DOI: 10.1148/rg.24si045514
RadioGraphics 2004;24:S73-S86
© RSNA, 2004
Adrenal Masses: MR Imaging Features with Pathologic Correlation1
Khaled M. Elsayes, MD,
Govind Mukundan, MD,
Vamsidhar R. Narra, MD,
James S. Lewis, MD, Jr,
Ali Shirkhoda, MD,
Aamer Farooki, MD and
Jeffrey J. Brown, MD
1 From the Mallinckrodt Institute of Radiology (K.M.E., G.M., V.R.N., A.F., J.J.B.) and Department of Surgical Pathology (J.S.L.), Washington University School of Medicine, 510 S Kingshighway Blvd, St Louis, MO 63110; and the Department of Radiology, William Beaumont Hospital. Royal Oak, Mich (A.S.). Presented as an education exhibit at the 2003 RSNA scientific assembly. Received March 19, 2004; revision requested April 14 and received May 3; accepted May 19. All authors have no financial relationships to disclose. Address correspondence to K.M.E. (e-mail: elsayesk@mir.wustl.edu).
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Abstract
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The detection of adrenal lesions has increased with the expanding use of cross-sectional imaging. Magnetic resonance (MR) imaging is often useful for characterizing adrenal masses. Adrenal masses can be classified into various groups on the basis of the presence of intracellular lipid, macroscopic fat, hemorrhage, and cystic changes and the vascularity and shape of the tumor. These imaging features can be used by the radiologist to suggest or confirm a diagnosis for most adrenal masses, including adenoma, hyperplasia, simple and complicated cysts, lymphangioma, myelolipoma, pheochromocytoma, hemorrhage, cortical carcinoma, neuroblastoma, lymphoma, and metastases. Adenomas and metastases are common, and a decrease in signal intensity on out-of-phase images can be used to differentiate between them. Carcinoma is a possible diagnosis if that decrease in signal intensity is heterogeneous. Benign disease is diagnosed if macroscopic fat or a homogeneous cystlike lesion is seen. Recognition of the typical MR imaging features is important because it often changes the treatment approach and may obviate surgery.
© RSNA, 2004
Index Terms: Adrenal glands, cysts, 86.31 • Adrenal gland, MR, 86.1214 • Adrenal gland, neoplasms, 86.32, 86.33
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LEARNING OBJECTIVES FOR TEST 1
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After reading this article and taking the test, the reader will be able to:
- Describe the MR imaging technique for the adrenal gland.
- Correlate imaging findings with pathologic features of adrenal masses.
- Differentiate and characterize various adrenal masses.
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Introduction
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The adrenal glands, which are well visualized with all magnetic resonance (MR) imaging examinations of the abdomen, are a common site of disease, with the frequency of adrenal abnormalities in the general population being 9% (1,2). Readers of MR images are often asked to further evaluate an adrenal lesion seen with another imaging modality such as computed tomography. In addition, adrenal lesions are often discovered incidentally at examinations performed for other purposes. Therefore, it is essential that all radiologists be well versed in the diagnosis and differentiation of adrenal lesions. A systematic approach for evaluating the adrenal gland with specific pulse sequences usually enables the diagnosis to be made with confidence. Herein, we review MR imaging of the adrenal glands from a practical standpoint. Each of the commonly seen adrenal lesions is discussed along with the specific MR imaging techniques used to diagnose them.
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Normal Anatomy
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Structure of the Adrenal Gland
The adrenal glands are two small, yellowish bodies located in the perirenal space, immediately anterosuperior to the upper pole of the kidneys. The adrenal glands are very vascular and receive blood supply from the superior, middle, and inferior suprarenal arteries, which originate from the inferior phrenic arteries, abdominal aorta, and renal arteries, respectively (Fig 1). Medullary veins emerge from the suprarenal hila to form the suprarenal veins, which drain to inferior vena cava (right side) and left renal vein (left side).
The adrenal gland is composed of an outer cortex and thinner inner medulla, which accounts for one-tenth of the gland by weight. The cortex is further subdivided into three zones: outer zona glomerulosa, middle zona fasciculata, and inner zona reticularis (Fig 2).
