Imaging Endocrine Systems Flashcards
what imaging modalities are used to evaluate endocrine organs
- ultrasound
- CT
- nuclear scintigraphy
- MRI
what is ultrasound used to evaluate
parenchymal structure and characteristics and screening for disease in:
- adrenal glands
- pancreas
- thyroid
- parathyroid
what is CT used to evaluate
identifying masses and surgical planning
what is nuclear scintigraphy used to evaluate
functional imaging of the thyroid (hyperthyroidism)
what is MRI used to evaluate
pituitary gland
what are the borders of the adrenal glands
LEFT:
- cranial: cranial mesenteric and celiac arteries
- caudal: renal vein/artery
- medial: aorta
- phrenicoabdominal vein runs across the middle
RIGHT:
- cranial: right liver
- caudal: renal vein/artery
- medial: caudal vena cava, portal vein
- phrenicoabdominal vein runs across the middle
what is the normal shape of the adrenal glands
smooth with rounded margins
dogs: left is peanut shaped, right is oval/boomerang shaped
cats: jelly bean shaped
normal size of adrenal glands
dogs: 0.4-0.75 cm
cats: 0.3-0.5 cm
echogenicity of the adrenal glands
hypoechoic or isoechoic to the spleen
mineralization can be normal in the cat but ALWAYS abnormal in the dog
what does hyperadrenocorticism (Cushing’s) look like on US
pituitary dependent: bilateral adrenal enlargement
adrenal dependent: heterogenous mass in one adrenal with contralateral atrophy
iatrogenic: bilateral adrenal atrophy
secondary changes: vacuolar hepatopathy (enlarged and hyperechoic), mineralization of surrounding structures
what does hypoadrenocorticism (Addision’s) look like on US
typical Addisons: bilateral adrenal atrophy
atypical Addisons: bilateral normal or small adrenal glands (only fasciculata is affected)
what does a pheochromocytoma look like on US
heterogenous, solid (non-cavitary) mass in the adrenals
- can NOT differentiate cortical vs medullary
- if >2-4 cm and invasive –> malignant
where is the pancreas located
pyloroduodenal junction (between duodenum and stomach/colon)
what does diabetes mellitus look like on US
no visible changes to the pancreas (signs of pancreatitis possible)
is ultrasound usually done to diagnose diabetes mellitus
NO - mostly used if previously diagnosed diabetes is difficult to control
look for signs of secondary underlying disease preventing control of diabetes
what secondary findings are common with diabetes mellitus
- hyperechoic liver
- pyelectasis (dilated renal pelvis)
- emphysematous cystitis
emphysematous cystitis
gas in the bladder wall/lumen from gas producing bacteria
what does insulinoma look like on US
small, hypoechoic nodules (difficult to identify)
often metastasizes to the liver and adjacent lymph nodes - easier to identify than primary tumor
what are the borders of the thyroid gland
- medial: larynx and trachea
- lateral: carotid artery
- caudal: medial retropharyngeal lymph nodes
what is the normal size of the thyroid gland
dogs: 0.4-0.6 cm
cats: 0.2-0.3 cm
what is the normal shape of the thyroid gland
ellipsoid/fusiform with smooth margins
echogenicity of the thyroid gland
isoechoic/slightly hyperechoic to the lymph nodes and homogenous
what does hyperthyroidism look like on US
unilateral or bilateral enlargement
(functional hyperplasia, nodular hyperplasia, adenoma, carcinoma)
is hyperthyroidism more common in cats or dogs
cats - usually benign
if in dogs - usually malignant but non-functional
what imaging is most commonly done to diagnose hyperthyroidism
nuclear scintigraphy - ingestion of radioactive tracer coupled to a metabolically active molecule that gets taken up by the thyroid gland and detected on scintigraphy
what markers are used to ID hyperthyroidism on nuclear scintigraphy
radioactive iodine or pertechnetate
what information does nuclear scintigraphy provide
if hyperthyroidism is unilateral or bilateral
presence of ectopic thyroid tissue
what does a thyroid carcinoma look like on US
variably sized mass with cavitations, highly vascularized, and locally invasive into adjacent vessels
where is the parathyroid located
adjacent to or within the thyroid near the cranial or caudal poles
NOT ALWAYS VISIBLE ON US
normal shape and size of the parathyroid
< 2 mm
oval to round with smooth margins
echogenicity of the parathyroid
very hypoechoic/anechoic
what does hyperparathyroidism look like on US
enlarged parathyroid glands from hyperplasia or adenomas (NOT carcinomas)
does not change shape or echogenicity - only gets bigger
> 4 mm is likely adenoma not hyperplasia
how does the pituitary gland appear on CT and MRI
CT: contrast enhancing region
MRI: T1 hyperintense, strongly contrast enhancing
