CT Scan of the Adrenal Glands and Anatomy

Tuesday, March 28, 2017

CT Scan of the Adrenal Glands

    CT scan has become the modality of choice in the detection and characterization of adrenal glands masses. This utilization can be traced to two major developments. First, because CT scan is so frequently used in the diagnosis of abdominal symptoms and disorders, it often uncovers unsuspected adrenal masses. In fact, because the CT Scan studies are often ordered as a result of unrelated symptoms and the adrenal masses are found incidentally, researchers have copied the term incidentalomas to describe them. Second, CT has gained widespread acceptance as the technique of choice for differentiating adrenal adenomas this are benign adrenal masses from matasteses.

Characteristic of Adrenal Masses

    The characterization of adrenal masses is accomplished by assessing their attenuation values and by evaluating the degree of iodinated contrast agent that is washed out of the mass on delayed imaging. Because accurate characterization often requires an adjustment in the scan protocol, CT scan technologist should be familiar with current information. An astute radiologic technologist can save a patient the time, money and the radiation exposure of a repeat scan examination by identifying an incidentaloma and tailoring the study to provide the radiologist with the data necessary to characterize the mass as benign or malignant.

We begin by reviewing the basic anatomy and physiology of the adrenal gland. Common adrenal gland disorders are defined. The background material is followed by a look at literature that outlines the role of CT scan in the detection and characterization of adrenal abnormalities.

Anatomy and Physiology of the Adrenal Gland

    The adrenal glands are part of the endocrine system endocrine system is a group of specialized organs and body tissue that produce, store, and secrete chemical substances known as hormones. As the body’s chemical hormones transfer information and instruction from one set of cells to another. Endocrine glands do not have ducts to transport their products. Unlike the endocrine glands, exocrine glands such as the mammary and salivary glands possess duct to carry their secretory products to a surface.

What is Endocrine Glands?

    The word endocrine glands produce hormones that are secreted directly into the blood and are the carried throughout the body, where they influence only those cells that have receptor sites for that hormone.

What is Adrenal Glands?

    The adrenal glands are complex endocrine organs named for their location, which is adjacent to the kidneys “thus to name ad-renal”. They are also occasionally referred to as suprarenal glands. “supra means above”. Located at the top of each kidney, they are triangular, and a normal gland weighs about 5grams

adrenal gland anatomy
The triangular-shaped adrenal glands are
located at the top of both kidneys.

    On the cross sectional image, adrenal glands have a characteristic Y, V or T shape. Encased in a connective tissue capsule and usually partially buried in an island of fat, the adrenal glands, like the kidneys, are retroperitoneal, that is they lie posterior to the peritoneum.

adrenal ct scan
On a cross-sectional image, the adrenal gland
has a characteristic Y, V, or T shape.

    The outer portion of the gland is called the cortex and the inner substance is called the medulla. Although the adrenal cortex and adrenal medulla are structurally 1 organ, they function as 2 separate glands. The cortex and medulla of the adrenal gland, like the anterior and posterior lobes of the pituitary, develop from different embryonic tissues and secretes different hormones. The adrenal cortex is important to life, but the medulla may be removed with no life threatening effects. The hypothalamus of the brain influences both portions of the adrenal gland.

What is the Adrenal Cortex and Functions?

    Adrenal Cortex has 3 different zones or layers and cells make up the adrenal cortex. Each region produces a different group or type of hormone. Chemically, all the cortical hormones are steroid derivatives. That is, molecularly they all in contain the 4-ring structure of the sterol nucleus. Mineralocoticoids are secreted by the outermost region of the adrenal cortex. As their name suggest, mineralocoticoids play an important part in regulating mineral salt called electrolyte metabolism. Glucocortiroids are secreted by the middle region of the adrenal cortex. Their main function is to affect the metabolism in diverse ways. They decrease inflammation and increase resistance to stress. The innermost zone of the adrenal cortex, the zona reticularis, secretes gonadocorticoids, or the sex hormones. Male hormones adrogens and female hormones estrogens are secreted in both sexes by the adrenal cortex, but their effect is usually masked by the hormones from the testes and ovaries. Tumors of the adrenal cortex that secrete large amounts of androgens are known as virilizing tumors because they produce masculinizing effects in the patient.

Adrenal Medulla

    The adrenal medulla secretes two catecholomines, about 80% epinephrine and 20 norepinephrine. Catecholamines is the general name for the group of compounds that mediate signaling in the symphathetic stimulation does, they serve to increase and prolong symphathetic effects. Increased epinephrine secretion by the adrenal medulla is one of the body’s first responses to stress.

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