DEPARTMENT OF MEDICAL RADIOGRAPHY AND

RADIOLOGICAL SCIENCES. Wi+[ k!$ RADIOLOGICAL EXAMINATION OF SRLLAR TURCLEA IN

b n

A SEMINAR

PRESENTED IN PARTIAL, FULFILLMENT OF THE

REQUIREMENT OF

THE COURGE

RG. 532 RESEARCH SEMINAR

PATIENTS WITH PITUITARY ADENOMAS.

BY

ARONYI EVERISTUS OBlNNA

REG NO: 98190652

TITLE PAGE

RADIOLOGICAL EXAMINATION OF SELLAR TURCICA IN

PATIENTS WITH PITUITARY ADENOMAS.

TABLE OF CONTENT

Titlepage - - - - - - - -1

CHAPTER ONE

I . 1 Introduction - - - - - - - -- 1

1.2 Brief Anatomy & Physiology of Pituitary Gland- - -2

CHAPTER TWO

2.1 Diseases of the Pituitary Gland - - - - - - -5

2.2 Signs and Symptoms of Pituitary Adenorna - -- - - 6

3.4 Effect of Pituitary Adenoma - - - -- -7

CHAPTER THREE

3.0 Radiological Techniques- -- - - -- 10

3.1 Skull Radiography- - - - - - - -10

Lateral Projection- - - - - - - - -1 1

Occipito-Frontal (With Angu1ation)- - -- - - - -1 1

Fronto-Occipital (With Angu1ation)- - - - - -13

Tomography- - - - - -- - I S

Pneumoencephalography -- - - - - - -16

Computed Tomography- - - - - - - -18

- Angiogrphy- -- - - - - - - - - -19

Conclusion- - - - -- --- - - -20

References. - - - - - -- -21

CHAPTER ONE

RADIOLOGICAL INVESTIGATION OF SELLAR TURCTCAL IN

PATIENT WITH PITUITARY ADENOMAS.

l .I Introduction:

Neoplasm or tumor according to eminent British Oncologist, Willis, is an

abnormal mass of tissue, the growth of which exceeds and in uncoordinated with

that of normal tissue and persist in the same excessive manner after cessation of

the stimulus which evoked the change1. All tumors are grouped into two broad

categories-benign and malignant depending on their level of anaplasia and

proliferation. Benign tumors are designated by attaching the suffix -oma to the

cell of origin. Tumors of epithelial origin or tumors derived from glands are

termed adenoma. Therefore pituitary adenoma is an abnormal growth of the

pituitary gland.

Owing to the fact that this growth is abnormal, it is purposeless and preys on

the host and above all. it disrupts the structure and function of the organ involved.

In pituitary adenoma, the functionality and structure of the pituita~y gland is

uttered. This impairment of pituitary gland function which is the master gland

whose secretion controls other endocrine gland results in a hydra- headed effect as

it lead to the impairment of growth, lactation, female reproduction functioning,

thyroid functioning and adrenal gland function. It is therefore imperative that

accurate diagnosis of pituitary adenoma be made at the early stage to forestall these

ugly incidences.

1.2 BRIEF ANATOMY AND PHYSIOLOGY OF PITUITARY GLAND.

Y 6. R - r r c i - ~ - h m w s

Pituitary gland is a bean shaped organ measuring one centimeter in its largest

diameter but it enlarges during pregnancy. l t lies in the sella turcica, a bony cavity

in the base of the skull. Physiological, the pituitary gland in divided into two

morphological and functionally distinct components- the anterior pituitary lobe

neurohypophysis. Between this is a relatively small avascular zone called the pars-

inter-media'. The anterior pituitary lobe consists of about 80% of the gland and is

derived embryologically from Rathke's pouc'h which is an extension of the

developing oral Cavity but was eventually cut off from its origin by the growth of

the sphenoid bone which creates the saddle like depression called the sella turcica.

