1. RADIOLOGY OF SKELETAL SYSTEM Lecture 1

2. A-PLAIN FILM
Plain film still the mainstay of radiological investigation of skeletal system . It is simple, low cost sensitive with good resolution . The radiological responses of bone to pathological process are limited ,so there are similar basic signs occur in different conditions.

3. Basic signs of bone diseases
1- decrease bone density : which
may be focal when it is usually
referred to as lytic area or it may be
generalized when it is referred to
osteopenia until specific diagnosis
such as osteomalacia or osteoporosis
can be made .

4. Basic signs of bone diseases
2-increase bone density:
(sclerosis )
which may be focal or
generalized.

5. Basic signs of bone diseases
3-periosteal reaction : excess new
bone produced by periosteum in
response to some condition as
trauma, inflammation and neoplasm .
In its simplest form the new bone is
seen as linear density separated
from the bony shaft by clear zone
,often later obliterated as the new
bone merges with cortex .

6. Basic signs of bone diseases
Periosteal reaction may be
focal or generalized , it may
take several forms but not
specific for condition .

7. Basic signs of bone diseases
4-cortical thickening : also involve the lying down of new bone by periosteum , but the process very slow so the
new bone showing homogenous
density as the normal cortex .

8. Basic signs of bone diseases
5-alteration in trabecular pattern :is a complex response
usually involving a reduction in the number of trabeculae
with an alteration in those remain .
6- alteration in shape of the bone :may be congenital
in origin as in bone dysplasia or may be acquired as in
acromegaly .
7- alteration in the age of bone: the time of
appearance of calcification and fusion of various
epiphyseal center depend on age of child

9. For diagnostic approach when interpreting bone radiograph :
1-age of patient
2-site of lesion : long or flat bone medullary or cortical , epiphyseal , diaphyseal metaphyseal
3-localized or generalized ,solitary or multiple , sclerotic or lytic .
4-adjacent cortex : any destruction of cortex indicates aggressive lesion.

11. For diagnostic approach when interpreting bone radiograph :
5-edge :the edge of any lesion should be examined carefully whether it is well or ill defined ,the well defined edge (narrow zone of transition ) between the normal and abnormal bone )mostly seen in slow growing process (benign ) like bone island.
The ill defined margin (wide zone of transition ) in the aggressive lesion like osteosarcoma .

13. 6- expansion :bone expansion with intact cortex usually indicate slow growing lesion such as aneurysmal bone cyst .

14. For diagnostic approach when interpreting bone radiograph :
7-periosteal reaction :the presence of active periosteal reaction with absent history of trauma usually indicate aggressive lesion .
8- consistency :patchy calcification usually indicate cartilage tumor ,while ill defined calcification suggest osteoid formation .
9- soft tissue swelling : the presence of soft tissue mass suggest aggressive lesion ,the better define mass more likely occur with neoplasm ,while the ill define mass occur in infection .

15. B-Nuclear medicine bone scan
A radioactive compound (technetium -99 phosphate )
accumulate in bone several hours after i. v. injection of
isotope .
The radiological sign of abnormal scan is increase uptake
of isotope (hot area ) seen when there is increase blood
supply and bone turn over (in child epiphyseal plate
showing increase uptake –it is normal ).

16. B-Nuclear medicine bone scan
OR decrease uptake of isotope as (cold area)
seen in early osteonecrosis , bone infarction
or anaplastic tumor .
Bone scan is sensitive for early detection of
bone disease but it is not specific .

17. Indications of bone scan
1-investigation of clinically suspected bone lesion
despite of normal plain film .
2- detection of osteomyelitis and other soft tissue
inflammatory changes as early as 48 hours after the
onset of disease ,even if clinical sign is equivocal .
3- detection of metastatic bone lesion :changes are seen much earlier than plain film .

18. C-ULTRASOUND:
Ultrasound is utilized for evaluation of:
1-neonatal hip for congenital dislocation .
2-soft tissue lesion :abscesses and masses .
3-joint effusion .

19. D-Competed tomography (CT scan ):
Indications of CT scan :
1-better demonstration of complex bone area ,like in pelvis ,spine than x-ray film because of cross section study .
2-demonstration the extra-osseous extension of lesion like soft tissue extension .
3- characterization of lesion after contrast injection .

21. E-Magnetic resonance imaging (MRI)
MRI is technique that produces tomographic images by means of magnetic field ,although CT scan evaluates only a single tissue parameter (x- ray attenuation ) ,
MR analyzes multiple tissue characteristics
including hydrogen (proton)density ,T1 and
T2 relaxation times of tissue and blood flow within tissue.

22. E-Magnetic resonance imaging (MRI)
The soft tissue contrast provided by MR is substantially better than for any other imaging modality .
Most tissues can be differentiated by significant
difference in their characteristic T1 and T2
relaxation times.

23. E-Magnetic resonance imaging (MRI)
T1 measure of how quickly a tissue can become magnetized .
T2 conveys how quickly a given tissue looses magnetization .
Bone cortex have low signal intensity on T1 &
T2 sequences while medullary bone (fat) have
high signal intensity on T1 and low signal on
T2.

25. Indications
1-staging of bone tumor (intra medullary extension ,soft tissue and neurovascular bundle invasion )
2-early detection of stress fracture , avascular necrosis .
3-demonstration disc degeneration ,disc herniation ,spinal cord compression .
4-Good detail about joint anatomy and ligament injury .
5- early detection of osteomyelitis .
6- detection of bone edema and bone infarction .

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