Imaging in Endocrinology Flashcards
where is the pituitary found in the brain?
midline
in sella turcica
connected to brain via pituitary stalk
closely related to sphenoid sinus
what structures are related to the pituitary?
optic gland sits above
carotid arteries laterally
hypothalamus sits above
imaging findings of bitemporal hemianopia?
mass extending from the sella turcica compressing on optic chiasm
“snowman sign”
what types of adenoma can affect the pituitary gland?
microadenoma
macroadenoma
describe the anatomy of the thyroid
right and left lobes connected by isthmus
lies deep to strap muscles of the neck
where does the thyroid lie?
anterior to trachea and oesophagus
what are the anatomical relations of the thyroid?
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)
differentials in midline neck mass in adults and children?
adults - usually thyroid
children - can be thyroglossal cyst, cystic hygroma, as well as thyroid
how can retrosternal goitre cause respiratory problems?
can cause tracheal deviation
aim of imaging in hyperthyroidism?
differentiate whether diffuse (graves, thyroiditis) or focal (dominant nodule)
achieved via radioisotope studies and US
how is US used in thyroid disease?
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
how is a radioisotope scan performed?
Tc 99 or I-123 used locally or injected IV and patients then imaged after 20 mins
assess pattern and quality of tracer uptake
radioisotope scan findings in graves/thyroiditis?
homogenously increased tracer uptake, >3% total tracer uptake in gland
what does a focal uptake in the right upper pole on radioisotope scan indicate?
multi-nodular goitre with dominant nodule
where are the adrenal glands?
suprarenal position
retroperitoneal
what are the 2 limbs of the adrenal glands?
medial and lateral
where does each adrenal gland lie specifically?
right = posterior to IVC left = lateral to aorta and left diaphragmatic crus
classical history of phaeochromocytoma?
months history of "shivering attacks" headaches sweating palpitations high BP
what is periosteum and what does it look like on imaging?
thin layer surrounding bone
highly vascular and innervated (cause of pain in break)
invisible on X ray
how do long bones ossify?
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
how does bone girth increase?
cells derived from the periosteum lay down circumfrential new bone on the periphery of existing cortex
how does bone length increase?
cartilage proliferation at the growth plates between metaphysis and epiphysis
cartilage then ossifies
diffuse vs focal bone abnormality?
diffuse = several bones (e.g all bones are too brittle) focal = single bone (trauma, neoplastic, inflammation, degenerative)
what are the 2 main groups of diffuse bone abnormalities?
bones too brittle - osteoporosis bones too soft - rickets and osteomalacia - pagets
what is osteoporosis?
brittle bones that are prone to fracture due to reduction in trabecular density
what can cause osteoporosis?
idiopathic steroids early menopause anorexia often in typical fracture sites
what can suggest than bones are too soft?
several bone deformities
what is rickets and what are the signs?
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
what is osteomalacia?
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
what is pagets disease (osteitis deformans)?
increased bone turnover with unknown cause
what are the early and late features of pagets?
initial lytic phase = well defined lucency
latter sclerotic phase = enlarged bone, increased density and coarse trabecular pattern
what two types of neoplastic disease can occur in bone?
lytic (bone destruction)
sclerotic (bone formation)
what are the features of lytic bone destruction?
medullary lucency and loss of trabeculae loss of inner cortex complete loss of cortex loss of both cortices potential for pathological fracture
what are the features of a sclerotic bone lesion?
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
what type of imaging can show sclerotic bone lesions well and why?
bone scan
shows osteoblastic activity
