Nukes bones Flashcards
MDP mechanism of action
chemisorption incorporated into the bone matrix in hydroxyapatite
what happens if not enough stannous ion is in your MDP kit?
oxidation of Tc-99m –> free tech
what happens if you pull air into the syringe right before injecting Tc99m-MDP?
oxygen gets in –> oxidation –> free tech
What happens if water gets into you Tc-MDP solution?
water –> tin colloid AND Tc-99m dioxide –> these are large clumps of stuff –> goes to RES ( liver, spleen, bone marrow)
what happens if you forget stannous ion in the MDP kit?
stannous ion (tin) is the reducing agent. If no stannous ion –> Free Tc
Free Tc
Wrong window. Window set too low for Tc-99m MDP.
If set too low, for example set to only accept Thallium keV range (70-80 keV) –> camera will exclude everything >80 keV –> you completely exclude Tc-99m 140 keV gamma ray –> only really imaging the scatter
Soccer player with lots of trauma to the thigh. Next step?
get more imaging - CT or XR to further evaluate possible myositis ossifcans
What additional imaging do you want?
CT Chest
Two main causes of hot kidneys on MDP?
- Chemotherapy
- urinary obstruction
autoinfarcted spleen in Sickle Cell Disease
osteosarcoma in a kid
hot uptake in the metaphysis of a kid
painful scoliosis
osteoid osteoma in the posterior elements
Enchondroma
Paget’s
aseptic loosening in a hip prothesis. uptake at wiggle points at the distal part of the femoral component and at the lesser trochanter
how long do you have to be on bisphosphonates before you get insuffiency fractures?
4 years
When is the best time to use a bone scan to evaluate for an occult fracture with an MDP bone scan?
At three days
sacral insufficiency fracture
Flair phenomenon. gets worse then better
osteomyelitis
progressively hotter on 3 phase bone scan
cellulitis
cellulitis is only two phase
Reflex sympathetic dystrophy (complex regional pain syndrome)
UNILATERAL periarticular uptake on delayed imaging
A diabetic patient presents with calcaneal ulcer, pain and leukocytosis. What may be useful on bone scan if osteomyelitis is suspected?
4th phase imaging at 24 hr
Diabetic and vasculopathic patients pose a difficult problem for skeletal scintigraphic evaluation of the feet. The small vessel disease and overall poor circulation do not allow enough time for the radiotracer to be delivered and taken up by the osseous structures and cleared by the soft tissues. One protocol that can be instituted is the use of 4th-phase imaging. This involves a 24-hour image being acquired to allow for greatest osseous uptake and soft tissue clearance. Plantar, posterior, or lateral views would best image the calcaneus.
what are the parameters for using strontium
WBC counts >2400 and platelets >60K. renal function
How do you treat brown fat?
warm up with blanklets or beta blockers
