Imaging in Endocrinology Flashcards
What can be used to image the pituitary gland?
MRI = midline structure, anterior and posterior parts
Where is the pituitary gland found?
In the sella turcica, connected to brain via pituitary sinus and is closely related to the sphenoid sinus
What are some anatomical relationships of the pituitary gland?
Inferior to optic chiasm, carotid arteries laterally, inferior to hypothalamus
Where may pathology occur that causes vision loss?
Eye, optic nerve, chiasm, optic tract, brain
Where does peripheral vision information strike?
Medial retina and crosses optic chiasm
What do lesions of the optic chiasm cause?
Bilateral peripheral vision loss
What can be used to image the thyroid gland?
Well visualised on CT and US, also imaged using Nuc Med
What is the anatomy of the thyroid gland?
Right and left lobes joined by isthmus, located deep to strap muscles of the neck
What are the anatomical relationships of the thyroid gland?
Anterior to trachea and oesophagus, medial to common carotid arteries and internal jugular vein
Inferiorly = sternum, great vessels, aortic arch
What structures can be damaged in surgery of the thyroid gland?
Recurrent laryngeal nerves and parathyroid glands
What are the differential diagnoses for midline neck masses?
Enlarged thyroid, enlarged lymph nodes
Thyroglossal cysts and cystic hygromas are rare outside childhood
What is the aim of imaging midline neck masses?
To differentiate between diffuse and focal causes = achieved with combination of radioisotope studies and US
What are the benefits of thyroid ultrasounds?
Safe, no ionising radiation, well-tolerated, can be combined with fine needle aspiration
What patients get thyroid ultrasounds?
Euthyroid patients with goitre or palpable nodules
Hyperthyroid patients with focal masses or radioisotope uptake
What are some features of thyroid scintigraphy?
I-123 or Tc 99m, Tc 99m used locally (injected IV, image after 20mins), images assessed for pattern and quantity of tracer uptake
What result of a thyroid scintigraphy indicates Grave’s disease?
Homogenously increased tracer uptake, >3% total tracer in gland
How does thyroiditis present on a thyroid scintigraphy?
Homogenously reduced tracer uptake
What does a multinodular goitre with a dominant nodule cause in a thyroid scintigraphy?
Focal uptake of the right upper pole
What are some features of the adrenal glands?
Two lines = medial and lateral
Right adrenal lies posterior to IVC
Left adrenal lies lateral to aorta and left of diaphragmatic crus
What is a phaeochromocytoma?
Uncommon tumour of adrenal gland, said to follow 10% rule = 10% extra-adrenal, 10% bilateral, 10% found in children, 10% familial, 10% not linked to hypertension
What kind of ossification do long bones undergo?
Endochondral ossification = starts as cartilage, osteoblasts replace cartilage with osteoid, which mineralises to form bony trabeculae
How are trabeculae arranged in long bones?
Loosely packed in the medulla but condense towards the cortex
Where do cartilaginous bones ossify?
Firstly within the diaphysis then secondly within the epiphysis (intramembranous ossification)
How is bone girth increased?
Cells derived from the periosteum lay down circumferential new bone on the periphery of the existing cortex
How is bone length increased?
Cartilage proliferation occurs at growth plates between the metaphysis and epiphysis = this cartilage then ossifies
What does diffuse mean when applied to bone abnormalities?
Affects lots of bones = bones are all too soft/brittle
Osteoporosis, Ricket’s, Paget’s, osteomalacia
What are some features of focal bone abnormalities?
Affect single area = traumatic, neoplastic (lytic, sclerotic), inflammatory, degenerative
What are some features of osteoporosis?
Brittle bones prone to fractures, reduction in trabecular density, common in post menopausal women
Where are some common fracture sites in patients with osteoporosis?
Proximal femur, sacrum, pubic rami, thoracolumbar vertebrae, distal radius
What are some secondary causes of osteoporosis?
Steroids, early menopause, anorexia
What is Ricket’s?
Vitamin D deficiency causing non-ossification of soft osteoid = bone deformity, pain, growth abnormality, widened growth plate, irregular flared metaphyses
What is osteomalacia?
Vitamin D deficiency causes non-ossification of soft osteoid = bone deformity, pain, tendency to partial fractures, poor cortico-medullary differentiation
What is Paget’s disease?
Increased bone turnover with unknown cause = single or multiple bones affected
What occurs in Paget’s disease?
Initial lytic phase results in well-defined Lucency
Later sclerotic phase with enlarged bone, increased density and coarse trabecular pattern
What occurs in lytic bone destruction?
Medullary Lucency and loss of trabeculae and inner cortex, complete loss of cortex and cortices
What occurs in sclerotic bone destruction?
Subtle medullary density and loss of trabeculae, spreading zone of density which excludes cortex, featureless white bone
What occurs as a result of lytic and sclerotic bone destruction?
Lytic = pathological fracture Sclerotic = expansion beyond normal bone limits with cortical destruction and pathological fracture