The anterior pituitary lobe is attached to the hypothaIamus by means of the

pituitary stalk. Also the anterior pituitary lobe contains five major different types

of cells with different function. These include the somatrotrophs which produces -

the growth hormone, the lactotrophs which produces proIactin that simulates the

- mammary gland, the corticotrophs which produces the adenocorticosterol hormone

- which is active in cell metabolism, the thyrotrophs which produces the thyroid

- stimuIating hormone and the gonadotrophs which produces the follicular

stimulating hormone and the luteinizing hormone. The posterior pituitary lobe on -

the other hand is derived embryologicalIy from the outpouching of the third

- ventricle, which grow down alongside the anterior lobe. The posterior lobe

- consisted of two groups of cells which produce anti-diuretic hormone (ADH)

which regulates water excretion from the body and oxytocin which reIeases the -

milk during suckling. The cells are made up of nerve fibres whose cell bodies lies

in the hypothalamus and releases those hormone in respone to nerve impulses from

these nerve5. The hormone from the anterior pituitary lobe is carried from the

hypothalamus by hypophyseal portal veins, while those from posterior pituitary

lobe are carried by both arterial and venous supply.

Relationships of pituitary gland.

Superiorly, the pituitary gland is related to the diaphragm sella.

Anteriorly, it is related to the optic chiasma

Inferiorly, the body of sphenoid and the sphenoid sinus.

Laterally is the dura and the cavernous sinus and its contents.

CHAPTER TWO

2.1 DISEASE OF THE PITUITARY GLAND.

The disease of the pituitary gland can be divided into two, those that primarily

affects the anterior pituitary lobe and those that predominately affects the posterior

lobe of the pituitary gland. Disease of the anterior pituitary lobe may come into

clinical attention because of the increased or decreased secretion of hormone

designated hyperpituitarism and hypopituitarism respectively. In most case,

hyperpituitarism is caused by a functional adenomas within the anterior lobe3.

These adenomas can be named according to the type of cell involved. Pituitary

adenornas are also designated microademomas if they are less than one centimeter

in diameter or macroadenomas if they exceeds one centimeter in diameter. The

following are different types of pituitary and their frequency of occurrence. I I I I Pituitary Adenomas I Frequency I

! Growth hormone cell adenoma i 5 I Prolactine ceIl adenoma 20-30 I

I

h i r e d growth hormone prolactin adenoma

( Gonadotroph cell adenorna ! 10-1 5 I

5 I Adenocorticotropic Hormone adenoma 10-15

Null cell adenomas

1 Thyroid stimulating hormone cell adenoma

On the other hand, disease of the posterior pituitary lobe can come into

clinical attention because of increased or decreasesed secretion of one of its

products, anti-diuretic hormone (ADH).

Hypopituitarism can result from diseases of the hypothalamus or of the

pituitary. Hypofimction of the anterior pituitary occurs when approximately 75%

of the parenchyma is lost or absent4. But in most cases. hypofinction arises from

destructive processes directly involving the anterior pituitary such as tumors,

ischemic necrosis of the pituitary gland and the empty sella syndrome; although

other mechanism have been identified.

2.2 SlGNS AND SYMPTOMS OF PITUITARY ADENOMAS

The signs and symptoms of pituitary adenomas include endocrine

abnormalities and mass effect. The abnormalities associated with the secretion of

excessive quantity of anterior pituitary hormones are specific with the type of

pituitary adenoma. Local mass effect may be encountered in any type of pituitaly

tumor. Among the earliest changes resulting from such effect are radiographic

1

/ Other plurihormonal adenoma I

15 I

abnormalities of the sellar turcica including sellar expansion, bony erosion and

disruption of the diaphragm sellar. The sella turcica forms parts of the base of the

skull and comprises of he pituitary fossa with the dorsum sellar and posterior

cliniod processes posteriorly, the tuberculum sellae and anterior cliniod processes

anteriorly. Because of the close proximity of the optic nerve and chiasma to the

selIa, expanding pituitary lesion often compress the nerve fibers in the optic chiasm

giving rise to visual field abnormalities called bitemporal hemianopsia. As in the

case of any expanding intracranial mass, pituitary adenomas may produce signs

and symptoms of elevated intracranial pressure, including headache, nausea and

vomiting. Finally, expanding pituitary adenomas may compress the adjacent non-

neoplastic anterior pituitary or the pituitary stalk sufficiently to compromise their

functions, resulting in hypopituitarism. Also acute haemorrhage into an adenoma

is sometimes associated with a rapid increase in local mass effect.

