• Seidenwurm DJ, Davis PC, Brunberg JA, De La Paz RL, Dormont PD, Hackney DB, Jordan JE, Karis JP, Mukherji SK, Turski PA, Wippold FJ II, Zimmerman RD, McDermott MW, Sloan MA, Expert Panel on Neurologic Imaging. Neuroendocrine imaging. [online publication]. Reston (VA): American College of Radiology (ACR); 2006. 11 p. [44 references]

This is the current release of the guideline.

This guideline updates a previous version: Seidenwurm D, Drayer BP, Anderson RE, Braffman B, Davis PC, Deck MD, Hasso AN, Johnson BA, Masaryk T, Pomeranz SJ, Tanenbaum L, Masdeu JC. Neuroendocrine imaging. American College of Radiology. ACR Appropriateness Criteria. Radiology 2000 Jun;215(Suppl):563-71.

The appropriateness criteria are reviewed annually and updated by the panels as needed, depending on introduction of new and highly significant scientific evidence.

ACR Appropriateness Criteria®

Clinical Condition: Neuroendocrine Imaging

Variant 1: Hypopituitarism.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 2: Obesity/eating disorder.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 3: Hyperthyroidism (high TSH).

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 4: Cushing's syndrome (high ACTH).

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 5: Hyperprolactinemia.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 6: Acromegaly/gigantism.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 7: Dwarfism (proportionate).

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 8: Diabetes insipidus.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 9: Pituitary apoplexy.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 10: Postoperative sella.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

Variant 11: Precocious puberty.

Note: Abbreviations used in the tables are listed at the end of the "Major Recommendations" field.

The imaging approach to the hypothalamic pituitary axis is based on specific endocrine testing suggested by clinical signs and symptoms. Endocrine disorders are generally characterized by excess or deficiency of specific hormones. Hormone excess is diagnosed under conditions that would ordinarily suppress hormone secretion. Endocrine deficiencies are diagnosed on the basis of hormone measurements under conditions of stimulation. Specific clinical syndromes of hormonal disorders are determined by the physiologic role of that particular hormone.

The hypothalamic pituitary axis consists of two separate neuroendocrine organs, the anterior pituitary system and the posterior pituitary system. The hormones of the anterior pituitary are TSH, ACTH, prolactin (PRL), growth hormone (GH), and the gonadotropins (follicle stimulating hormone [FSH] and luteinizing hormone [LH]). These are secreted under the influence of hypothalamic trophic factors, corticotrophin releasing factor (CRF), thyrotropin releasing factor (TRF) and somatostatin- and gonadotropin-releasing hormone (GnRH). Prolactin release is under the control of a dopaminergic circuit. The hypothalamic-releasing hormones are transported to the pituitary gland by the hypophyseal portal system.

The posterior pituitary gland consists of axonal terminations of neurons whose cell bodies are located in the hypothalamus. The principal hormones secreted by these cells are oxytocin and vasopressin or antidiuretic hormone (ADH). The hypothalamus also participates in complex mediation of food intake, temperature regulation, sleep and arousal, memory, thirst, and other autonomic functions.

Structural causes of obesity, anorexia, central hypothermia and hyperthermia, insomnia and hypersomnia are only very rarely demonstrated in the hypothalamus and pituitary gland. Imaging in patients who present with these symptoms absent other specific neurological or endocrine abnormality is almost always unrewarding. An exception is in children in whom the "diencephalic syndrome" of hypothalamic lesions is relatively common. Also precocious puberty in children can result from hypothalamic lesions.

Pituitary adenomas are the most common lesions of the pituitary gland. These may secrete prolactin, TSH, GH, ACTH, or gonadotropins. Prolactinomas are the most common and are generally present as microadenomas in premenopausal females with amenorrhea and galactorrhea. Prolactin elevation by itself is nonspecific and may be due to a variety of medical, neurological, or pharmacological causes as well as pituitary adenoma, depending on serum hormone level. In males, prolactinomas may be entirely asymptomatic until visual symptoms occur, due to compression of the chiasm, or they may result in hypogonadotropic hypogonadism with loss of libido and impotence. Growth-hormone-secreting tumors generally present as larger lesions manifesting clinical acromegaly. Because of the gradual onset of deformity, these tumors may be present for many years and grow to substantial size prior to their detection. In a prepubertal individual the growth-hormone-secreting tumor may result in gigantism. TSH- and ACTH-secreting tumors may present at very small size because the impact of their hormone product is usually apparent more rapidly. Gonadotropin-secreting tumors are rare.

