Radiology - Exam 1 Flashcards
contrast material used with CT and contraindications for use
iodine
allergy to iodine
contraindications for abdominal CT:
- retroperitoneal bleed
- diabetes (not on Metformin)
- acute renal failure (serum creatinine >1.5 concern; GFR < 30 concern)
contrast material used with MRI and contraindications for use
gadolinium
severe renal failure (GFR<30)
resource: indication of when to do head CT (HCT) in trauma cases
PCARN
preferred imaging - appendicitis in adults
abdominal CT
preferred imaging - appendicits in kids / pregnant women
abdominal U/S - first
CT with contrast - if not seen on U/S
preferred imaging - bony areas of head (posterior fossa and stella turcica)
use plain x-ray or MRI
- CT not good due to highly dense bony areas
things to consider when ordering imaging
cost
radiation exposure (risks)
burden (time)
Must be indication driven imagining - particular reason for ordering study
imaging for trauma in child
stable: trauma series (plain film of chest, pelvis, c-spine)
unstable / suspicion of head trauma: CT
imaging for limp in child
plain film (1st): fracture, foreign body
U/S: hip effusion, infection, synovitis
MRI: myositis, marrow, abscess, osteomylitis
Bone scan: osteomyelitis, bone METS
standard imaging - chest radiograph
upright PA view with corresponding lateral view
standa imaging - abdomen
3-way: upright and supine abdomen, upright chest
when to do a CXR for acute respiratory illness in a healthy (immunocompetent) person
based on ACR appropriateness criteria
older than 40
dementia
positive PE
hemoptysis (cough up blood)
associated abnormalities (leukocytosis, hypoxemia)
other risk factors: CAD, CHF, drug-induced acute resp. failure
silhouette sign - what is it used for
helps to identify location of of pneumonias or lesions on CXR
loss of normal radiographic silhouette due to two substances of same density being in direct contact
air bronchogram sign
seen on CXR with fluid in lungs
typically, air in bronchi and lungs makes it difficult to see bronchial tree; however, they stand out (dark) when fluid is in lungs (pneumonia)
effusion (e.g. pleural effusion)
excess fluid in lungs
most sensitive view for pleural effusion
decubitus - can demonstrate effusions of 15-20 ml
pneumothorax - abnormalities on CXR
visceral pleural line (necessary!) convex curve of visceral pleural line absent lung markings distal to visceral pleural line cardiac/hemidiaphragm shift deep sulcus sign
deep sulcus sign
excess air in costophrenic angle indicative of pneumothorax
- seen on supine view
pleural effusion - abnormalities on CXR
fluid in pleural space
- shifts with position (unlike pneumonia)
- fist seen below lungs (subpulmonic location)
- decubitus: most sensitive view for pleural effusion
aortic aneurysm - abnormalities on CXR
widened mediastinum
pneumoperitoneum - abnormalities on CXR
air in peritoneum (lining of abdominal cavity)
- crescent lucency on undersurface of rt hemidiaphragm
causes: ruptured bowel, trauma, post-surgery
COPD - abnormalities on CXR
elongation and narrowing of heart
flattening of diaphragm
inc. rib count (>9)
cardiomegaly - abnormalities on CXR
cardiac:thoracic ratio > 50%
Note: heart should take up less than 50% thorax
aspiration pneumonia - abnormalities on CXR
right and left heart borders obscured; infiltrate to bases
Rigler’s sign
both walls of bowel visible (typically not) - indicates large amount of free air in supine abdominal x-ray
hematochezia
passage of fresh blood through anus with or w/o stool
- indication for barium enema
standard imaging - gallbladder disease (biliary disease, acute cholecystitis)
abdominal U/S
imaging of GI (non-invasive)
esophagram
barium upper GI study (“barium swallow”
small bowel follow through
imaging of GI (invasive)
EGD: esophagogastroduodenoscopy ERCP capsule endoscopy sigmoidoscopy / colonoscopy EUS: endoscopic ultrasound
abdominal MRI - when to use (rare)
