Musculoskeletal 2 - The radiology of Metabolic Bone Disease Flashcards
Name 3 imaging methods used to measure bone density
- X rays
- CT
- Bone densitometry
What does MRI determine
Biochemical composition of bones
What do radionuclide bone scans determine
Bone turnover
Very dense things (e.g. bone) are what colour on X rays / CT?
White
Things like fat etc are darker
In MRI, what colour does fat show up as?
White
What 2 things does imaging enable us to do?
- Reveal structural failures
2. Serves as proxy to metabolic dysfunction
How is osteoporosis diagnosed?
Use a DEXA scan
T score from -1.5 to -2.5 is osteopenia
Less than -2.5 = osteoporosis
Before DEXA, check radiological signs of osteoporosis, which include?
- Loss of cortical bone (outer white line)
- Loss of trabeculae
- Insufficiency fractures - stress fracture due to normal stress on abnormal bones
Name 4 areas prone to getting insufficiency fractures
- Sacrum
- Underside of femoral neck
- Vertebral bodies
- Pubic rami
How may insufficiency fractures show on different imaging modalities?
XR/CT : periosteal reaction and callus (rare), increased sclerosis around fracture lines (common)
MRI: bone oedema
Bone scan: increased osteoblastic activity
Osteomalacia = osteopenic, soft bones, caused by decreased bone mineralisation. What is also common in osteomalacia
Loosers zone - caused by too much unmineralised osteoid
What may osteomalacia result in if calcium stays low?
Secondary hyperparathyroidism
Radiologically, how may osteomalacia signs differ in adults and children
In adults - codfish vertebrae, bending deformities etc
In children (rickets) - occurs before growth plate closure - radiological signs are centred mainly to growth plates
Where are common areas for Loosers zones?
- Medial proximal femur
- Lateral scapula
- Pubic rami
- Posterior proximal ulna
- Ribs
Loosers zone = irregular sclerotic margins
What are codfish vertebrae
Biconcave appearance of vertebrae - seen in osteoporosis and osteomalacia
What is a giveaway sign of rickets?
Cupping of metaphysis - in femur, ulna, etc
Anterior rib may also be enlarged
What are the differences in primary and secondary hyperparathyroidism in terms of bone
Primary hyperparathyroidism = bone resorpton
Secondary hyperparathyroidism = bone resorption and increased density
What are causes of primary and secondary hyperparathyroidism
primary - due to parathyroid adenoma. High PTH, low Ca and PO3
secondary - CKD, rickets/osteomalacia. High PTH, low CA, low/normal PO3
Where are common sites of bone resorption - sign of primary/secondary hyperparathyroidism
- Subperiosteal
- Subchondral
- Intracortical
- Brown tumours
What are the features of renal osteodystrophy
- Osteomalacia and osteoporosis
2. Secondary hyperparathyroidism - superiosteal erosions, brown tumours, sclerosis, soft tissue calcification
Rubber jersey spine, what is it a feature of?
Renal osteodystrophy.
The end plates have increased density but the middle has reduced density
It is a sign of sclerosis, which is a feature of renal osteodystrophy
What is Paget’s disease and what are the stages?
It is a disease of bone remodelling.
3 stages:
- Lytic phase
- Mixed lytic/sclerotic phase
- Sclerotic phase
What are the symptoms of Pagets
Bone pain, deformity, spontaneous fractures.
Nerve entrapment, spinal stenosis and deafness
Osteogenic sarcoma
Raised serum alkaline phosphate, urinary hydroxyproline, pyridinoline cross links
What are the radiological features of Pagets
- Cortical thickening
- Bone expansion
- Trabeculae coarsening
- Osteolytic, osteosclerotic and mixed lesions
- Osteoporosis circumscripta
