Author: Jonathan Steinberger
NECT CECT - venous CECT - delayed MRI - T1 MRI - T2 MRI - Post-contrast T1 venous MRI - Post-contrast T1 delayed Gross Pathology Histology Additional comments
Malignancy:
Metastases Heterogeneous, irregularly shaped. Typically have little intracellular lipid content; if >10 Houndsfield Units, lesion is considered indeterminate and needs additional evaluation with contrast enhanced study Increased attenuation persistent enhancement of the adrenal gland, with no significant washout of contrast media at 10 minutes Usually exhibit low signal intensity on T1-weighted images Usually high signal intensity on T2-weighted images Lack of signal loss on out-of-phase images

no significant signal loss on out-of-phase images, spleen used as internal reference standard
Collision tumor Imaging characteristics depend on tissue types in the collison tumor;; Association of adenomatous tissue, fatty tissue, fibrotic tissue, and hemorrhagic vascular structures Imaging characteristics depend on tissue types in the collison tumor;; Association of adenomatous tissue, fatty tissue, fibrotic tissue, and hemorrhagic vascular structures. Fat elements may drop signal with suppression. Imaging characteristics depend on tissue types in the collison tumor;; Association of adenomatous tissue, fatty tissue, fibrotic tissue, and hemorrhagic vascular structures. Independently coexisting neoplasms without significant tissue admixture, may include fat and soft tissue components Imaging characteristics depend on tissue types in the collison tumor
Adrenocortical carcinoma enhances heterogeneously, often peripherally, with a thin rim of enhancing capsule seen in some cases

enhances heterogeneously, often peripherally, with a thin rim of enhancing capsule seen in some cases
tend to be large (6-20cm), with heterogeneous T1 signal tend to be large (6-20cm), with heterogeneous T2 signal tend to be large, with yellow and red components, large areas of hemorrhage
Pheochromocytoma May be homogeneous or heterogeneous, solid or cystic complex masses or may show calcification. Typically have attenutation >10 HU, although rarely can have lower attenuation Typically enhance avidly but can be heterogeneous or show regions of no enhancement due to cystic changes. Theoretical risk of iodinated contrast in pheochromocytoma so generally not used in standard practice Can demonstrate different and variable washout patterns and may again, therefore, be confused with either adenomas or metastases. Theoretical risk of iodinated contrast in pheochromocytoma so generally not used in standard practice Typically high signal intensity, and even more hyperintense on fat-suppressed T2-weighted images due to a signal intensity rescaling effect although can often be atypical and have low T2 signal Typically demonstrate avid enhancement, although enhancement dynamics can vary Washout patterns can be inconsistent Characteristically demonstrate a nesting (Zellballen) microscopic pattern composed of well-defined clusters of tumor cells containing eosinophilic cytoplasm separated by fibrovascular stroma Opposed phase imaging may not be able to distinguish from benign lesions, as intracellular fat content can vary

MIBG scintigraphy is often useful when clinically suspected pheochromocytoma cannot be localized, to confirm that a mass is a pheochromocytoma, or to exclude metastatic disease (highly specific, not sensitive). In practice, combination of F18 PET CT and C11 PET CT is most commonly used
Neuroblastoma Heterogeneous low signal intensity on T1-weighted images. Hemorrhagic areas may manifest as areas of high signal intensity on T1-weighted images High signal intensity on T2-weighted images. Cystic areas may appear hyperintense on T2-weighted images typically a soft, lobular tumor. Necrosis, hemorrhage, and calcification may be detected. Areas of tan stroma interposed between areas of hemorrhagic neuroblastic tissue are common
Lymphoma Discrete mass of variable attenuation or an infiltrative, ill-defined appearance

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Usually characterized as an area of low signal intensity on T1-weighted images No significant dropout on out of phase sequence

Radionuclide - PET usually demonstrates increased radionuclide uptake, but uptake can rapidly decrease after the use of appropriate chemotherapy
Ganglioneuroma/ Ganglioneuroblastoma Generally hypointense on T1-weighted images Usually heterogeneously but markedly hyperintense on T2-weighted images Delayed heterogeneous uptake of contrast material; the result is incomplete filling of the tumor without a centripetal tendency Delayed heterogeneous uptake of contrast material; the result is incomplete filling of the tumor without a centripetal tendency Densely fibrous, well-limited tumor Bundles of ganglion cells (*) encompassing the adrenal gland
Hemangiosarcoma Mass with punctate calcifications, intense peripheral enhancement, and a necrotic center Intense peripheral enhancement, commonly with necrotic center Bulky, irregular mass with internal vascular lakes Vascular clefts (*) lined with one or more layers of tumor cells
Benign:
Adenoma Smaller lesions with fat attenuation (<10 HU) Demonstrate hyperenhancement 10 minute delayed images should demonstrate > 50% decrease in attenuation (washout) as measured in Houndsfield Units Most adrenal adenomas decrease in signal intensity on out-of-phase images, and >20% reduction in signal is diagnostic

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Myelolipoma Low attenuation at CT compatible with fat elements Hyperintense on T1-weighted in-phase MR images with signal loss on fat suppressed sequences Fat and maturing marrow elements in otherwise normal adrenal cortex Text soon coming
Hemorrhage Characteristically round or oval with periadrenal fat stranding. Attenuation value depends on its age, with acute to subacute hematomas containing areas of high attenuation that usually range from 50 to 90 HU that decrease in size and attenuation over time and may calcify after 1 year MR imaging features vary according to the age of the hematoma. In acute (<7 days) period, hematoma typically isointense or slightly hypointense on T1-weighted images.

In the subacute stage (7 days to 7 weeks after onset), it appears hyperintense on T1-weighted images.

In the chronic stage (>7 weeks), a hypointense rim is present on T1-weighted images
In acute phase (<7 days), hematoma appears markedly hypointense on T2-weighted images due to a high concentration of intracellular deoxyhemoglobin. In subacute stage (7 days to 7 weeks after onset), the hematoma appears hyperintense on T2-weighted images. In the chronic stage (>7 weeks), a hypointense rim is present on T2-weighted images
Pseudocyst Complicated appearance on MR images, manifesting with septations, blood products, or a soft-tissue component secondary to hemorrhage or hyalinized thrombus Complicated appearance on MR images, manifesting with septations, blood products, or a soft-tissue component secondary to hemorrhage or hyalinized thrombus
Cyst Low T1 signal intensity High T2 signal Cystic lesion with simple cuboidal mesothelial lining
Asymmetric adrenal cortical hyperplasia Text soon coming Text soon coming

Text soon coming
Granulomatous disease (TB, Histoplasmosis) Unilateral or bilateral adrenal masses with central areas of necrosis

bilateral adrenal masses with low-attenuation centers and peripheral calcifications

adrenal masses caused by granulomatous disease or hemorrhage may involute and subsequently calcify
Soft-tissue masses with a nonspecific appearance are seen in the acute and subacute stages

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Lymphangioma Thin-walled cystic lesions with low signal intensity at T1-weighted imaging Thin-walled cystic lesion