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Figure 2. Photomicrograph (original magnification, x40; hematoxylin-eosin [H-E] stain) of a normal adrenal gland specimen shows an outer capsule (C) and the cortical layers: zona glomerulosa (G), fasciculata (F), and reticularis (R). The medulla (M) is present centrally.
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Normal MR Imaging Appearance
On axial and coronal MR images, the right adrenal gland is located immediately posterior to the inferior vena cava and superior to the upper pole of the right kidney. It has a linear, inverted V, or Y configuration (Fig 3). The left adrenal gland is anteromedial to the upper pole of the kidney and posterior to the pancreas; it has a triangular, inverted Y, or V configuration. Normal adrenal glands range from 2 to 6 mm in thickness and from 2 to 4 cm in length.
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MR Imaging Technique
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The most important component of the adrenal MR imaging protocol is chemical shift imaging. Chemical shift imaging is performed with in-phase and out-of-phase spoiled gradient-recalled-echo (GRE) sequences, which, with some imaging units, can be combined into a single sequence. Our standard protocol for adrenal imaging includes the following sequences: (a) coronal T2-weighted imaging with half-Fourier rapid acquisition with relaxation enhancement (RARE) performed during a single breath hold; (b) axial turbo or fast spin-echo T2-weighted or long-echo-time inversion-recovery sequence performed during a single breath hold; (c) axial and coronal GRE T1-weighted chemical shift in-phase and out-of-phase imaging in the axial and coronal planes during a single breath hold; and (d) axial and coronal three-dimensional GRE sequence (eg, volumetric interpolated breath-hold examination [VIBE]), performed before and after administration of a gadolinium-based contrast agent and with breath hold.
For MR imaging units with lower field strengths, the key sequences would be turbo spin-echo or spin-echo T2-weighted imaging with fat saturation and chemical shift imaging. The echo time for in-phase and out-of-phase imaging is dependent on the individual field strength of a given unit.
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Fat-containing Adrenal Masses
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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 masses that contain intracellular fat have been shown to lose signal intensity on chemical shift out-of-phase images compared with in-phase images owing to the presence of intracellular lipid. Adrenal lesions that contain macroscopic fat demonstrate a loss of signal intensity on fat-saturated images. A loss of signal intensity at chemical shift imaging can be seen at fat-water interfaces, typically at the borders of such lesions (3).
Adrenal Adenoma
Adrenal adenomas are the most common adrenal lesions, found in 3% of cases at autopsy. The most important characteristic feature of adrenal adenoma is the presence of intracellular lipid. Chemical shift imaging is the most reliable technique for diagnosing adrenal adenoma. Most adrenal adenomas demonstrate a loss of signal intensity on out-of-phase images (4,5,7) (Fig 4). A decrease in signal intensity of more than 20% is considered diagnostic of an adenoma (6–9).
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Figure 4a. (a, b) Axial in-phase (a) and out-of-phase (b) MR images show an adrenal adenoma (arrow), which exhibits the typical decrease in signal intensity on the out-of-phase image. (c) Photograph of the specimen shows a well-circumscribed bright yellow nodule, an appearance that is typical of adrenocortical adenoma.
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Figure 4b. (a, b) Axial in-phase (a) and out-of-phase (b) MR images show an adrenal adenoma (arrow), which exhibits the typical decrease in signal intensity on the out-of-phase image. (c) Photograph of the specimen shows a well-circumscribed bright yellow nodule, an appearance that is typical of adrenocortical adenoma.
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Figure 4c. (a, b) Axial in-phase (a) and out-of-phase (b) MR images show an adrenal adenoma (arrow), which exhibits the typical decrease in signal intensity on the out-of-phase image. (c) Photograph of the specimen shows a well-circumscribed bright yellow nodule, an appearance that is typical of adrenocortical adenoma.
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Uniform enhancement on immediate contrast material–enhanced images is also typical of adenomas (10). Small, rounded foci of altered signal intensity may be seen within an adenoma owing to cystic changes, hemorrhage, or variation in vascularity. MR imaging findings do not allow the differentiation of functioning from nonfunctioning adenomas.
