Imaging in Endocrinology

Question 1

where is the pituitary found in the brain?

Answer 1

midline
in sella turcica
connected to brain via pituitary stalk
closely related to sphenoid sinus

Question 2

what structures are related to the pituitary?

Answer 2

optic gland sits above
carotid arteries laterally
hypothalamus sits above

Question 3

imaging findings of bitemporal hemianopia?

Answer 3

mass extending from the sella turcica compressing on optic chiasm
“snowman sign”

Question 4

what types of adenoma can affect the pituitary gland?

Answer 4

microadenoma

macroadenoma

Question 5

describe the anatomy of the thyroid

Answer 5

right and left lobes connected by isthmus

lies deep to strap muscles of the neck

Question 6

where does the thyroid lie?

Answer 6

anterior to trachea and oesophagus

Question 7

what are the anatomical relations of the thyroid?

Answer 7

deep to strap muscles
medial to common carotid arteries
medial to internal jugular veins
recurrent laryngeal nerves
parathyroid glands
sternum sits inferiorly
great vessels and aortic arch (posterior inferior)

Question 8

differentials in midline neck mass in adults and children?

Answer 8

adults - usually thyroid

children - can be thyroglossal cyst, cystic hygroma, as well as thyroid

Question 9

how can retrosternal goitre cause respiratory problems?

Answer 9

can cause tracheal deviation

Question 10

aim of imaging in hyperthyroidism?

Answer 10

differentiate whether diffuse (graves, thyroiditis) or focal (dominant nodule)
achieved via radioisotope studies and US

Question 11

how is US used in thyroid disease?

Answer 11

safe, no radiation
can be combined with fine needle aspiration
first line in euthyroid patients with goitre/palpable nodules and hyperthyroid patients with focal masses/radioisotope uptake

Question 12

how is a radioisotope scan performed?

Answer 12

Tc 99 or I-123 used locally or injected IV and patients then imaged after 20 mins
assess pattern and quality of tracer uptake

Question 13

radioisotope scan findings in graves/thyroiditis?

Answer 13

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

Question 14

what does a focal uptake in the right upper pole on radioisotope scan indicate?

Answer 14

multi-nodular goitre with dominant nodule

Question 15

where are the adrenal glands?

Answer 15

suprarenal position

retroperitoneal

Question 16

what are the 2 limbs of the adrenal glands?

Answer 16

medial and lateral

Question 17

where does each adrenal gland lie specifically?

Answer 17

right = posterior to IVC
left = lateral to aorta and left diaphragmatic crus

Question 18

classical history of phaeochromocytoma?

Answer 18

months history of "shivering attacks"
headaches
sweating
palpitations
high BP

Question 19

what is periosteum and what does it look like on imaging?

Answer 19

thin layer surrounding bone
highly vascular and innervated (cause of pain in break)
invisible on X ray

Question 20

how do long bones ossify?

Answer 20

start as cartilage and undergo endochondral ossification
- osteoblasts replace the cartilage with osteoid, which mineralises to form bony trabeculae. trabeculae are loosely packed into the medulla (cancellous bone) but condense towards the cortex (compact bone

Question 21

how does bone girth increase?

Answer 21

cells derived from the periosteum lay down circumfrential new bone on the periphery of existing cortex

Question 22

how does bone length increase?

Answer 22

cartilage proliferation at the growth plates between metaphysis and epiphysis
cartilage then ossifies

Question 23

diffuse vs focal bone abnormality?

Answer 23

diffuse = several bones (e.g all bones are too brittle)
focal = single bone (trauma, neoplastic, inflammation, degenerative)

Question 24

what are the 2 main groups of diffuse bone abnormalities?

Answer 24

bones too brittle
- osteoporosis
bones too soft
- rickets and osteomalacia
- pagets

Question 25

what is osteoporosis?

Answer 25

brittle bones that are prone to fracture due to reduction in trabecular density

Question 26

what can cause osteoporosis?

Answer 26

``` idiopathic steroids early menopause anorexia often in typical fracture sites ```

Question 27

what can suggest than bones are too soft?

Answer 27

several bone deformities

Question 28

what is rickets and what are the signs?

Answer 28

non-ossification of soft osteoid due to vitamin D deficiency leading to bone deformity, pain and growth abnormality, widened growth plates and irregular, flared metaphyses

Question 29

what is osteomalacia?

Answer 29

non-ossification of soft osteoid in adults due to vitamin D deficiency leads to bone deformity, pain and tendency to partial fractures and poor cortico-medullary differentiation

Question 30

what is pagets disease (osteitis deformans)?

Answer 30

increased bone turnover with unknown cause

Question 31

what are the early and late features of pagets?

Answer 31

initial lytic phase = well defined lucency | latter sclerotic phase = enlarged bone, increased density and coarse trabecular pattern

Question 32

what two types of neoplastic disease can occur in bone?

Answer 32

lytic (bone destruction) | sclerotic (bone formation)

Question 33

what are the features of lytic bone destruction?

Answer 33

``` medullary lucency and loss of trabeculae loss of inner cortex complete loss of cortex loss of both cortices potential for pathological fracture ```

Question 34

what are the features of a sclerotic bone lesion?

Answer 34

subtle medullary density and loss of trabeculae spreading zone of density which includes cortex featureless white bone expansion beyond normal bone limits, with cortical destruction and potential for pathological fracture

Question 35

what type of imaging can show sclerotic bone lesions well and why?

Answer 35

bone scan | shows osteoblastic activity