Radiology 3 Flashcards
(28 cards)
1
Q
DXA scan for diagnosis of osteoporosis
A
- Dual-energy x-ray absorptiometry (DXA) measures bone mineral density of the hip, spine or radius
- Hip and spine because they are weightbearing bones with physiological stress and they are the most commonly
o Lumbar vertebra
o Femoral neck
2
Q
Dual energy mechanism of DXA scan
A
o One image is of bone and soft tissue, one image is just bone
o Take the difference between the two to determine bone density
3
Q
Notes on DXA scan
A
- Precision is superior and takes less of a change to be considered significant (disease progression), making it the gold standard for bone density testing and monitoring
- T-score cannot be used to follow progress
- Each machine is different, should be calibrated to standards, read by certified clinician
- Over the age of 70, spine scan is not accurate
- DXA scan is only 1/3 of the story
4
Q
T score
A
- T- scores represent a standard deviation above/below that of a 30 y.o. of the same sex
- Risk of vertebral fracture based on T-score (2T score)
- Score measures the difference in standard deviation from the mean
o **T-score of –1 indicates 10% decrease in BMD below an average 30-year-old
o **T-score of +1 indicates 10% increase in BMD above an average 30-year-old
5
Q
VFA for diagnosis of osteoporosis
A
- Vertebral Fracture Assessment (VFA) is a new technology using central DXA that permits imaging of the thoracic and lumbar spine to evaluate for the presence of vertebral fractures.
- Patients with prevalent vertebral fractures are at increased risk for future osteoporotic fractures of the spine, wrist and hip.
6
Q
VFA notes
A
- 2/3rds of patients with vertebral fractures are asymptomatic, so patients often do not present with complaints of back pain
o They are cancellous fractures, so they don’t hurt as much, the patient puts up with the pain
o On lateral x-ray, a previous vertebral fracture will make the vertebra wedge shaped, with anterior shortening
o MOST RELIABLE IS VFA X-RAY WHICH CAN CLEARLY DIANOSE OSTEOPOROSIS
o If a patient does not show osteoporosis on DXA, has risk factors for fracture, and has evidence of previous vertebral fracture, VFA is MORE sensitive than DXA and can be a better, more reliable diagnostic modality TEST QUESTION?
7
Q
Sensitivity of VFA
A
- Up to 40% of patients who have osteoporotic vertebral fractures have BMD values that are better than -2.5, the WHO established definition for osteoporosis in post-menopausal women measured by central DXA. – MORE sensitive***
- Prior vertebral fractures are a better predictor of future fracture than low BMD alone
- Patients with prevalent vertebral fracture demonstrate a greater response to medical therapy than patients without prior fracture.
8
Q
IVA for diagnosis of osteoporosis
A
- Instant vertebral assessment (IVA)
- The majority of vertebral fractures are silent, and lateral X-rays (the standard method for identification) are not routinely obtained.
- Instant vertebral assessment (IVA), a technology that utilizes dual X-ray absorptiometry (DXA), provides rapid assessment of vertebral fractures and is highly correlated with vertebral fractures, as assessed on standard lateral spine X-rays.
9
Q
Ultrasound for diagnosis of osteoporosis
A
- DXA has specific limitations (e.g., use of ionizing radiation, large size of the equipment, high costs, limited availability) that hinder its application for population screenings and primary care diagnosis.
- This has resulted in an increasing interest in developing reliable pre-screening tools for osteoporosis such as quantitative ultrasound (QUS) scanners, which do not involve ionizing radiation exposure and represent a cheaper solution exploiting portable and widely available devices.
- Furthermore, the usefulness of QUS techniques in fracture risk prediction has been proven and, with the last developments, they are also becoming a more and more reliable approach for assessing bone quality.
- However, the US assessment of osteoporosis is currently used only as a pre-screening tool, requiring a subsequent diagnosis confirmation by means of a DXA evaluation.
-
Calcaneus is commonly looked at on ultrasound
o If signs of osteoporosis are present, DXA is recommended
10
Q
T and Z scores: What is the normal range of each score?
A
- Normal: T score -1.0 to +1.0 (T compares to Thirty-year-old)
- Z-score < -2.0 indicates secondary cause of osteoporosis (age matched)
11
Q
T and Z scores: Who are the population groups that use T and Z scores?
A
T score – comparison to young adults (30-year-old)
o **Post-menopausal women
o **Men over 50 years old
o Never use in children, pre-menopausal women or men <50 years old
Z score – comparison to age-matched adults
o **Young patients (younger than peak bone mass)
o **Pre-menopausal women (when bone density is lower than expected)
o ***Men < 50 years old
o Evaluating for secondary causes of osteoporosis
12
Q
Most common type of osteoporosis?
A
- MOST COMMON TYPE IS POST-MENOPAUSAL OSTEOPOROSIS
13
Q
T and Z scores: What is the fracture risk of vertebra and hip based on T-scores?