Rarely, adrenal adenomas may contain foci of hemorrhage. The appearance of blood products at MR imaging varies with their stage of evolution. Acute blood in the form of deoxyhemoglobin is isointense relative to muscle on T1-weighted images and has low signal intensity on T2-weighted images. Subacute blood in the form of methemoglobin is hyperintense on T1-weighted images (Fig 5). Initially, methemoglobin is intracellular and has low signal intensity on T2-weighted images. Subsequently, as the red cells lyse and the methemoglobin becomes extracellular, it has high signal intensity on T2-weighted images. Old hemorrhage has low signal intensity on both T1- and T2-weighted images because of the presence of hemosiderin. T1-weighted fat-saturated images are quite sensitive in the detection of methemoglobin. GRE images can magnify the susceptibility effects of decreased signal intensity seen with hemosiderin and deoxyhemoglobin, thereby increasing their conspicuity. Similarly, a lesion that loses a substantial amount of signal intensity on in-phase images compared with out-of-phase images obtained with a shorter echo time may contain blood products.
Myelolipoma
The myelolipoma is an uncommon benign tumor composed of mature adipose tissue and hematopoietic tissue. Most of these lesions are discovered incidentally. The fatty component of this tumor is hyperintense on non-fat-suppressed T1-weighted images. The use of fat suppression can help confirm the diagnosis by demonstrating a loss of signal intensity within the fatty component (Fig 6). Myelolipomas can be categorized into three main groups on the basis of their MR imaging features (11), as follows: (a) homogeneous, hyperintense masses on T1-weighted images with intermediate signal intensity on T2-weighted images, findings that are suggestive of lesions that are predominantly composed of fat; (b) heterogeneous masses containing foci with the same signal intensity as that of fat intermixed with focal high-signal-intensity areas on T2-weighted images and contrast-enhanced T1-weighted images, findings that are indicative of mixed fatty and myeloid elements; and (c) nodules that are hypointense relative to liver on T1-weighted images and hyperintense relative to liver on T2-weighted images and that enhance after administration of gadolinium chelate contrast material, resulting in an appearance of focal masslike areas primarily composed of myeloid cells.
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Figure 6a. (a, b) Axial T1-weighted MR images obtained without fat suppression (a) and with fat suppression (b) show typical MR imaging features of right adrenal myelolipoma. The fatty component of the myelolipoma (arrow in a) shows a decrease in signal intensity on the fat-suppressed image. (c) Photomicrograph (original magnification, x100; H-E stain) shows the typical microscopic appearance of myelolipoma. There is fat and a maturing marrow element on the right side and an otherwise normal adrenal cortex on the left.
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Figure 6b. (a, b) Axial T1-weighted MR images obtained without fat suppression (a) and with fat suppression (b) show typical MR imaging features of right adrenal myelolipoma. The fatty component of the myelolipoma (arrow in a) shows a decrease in signal intensity on the fat-suppressed image. (c) Photomicrograph (original magnification, x100; H-E stain) shows the typical microscopic appearance of myelolipoma. There is fat and a maturing marrow element on the right side and an otherwise normal adrenal cortex on the left.
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Figure 6c. (a, b) Axial T1-weighted MR images obtained without fat suppression (a) and with fat suppression (b) show typical MR imaging features of right adrenal myelolipoma. The fatty component of the myelolipoma (arrow in a) shows a decrease in signal intensity on the fat-suppressed image. (c) Photomicrograph (original magnification, x100; H-E stain) shows the typical microscopic appearance of myelolipoma. There is fat and a maturing marrow element on the right side and an otherwise normal adrenal cortex on the left.
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Myelolipomas can be large and symptomatic secondary to spontaneous hemorrhage. Large myelolipomas can be confused with other retroperitoneal lipomatous tumors such as liposarcoma.
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Cystic Masses
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Adrenal cysts are rare and are often detected incidentally during radiologic investigation or at autopsy. The frequency of adrenal cysts seen at autopsy studies ranges from 0.064% to 0.18% (12,13). Although adrenal cysts are usually asymptomatic, physical manifestations may consist of pain or palpable mass, especially with larger lesions. Acute symptoms can also occur with cyst hemorrhage, rupture, or infection.
