Metabolic Bone Disease – Radiology

Question 1

What are the 2 main radiographic signs?

Answer 1

Osteopenia

Osteosclerosis

Question 2

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

Answer 2

X rays: Density 
Densitometry: Density + attenuation
CT scans: Density + attenuation 
MRI scans: Biochemical composition
Radionuclide bone scans: Bone turnover

Question 3

What is the main difference between osteoporosis and osteomalacia?

Answer 3

Osteoporosis: decreased bone mass
Osteomalacia: decreased bone mineralisation

Question 4

Describe the microstructure in osteoporosis.

Answer 4

Normal

Though there is an overall decreased quantity of bone

Question 5

What are 3 features of osteomalacia?

Answer 5

Too little mineral: osteopenic + soft bone bends + deforms
Looser’s zones
If calcium remains low –> secondary hyperparathyroidism

Question 6

What are Looser’s zones? Where are they found?

Answer 6

Insufficiency fracture at high tensile stress areas
Short Lucent lines with irregular sclerotic margins
Found in proximal femur, scapular, pubic rami, proximal ulna + lower ribs

Question 7

What is a distinctive feature of osteomalacia that can be seen in an X-ray of the vertebrae?

Answer 7

Codfish vertebrae: biconcave loss of height

Question 8

What radiographic feature is common to both osteomalacia and osteoporosis?

Answer 8

Osteopenia

Question 9

What is the key difference between osteomalacia and rickets?

Answer 9

Rickets occurs before the growth plates have fused

As the metaphysis grows most rapidly, it shows the most obvious changes

Question 10

What are 5 radiographic features of rickets?

Answer 10

Indistinct frayed metaphyseal margin
Widened growth plate (no calcification taking place)
Splaying metaphyses due to weight bearing
Rickety rosary
Osteopenia

Question 11

What is Rickety Rosary?

Answer 11

Enlargement of the anterior ribs

Question 12

Describe how PTH, calcium and phosphate change in:

a. Primary HPT
b. Secondary HPT
c. Tertiary HPT

Answer 12

Primary: PTH high, Ca2+ high, Phosphate low
Secondary: PTH high, Ca2+ low, Phosphate normal/ high
Tertiary: PTH high, Ca2+ high, Phosphate high

Question 13

What are the main consequences of secondary HPT to bone?

Answer 13

Resorption

Question 14

List 4 types of bone resorption.

Answer 14

Subperiosteal
Subchondral
Intracortical
Brown tumours

Question 15

Describe 4 radiological features of renal osteodystrophy.

Answer 15

Subperiosteal bone erosions
Brown tumours
Sclerosis: vertebral end plates (rugger jersey spine)
Soft tissue calcification (vessels/ cartilage)

Question 16

What is a radiological sign?

Answer 16

A change in imaging appearance (structural/ functional) that may indicate a pathology

Question 17

How is osteoporosis diagnosed? What further tool may be used?

Answer 17

DEXA scan: T score < -2.5

FRAX 2: Gives 10 year major fracture risk

Question 18

Describe 3 radiological features of osteoporotic bone

Answer 18

Loss of cortical bone/ thinning of cortex
Loss of trabeculae
Insufficiency fractures (stress fractures due to normal stress on abnormal bones)

Question 19

List 4 common sites of insufficiency fractures

Answer 19

Sacrum
Underside of femoral neck
Vertebral bodies
Pubic rami

Question 20

Describe the findings on XR/CT, bone scan and MRI of osteoporotic bone

Answer 20

XR: Periosteal reaction + callus, increased sclerosis lines around fracture
MRI: Bone oedema
Bone scan: Increased uptake

Question 21

List 4 radiological features of osteomalacic bone

Answer 21

Osteopenia
Looser’s zones
Codfish vertebrae
Bending deformities

Question 22

Describe 6 radiological features of Paget’s disease

Answer 22

Cortical thickening
Bone expansion
Coarsening of trabeculae
Osteolytic, osteosclerotic + mixed lesions
Osteoporosis circumscripta (skull)
Usually focal on 1 bone (doesn’t jump joints)