Musculoskeletal NM Flashcards
Radiotracer used in MSK NM
Tc-99m MDP (diphosphonate)
Timing of imaging after administration of radiotracer for MSK NM exam / bone scan
2-4 hours after administration.
Increased MDP uptake in soft tissues diffusely?
Renal failure.
3 Phase Bone Scan consists of what?
Angiogram (flow) phase - increased flow suggests hyperemia.
Bloodpool phase: extracellular distribution.
Delayed: images are performed at 3 hours after injection.
Tc-99 MDP uptake in two adjacent ribs?
Trauma
Multiple MDP photoPENIC lesions
Infarction, avascular necrosis, radiation therapy.
Single MDP photopenic lesion is concerning for what malignancies?
Neuroblastoma, RCC, Thyroid CA
Increased uptake in brain or heart?
Recent infarction
Increased soft tissue uptake
osteosarcoma, neuroblastoma, mucin producing tumors (GI/Ovarian).
Additionally, inflammatory disease, i.e. myositis ossificans, dermatomyosititis, and rhabdomyolysis can cause radiotracer uptake.
Breast uptake of MDP, normal or abnormal?
Low uptake = normal
High uptake = breast CA.
Increased uptake when recent breast procedure (bx).
Superscan
No renal activity is visualized secondary to diffuse bony uptake.
Most common malignancies resulting in a superscan?
Prostate CA (diffuse osteoblastic mets).
Breast CA
Lymphoma.
How to distinguish superscan from renal failure
Renal failure = diffuse soft tissue uptake
Superscan (malignancy) = diffuse bony uptake.
How to differentiate superscan from hyperparathyroidism from malignancy?
Hyperparathyroidism - long bones primarily.
Metastatic - Axial skeleton and proximal humeri and femora.
MDP findings of osteosarcoma?
Increased uptake, with increased uptake in the entire limb.
