2. Metabolic bone disease - radiology Flashcards
What imaging looks at the density of bones?
- X-rays
- CT
- Bone densitometry
What imaging looks at the biochemical composition of bone material?
MRI
What imaging looks at the bone turnover and osteoblastic activity of bone?
Radionuclide bone scans
What colour are very dense materials on x-rays and CT scans?
White
What turns bright in T1 MRI scans and why is bone white?
- Fat shows up bright
* Bones show up white because there’s lots of fat in the bone marrow
What sites does the radionuclide bone scan go to?
Sites of increased osteoblastic activity
What is a pathology and radiological sign?
- Pathology - disease process that gives rise to symptoms, signs, biochemical disturbances and changes in imaging appearance
- Radiological sign - change in imaging appearance (structural or functional) that may point towards a pathology
In BMD, what is a T and Z-score?
- T-score - reference database with white adult premenopausal females
- Z-score - reference database that is age and sex matched
What is a FRAX tool?
- Can enter patient data from DEXA scan, along with age, weight, sex and height
- This software generates a risk score
- Refer to the Nogg guidelines with this information
What signs of osteoporosis can be seen in radiology?
- Loss of cortical bone/thinning of cortex
- Loss of trabeculae
- Development of insufficiency fractures
What are insufficiency fractures?
- Stress fractures due to normal stress on abnormal bones
- Not limited to osteoporosis
- Common in sacrum, underside of femoral neck, vertebral bodies, pubic rami
How can insufficiency fractures be detected in X-rays, MRIs and bone scans?
- X-ray - initially normal but can get periosteal reaction and callus. Increased sclerosis around fracture lines is more commonly seen.
- MRI - bone oedema (low signal on T1, high signal on T2 and STIR)
- Bone scan - increased osteoblastic activity
How does density change in sclerosis?
Increases
What does increase bone turnover in the pelvic area look like?
Honda sign
When do patients develop Looser’s zone?
When there is too much un-mineralised osteoid
What will a patient with a mature skeleton and closed growth plates get if there is reduced bone mineralisation?
- Looser’s zones osteopenia
- Codfish vertebrae
- Bending deformities
(osteomalacia)
Where do the radiological signs mainly centre towards in children with reduced bone mineralisation?
Towards growth plates - develop rickets
What are Looser’s zones and where are they found?
• Pseudofractures at high tensile strength areas
• Type of insufficiency fracture - found in similar areas to them
- medial promixal femur
- lateral scapula
- pubic rami
- posterior proximal ulna
- ribs
What do Looser’s zones look like?
- Less clean than normal insufficiency fractures
- Short lucent lines with irregular sclerotic margins
(because the bones cannot heal properly)
What happens to the metaphyseal margin, growth plate, metaphyses and anterior ribs in rickets?
- Frayed metaphyseal margin
- Widened growth plate without calcification
- Cupping metaphyses
- Enlargement of anterior ribs
What are lucencies and when do they form?
- Due to hyperparathyroidism
- Areas of intracortical resorption (where bone has been eroded away)
- Lack of crisp cortical edges due to periosteal reactions
- ‘pepper pot skull’
- Can become brown tumours if large
What type of disease is renal osteodystrophy and how does it affect the bone?
- Specialised type of primary hyperparathyroidism
- Patient gets osteomalacia and osteoporosis
- Leads to secondary hyperparathryoidism
- Subperiosteal erosions and brown tumours
- Sclerosis - rugger jersey spine
- Soft tissue calcification
How is osteoporosis and osteomalacia different?
- Osteoporosis - reduced total bone
* Osteomalacia - reduced bone mineralisation
Group the following into osteoporosis and osteomalacia: • Looser's zone • Osteopenia • Insufficiency fractures at end plates • Bending of the bone
- Osteoporosis - osteopenia and insufficiency fractures at end plates
- Osteomalacia - Looser’s zone, osteopenia, bending of the bone
How does the density of bone change at endplates and the middle of the bone in abnormal vertebrae?
- Increased density at endplates
* Reduced density in the middle
What can be seen in the radiology of Paget’s?
- Cortical thickening
- Bone expansion
- Coarsening of trabeculae
- Osteolytic and osteosclerotic
- Mixed lesions
- Osteoporosis circumscripta
Can Paget’s disease cross the joint to another bone?
No (but still possible to get poly-ostotic Paget’s - adjacent bone unlikely)