Simple Cysts
Endothelialized cysts are the most common pathologic subtype of adrenal cyst, accounting for approximately 40% of adrenal cysts. Simple cysts are hypointense on T1-weighted images and hyperintense on T2-weighted images, with no soft-tissue component and no internal enhancement (Fig 7) (14).
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Figure 7a. (a, b) Coronal T1-weighted in-phase (a) and T2-weighted half-Fourier RARE (b) MR images show an oval, well-circumscribed, right adrenal cyst (arrow in b) with a thin wall (arrowhead in b). The cyst has a typical appearance, showing low signal intensity at T1-weighted imaging and high signal intensity at T2-weighted imaging. (c) Photomicrograph (original magnification, x100; H-E stain) shows a cystic lesion with a simple cuboidal mesothelial lining.
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Figure 7b. (a, b) Coronal T1-weighted in-phase (a) and T2-weighted half-Fourier RARE (b) MR images show an oval, well-circumscribed, right adrenal cyst (arrow in b) with a thin wall (arrowhead in b). The cyst has a typical appearance, showing low signal intensity at T1-weighted imaging and high signal intensity at T2-weighted imaging. (c) Photomicrograph (original magnification, x100; H-E stain) shows a cystic lesion with a simple cuboidal mesothelial lining.
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Figure 7c. (a, b) Coronal T1-weighted in-phase (a) and T2-weighted half-Fourier RARE (b) MR images show an oval, well-circumscribed, right adrenal cyst (arrow in b) with a thin wall (arrowhead in b). The cyst has a typical appearance, showing low signal intensity at T1-weighted imaging and high signal intensity at T2-weighted imaging. (c) Photomicrograph (original magnification, x100; H-E stain) shows a cystic lesion with a simple cuboidal mesothelial lining.
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Pseudocysts
Pseudocysts are the second most common cystic lesions of the adrenal gland, accounting for approximately 39% of adrenal cysts. They are more likely than simple adrenal cysts to be symptomatic. Pseudocysts typically arise after an episode of adrenal hemorrhage and do not have an epithelial lining. Adrenal pseudocysts may have a complicated appearance on MR images, manifesting with septations, blood products, or a soft-tissue component secondary to hemorrhage or hyalinized thrombus (Figs 8, 9) (12,13). Peripheral curvilinear calcification may be present, but it is difficult to appreciate on MR images (13,15).
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Figure 8a. (a) Axial T2-weighted MR image obtained with inversion recovery shows a left adrenal pseudocyst. Note the soft-tissue component in the wall and the posteriorly located calcification (arrow). (b) Photograph of the specimen shows a well-circumscribed cystic mass with abundant gummous tan material compressing the nearby kidney (arrowhead) without infiltrating it or the surrounding soft tissue.
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Figure 8b. (a) Axial T2-weighted MR image obtained with inversion recovery shows a left adrenal pseudocyst. Note the soft-tissue component in the wall and the posteriorly located calcification (arrow). (b) Photograph of the specimen shows a well-circumscribed cystic mass with abundant gummous tan material compressing the nearby kidney (arrowhead) without infiltrating it or the surrounding soft tissue.
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Figure 9. (a, b) Coronal T2-weighted MR image obtained with half-Fourier RARE (a) and axial contrast-enhanced VIBE image (b) show a left adrenal mass with areas of signal intensity similar to that of blood. (c) Photograph of the specimen shows a hemorrhagic complicated adrenal cyst with hyalinized material.
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Figure 9b. (a, b) Coronal T2-weighted MR image obtained with half-Fourier RARE (a) and axial contrast-enhanced VIBE image (b) show a left adrenal mass with areas of signal intensity similar to that of blood. (c) Photograph of the specimen shows a hemorrhagic complicated adrenal cyst with hyalinized material.
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Figure 9. (a, b) Coronal T2-weighted MR image obtained with half-Fourier RARE (a) and axial contrast-enhanced VIBE image (b) show a left adrenal mass with areas of signal intensity similar to that of blood. (c) Photograph of the specimen shows a hemorrhagic complicated adrenal cyst with hyalinized material.
