Bone Classic NM Flashcards
Osteoblast:
Function
Stimulated by
Synthesize bone matrix - - bone formation
PTH, prostaglandin, growth factor
Matrix constituent
Collagen I
Non-collagen proteins 10-15%
Elasticity and flexibility
Osteoclasts
Function
Regulation
Bone remodeling - - remove old bone - - release Ca
PTH, TGF, TNF, interleukin 1,6
Vit D stimulate
Calcitonin inhibit
Age, osteoporosis, fractures, myeloma, MTS
Cortical bone
80-90% calcified
Female lose after 40 years
Thick at diaphysis
Thin at epiphysis - - trabecular bone, 15-25 % calcified
Female lose after menopause
Ca level
Soft tissue - low level 0.005%
Bone - high level 14-24%
Degree of uptake
bone perfusion,
nature of Ca-P deposits (size, hydration status, Ca/P ratio), osteoblastic/osteoclastic metabolic activity
Three-phase scan
dynamic (30-60 frames of 1-2 sec)
BP (3-5 min, matrix 128×128 or 256×256, zoom factor 1.33) 5-10 min after injection
delayed 3 hours after
Quantitative SPECT
after 3 h vertebral radioactivity 50 KBq/mL = SUV 6
Trabecular bone
higher retention index than cortical
femur (thick cortex) has lower retention index than ribs
Metaphysis
14.3% Ca content, rich vascularization, high metabolic activity
higher dose than diaphysis
Dose MDP
Adult 500 MBq 13 mCi,
children min 40 MBq
Total-body image
matrix 256×1024 or 512×2048
zoom factor 1
scanning speed 10-15 cm/min (>1.5 mln counts ant and post)
sequential image (acquisition at the end) or continuous image (adults)
Planar image
matrix 128×128 or 256×256
zoom factor 1.33
predefined acquisition time 4-10 min or number of counts
pinhole collimator for small structures (50000-100000 counts)
SPECT
step-and-shot modality
60 or 64 frames per detector head, each 10-30 sec
matrix 128×128, pixel size 4.6×4.6 mm acquisition time increased 30-40 sec per angular view when low counts (skull)
Renal or heart failure, obesity and advanced age
↑dose and time
affect quality of image
incomplete labeling if air is introduced into the vial
free pert
uptake in thyroid, stomach
Excess Al from generator
colloid – accumulate in liver
Bones poorly visualized posterior
wrong energy
Spine is not visualised
inadequate counts
ROI counts
Skull and large joints
Thoracoabdominal region
Distal joints
250000-400000
700000-1000000
150000-250000
F-fluoride similar to MDP
Deposits on hydroxyapatite surface of newly forming bone – Exchange of F with hydroxyl group of hydroxyapatite crystals – fluorapatite
50% absorbed by bone
Adult dose 4 mSv (MDP 3 mSv)
Fluoride unlike MDP
Waiting time 15-30 min vs 3h
Aquisition time 15-30 min vs 40 min
Children dose 3.5 mSv vs 2 mSv
Partial extravasation
visualization of LN
Injection in artery
intense tracer accumulation in portion of arm distal from injection (evening glove)
Focal soft tissue spot
intramuscular injection, hematoma, severe renal failure, hypercalcemia
X-ray positive
Bone density reduction 30-75% required
Bone scan positive
5-10% bone destruction required
Fibrous bone dysplasia
congenital
bone replaced with fibrous-like tissue
Polyostotic ass with McCune-Albright or Mazabraud sy (intramuscular myxoma – FDG)
malignant degeneration 1% – FDG
Fibrous bone dysplasia
Bone scan
Skull (pirate sign), ribs, femur
Areas of reduced uptake + increased uptake
Giant Cell Tumor
fusion of growth plate
extend from metaphysis to epiphysis of knee
Benign, osteolytic – transform into sarcoma (no MTS – quasi-malignant)
Giant cell tumor FDG
Doughnut sign
Regional hyperemia - - diffuse uptake
Extremely avid
Non-ossifying fibroma
cortical lesion of long bones
regress spontaneously
Non-ossifying fibroma Bone scan
normal (osteolytic)
Ringlike pattern around photopenic lesion
Calcification – uptake
Myositis ossificans
secondary to contusion, trauma
high uptake on bone scan
MTS
Bone pain, path fracture, cord compression
↑ AlcPhos, hypercalcemia, bone marrow aplasia
Hematogenous spread – not joints – axial skeleton (prox humerus, femur)
Risk Prostate Ca bone MTS
PSA>10,
Gleason>8, locally advanced,
↑ AlcPhos,
bone pain
Lytic MTS
RCC, ATC, neuroblastoma, lung, MM, lymphoma
Hypertrophic pulmonary osteoarthropathy
Primary – pachydermoperiostosis
Secondary – lung ca (NSCLC), bronchiectasis, emphysema
tram line sign
MTS Bone scan
Multiple asymmetric focal lesions:
spine>sternum>ribs> long bones>skull
MTS>arthritis>trauma> Paget>MBD>OM
Spine MTS: body and pedicles
FDG :DD MTS vs osteoporosis – no uptake in osteoporosis
Superscan MTS
↓ uptake in soft tissue and nephron-urinary tract
long bones, skull, no kidneys
DD hyperpara