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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
THANK YOU