2.3 EFFECTS OF PITUITARY ADENOMAS. -

Prolactinomas which accounts for about 30% of all cli

pituitary adenomas is characterized by its efficiency as even

nical recognized

. micro adenoma

secrete sufficient prolactin to cause hyperprolactinemia. Increased serum level of -

prolactin or prolactinemia causes amenorrhoea, galactorrhea, 1 oss of libido and

infertility, The diagnosis of this adenoma is made readily in women than in men

especially between the ages of 20 and 40 years because of the sensitive of menses

to disruption by hyperprolactinemia. This tumor underlies almost a quarter case of

amenorrhea. However hyperprolactinemia can be caused by other meals other

than prolacin-secreting pituitary adenomas. This includes physiological

hyperprolactinemia which occur in pregnancy, and mass in the supra sellar

compartment as this may disturb the normal inhibitory influence of the

hypothalamus on prolactin secretion, resulting in hyperprolactinernia, a

phenomenon known as stalk effect.

Hypersecretion of growth hormone by growth hormone secreting tumors

which are second most common type of functioning pituitary adenoma stimulates

the hepatic secretion of insulin-like growth factor-1 which causes many of the

clinical manifestationss. If the adenoma appears in children before the epiphyses

have closed, the elevated level of growth hormone results in gigantism. But if it

occurs after the closure of the epiphyses, the patient develops acromegaly. In this

condition, growth is most conspicuous in skin and soft tissue and bmes of the face.

hand and feet. Also there is increase bone density both in the spine and the hips.

Growth hormone excess is also correlated with a variety of other disturbances

including gonadal dysfunction, diabetes mellitus, generalized body weakness,

hypertension, arthritis, congestive heart failure and increased risk of

gastrointestinal cancers.

Excess production of adenocorticotropic honnone (ACTH) by the

corticotroph adenomas which are usually small microadenomas at the time of

diagnosis leads to adrenal hypersecretion of cortisol and the development of

hypercortisolism also known as Cushing's syndrome. Large destructive adenotnas

- which can develop in ppatients after surgical removal of adrenal gland due to

- inhibitory effect of adrenal corticosteri ods on a pre existing corticotroph

microadenom in condition termed Nelson syndrome presents with mass effect of - pituitary tumor.

Null cell adenomas which are adenomas that generates no detectable hormonal -

products and accounts for 20% of all pituitary adenomas typically present with

+.

mass effects. These lesions many also compromise the residual anterior pituitary

sufficiently to produce hypopituitarism. This may occur as a result of gradual

enlargement of the adenoma or after abrupt enlargement of the tumor because of

acute hemorrhage (pituitary apoplexy). Deficiency of antidiuretic hormone (ADH)

which is produced by the posterior pituitary lobe causes diabetes lnsipidus, a

condition characterized by excessive urination (polyuria ) owing to the inability of

the kidney to reabsorb water properly from the urine. On the other hand, excessive

secretion of ant diuretic hormone causes excessive resorption in hyponatremia.

CHAPTER THREE

3.0 RADIOLOGICAL TECHNIQUES

Patients who are referred to the radiology department for investigation of a

possible abnormality involving the contents of sellar turcica can be divided into

two groups. The first category are patients with clinical evidence suggestive of a

lesion within or adjacent to the sellar turcica. The second categories are patients

who have abnormal sellar turcica identified as an accidental findings on skull

radiographs which were obtained for other reasons. Many radiological

examinations are used to study the abnormalities of the sellar turcica and these

include, skrill radiography, Tomography, Pneumoencephalography, Angiography

and computerized tomography.

3.1 SKULL RADIOGRAPHY: many projections are used in the demonstration

of the sellar turcica using conventional radiography. These include Lateral

projection, occipito-frontal projection with angulations and fkonto-occipital

projection with angulations

A LATERAL PROJECTION

POSITIONING OF PATIENT AND FILM:

The patient sits with one side of the head against an erect bucky, the a m of

the same side extended comfortably by the trunk and the arm of the opposite side

flexed to grip the bucky support to help immobilization. The head and bucky

height are adjusted so that the center of the bucky is 2.5cm vertically above a point

2.5cm along the base line fi-om the external auditory meatus. The median sagittal

plane is brought parallel to the film by ensuring that the interorbital line is at right

angle to the bucky and the nasion and external occipital prot~~berance are

equidistant from it. A 18cm X 24 cm cassette is placed in the tray with its center to

the center of the bucky.

DIMCTON AND CENTRING OF THE X-RAY REAM.