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Lymphangioma
Cystic lymphangioma of the adrenal gland is rare and asymptomatic. MR imaging features of adrenal lymphangioma are similar to those of other lymphangiomas that arise elsewhere in the human body. Adrenal lymphangiomas can be visualized as thin-walled cystic lesions with low signal intensity at T1-weighted imaging and high signal intensity at T2-weighted imaging without substantial internal enhancement (16–18) (Fig 10).
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Figure 10a. (a) Coronal T1-weighted, three-dimensional, GRE MR image obtained with VIBE shows a lymphangioma, which has the typical appearance of a well-circumscribed area of low signal intensity. (b) Photograph of the specimen shows the thin-walled lymphangioma.
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Figure 10b. (a) Coronal T1-weighted, three-dimensional, GRE MR image obtained with VIBE shows a lymphangioma, which has the typical appearance of a well-circumscribed area of low signal intensity. (b) Photograph of the specimen shows the thin-walled lymphangioma.
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Hypervascular Lesions
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Pheochromocytoma
Pheochromocytomas are tumors that arise from pheochromocytes, the predominant cells of the adrenal medulla. Pheochromocytomas do not contain a substantial amount of cytoplasmic lipid, and, therefore, they maintain their signal intensity on out-of-phase GRE chemical shift images (Fig 11). Most pheochromocytomas demonstrate high signal intensity on T2-weighted images (light bulb sign). High signal intensity should not be used as a feature to suggest or exclude pheochromocytoma, because these tumors also manifest with moderate signal intensity on T2-weighted images (19,20). Most lesions show intense enhancement after the administration of contrast material (20,21).
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Figure 11a. (a-c) Axial T1-weighted in-phase MR image (a), out-of-phase MR image (b), and three-dimensional GRE contrast-enhanced MR image with VIBE (c) show a pheochromocytoma (arrow). The pheochromocytoma shows the typical features of no loss of signal intensity on the out-of-phase image and intense enhancement on the contrast-enhanced image. (d) Photograph of sections of the resected specimen shows a typical, homogeneous, well-circumscribed, tan-pink lesion, an appearance typical of pheochromocytoma.
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Figure 11b. (a-c) Axial T1-weighted in-phase MR image (a), out-of-phase MR image (b), and three-dimensional GRE contrast-enhanced MR image with VIBE (c) show a pheochromocytoma (arrow). The pheochromocytoma shows the typical features of no loss of signal intensity on the out-of-phase image and intense enhancement on the contrast-enhanced image. (d) Photograph of sections of the resected specimen shows a typical, homogeneous, well-circumscribed, tan-pink lesion, an appearance typical of pheochromocytoma.
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Figure 11c. (a-c) Axial T1-weighted in-phase MR image (a), out-of-phase MR image (b), and three-dimensional GRE contrast-enhanced MR image with VIBE (c) show a pheochromocytoma (arrow). The pheochromocytoma shows the typical features of no loss of signal intensity on the out-of-phase image and intense enhancement on the contrast-enhanced image. (d) Photograph of sections of the resected specimen shows a typical, homogeneous, well-circumscribed, tan-pink lesion, an appearance typical of pheochromocytoma.
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Figure 11d. (a-c) Axial T1-weighted in-phase MR image (a), out-of-phase MR image (b), and three-dimensional GRE contrast-enhanced MR image with VIBE (c) show a pheochromocytoma (arrow). The pheochromocytoma shows the typical features of no loss of signal intensity on the out-of-phase image and intense enhancement on the contrast-enhanced image. (d) Photograph of sections of the resected specimen shows a typical, homogeneous, well-circumscribed, tan-pink lesion, an appearance typical of pheochromocytoma.
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Pheochromocytoma has been called the 10% tumor. This designation is based on the fact that approximately 10% of pheochromocytomas are bilateral, 10% are extraadrenal, 10% occur in children, and 10% are malignant (22).
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Adreniform Adrenal Masses
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Adrenal Cortical Hyperplasia
Adrenal cortical hyperplasia is often seen in patients with Cushing syndrome (the result of hyperproduction of cortisol). The hyperplasia may be diffuse or nodular and is typically bilateral. The signal intensity of hyperplastic adrenal glands is usually similar to that of the normal adrenal gland. Their signal intensity may, however, decrease on out-of-phase images (Fig 12), especially in patients with adenomatous cortical nodules. Bilateral cortical hyperplasia is seen in 45% of patients with Cushing syndrome, whereas nodular cortical hyperplasia is seen in only 3% of these patients (23).
