Bone Densitometry and Other Imaging

Question 1

T2 signal and T1 signal

Answer 1

T1 signal bright on fats but dark in water
T2 signal bright on the water

T1 displays anatomy well
T2 displays the volume of the water well (nucleus pulposis, CSF)

Question 2

2 common sites of DEXA scan are recommended

Answer 2

hip and lumbar

Question 3

What is T-score and Z-score

Answer 3

T score: Comparison by standard deviation (SD) to a young adult population, matched for sex and ethnicity

Z-score: compared by SD to an age, sex and ethnicity population

≥-1.0: normal
<-1.0 to >-2.5: osteopenia
≤-2.5: osteoporosis
≤-2.5 plus fragility fracture: severe osteoporosis

Question 4

How Scintigraphy can take different body part with different interval

Answer 4

Angiogram phase
- Images taken every 2-3 sec for 30 seconds

Capillary and blood pool phase
- tracer is located in the extravascular space after 2-4mins and images are taken

Delayed or bone scan phase
- 2-4 hrs after injection the tracer is located in bones

Detect abnormal metabolic rates
- hot spots indicate increased uptake
- cold spot indicate photopenia