adrenal pathology biliary pathology (MRCP - similar to ERCP) female pelvis (transplants)
gallbladder disease: imaging and labs
imaging: abdominal U/S
labs:
- gallbladder (bile)
- liver: ALT/AST
- pancreas: lipase/amylase
plain films of skull - indications
penetration
foreign body
presence of depressed skull fragments (likely CT)
bony areas: posterior fosse / stella turcica
waters’ view: sinuses
Waters’ view
45 degree angle (plain film) into anterior skull / face
- good image of sinuses
- compare bilaterally
CT of head/brain (non-contrast) - indications
trauma (at all unstable) depressed skull or facial fracture acute intracranial hemorrhage hydrocephalus (water in brain) intracranial infection (meningitis, sinusitis) acute venous/dural sinus thrombosis
MRI of head/brain - indications
neoplasma demyelinating diseases (MS) vascular malformations (AVM or aneurysm) new onset seizure examine bony areas (posterior fosse / stella turcica) infection or inflammation trauma (diffuse axonal injury)
MRI of spine - indications
disc disease (degenerative, infection) spondylolydid: bony defect or fracture congential abnormalities neoplasm: cord, meningeal infection: epidural absces inflammation: MS
CT of spine - indications
spinal column damage
trauma / emergencies: internal injuries or bleeding
- FAST!
if MRI contraindicated (metal in body) or unavailable
acute stroke - approach to imaging
head CT (no contrast) - 1st - determine if hemorrhagic v. ischemic stroke
MRI (follow-up): more sensitive
headache - approach to imaging
MRI: Thunderclap H/A (CT if unstable) HA that worsens with exertion, associated w/ dec. alertness, positionally related, awakens one from sleep, changes pattern over time New HA in HIV pos. pt HA w/ papilledema HA w/ focal neurological defect HA w/ mental status change
CT:
Trauma, unstable (FAST!)
Suspected hematoma
MRI contraindicated or unavailable
vertigo - approach to imaging
typically no imaging
brain CT: signs of conductive hearing loss
brain MRI: signs of sensorimotor hearing loss
seizure - approach to imaging
MRI:
- new onset - anyone (including alcoholic)
- epilepsy w/ poor therapeutic response
- focal nerological defect
- abnormal EEG
CT (non contrast):
- trauma
No imagining:
- otherwise healthy children
- febrile seizure
- chemical withdraw
dementia - approach to imaging
MRI: useful for diagnosing treatable conditions (vascular disease, etc.)
radiculopathy - approach to imaging
red flag for spinal imaging (likely MRI or CT)
when to use CT or MRI contrast
head: no
chest: no (except nodules, interstitial disease, pulmonary emboli)
abdomen/pelvis: yes (except kidney stones)
constipation - approach to imaging
plain x-ray (visualize masses - more dense)
- combine with hx and PE
note: bowel looks like mass/density with air bubbles
FAST exam - definition and purpose
Focused Assessment with Sonography in Trauma
- purpose of bedside ultrasound in trauma is to rapidly identify free fluid (usually blood) in the peritoneal, pericardial, or pleural spaces
abdominal CT - indications
test of choice for abdominal pain unless gallbladder is suspected (use U/S)
pituitary gland concerns - clinical/labs
thyroid (TSH) gonads (LH, FSH) growth hormone adrenal glands (ACTH / cortisol) breasts (prolactin)
angiography
Inject contrast into artery to highlight vessels with x-ray is taken
Indications:
- Definition of atherosclerotic occlusive disease.
- Evaluation of aneurysms
- Trauma to cervicocerebral vessels
- Evaluation of tumor vascularity
- Evaluation of vasculitis
acute back pain - imaging
pain > 6 weeks (unless “red flags”
red flags:
- inc. risk of cancer
- risk of spinal infection
- sx of cauda equina syndrome
- trauma hx (esp. w/ osteoporosis, or >50)
- radiculopathy (severe neuro deficits)
spondylolosthesis
slippage of one vertebral body on the one below - often L5-S1 area (curvature of low back)
spondylolysis
fracture of pars interacticularis
“scotty dog sign”