Precocious puberty and other neurological symptoms can be produced by hypothalamic lesions such as hamartoma. MRI is generally indicated in all patients with endocrinologically confirmed precocious puberty, especially when rapid progression of development and neurological symptoms are present. Posterior pituitary dysfunction with loss of antidiuretic hormone results in the clinical syndrome of diabetes insipidus. This may occur as a transient phenomenon after trauma or neurosurgical procedures. The etiology is usually evident, and the phenomenon is frequently transient. Imaging is performed to search for the cause of stalk transsection, which can be a manifestation of numerous sellar or parasellar pathologies, trauma, or congenital. Rarely, the hormone is absent developmentally. The syndrome of inappropriate ADH is usually due to an extracranial source. Frequently this is a paraneoplastic phenomenon related to small-cell lung carcinoma, though a variety of pulmonary diseases and pharmacological disturbances can result in syndrome of inappropriate antidiuretic hormone secretion (SIADH).

Other common mass lesions that may affect the neuroendocrine system are germ-line tumors, meningioma, craniopharyngioma, and Rathke's cleft cyst among others. Metastatic lesions may affect the sella. Sarcoid and other inflammatory processes occur in the sellar and suprasellar regions as well. Pituitary apoplexy is a syndrome of headache ophthalmoplegia and visual loss that results from pituitary hemorrhage. In the postpartum period, pituitary infarcts may occur, and hypophysitis is an uncommon disorder resulting in endocrine disturbance and other symptoms.

Classically, plain radiography and pluridirectional x-ray tomography was the mainstay of sellar imaging. CT largely replaced these modalities through the seventies and eighties. More recently, MRI has largely supplanted CT. MRI for sellar pathology includes thin-section multiplanar imaging with slice thickness of 3 mm or less, often before and after contrast administration. Other techniques that are used for evaluation of this anatomical region are CTA, MRA, direct catheter angiography, and petrosal sinus sampling.

Plain radiography and pluridirectional tomography are insensitive and nonspecific imaging modalities for evaluating sellar pathology. Pituitary microadenoma and even small pituitary macroadenomas are frequently associated with a normal sella size. The sella turcica can be enlarged when no neoplasm or mass is present. This is due to pulsations of cerebral spinal fluid (CSF) transmitted through a developmental or acquired dehiscence of the diaphragm sella in the empty sella syndrome. Therefore, these imaging modalities are rarely, if ever, employed productively in the evaluation of endocrine disease.

CT revolutionized evaluation of the sella and suprasellar region. Due to the ability of CT, especially with intravenous contrast, to depict pathology within the unenlarged sella, and its ability to visualize suprasellar pathology noninvasively, this technique facilitates accurate diagnosis of neuroendocrine abnormality. Pituitary microadenomas and macroadenomas are reliably detected. There is, however, difficulty at times in distinguishing the tumor from the optic chiasm, diagnosis of cavernous sinus invasion is difficult, and on occasion, cystic lesions of the suprasellar region may be confused with normal CSF. Additionally, artifact due to dental amalgam, difficulty in obtaining reliable contrast enhancement and awkward positioning for direct coronal scanning limit the utility of this imaging modality. In the hands of experienced radiologists this technique can result in excellent diagnostic accuracy, though the examinations are sometimes difficult to interpret despite excellent technique.

MRI provides excellent noninvasive evaluation of the hypothalamus and pituitary gland. It is the only imaging modality that reliably depicts the hypothalamus in a useful fashion. It depicts the anatomy of the pituitary gland, infundibulum, optic chiasm, cavernous sinuses and neighboring vascular structures accurately and noninvasively. The addition of gadolinium facilitates diagnosis of microadenoma and increases the confidence with which cavernous sinus invasion can be diagnosed or excluded. The specific bony landmarks may be difficult to demonstrate but the signal pattern of sphenoid sinus mucosa permits assessment of septa for operative planning. Visualization of vascular structures in the parasellar region or even intrasellar carotid artery loop or aneurysm is crucial in some cases.

