THE COURGE RG. 532 RESEARCH SEMINAR. DEPARTMENT OF MEDICAL RADIOGRAPHY AND k!$ RADIOLOGICAL SCIENCES. RADIOLOGICAL EXAMINATION OF SRLLAR TURCLEA IN

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1 DEPARTMENT OF MEDICAL RADIOGRAPHY AND k!$ RADIOLOGICAL SCIENCES. RADIOLOGICAL EXAMINATION OF SRLLAR TURCLEA IN Wi+[ bn PATIENTS WITH PITUITARY ADENOMAS. A SEMINAR PRESENTED IN PARTIAL, FULFILLMENT OF THE REQUIREMENT OF THE COURGE RG. 532 RESEARCH SEMINAR BY ARONYI EVERISTUS OBlNNA REG NO:

2 TITLE PAGE RADIOLOGICAL EXAMINATION OF SELLAR TURCICA IN PATIENTS WITH PITUITARY ADENOMAS.

3 TABLE OF CONTENT Titlepage 1 CHAPTER ONE I. 1 Introduction Brief Anatomy & Physiology of Pituitary Gland 2 CHAPTER TWO 2.1 Diseases of the Pituitary Gland Signs and Symptoms of Pituitary Adenorna Effect of Pituitary Adenoma 7 CHAPTER THREE 3.0 Radiological Techniques Skull Radiography 10 Lateral Projection 1 1 OccipitoFrontal (With Angu1ation) 1 1 FrontoOccipital (With Angu1ation) 13 Tomography IS Pneumoencephalography 16 Computed Tomography 18 Angiogrphy 19 Conclusion 20 References. 21

4 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 categoriesbenign 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

5 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. Rrrci~hmws Pituitary gland is a bean shaped organ measuring one centimeter in its largest diameter but it enlarges during pregnancy. lt 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

6 neurohypophysis. Between this is a relatively small avascular zone called the parsintermedia'. 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 antidiuretic hormone (ADH) which regulates water excretion from the body and oxytocin which reieases the

7 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.

8 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 Pituitary Adenomas I Frequency I Prolactine ceil adenoma 2030 I Growth hormone cell adenoma 5! i hired growth hormone prolactin adenoma Adenocorticotropic Hormone adenoma I ( Gonadotroph cell adenorna! I

9 Null cell adenomas 1 Thyroid stimulating hormone cell adenoma 1 / Other plurihormonal adenoma 15 I I 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, antidiuretic 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

10 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 nonneoplastic 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 nical recognized pituitary adenomas is characterized by its efficiency as even. 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

11 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 prolacinsecreting 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 insulinlike growth factor1 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

12 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.

13 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, occipitofrontal projection with angulations and fkontooccipital projection with angulations

14 A LATERAL PROJECTION POSITIONING OF PATIENT AND FILM: The patient sits with one side of the head against an erect bucky, the am 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 fiom 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 XRAY REAM. Using a wellcollimated 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 xray tube. B Occipitofrontal projection (with angulations)

15 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 orbitomeatal 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. Occipitofrontal20 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 orbitomeatal 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.

16 Occiptofrontal IS degrees cephalad. Direction and centering of the xray 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 orbitomeatal 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. Occipitofrontal30 degree Cephalad. Direction and centering of the xray be= Using a well collimated beam, the central ray is angled cranially so that it makes an angle of 30 degrees to the orbitomeatal 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. Frontooccipital30 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

17 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 orbitomeatal 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 xray 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 occipitofrontal 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

18 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 fossa Tomography multidirectional 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.

19 Although multidirectional 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 socalled 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 backedgrown. 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

20 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 xray 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 cerebrospinal 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 frontoaccipital, Townes, lateral etc. The role of pneumoencephalography however, has almost ceased to exist with the advent of computerized tomography.

21 3.4 COMPUTED TOMOGRAPHY C.T Computed tomography has dramatically changed the method of investigation of patient suspected of lesions within or adjacent 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 P since it may occur in pituitary adenoma, blood vessel abnormality (aneuxysm) and 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

22 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.

23 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.

24 REFERENCE Ramzi S, kumar v, and Tucker C,: Endocrine system. Pathologic basic of diseases, (sixth ed) W.B saunders company, , schlechte J.; The natural history of untreated hyperprotactinemia; Journal of clinical endocrinol metab, 68: 412,1989. yeh Pj, chen J w: pituitary tumors: surgical and management. Surgical oncology 67, Alexander J.M. : Clinical nonfunctional pituitary tumors are monoclonal in origin. Journal of clinical investigation 86:336, Devil CJ.; Growth and endocrine sequelae of craniopharyngioma. Arch dis child, 75: 108, E de stemich, R.J. and K. G: Radiological investigation of sella turcica and its content: Radiology, 139;314318,1993. Tynell, J.B., Brooks, R.M. fitzgerald P.A. Cofoid, P. B. forsham et a1 cushing's disease; New England journal of medicine 298: , Geehr RB. Allen W.E. Rothman S I G et a1 : pluridirectional tomography in the evaluation of pituitary tumor. America journal of Roentgen 130: , Miller J. H. pena A.M. and segall H. D. Radiological investigation of sellar region masses in children: radiology 134: , 1980