, typically have both rapid contrast enhancement and rapid subsequent washout of contrast material over time

CT histogram determines the number of pixels in an adrenal mass, which has a negative HU value

CONTRAST WASHOUT MEAS

RPW- No NCCT prior to CECT. RPW - enhanced attenuation minus the delayed

attenuation over the enhanced attenuation (E – D/E).

APW- NCCT prior to CECT. APW- enhanced attenuation minus the delayed

attenuation over the enhanced attenuation minus the precontrast attenuation (E – D/E – N).

ROLE OF MRI

clinically significant lesions have a larger component of fluid than adenomas and are therefore generally brighter on T2-weighted images

The contrast enhancement washout patterns of adenomas and non adenomas are similar to CT – less reliable and not cost effective

CHEMICAL SHIFT IMG

The magnetic moments of the protons in fat molecules are oriented in the same direction as the protons in water molecules when they are “in-phase.”

However, because of their differing phase frequencies, the protons are oriented in opposite directions when they are “opposed-phase.”

CHEMICAL SHIFT IMG

This opposite orientation results in signal cancellation, or “signal dropout” in adrenal masses that have both intracellular lipid and water within the same voxel when compared to the in-phase sequence

Benign lesion- Signal loss on on the opposed-phase sequence

Malignant lesion- No Signal loss

CHEMICAL SHIFT IMG

Lesion signal intensity should be compared with that of spleen on both in-phase and out-of-phase images

SI index - (SI on in-phase imaging – SI on opposed-phase imaging)/(SI on in-phase imaging)

Pitfalls – non homogenous signal loss of adenoma and collision tumors (adenoma + Mets)

POSITRON EMISSION TOMOGRAPHY

Fusion CT PET has been found to be near 100% sensitive and 93.8% specific for detecting malignant lesions

Adrenal gland masses are considered positive for malignancy when the activity within the adrenal mass is more intense than background activity or more intense than normal liver parenchyma

POSITRON EMISSION TOMOGRAPHY

Traditional nuclear medicine examination for the evaluation of adrenal disease was metaiodobenzylguanidine (MIBG)

Fluorodeoxyglucose (18FDG) is a radiolabeled analogue of glucose used in PET imaging that is taken up by tissues according to the tissue's metabolic rates

malignant diseases of the adrenal gland have higher metabolic rates than either normal adrenal glands or benign disease, and they are therefore more likely to be positive on an FDG PET study.

BENIGN ADRENAL ADENOMAS

ADRENAL METASTASES

On CT- gland to appear larger and less well defined ( HU > 20)

Bilateral, and have an inhomogeneous centre with a thick, irregularly enhancing rim

T1 SI -low or intermediate,T2- hyper intense

Larger metastases may have central necrosis

ADRENOCORTICAL CARCINOMA

large mass, which often involves much of the peri adrenal region

degenerative, cystic, and/or hemorrhagic changes, and 33% contain calcifications

Contrast enhancement is often intense but is typically heterogeneous on both CT and MRI

MYELOLIPOMA

round, well-marginated encapsulated masses

US- hyperechoic CT- low-density fat are

interspersed with foci of high-attenuation myeloid tissue

MRI- lose SI with fat suppression

NEUROBLASTOMA

Plain X ray and IVU- large mass with calcification and displacement of kidney

US- echogenic to heterogenous

CT- vessel invasion, LN MIBG – primary and mets

NEUROBLASTOMA VS WILM’S

GANGLIONEUROMA

Calcification in a paraspinal mass

CT- low attenuation MRI- intermediate SI on T1

and T2, early enhancement and little washout

Atypical component & spinal canal invasion may present

PHEOCROMOCYTOMA

PHEOCROMOCYTOMA

ADRENAL HEMORRHAGE

Common in neonates Post traumatic, sepsis,

anticoagulation treatment, perinatal period, tumour hmg

CT- round or oval hyperdense mass

US- echogenic lesion Calcification and

psudocyst formation

MRI- 1. < 7 days -iso or hypo on

T1. Markedly hypo on T2 (intracellular deoxy haemoglobin)

2. 7 d- 2 mo- hyperintense on both T1and T2 ( free methemoglobin)

3. High SI rim sign

ADRENAL CYST

PERCUTANEOUS ADRENAL BIOPSY

Indications- to exclude metastasis, to identify primary adrenal tumors, infectious disease of the adrenal gland, and adrenal hemorrhage

Technique- CT guided coaxial technique- transhepatic or posterior approach for right and posterior approach for left gland

Complication- adrenal haemorrhage Percut ablation- tumour or cyst

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