A
- T score > -1.0 = normal
- T score -1.0 - -2.5 = osteopenia (low bone mass)
- T score
14
Q
Visible bone changes
A
- Human eye can see 30-50% bone loss on x-ray
- By the time you see osteoporosis on x-ray, you would already have a score of -3.0, which means they already qualify for the diagnosis of osteoporosis
- This is why you need DXA scan instead of relying on x-ray alone
- A single standard deviation represents a 10% decrease in bone mineral density, so it is much more sensitive
15
Q
Who to treat for osteoporosis
A
- ***FRAX 10-year hip fracture probability ≥3%
- ***FRAX 10-yr all major osteoporosis-related fracture probability of ≥ 20%
16
Q
Non-pharm treatment
A
o Resistance training, walking, any exercise
o Avoid smoking, alcohol, caffeine
17
Q
Pharmacologic agents for treatment
A
o Calcium and vitamin D o Bisphosphonates (alendronate, ibandronate, risedronate, and zoledronate) o Calcitonin o Estrogens and/or hormone therapy o Raloxifene o Parathyroid hormone
Test and monitor bone loss every 2 years
18
Q
Calcium
A
- 1,000-1,500 mg calcium per day
- Use calcium citrate (over calcium carbonate) because it is better absorbed, but it is more expensive
19
Q
Vitamin D
A
- 2000 IU per day
- Increases absorption of calcium
- Can order a vitamin D level on your patient because it appears that low vitamin D levels in diabetics predisposes them to Charcot
- Can get a vitamin D level q3 months with A1c levels in your diabetics
- Some podiatric surgeons are getting vitamin D levels pre-operatively to prevent non-unions in diabetics and won’t do surgery on someone with low vitamin D levels
- When you draw blood, you don’t get it in IU, you get nanograms/mL
- Anything less than 20 ng/mL you get nervous about, should be above 30 ng/mL
- You can calculate how many IUs of vitamin D to prescribe your patients because 100 IU daily will raise the serum vitamin D levels by 1 ng/mL
- Example: 2000 IU per day will raise serum vitamin D levels 20 ng/mL
20
Q
Bisphosphonates
A
- First line treatment, anti-resorption
- Prevent osteoclasts (prevent reabsorption), so NOT fast acting
- Oral or IV
o Fosfomax (daily/weekly), Acetonel (daily/weekly), Boniva (PO monthly/IV q3 months – only for vertebral fractures), Reclast (yearly) - Side effect: GI/esophogitis issues
o Take will full glass of fluid and sit upright for 30 minutes - Side effect: Atypical fractures
o ***Atypical femoral fractures - Side effect: Jaw necrosis, bone pain
o Rare but very debilitating
21
Q
Atypical femoral fractures
A
- ***Atypical femoral fractures (can break down the femur)
- Research to support that effects are “maximized” after 5 years of use
o Drug holiday is necessary to prevent femur fractures and osteonecrosis of the jaw due to osteo-fragility due to lack of appropriate remodeling of bone
o Drug holiday is at least 3 years, there are protective effects that last during this period - ***Do not give to patients with kidney disease
22
Q
Hormone replacement therapy
A
- Women aged 65-72
- Spine BMD increased by about 6% during 3 years on HRT; about two thirds of this gain was lost during 2 years off HRT
- Femoral-neck BMD increased by about 4% during HRT; about two thirds of the gain was lost during 2 years off HRT
- Effective in both primary prevention and secondary prevention.
- Problems with breast cancer, uterine cancer, ovarian cancer
- Can use with progesterone to prevent some of the cancer risks
- Prevents bone reabsorption (breakdown) – have to balance with risk of HRT in women
- Testosterone in men – only helped those over 65 y/o who were low for their age groups
23
Q
Raloxifine (Evista) – SERM
A
- Positive estrogen effects on bone, blocks it in breast and uterus
- Used to prevent recurrence of Breast CA
- Increases risk of clotting
- Save for women with no CV risk but at risk for breast cancer
24
Q
Calcitonin
A
- Fortical or Miacalcin
- Prevents reabsorption
- Not greatly effective – should be used in post-menopausal women who can’t use estrogen and only have vertebral fracture
- Daily SubQ injections or intranasally (aternate nostrils daily)
- Only using intranasally to prevent pain of osteopososis, does not do much to prevent reabsorption
25
PTH (with bone anabolic activity)
- Stimulates osteoblasts – one new med – no one using too spendy
- Teriparadete (aka Foteo) – given daily, SQ, loses effectiveness after 2 years ***
- Only one that lays down bone
- Research showing using this plus med that decreases osteoclast activity gives the best results
26
RANKL
- Prolia is an antibody to the RANKL receptor, considered a biologic
- Inhibits the development and activity of osteoclasts, also messes with T cells
- ***Given SQ q 6 months***
- Loses its effects after 1 year and then is not effective
- Adverse reactions – bone pain, jaw necrosis, unusual femur fracture, infection
27
FRAX definition
- The FRAX® tool has been developed to evaluate fracture risk of patients. It is based on individual patient models that integrate the risks associated with clinical risk factors as well as bone mineral density (BMD) at the femoral neck
- The FRAX® algorithms give the 10-year probability of fracture.
28
FRAX value at which you begin treatment
- 10-yr all major osteoporosis-related fracture risk of >20%
| - 10-yr hip fracture risk >3%
