Imaging in Endocrinology

Question 1

What can be used to image the pituitary gland?

Answer 1

MRI = midline structure, anterior and posterior parts

Question 2

Where is the pituitary gland found?

Answer 2

In the sella turcica, connected to brain via pituitary sinus and is closely related to the sphenoid sinus

Question 3

What are some anatomical relationships of the pituitary gland?

Answer 3

Inferior to optic chiasm, carotid arteries laterally, inferior to hypothalamus

Question 4

Where may pathology occur that causes vision loss?

Answer 4

Eye, optic nerve, chiasm, optic tract, brain

Question 5

Where does peripheral vision information strike?

Answer 5

Medial retina and crosses optic chiasm

Question 6

What do lesions of the optic chiasm cause?

Answer 6

Bilateral peripheral vision loss

Question 7

What can be used to image the thyroid gland?

Answer 7

Well visualised on CT and US, also imaged using Nuc Med

Question 8

What is the anatomy of the thyroid gland?

Answer 8

Right and left lobes joined by isthmus, located deep to strap muscles of the neck

Question 9

What are the anatomical relationships of the thyroid gland?

Answer 9

Anterior to trachea and oesophagus, medial to common carotid arteries and internal jugular vein
Inferiorly = sternum, great vessels, aortic arch

Question 10

What structures can be damaged in surgery of the thyroid gland?

Answer 10

Recurrent laryngeal nerves and parathyroid glands

Question 11

What are the differential diagnoses for midline neck masses?

Answer 11

Enlarged thyroid, enlarged lymph nodes

Thyroglossal cysts and cystic hygromas are rare outside childhood

Question 12

What is the aim of imaging midline neck masses?

Answer 12

To differentiate between diffuse and focal causes = achieved with combination of radioisotope studies and US

Question 13

What are the benefits of thyroid ultrasounds?

Answer 13

Safe, no ionising radiation, well-tolerated, can be combined with fine needle aspiration

Question 14

What patients get thyroid ultrasounds?

Answer 14

Euthyroid patients with goitre or palpable nodules

Hyperthyroid patients with focal masses or radioisotope uptake

Question 15

What are some features of thyroid scintigraphy?

Answer 15

I-123 or Tc 99m, Tc 99m used locally (injected IV, image after 20mins), images assessed for pattern and quantity of tracer uptake

Question 16

What result of a thyroid scintigraphy indicates Grave’s disease?

Answer 16

Homogenously increased tracer uptake, >3% total tracer in gland

Question 17

How does thyroiditis present on a thyroid scintigraphy?

Answer 17

Homogenously reduced tracer uptake

Question 18

What does a multinodular goitre with a dominant nodule cause in a thyroid scintigraphy?

Answer 18

Focal uptake of the right upper pole

Question 19

What are some features of the adrenal glands?

Answer 19

Two lines = medial and lateral
Right adrenal lies posterior to IVC
Left adrenal lies lateral to aorta and left of diaphragmatic crus

Question 20

What is a phaeochromocytoma?

Answer 20

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

Question 21

What kind of ossification do long bones undergo?

Answer 21

Endochondral ossification = starts as cartilage, osteoblasts replace cartilage with osteoid, which mineralises to form bony trabeculae

Question 22

How are trabeculae arranged in long bones?

Answer 22

Loosely packed in the medulla but condense towards the cortex

Question 23

Where do cartilaginous bones ossify?

Answer 23

Firstly within the diaphysis then secondly within the epiphysis (intramembranous ossification)

Question 24

How is bone girth increased?

Answer 24

Cells derived from the periosteum lay down circumferential new bone on the periphery of the existing cortex

Question 25

How is bone length increased?

Answer 25

Cartilage proliferation occurs at growth plates between the metaphysis and epiphysis = this cartilage then ossifies

Question 26

What does diffuse mean when applied to bone abnormalities?

Answer 26

Affects lots of bones = bones are all too soft/brittle

Osteoporosis, Ricket’s, Paget’s, osteomalacia

Question 27

What are some features of focal bone abnormalities?

Answer 27

Affect single area = traumatic, neoplastic (lytic, sclerotic), inflammatory, degenerative

Question 28

What are some features of osteoporosis?

Answer 28

Brittle bones prone to fractures, reduction in trabecular density, common in post menopausal women

Question 29

Where are some common fracture sites in patients with osteoporosis?

Answer 29

Proximal femur, sacrum, pubic rami, thoracolumbar vertebrae, distal radius

Question 30

What are some secondary causes of osteoporosis?

Answer 30

Steroids, early menopause, anorexia

Question 31

What is Ricket’s?

Answer 31

Vitamin D deficiency causing non-ossification of soft osteoid = bone deformity, pain, growth abnormality, widened growth plate, irregular flared metaphyses

Question 32

What is osteomalacia?

Answer 32

Vitamin D deficiency causes non-ossification of soft osteoid = bone deformity, pain, tendency to partial fractures, poor cortico-medullary differentiation

Question 33

What is Paget’s disease?

Answer 33

Increased bone turnover with unknown cause = single or multiple bones affected

Question 34

What occurs in Paget’s disease?

Answer 34

Initial lytic phase results in well-defined Lucency

Later sclerotic phase with enlarged bone, increased density and coarse trabecular pattern

Question 35

What occurs in lytic bone destruction?

Answer 35

Medullary Lucency and loss of trabeculae and inner cortex, complete loss of cortex and cortices

Question 36

What occurs in sclerotic bone destruction?

Answer 36

Subtle medullary density and loss of trabeculae, spreading zone of density which excludes cortex, featureless white bone

Question 37

What occurs as a result of lytic and sclerotic bone destruction?

Answer 37

Lytic = pathological fracture
Sclerotic = expansion beyond normal bone limits with cortical destruction and pathological fracture