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Figure 12a. (a, b) Coronal in-phase (a) and out-of-phase (b) MR images show bilateral large, adreniform masses (arrows), which represent adrenal cortical hyperplasia. (c) Photomicrograph (H-E stain) shows that the adrenal cortex has extensive nodules of clear cells (arrows), a finding typical of adrenal cortical hyperplasia.
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Figure 12b. (a, b) Coronal in-phase (a) and out-of-phase (b) MR images show bilateral large, adreniform masses (arrows), which represent adrenal cortical hyperplasia. (c) Photomicrograph (H-E stain) shows that the adrenal cortex has extensive nodules of clear cells (arrows), a finding typical of adrenal cortical hyperplasia.
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Figure 12c. (a, b) Coronal in-phase (a) and out-of-phase (b) MR images show bilateral large, adreniform masses (arrows), which represent adrenal cortical hyperplasia. (c) Photomicrograph (H-E stain) shows that the adrenal cortex has extensive nodules of clear cells (arrows), a finding typical of adrenal cortical hyperplasia.
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Adrenal Hemorrhage
Adrenal hemorrhage can occur in the setting of trauma, adrenal vein thrombosis, stress, hypotension, and various bleeding diatheses. Adrenal insufficiency (Addison disease) can be a secondary effect of bilateral adrenal hemorrhage (24).
MR imaging is the most sensitive and specific modality for diagnosing adrenal hemorrhage. MR imaging features vary according to the age of the hematoma (Fig 13).
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Figure 13. Axial unenhanced T1-weighted three-dimensional GRE MR image obtained with VIBE demonstrates a right adrenal gland with a high-signal-intensity rim (arrows), a finding that is consistent with subacute hematoma.
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Malignant Neoplasms
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Adrenocortical Carcinoma
Primary carcinoma of the adrenal gland is a rare tumor, affecting approximately two patients per million (25). The peak prevalence of this disease occurs in patients 30–70 years of age. In general, the tumor is large at diagnosis, with diameters of more than 6 cm and up to 20 cm. Adrenocortical carcinoma can manifest as a hyperfunctioning mass causing Cushing syndrome or Conn syndrome (also known as primary aldosteronism). Other manifestations include an abdominal mass and abdominal pain.
Adrenocortical carcinomas are usually large at diagnosis and appear heterogeneous on both T1- and T2-weighted images owing to the presence of internal hemorrhage and necrosis (26) (Fig 14). Hemorrhagic byproducts, principally methemoglobin, can result in areas of high signal intensity within the lesion on T1-weighted images; areas of necrosis have high signal intensity on T2-weighted images. Adrenocortical carcinoma can contain foci of intracytoplasmic lipid, which results in a loss of signal intensity on out-of-phase images (26,27). Large adrenal carcinomas tend to invade the adrenal vein and inferior vena cava.
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Figure 14a. (a, b) Sagittal T1-weighted three-dimensional contrast-enhanced GRE MR image obtained with VIBE (a) and coronal T2-weighted MR image obtained with half-Fourier RARE (b) show a large mass involving the right adrenal gland. The mass exhibits heterogeneous low signal intensity on the T1-weighted image and high signal intensity with a heterogeneous pattern of contrast enhancement and areas of necrosis (arrow in b) on the T2-weighted image. (c) Photograph of the specimen shows a yellow and red tumor with large areas of necrosis, findings typical of adrenocortical carcinoma.
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Figure 14b. (a, b) Sagittal T1-weighted three-dimensional contrast-enhanced GRE MR image obtained with VIBE (a) and coronal T2-weighted MR image obtained with half-Fourier RARE (b) show a large mass involving the right adrenal gland. The mass exhibits heterogeneous low signal intensity on the T1-weighted image and high signal intensity with a heterogeneous pattern of contrast enhancement and areas of necrosis (arrow in b) on the T2-weighted image. (c) Photograph of the specimen shows a yellow and red tumor with large areas of necrosis, findings typical of adrenocortical carcinoma.