Using a well-collimated beam, the horizontal central ray is centered to a

point 2.5cm vertically above a point 2.5cm along the base line from the external

auditory meatus nearer the x-ray tube.

B Occipito-frontal projection (with angulations)

Positioning of patient and film;

The patient lies prone centered to the midline of the table with the forehead

and nose in contact with the table and with the hands at either side of the head so

that the forearms support the body and aid stability. The neck is flexed to bring the

orbito-meatal line are right angle to the table. The head s adjusted to bring the

external auditory meatuses equidistant from the table so that the median sagittal

plane is at right angles to the midline of the table. The head is immobilized in this

position using a head binder or pads and sand bags. The cassette is placed in the

bucky tray with its center at the level of the glabella.

Occipito-frontal20 degrees caudad.

With the beam well collimated, the central ray is angled caudally 20 degrees from

the vertical (to make an angle of 20' with the orbito-meatal plane) and centered in

the midline above the external occipital protuberance to emerge from the glabella.

This projection demonstrates the floor of the pituitary fossa superimposed on

the eth~noidal sinuses.

- Occipto-frontal IS degrees cephalad.

- Direction and centering of the x-ray beam. With the beam well collimated

- the central ray in angled cranially 15 degrees from the vertical (to make an angle of

15 degrees with the orbito-meatal pIane) and centered in the midline below the -

external occipital protuberance to emerge from the glabella.

*

This demonstrates the dorsum sellae and anterior clinoid processes

- superimposed on the frontal bone.

Occipito-frontal30 degree Cephalad.

Direction and centering of the x-ray be=

Using a well collimated beam, the central ray is angled cranially so that it makes

an angle of 30 degrees to the orbito-meatal line and is directed in the midline to

pass midway between the external auditory meatuses.

This demonstrates the dorsum sellae and the posterior clinoid process

superimposed on the foramen magnum at the base of the skull.

Fronto-occipital30 degrees caudad.

Positioning of Patient and Film.

The patient lies supine centred to the midline of the table with the arms

extended to the sides. The head is adjusted to bring the external auditory meatuses

equidistance from the table so that the median sagittal plane is at right angle to the

midline of the table. The chin is depressed to bring the orbito-meatal line at right

angles to the table and the head is immobilized in this position. The cassette is

placed in the bucky tray with its center approximately I Ocm below the level of the

external auditory meatus.

Direction and centring of the x-ray bean.

Using a well collimated beam, the central ray is angled caudally 30 degrees

from the vertical and directed in the midline to point midway between the external

auditory meatused.

This projection will demonstrate the posterior clinioid process and the

dorsum sella within the foramen magnum. This projection can only he taken if

occipito-frontal projection is not possible as there is increased radiation dose to the

eyes.

Skill radiography may reveal evidence of gross enlargement of the sellar

indicating a large intrasellar mass lesion or frank destruction of the seIla indicating

a more aggressive type of lesion in and adjacent to the sella. Abnormal

calcification may be detected within or above the sella. it also allows for

evaluation of the entire cranial vault and this may be important since certain

pituitary adenomas are associated with an increased thickness of the vault and

enlargement of the paranasal sinuses and mandible as in the case in patient with

acromegaly.

Plain skull radiographs, however, are frequently misleading and show no

abnonnality. Clinical study by Kleinberg et a1 indicate that approximately 80% of

patients with proven tumor of the pituitary gland have normal skull radiographsb.

The reason why the skull findings are normal is that the changes are too subtle to

be detected or the tumor is still too small to cause any bony changes.

Skull radiographs therefore, are of limited value in the investigation of

patients with possible pathology within the pituitary fossa7 .

3.2 Tomography

multi-directional tomography in the AP, lateral and basal projection may be

useful in the investigation of the sellar and parasellar structures. It has the

advantage over a skull radiograph in that it mzy show subtle changes in the cortical

outline of the sellar turcica which may indicate a small lesion adjacent to the body

cortex. It may also clarify the exact location of intra and parasellar calcification8. if

transphenoidal surgery is contemplated for removal of a pituitaly adenoma,AP

tomography is of great value to asses the precise anatomy of the paranasal sinuses.

Although multi-directional tomography is superior to plain skull radiograph,it is

still normal in as high as 40% of patients with proven pituitary adenomas.

3.3 PNEUMOENCEPHALOGRAPHY.

Pneumoencephalography has been used in the past to determine the so-called

empty sella and to evaluate the suprasellar extent of pituitary lesion.

