CME article 11
|Imaging in Adrenal hemorrhage: Review & Protocol|
Dr. Ashok Raghavan, Manipal
Nontraumatic hemorrhage of the
adrenal gland is uncommon. The causes of such hemorrhage can be
classified as stress, hemorrhagic diathesis or coagulopathy, neonatal
stress, underlying adrenal tumors, and idiopathic disease.
US is the examination of choice
in neonates with suspected adrenal hematoma. Initial US
typically reveals a complex, echogenic mass. If the mass is
large, the kidney may be displaced inferiorly. Regression of
the mass over a period of weeks is shown on serial US scans
(Fig 1 & 2).
Fig 1 (subacute stage)
Fig 2: Wall calcification noted
The appearance of an adrenal hematoma in a patient without an underlying adrenal condition depends on the age of the patient and the age of the hematoma.
3: Chronic adrenal hematoma (adrenal pseudocyst)
US is the modality of choice for initial and follow-up evaluation of a flank mass in a neonate. In neonates, the normal adrenal glands are clearly visualized at US and consist of a hypoechoic cortex and a thin, echogenic medulla. The pattern of echogenicity of an adrenal hematoma depends again on its age. An early-stage hematoma appears solid with diffuse or inhomogeneous echogenicity. As liquefaction occurs, the mass demonstrates mixed echogenicity with a central hypoechoic region and eventually becomes completely anechoic and cystlike. Calcifications may be seen in the walls of the hematoma as early as 1–2 weeks after onset and gradually compact as the blood is absorbed. Color Doppler and power Doppler imaging allow confirmation of the avascular nature of the mass.
In the acute
stage (less than 7 days after onset), the
hematoma typically appears isointense or slightly hypointense
on T1-weighted images and markedly hypointense on T2-weighted
images due to a high concentration of intracellular deoxyhemoglobin,
which leads to preferential T2 proton relaxation enhancement.
In the subacute
stage (7 days to 7 weeks after onset), the hematoma appears
hyperintense on T1- and T2-weighted images.
In the chronic
stage (7 weeks after onset), a hypointense rim
is present on T1- and T2-weighted images due to
preferential T2 proton relaxation enhancement, which is attributed
to hemosiderin deposition and the presence of a fibrous capsule.
Calcifications are not evident on MR images.
: Suprarenal masses are rarely appreciable on
plain radiographs unless curvilinear or eggshell calcifications are
present. Ipsilateral atelectasis and small pleural effusions may
be seen at the lung bases.
A large adrenal hematoma appears as a relatively lucent
suprarenal mass; urography is helpful in distinguishing an
adrenal mass from the adjacent kidney, which may be displaced inferiorly.
Angiography is rarely used to evaluate an adrenal hematoma.
Angiography can demonstrate the vascular supply of an
adrenal mass and occasionally shows the contour of an adrenal
cyst and hematoma or neovascularity in a tumor associated with
a hematoma, but the findings are not diagnostic.
Medicine: An adrenal hematoma typically appears as
a photopenic suprarenal mass with inferior displacement of the
Needle Aspiration, Biopsy, and Drainage: In most
cases, the presence of the typical imaging features of hemorrhage
obviates fine-needle aspiration. CT- or US-guided percutaneous
aspiration and drainage are usually indicated when an
adrenal abscess is suspected.
Computed tomography (CT),
ultrasonography (US), and magnetic resonance (MR) imaging
play an important role in diagnosis and management. CT is
the modality of choice for evaluation of adrenal hemorrhage
in a patient with a history of stress or a hemorrhagic diathesis
or coagulopathy (anticoagulant therapy). CT may yield the
first clue to the diagnosis of adrenal insufficiency secondary to
bilateral massive adrenal hemorrhage. US is the modality of choice for
evaluation of neonatal hematoma, and MR imaging is helpful for
further characterization. MR imaging is also useful in the
diagnosis of coexistent renal vein thrombosis. When an
adrenal abscess is suspected, percutaneous aspiration and
drainage under imaging guidance should be performed.
Hemorrhage into an adrenal cyst or tumor can cause acute
onset of symptoms and signs in a patient without
discernible risk factors for adrenal hemorrhage. A hemorrhagic adrenal
tumor should be suspected when CT or MR imaging reveals a
hemorrhagic adrenal mass of heterogeneous attenuation or signal intensity
that demonstrates enhancement.