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Figure 14c. (a, b) Sagittal T1-weighted three-dimensional contrast-enhanced GRE MR image obtained with VIBE (a) and coronal T2-weighted MR image obtained with half-Fourier RARE (b) show a large mass involving the right adrenal gland. The mass exhibits heterogeneous low signal intensity on the T1-weighted image and high signal intensity with a heterogeneous pattern of contrast enhancement and areas of necrosis (arrow in b) on the T2-weighted image. (c) Photograph of the specimen shows a yellow and red tumor with large areas of necrosis, findings typical of adrenocortical carcinoma.
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Adrenal Lymphoma
Lymphoma occasionally involves the adrenal glands, with non-Hodgkin lymphoma being more common than Hodgkin disease at this site. Bilateral involvement is seen in 50% of patients (Fig 15). Lymphoma is usually characterized as an area of low signal intensity on T1-weighted images and as an area of heterogeneous high signal intensity on T2-weighted images (28), with minimal progressive enhancement after administration of contrast material.
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Figure 15a. (a, b) Axial T1-weighted in-phase (a) and out-of-phase (b) MR images show bilateral lymphomatous deposits. The deposits have low signal intensity, and the signal intensity does not decrease on the out-of-phase compared with the in-phase image. (c) Photomicrograph (H-E stain) shows moderately pleomorphic large tumor cells in sheets, with abundant apoptosis and mitotic activity. These findings helped characterize this diffuse large cell lymphoma that manifested as an adrenal mass.
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Figure 15b. (a, b) Axial T1-weighted in-phase (a) and out-of-phase (b) MR images show bilateral lymphomatous deposits. The deposits have low signal intensity, and the signal intensity does not decrease on the out-of-phase compared with the in-phase image. (c) Photomicrograph (H-E stain) shows moderately pleomorphic large tumor cells in sheets, with abundant apoptosis and mitotic activity. These findings helped characterize this diffuse large cell lymphoma that manifested as an adrenal mass.
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Figure 15c. (a, b) Axial T1-weighted in-phase (a) and out-of-phase (b) MR images show bilateral lymphomatous deposits. The deposits have low signal intensity, and the signal intensity does not decrease on the out-of-phase compared with the in-phase image. (c) Photomicrograph (H-E stain) shows moderately pleomorphic large tumor cells in sheets, with abundant apoptosis and mitotic activity. These findings helped characterize this diffuse large cell lymphoma that manifested as an adrenal mass.
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Metastases
Metastases are the most common malignant lesions involving the adrenal gland. Adrenal metastases are found in up to 27% of patients with malignant epithelial tumors at autopsy (29).
Common primary sites of tumors that metastasize to the adrenal glands include the lung, bowel, breast, and pancreas (30). Metastases are usually bilateral but may also be unilateral. Adrenal metastases usually exhibit low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, with progressive enhancement after administration of contrast material (Fig 16). The most important diagnostic feature is the lack of signal loss on out-of-phase images (in contradistinction to that seen with adrenal adenoma) (6–9,31).
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Figure 16a. (a, b) Axial T2-weighted MR image obtained with inversion recovery (a) and contrast-enhanced T1-weighted MR image obtained with VIBE (b) show metastasis from renal cell carcinoma, which has a central area of necrosis. (c) Photograph of the specimen shows tan to yellow nodules of focally hemorrhagic tumor (left side, arrow) within an otherwise normal yellow and brown adrenal cortex and medulla (right side).
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Figure 16b. (a, b) Axial T2-weighted MR image obtained with inversion recovery (a) and contrast-enhanced T1-weighted MR image obtained with VIBE (b) show metastasis from renal cell carcinoma, which has a central area of necrosis. (c) Photograph of the specimen shows tan to yellow nodules of focally hemorrhagic tumor (left side, arrow) within an otherwise normal yellow and brown adrenal cortex and medulla (right side).
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Figure 16c. (a, b) Axial T2-weighted MR image obtained with inversion recovery (a) and contrast-enhanced T1-weighted MR image obtained with VIBE (b) show metastasis from renal cell carcinoma, which has a central area of necrosis. (c) Photograph of the specimen shows tan to yellow nodules of focally hemorrhagic tumor (left side, arrow) within an otherwise normal yellow and brown adrenal cortex and medulla (right side).