Preparation of patient

I . Routine view of the skull and chest are taken

2. Patient must have nothing to eat or drink for five hours

3. Patient should micturate before the examination

4. All radiopaque objects must be removed.

5. Patient should wear an open backed-grown.

Premeditation

premeditation such as Diazepam is given.

Preliminary film

A preliminary lateral film is sometimes taken but this is not routine in all

department.

Techniques

The pinnae of the ears are pushed forward and downward and secured by

adhesive strapping. The patient sits on a special hydraulic encephalography chair,

on a special hydraulic encephalography chair. The patient must be made as

comfortable as possible, with the back ached and the forehead resting on a foam

block secured to the suill table. The chin is tucked in so that the radiographic base

line is at 20' to the horizontal. An 18x24cm cassette and grid are adjusted to the

side of the patients head. The x-ray tube is directed horizontally and just superior

to the external auditory meatuses.

A lumbqr puncture is performed and lOmls of air are injection. A

lateral view is taken and film is processed and viewed as fast as possible to

ascertain whether air has entered the ventricular system. If so more air is injected

and a further lateral view is taken. A reverse townes view with the tube angled 25"

cephalad is then taken. If the radiographs are satisfactory, a specimen cerebro-

spinal fluid is taken for pathological analysis. The lumbar puncture needle is then

removed and patient is placed horizontal for the routine spine and prone

radiographs to be taken and this includes fronto-accipital, Townes, lateral etc.

The role of pneumoencephalography however, has almost ceased to

exist with the advent of computerized tomography.

3.4 COMPUTED TOMOGRAPHY C.T

Computed tomography has dramatically changed the method of

investigation of patient suspected of lesions within or ad-jacent to the sella.

Computed tomography will show the bony anatomy similar to skull films and

tomography but in addition it will reveal the soft tissue anatomy and its

relationship to the bony structures. Computed tomgraphy may be done in the

- transsexual and coronal plane with a slice thickness of 6mm or less. The coronal

- mode is preferred to transaxial method since it shows more clearly the suprasellar

extension of intrasellar lesion or possible involvement of the base of the skull -

and facial structures.

- Examination shouId be done without or with intravenous injection of

- contrast agents. Enhancement of a lesion within the sellar turcica is not specific

since it may occur in pituitary adenoma, blood vessel abnormality (aneuxysm) and P

tumor arising from the membrane covering the sellar turcica (meningioma) 9. -

Since most pituitary tumors are cystic, they exhibit a density similar to

- fluid (cerebrospinal fluid). Under this condition it may be difficult to differentiate

- neoplasm from another condition which may enlarge the sellar i.e. empty sellar

which represent out pouching of the normal subarachnoid space into the sellar due

to absence of the diaphragm that normally covers the sellar. In these cases where

there is an enlarged sellar with contents of fluid density, the scan may be repeated

often water soluble contrast material like iopamidol is introduced into the

subarachnoid space in order to see whether the contrast material enters the sellar in

empty sellar or not as is the case with cystic pituitary tumors.

E Angiography

The role of cerebral angiography is limited to preoperative assessment

of patient who will undergo transphenoidal removal of pituitary adenoma in order

to visualize the vascular anatomy and to exclude an aneurysm which may coexist

with the pituitary adenoma . Angiography is performed when the findings of

tomography and computed tomography suggest that sellar enlargement could be

possible to cause an aneurysm. Angiography is also indicated when the findings of

tomography and computed tomography suggest that the abnormal sellar is caused

by a lesion originating above or behind the sellar turcica(meningioma, chordroma)

with secondary invovement of the sellar.

CONCLUSION

Computed tomography is an important new modality in the investigation of

patients suspected of a lesion involving the sellar turcica and its content, the

pituitary gland. Computed tomography after intrathecal injection of water soluble

contrast material is sometimes necessary to distinguish the low density within the

sella caused by a so called empty sella from cystic pituitary adenomas. On the

other hand,angiography, has limited role in the preoperative assessment of patients

with a pituitary adenomas and in patients in which the abnormal sella is caused by

an aneurysm. Although conventional skull radiograph is routinely used in

investigation of pituitary adenomas, its result is not always conclusive and so other

imaging modalities like C.T should be used to rule it out completely in patient

which has negative result from skull radiograph.

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