Bone disease - Radiology Flashcards
What are the two main radiographic signs in metabolic bone diseases?
Osteopenia
Osteosclerosis
What is the lucency of the following scans proportional to: a. X rays b. Densitmetry c. CT scans d. MRI scans e. Radionucline bone scans
X rays - Density
Densitometry - Density and attenuation
CT scans - Density and attenuation
MRI scans - Chemical and water content
Radionuclide bone scans - Bone turnover
What is the main difference between osteoporosis and osteomalacia?
Osteoporosis – decreased bone mass
Osteomalacia – decreased bone mineralisation
(Osteopenia is main radiological feature of both)
Describe the microstructure in osteoporosis.
Normal (Though there is an overall decreased quantity of bone)
What are the features of osteomalacia?
Too little mineral – osteopenic and soft bone bends and deforms
Too much osteoid – Looser’s zones
If calcium remains low –> secondary hyperparathyroidism
What are Looser’s zones? Where are they found?
Narrow lucency, perpendicular to the bone cortex
Found in the pubic rami, proximal femur, scapular and lower ribs
What is a distinctive feature of osteomalacia that can be seen in an X-ray of the vertebrae?
Codfish vertebrae – biconcave loss of height
What is the key difference between osteomalacia and rickets?
Rickets occurs before the growth plates have fused As the metaphysis grows most rapidly, it shows the most obvious changes
What are the radiographic features of rickets that are linked to the metaphysis?
Indistinct frayed metaphyseal margin
Widened growth plate (no calcification taking place)
Bowing of weight bearing bones
What is Rickety Rosary?
Enlargement of the anterior ribs at costochondral joint causing large ‘bead-like’ knobs beneath the skin
Describe how PTH, calcium and phosphate change in: Primary HPT Secondary HPT and Tertiary HPT
Primary HPT
PTH – high
Calcium – high
Phosphate – low
Secondary HPT
PTH – high
Calcium - low
Phosphate – normal or low
Tertiary HPT
PTH – high
Calcium –high
Phosphate – low
What are the main consequences of secondary HPT to bone?
Resorption and increased density
List 4 types of bone resorption.
Subperiosteal
Subchondral
Intracortical
Brown tumours
What are the differences between slow and fast bone loss?
Slow
Involutional Osteoporosis
Bone has time to remodel
Bone loss occurs according to mechanical needs
Fast
hyperparathyroidism/disuse osteoporosis
Bone loss is too rapid
Loss does not cater to mechanical needs
Describe the radiological features of renal osteodystrophy.
Subperiosteal bone erosions
Brown tumours
Sclerosis – axial skeleton/vertebral end plates (rugby jersey spine)
Soft tissue calcification (arteries/cartilage)