Angiography is reserved for those patients in whom vascular pathology is known or suspected on the basis of clinical or radiological findings. Aneurysm is the most important vascular lesion in the parasellar region, but these lesions rarely present as endocrine disorders. Knowledge of vascular anatomy guides surgery. Occasionally, a sellar lesion may grow to displace or encase the carotid arteries or other major intracranial vessels. Interventional neuroradiology procedures can be planned on the basis of CTA, MRA, or catheter angiography.

Petrosal sinus venous sampling is reserved for those cases in which a definite excess of pituitary hormone is present, medical management has failed, sectional imaging is negative or equivocal and surgery is planned. When a significant discrepancy in hormone level, usually ACTH, exists between the vessels studied, tumor localization is very accurate. Complications occur uncommonly in experienced hands.

A significant problem encountered in CT and MRI of the pituitary, particularly when endocrine findings suggest microadenoma, is the false-positive examination. Since the endocrine studies confirm the presence of a lesion, and first-line therapy is usually medical, false negative examinations are less problematic once chiasmatic compression has been excluded. Approximately 20% of the population may harbor small incidental nonfunctioning adenomas or cysts. It is important, therefore, that the probability of disease be high in the target population if positive MRI is to be relied upon for surgical planning. Additional problems are created by variations in size of the pituitary gland, which occur normally in response to physiological hormonal changes. The gland may enlarge in puberty and pregnancy. Pituitary hyperplasia in hypothyroidism may simulate a pituitary adenoma in some patients. Similar problems arise in imaging the posterior pituitary since up to 29% of normal subjects do not demonstrate a bright posterior pituitary.

Abbreviations

• ACTH, adrenal corticotrophic hormone
• CT, computed tomography
• CTA, computed tomography angiography
• INV, invasive
• MRA, magnetic resonance angiography
• MRI, magnetic resonance imaging
• TSH, thyroid stimulating hormone

Algorithms were not developed from criteria guidelines.

The recommendations are based on analysis of the current literature and expert panel consensus.

• Seidenwurm DJ, Davis PC, Brunberg JA, De La Paz RL, Dormont PD, Hackney DB, Jordan JE, Karis JP, Mukherji SK, Turski PA, Wippold FJ II, Zimmerman RD, McDermott MW, Sloan MA, Expert Panel on Neurologic Imaging. Neuroendocrine imaging. [online publication]. Reston (VA): American College of Radiology (ACR); 2006. 11 p. [44 references]

Not applicable: The guideline was not adapted from another source.

1999 (revised 2006)

American College of Radiology - Medical Specialty Society

The American College of Radiology (ACR) provided the funding and the resources for these ACR Appropriateness Criteria®.

Committee on Appropriateness Criteria, Expert Panel on Neurologic Imaging

Panel Members: David J. Seidenwurm, MD; Patricia C. Davis, MD; James A. Brunberg, MD; Robert Louis De La Paz, MD; Pr. Didier Dormont; David B. Hackney, MD; John E. Jordan, MD; John P. Karis, MD; Suresh Kumar Mukherji, MD; Patrick A. Turski, MD; Franz J. Wippold II, MD; Robert D. Zimmerman, MD; Michael W. McDermott, MD; Michael A. Sloan, MD, MS

Not stated

This is the current release of the guideline.

This guideline updates a previous version: Seidenwurm D, Drayer BP, Anderson RE, Braffman B, Davis PC, Deck MD, Hasso AN, Johnson BA, Masaryk T, Pomeranz SJ, Tanenbaum L, Masdeu JC. Neuroendocrine imaging. American College of Radiology. ACR Appropriateness Criteria. Radiology 2000 Jun;215(Suppl):563-71.

The appropriateness criteria are reviewed annually and updated by the panels as needed, depending on introduction of new and highly significant scientific evidence.

None available

This summary was completed by ECRI on July 31, 2001. The information was verified by the guideline developer as of August 24, 2001. This summary was updated by ECRI on August 17, 2006. This summary was updated by ECRI Institute on May 17, 2007 following the U.S. Food and Drug Administration (FDA) advisory on Gadolinium-based contrast agents. This summary was updated by ECRI Institute on June 20, 2007 following the U.S. Food and Drug Administration (FDA) advisory on gadolinium-based contrast agents.