Adrenal Masses: MR Imaging Features with Pathologic Correlation By : Nour Eldin Mohammed Ref: Khaled M. Elsayes, et al , 2004, Radiographics

Normal Anatomy The adrenal glands are two small, yellowish bodies located in the perirenal space, immediately anterosuperior to the upper pole of the kidneys. They are very vascular and receive blood supply from the superior, middle, and inferior suprarenal arteries

The adrenal gland is composed of an outer cortex and thinner inner medulla. The cortex is further subdivided into three zones: outer zona glomerulosa, middle zona fasciculata, and inner zona reticularis

Normal MRI Appearance The right adrenal gland is located posterior to the inferior vena cava and superior to the upper pole of the right kidney. The left adrenal gland is anteromedial to the upper pole of the kidney and posterior to the pancreas Normal adrenal glands range from 2 to 6 mm in thickness and from 2 to 4 cm in length

Fat-containing Adrenal Masses Fat-containing adrenal masses can be classified into two main types: those that contain intracellular fat (eg, adenoma) and those with macroscopic fat (eg, myelolipoma).

Adrenal Adenoma The most common adrenal lesions. Characterised by the presence of intracellular lipid. Chemical shift imaging is the most reliable technique for diagnosing adrenal adenoma with loss of signal intensity on out-of-phase images. Uniform enhancement with contrast enhanced images is typical of adenomas. Cystic changes, hemorrhage, or variation in vascularity lead to small, rounded foci of altered signal intensity.

Axial in Phase MRI Axial out of phase MRI

Myelolipoma The myelolipoma is an uncommon benign tumor composed of mature adipose tissue and hematopoietic tissue. Mostly discovered accidentally. The fatty component of this tumor is hyperintense on T1- weighted images. With loss of signal intensity of the fatty component on Fat-Suppressed Technique.

Axial T1 with Fat Suppressed Technique Axial T1 MRI

Cystic Masses These include : Simple Cysts Pseudocysts Lymphangioma

Simple Cysts T1 Coronal MRI T2 Coronal MRI

Pseudocysts Pseudocysts typically arise after an episode of adrenal hemorrhage and do not have an epithelial lining. Have a complicated appearance on MR images, manifesting with septations, blood products, or a soft- tissue component secondary to hemorrhage or hyalinized thrombus. Peripheral curvilinear calcification may be present.

Coronal T2 MRI Axial T1 with Contrast

Lymphangioma Low signal intensity at T1-weighted imaging and high signal intensity at T2-weighted

Hypervascular Lesions (Pheochromocytoma) It arises from the adrenal medulla. 10% of pheochromocytomas are bilateral,10% are extraadrenal,10% occur in children, and 10% are malignant Pheochromocytomas do not contain a substantial amount of cytoplasmic lipid, So they maintain their signal intensity on out-of-phase GRE chemical shift images. Most pheochromocytomas demonstrate high signal intensity on T2-weighted images (light bulb sign).

Axial T1 in Phase MRI Axial T1 out of Phase MRI Contrast-enhanced Image

Malignant Neoplasms Adrenocortical Carcinoma Adrenal Lymphoma Metastases

Adrenocortical Carcinoma a rare tumor. Age : 30 - 70 Large size Can manifest as a hyperfunctioning mass causing Cushing syndrome or Conn syndrome. Other manifestations include an abdominal mass and abdominal pain.

Sagittal 3D contrast-enhanced MRI Coronal T2-weighted MRI

Adrenal Lymphoma More with non-Hodgkin lymphoma Bilateral involvement occurs in 50% of patients . Characterized by low signal intensity on T1 WI and heterogeneous high signal intensity on T2 WI , with minimal progressive enhancement after administration of contrast material.

Axial T1-weighted MRI Axial T2-weighted MRI

Metastases The most common malignant lesions involving the adrenal gland. Found in up to 27% of patients with Carcinomas at autopsy. Common primary sites of tumors that metastasize to the adrenal glands include the lung, bowel, breast, and pancreas. Usually bilateral but may also be unilateral.

Contrast Enhanced T1 Image Of Metastatic Deposit From Renal Cell Carcinoma

Pediatric Neoplasms Neuroblastoma Ganglioneuroblastoma

Neuroblastoma The 2nd most common pediatric abdominal mass (after Wilms tumor). Representing 5%–15% of all malignant tumors in children . Arises from the neural crest in the adrenal medulla or along the sympathetic chain. Usually demonstrates heterogeneous low signal intensity on T1-weighted images, high signal intensity on T2-weighted images , and enhancement after administration of contrast material. Calcification is present in 80%–90% of the lesions

Coronal unenhanced T1 MRI Axial T2 MRI

Ganglioneuroblastoma Intermediate in malignancy between that of neuroblastoma and ganglioneuroma arise from the neural crest. Ganglioneuroblastoma are smaller and more well defined than neuroblastoma Demonstrates Intermediate signal intensity on T1 WI and heterogeneously high signal intensity on T2 WI, with heterogeneous enhancement after administration of contrast material.

T1-WI shows a heterogeneous mass with intermediate signal intensity

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