Osteoporosis Imaging Flashcards
WHAT IS OSTEOPOROSIS?
i) which two things characterise it?
ii) what does it lead to increased risk of?
iii) what are the two types of primary OP and who does each present in? do females or males predominate?
iv) name two things that can cause secondary OP? does it affect males or females more?
i) characterised by low bone mass and microarchitectural deterioration of bone tissue
ii) increased risk of fracture
iii) primary - type I is post menopausal and type 2 is senile (>70-75yrs)
F > M
iv) secondary - can be caused be medical disease eg rheumatoid or medications eg steroids or anti epilep, thyroxine, PPIs
- aff F and M equally of any age
BONE MASS
i) what can be two causes of low bone mass?
ii) name three things that bone mass relies on?
iii) at what age is peak bone mass reached? what happens after this age?
iv) name three things that can determine peak bone mass and three things that can affect rate of bone loss?
i) inadequate peak bone mass during growth
- reduction in bone mass due to imbalance between resorp and formation
ii) relies on oestrogen levels (resorp), calcium/vit D (depos), PTH (resorp)
iii) peak bone mass at age 30 then progressive bone loss and inc risk of fracture
iv) peak bone mass det by genes, nutrition, phys activ, hormones
rate of loss det by menopause, smoking, diet, alcohol, drugs
DEXA SCAN
i) what does it measure?
ii) is it high or low dose radiation?
iii) what is a strong predictor of fracture risk?
iv) name three clinically relevant sites to be imaged
i) measures bone density calc by computer software
ii) low dose radiation (less than background)
iii) reduced bone mineral density is a strong predictor of fracture risk
iv) image - lumbar spine (L1-4), hip and forearm (right)
BMD MEASUREMENT BY DEXA
i) name two things that BMD is compared against?
ii) what is the T score?
iii) what is the Z score?
iv) what does WHO define osteoporosis as in relation to BMD and peak bone mass?
i) compare BMD with that expected of a young healthy adult and a healthy adult of the same age
ii) T score = difference (SD) between measured BMD and that of a young healthy adult
iii) Z score = difference (SD) bet measured BMD and someone of the same age
iv) WHO - osteoporosis = BMD of 2.5 SD or more below the mean peak bone mass as measured by DEXA
BMD MEASUREMENT BY DEXA
i) what is a normal T score for post meno women/men over 50? what criteria is used?
ii) what T score will indicate osteopenia?
iii) what T score will indicate osteoporosis
iv) what does a Z score of
v) what can cause increased BMD on DEXA scan and should be excluded?
i) normal T score is equal or greater than -1 - use WHO criteria
ii) T between -1 and -2.5 = osteopenia
iii) T equal or below -2.5 = osteoporosis
iv) Z score < -2 means BMD is lower than is should be for someone age matched
v) artefact such as jewelry, buttons, compression fractures
BMD MEASUREMENT BY DEXA
i) is WHO criteria used for pre meno women and men <50yrs?
ii) what Z score is categorised as low bone mineral density for age?
iii) how can a clinical diagnosis of OP be made for patients?
iv) what can DEXA measurements be combined with?
i) no - use Z score
ii) Z score below -2 are low BMD for age
iii) clinical dx can be made for patients with a fragility fracture irrespective of BMD measurement
iv) combine DEXA measurements with fracture risk assessment tools eg FRAX
FRAX TOOL
i) who (!) developed it?
ii) what anatomical area does it measure BMD from? name four other clinical risk factors that are combined with it?
iii) what does it calculate?
iv) name two groups of people it may be useful for
i) the WHO
ii) measure BMD from femoral head on DEXA then combine with RFs such as age, weight, height, fragility fracs, smoking, alcohol, RA
iii) calculates 10 year probability of hip fracture or major osteoporotic fracture
iv) may be useful for post meno women and men >50yrs who have RF for fracture
DETERMINANTS OF BONE STRENGTH
i) name the three determinants
ii) what is the main determinant? what are the two types of bone that fall into this category?
i) macroarchitecture, microarchitecture and material properties of bone
ii) main det is microarchitecture = cortical and trabecular bone
BONE MICRO ARCHITECTURE
i) what is the dense outer part of bone?
ii) what is the less dense inner part of bone?
iii) how can information about microarchitecture of bone be investigated? (2)
i) cortical bone is the dense outer shell
ii) trabecular bone is the inner lattice like structure - strength is dep by thickness, number and connectivity
iii) microarchitecture by bone bioopsy and non invasive new techniques eg TBS and high res periph CT
TRABECULAR BONE SCORE
i) what does it do?
ii) name three things that is is related to?
iii) what does it provide? what can it be input into?
iv) does it correlate with BMD
i) quantifies variation in grey level texture - derived from textural analysis of DEXA spine image
ii) related to 3D bone mictoarchiecture = trabecular number, seperation and density
iii) provides fracture risk assessment indep of BMD, FRAX and clinical risk factors
- can be input into FRAX tool for further fracture risk assessment
iv) same BMD can have different TBS
TRABECULAR BONE SCORE
i) what does a raised TBS represent?
ii) what does a low TBS reflect?
iii) from what age does it normall increase?
i) raised TBS = strong, fracture resistant microarchitecture
ii) low TBS reflets weak, fracture prone microarchitcture
iii) TBS decreases with age from 45yrs
HIGH RESOLUTION PERIPHERAL CT
i) in what situation is it mainly used?
ii) what is it used to image
iii) name a pro in comparison to conventional CT
iv) what does it provide?
v) can it assess bone micro architecture?
i) mainly used in research
ii) used to image the peripheries
iii) higher spatial resol than conventional CT
iv) provides quantitive volumetric bone mineral density
v) can be used to look at bone microarchitecture (cortical and trabecular bone seperately)
- gives info only prev availble from bone biopsy
SUMMARY
i) what is osteoporosis?
ii) name three imaging techniques that can be used to look at bone quality and mech strength
i) OP is a disorder of bone charac by low bone mass and microarchitctural deterioration > increased risk of fracture
ii) DEXA, trabecular bone score (microarch) and high res peripheral CT
