Diagnostic Ultrasound - Abdomen and Pelvis

Adrenal Hemorrhage
TERMINOLOGY
Abbreviations
• Adrenal hemorrhage (AH), adrenal hematoma
Definitions
• Hemorrhage within adrenal gland or adrenal tumor
IMAGING
General Features
• Best diagnostic clue
○ Well-defined, avascular homogeneous or heterogeneous
adrenal mass in proper clinical context
Ultrasonographic Findings
• Grayscale ultrasound
○ Unilateral or bilateral
○ Round or oval, well-defined adrenal mass with variable
echogenicity depending on stage of hemorrhage
– Acute hematoma: Hyperechoic
– Subacute hematoma: Mixed echogenicity ± central
hypoechoic area
– Chronic hematoma: Hypo- or anechoic cyst-like lesion
□ ± curvilinear/eggshell calcification &/or internal
echoes or layering debris
○ Asymmetric adeniform enlargement of adrenal gland
○ May see adjacent area(s) of ill-defined hypoechoic fluid
or fluid collections related to adjacent organs (e.g., liver
or kidney)
○ Displacement & mass effect on kidney & IVC
• Color Doppler
○ Avascular on color Doppler
○ Secondary adrenal hemorrhage shows variable
vascularity of underlying adrenal tumor
– Adrenal carcinoma/pheochromocytoma; usually
hypervascular
– Myelolipoma/adrenal cyst; hypo- to avascular
○ ± extension of thrombus into IVC
CT Findings
• Acute or subacute hematoma
○ Round or oval mass of high attenuation (50-90 HU)
○ May show heterogeneous density with evolving/layering
hyperdensity
○ No enhancement with contrast
○ Periadrenal fat infiltration
○ Thickening of adjacent diaphragmatic crura
○ ± associated upper abdominal trauma findings
– Pneumothorax, hydropneumothorax, rib fracture
– Contusion of lung, liver, spleen, or pancreas
• Chronic hematoma
○ Decreases in size and attenuation over time, leading to
– Adrenal atrophy
– Hemorrhagic pseudocyst = thin-rimmed collection
with central hypoattenuation close to simple fluid
○ Lack of enhancement
○ Calcification: Usually seen after 1 year in adults
– Neonates: Seen within 1-2 weeks after trauma
• ± underlying adrenal mass (pheochromocytoma, adrenal
carcinoma, myelolipoma, or cyst)
○ Intralesional calcification and enhancing components
suggest underlying tumor
MR Findings
• T1 & T2WI: Varied signal based on age of hematoma
• Acute hematoma (< 7 days after onset)
○ T1WI: Isointense or slightly hypointense
○ T2WI: Markedly hypointense
• Subacute hematoma (7 days to 7 weeks after onset)
○ T1WI: Hyperintense; due to free methemoglobin
○ T2WI: Markedly hyperintense; due to serum & clot
○ Large hematoma: Irregular clot lysis; multilocular, fluidfluid
levels
• Chronic hematoma (beyond 7 weeks after onset)
○ T1 & T2WI: Hyperintense hematoma; due to persistence
of free methemoglobin
○ T1 & T2WI: Hypointense rim; due to hemosiderin
deposition in fibrous capsule
• Gradient-echo imaging
○ Demonstrates "blooming" effect (magnetic
susceptibility) due to hemosiderin deposition
• T1WI C+ FS: Can be helpful in detecting intralesional
enhancement
Nuclear Medicine Findings
• PET/CT: May show increased activity due to inflammatory
reaction from fat necrosis
○ Look for lack of associated enhancing mass to exclude
underlying tumor
○ Can see calcification with underlying tumor or chronic
adrenal hematoma
Imaging Recommendations
• Best imaging tool
○ US for initial screening & detection followed by CT/MR
for further characterization
– Left adrenal gland can be difficult to see on US, &
small lesions may be obscured
• Protocol advice
○ CT: Thin sections < 3 mm
○ MR: Include gradient-echo imaging to look for
susceptibility artifact
DIFFERENTIAL DIAGNOSIS
Adrenal Adenoma
• Hypoechoic mass on US and homogeneously hypodense on
CT ± calcification
• However, lacks associated findings of adjacent fluid
collection or periadrenal fat stranding
• Shows avid enhancement with contrast
Pheochromocytoma
• Variable appearance; purely solid (68%), complex (16%), &
cystic tumor (16%)
• Large tumors may appear purely solid with homogeneous
(46%) or heterogeneous (54%) echo pattern
• Predominantly cystic lesions are due to chronic hemorrhage
& necrotic debris (± fluid-fluid levels)
Myelolipoma
• Well-defined homogeneous echogenic mass (when fat cells
predominate)
Diagnoses: Adrenal Gland
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