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Pediatric Neoplasms
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Neuroblastoma is the most common extracranial solid tumor in children. Other adrenal tumors, such as pheochromocytoma, adrenocortical carcinoma, and lymphoma, are rare in children.
Neuroblastoma
Neuroblastoma is the second most common pediatric abdominal mass (after Wilms tumor), representing about 5%–15% of all malignant tumors in children (32). This lesion arises from the neural crest in the adrenal medulla or along the sympathetic chain. In general, neuroblastoma is clinically silent until it invades or compresses adjacent organs, metastasizes, or causes paraneoplastic syndromes. Neuroblastoma usually demonstrates heterogeneous low signal intensity on T1-weighted images, high signal intensity on T2-weighted images (Fig 17), and enhancement after administration of contrast material. Calcification is present in 80%–90% of the lesions, but it is difficult to discern on MR images. Areas of intratumoral hemorrhage typically have high signal intensity on T1-weighted images (Fig 17). Cystic changes have high signal intensity on T2-weighted images. MR imaging has been found to be more sensitive than CT in the diagnosis of these tumors owing to its higher soft-tissue contrast resolution and multiplanar capabilities that allow excellent detection of the tumor origin (33–37).
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Figure 17a. (a, b) Coronal unenhanced T1-weighted MR image (a) and axial T2-weighted MR image obtained with inversion recovery (b) show a right adrenal tumor. The tumor is predominantly hypointense on the T1-weighted image and has areas of high-signal-intensity hemorrhage (arrow in a). The tumor is hyperintense on the T2-weighted image. (c) Photograph of the specimen shows a lobulated and hemorrhagic-appearing neuroblastoma originating in the adrenal gland. (Case courtesy of Marilyn Siegel, MD, Mallinckrodt Institute of Radiology, Washington University, St Louis, Mo.)
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Figure 17b. (a, b) Coronal unenhanced T1-weighted MR image (a) and axial T2-weighted MR image obtained with inversion recovery (b) show a right adrenal tumor. The tumor is predominantly hypointense on the T1-weighted image and has areas of high-signal-intensity hemorrhage (arrow in a). The tumor is hyperintense on the T2-weighted image. (c) Photograph of the specimen shows a lobulated and hemorrhagic-appearing neuroblastoma originating in the adrenal gland. (Case courtesy of Marilyn Siegel, MD, Mallinckrodt Institute of Radiology, Washington University, St Louis, Mo.)
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Figure 17c. (a, b) Coronal unenhanced T1-weighted MR image (a) and axial T2-weighted MR image obtained with inversion recovery (b) show a right adrenal tumor. The tumor is predominantly hypointense on the T1-weighted image and has areas of high-signal-intensity hemorrhage (arrow in a). The tumor is hyperintense on the T2-weighted image. (c) Photograph of the specimen shows a lobulated and hemorrhagic-appearing neuroblastoma originating in the adrenal gland. (Case courtesy of Marilyn Siegel, MD, Mallinckrodt Institute of Radiology, Washington University, St Louis, Mo.)
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Ganglioneuroblastoma
The malignant potential of ganglioneuroblastoma is intermediate—between that of neuroblastoma and ganglioneuroma. Similar to neuroblastomas, ganglioneuroblastomas also arise from the neural crest. Ganglioneuroblastoma tends to be smaller and more well defined than neuroblastoma at diagnosis (38). It usually demonstrates intermediate signal intensity on T1-weighted images (Fig 18) and heterogeneously high signal intensity on T2-weighted images, with heterogeneous moderate enhancement after administration of contrast material (31).
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Figure 18a. (a) Axial in-phase T1-weighted MR image shows a heterogeneous mass with intermediate signal intensity involving the right adrenal gland. (b) Photograph of the specimen shows a dark brown to tan lobulated ganglioneuroblastoma with areas of necrosis and compression of the adjacent kidney. There is a rim of residual yellow cortex.
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Abstract
LEARNING OBJECTIVES FOR TEST...
