Radioloy of metabolic bone disease Flashcards
Imaging used in bone
X ray CT Bone densitometry MRI radionuclide bone scans
Which scans are based on density
X ray
CT
Bone densitometry
What is MRI bone scan based on
Biochemical composition
What are radionuclide scans based on
Bone turnover (bone formation, purely osteoclastic resorption won’t show up)
What colour would fat show up as on mri
white
Why would the inside of a vertebral bone be dark on MRI
Should be white (to show bone marrow which is fatty….) if dark… oedema or soft tissue lesion e.g. tumour
What can happen on the bone marrow following radiotherapy
`Fatty changes to bone marrow
In radionuclide bone scans, which areas appear dark
Increased bone turnover regions
Which areas might have increased bone turnover and thus show up dark on nuclear medicine scan
Joints (bit of wear and tear)
Metabolic bone disorders
Fractures
Tumours
Differentiate radiological sign with pathology
Pathology: A disease process that gives rise to symptoms, signs, biochemical disturbances and changes in imaging appearance.
Radiological sign A change in imaging appearance, whether structural or functional, that may point towards a pathology
What does microstructure of osteoporotic bone look like
Completely normal, just a lot less of it
What happens to bones in osteoporosis
Fragility fractures, deformity otr pain
Differentiate T score and Z score in dexa scans
▪ T-score (ref database white adult premenopausal females) ▪ Z-score (ref database age and sex matched)
T score range for osteoporosis and osteopenia
T-score -1.5 to -2.5 = osteopenia; less than -2.5 = osteoporosis
Which areas are commonly assessed on DEXA
Vertebrae and pelvis
look specifically at L2-L4
T/F how low the BMD is (t score) is reflective of fracture risk and severity of osteoporosis
F
What is used to assess risk of fracture
FRAX, BMD put in along with other risk factors, gives 10 year fracture risk
then look at nogg guidelines
Radiology signs for osteoporosis (not DEXA but imaging)
Loss of cotical bone/thinning of cortex
Loss of trabeculae
Insufficiency fracture
What is insufficiency fractures
Stress fractures: normal stress on absormal bone
Common site for insufficiency fractures
Sacrum, underside of femoral head, vertebral bodies, pubic rami
What is seen in insufficiency fractures:
XR/CT
MRI
BONE SCAN
XR/CT = normal initially, periosteal reaction/callus, increased sclerosis around fracture line (major)
MRI= Bone oedema i.e. low signal on T1, high signal on T2 and STIR
Bone scan= osteoblastic activity as bones try to heal
Sign for insufficiency fracture at back of pelvis
Honda sign
What is the pathology in osteomalacia
Unmineralised bones
osteopaenic and soft bones
What zones do you get in osteomalacia
looser’s zones
Radiology for osteomalacia depends on what
Biochemistry: vit d low, calc: N/low, PTH up Inadequate or delayed mineralisation
Radiology depends on age and closure of growth plate
What may be found in osteomalacia
- looser’s zone
- osteopenia
- mature skeleton
- codfish vertebrae
- bending deformity
What might be seen in rickets
Before growth plate closure
Radiological signs centred mainly to growth plates
Changes of osteomalacia
What are Looser’s zone where do they occur
Pseudofractures
Are also types of insufficiency fracture
Medial proximal femur Lateral scapula
Pubic rami
Posterior proximal ulna
Ribs
What do looser zones look like
At right angle do the bone
Irregular sclerotic margins
Bone may be osteopaenic/expanded
When are codfish vcertbrae seen AND WHAT IS IT
Osteoporosis and ostoepaenia
Biconcave vertebrae
Ricket what is seen on imaging
Frayed metaphyseal margin
Widened growth plate without calcification
Cupping/splaying metaphyses due to weight bearing
Enlargement of anterior ribs
Osteopenia
What is seen on imaging with primary and secondary HPT
Primary - increased bone resopriton
Secondary- increased bone resorption and increased density
Types of bone resorption
Subperiosteal
Subchondral
Intracortical
Brown tumours (if large)
What does sub-periosteal resorption look like
No straightened edge to the bone (not like wavey but just not a definitive line)
What do circular lucencies or small speckles of black on skull bone represent
What is the name for lots of little spckles on skull
Intracortical
Pepper pot sign
Give an example of a lytic bone lesion found in primary HPT
Brown tumour
t/f radiology can easily identify the cause of a lytic bone lesion
F…. look like infection, malignancy or brown tumour
Outline pathogenesis of renal osteodrystrophy
Cannot excrete phosphate due to renal failure
Phosphate can bind calcium (i.e. anion bound) so low free (ionised) calcium
High phosphate and the low free calcium increases PTH which increases bone resorption
Vit D decreases due to renal failure also increasing PTH
Therefore you get
- Osteoporosis due to increased bone resorption
- Osteomalacia due to reduced bone mineralisation due to vit D decificiency
SECONDARY HPT
Which lesions could be seen in renal osteodystroph u
Subperiosteal erosions,
brown tumours,
Sclerosis – vertebral endplates giving a rugger jersey spine,
Soft tissue calcification (vessels, cartilages)
What is rugger jersey sign
Occuring in renal osteodystrophy due to secondary HPT
Increased density at the end plates and then increased lucency in between
Giver an example of soft tissue calcification in secondary HPT
Menisci in the knee are white
Differentiate density of sclerotic vs lytic lesions
Sclerotic is hardened and dense
Lytic is not
Outline the stages of pagets
lytic
mixed lytic and sclerotic
sclerotic
Symptoms of pagets, bone and other wise
Bone: pain, derformity, fracture (same as osteoporosis)
Other: NERVE ENTRAPMENT, spinal stenosis and deadness
Biochemical signs in pagets
Increased Alk Phos.
What are patients with pagets prone to
Osteogenic sarcoma
Radiological signs in paget’s
Cortical thickening
Bone expansion
Coarsening of trabeculae
Osteolytic, osteoclerotic and mixed lesions
Osteoporosis circumscripta (in lytic part)
How can u distinguish pagets from the other diseases
Usually focal, not usually present in adjacejnt bone
T/f the osteoporosis circumscripta is related to osteoporosis
f….. THIS IS JUST THE NAME FOR LUCENCY IN PAGET’S DISEASE
Sign for the increase bone turnover sometimes seen in the spine in radionuclear medicine scans in pagets
Micky mouse sign
