This document provides an overview of various imaging techniques used in orthopaedics, including their principles, applications, advantages, and limitations. It discusses plain film radiography, computed tomography, magnetic resonance imaging, ultrasound, radionuclide imaging techniques like bone scintigraphy, and emerging techniques like SPECT and PET imaging. The key information provided includes the physical principles behind each technique, their clinical utility in evaluating bone fractures, tumors, infections and other musculoskeletal abnormalities, and factors like radiation exposure, soft tissue contrast, and cost.

1. IMAGING IN
ORTHOPAEDICS
Dr. BIPUL BORTHAKUR
PROFESSOR
DEPT. OF ORTHOPAEDICS, SMCH

2. INTRODUCTION
• The availability of diagnostic images to physical therapists
greatly depends on the practise setting
• The results from imaging studies should be used in conjuction
with other clinical findings
• In general , imaging tests have a high sensitivity ( few false
negatives ) , but low specificity ( high false positive rate )

3. IMAGING TECHNIQUES
• Plain film Radiography
• X – rays with contrast media
• Plain tomography
• Computed tomography ( CT )
• Magnetic resonance imaging ( MRI )
• Diagnostic Ultrasound
• Radionuclide imaging
• Single – photon emission computed tomography
( SPECT )
• Positron emission tomography ( PET )
• Bone mineral densitometry ( BMD )

4. PLAIN FILM RADIOGRAPHY
• First order & Most useful method of diagnostic imaging
• Provides information on size , shape , tissue density & bone
architecture
• Overview - Radiographic image
Radiographic interpretation
Diagnostic associations
Limitations

5. RADIOGRAPHIC IMAGE
• X- Rays - part of elecromagnetic spectrum - ability to penetrate
body tissues of varying densities
• Exposure to xray particles causes the film to darken , while on
areas of absorption , appear lighter on x-ray film
• Denser the tissue - lighter it appears on the film
• Structures in order of deceasing density
METAL > BONE > SOFT TISSUE > WATER ( BODY FLUID ) > FAT > AIR
BONE - Cancellous bone is less dense than cortical bone &
appear lighter than cortical bone

6. RADIOGRAPHIC INTERPRETATION
• Convenient sequence of examination is
Patient
Soft tissues
Bones
Joints
PATIENT - AGE - important criteria
< 10 yrs – ewing’s sarcoma
10 – 20 yrs - osteosarcoma
> 50 yrs – metastatic deposit

7. • SOFT TISSUES
1) GENERALIZED CHANGE - Muscle planes
Bulging - joint effusion ( hip ) / rheumatoid arthritis (
interphalangeal joint )
Displaced - tumours
Obliterated – infection
2) LOCALIZED CHANGE - in case of mass , soft tissue calcification ,
ossification , gas , radioopaque foreign body

8. • BONES
Shape
Generalized change – bone density ( osteopenia/osteosclerosis)
abnormal trabeculations ( Paget’s disease )
sclerotic /lytic lesions ( diffuse metastatic infiltration)
Localized change - BENIGN TUMOURS – well defined , sclerotic
margin, smooth periosteal reaction
MALIGNANT TUMOUR - Ill defined areas , permeative
bone destruction & speculated periosteal reactions

11. JOINTS
JOINT SPACE -
appears wider in children > adults
chondrocalcinosis ( lines of increased within radiographic
articular space )
SHAPE - narrowing / asymmetry of joint space
1) infection
2) inflammatory arthropathies
3) osteoarthritis
EROSIONS - Periarticular erosions - Rheumatoid arthritis , psoriasis
juxta articular erosions - Gout

12. DIAGNOSTIC ASSOCIATIONS
• Osteoarthritis -Narrowing of joint space+subchondral sclerosis +cyst
– Inflammatory arthritis -Narrowing of joint space + osteoporosis
+ periarticular erosions
– Infection / malignancy - Bone destruction + periosteal new bone
formation

13. • LIMITATIONS OF PLAIN RADIOGRAPHY
1) Exposure to ionizing radiation - radiation induced cancer
2) Provides poor soft tissue contrast

14. X RAYS WITH CONTRAST MEDIA
• SINOGRAPHY - simplest form of contrast radiography
• ARTHROGRAPHY -
knee – torn menisci , ligament tears , capsular ruptures
AVN ( femoral head ) in adults - torn flaps of cartilage
spine - diagnose disc degeneration ( DISCOGRAPHY )
small facet joints abnormalities ( FACETOGRAPHY )
MYELOGRAPHY - for diagnosing nerve root lesion

16. PLAIN TOMOGRAPHY
• Provides image ‘ focussed ‘ on a selected plane
• Useful in diagnosing segmental bone necrosis & depressed
fractures in cancellous bone
• Conventional tomography has been supplanted by CT & MRI

17. COMPUTED TOMOGRAPHY ( CT )
• CT SCAN produces sectional images through selected tissue
planes - but with greater resolution
• As compared to conventional tomography , computed tomography
produces trans – axial images ( transverse anatomical sections )
• In new multislice CT scanners , 3D surface rendered
reconstructions & volume rendered reconstructions - help in
demonstrating anatomical contours

18. CLINICAL APPLICATIONS OF CT SCAN
• Since it provides excellent contrast resolution and spatial localization
it’s ideal for evaluating
Acute trauma to the head , spine , chest , abdomen & pelvis
• Better than MRI - fine bone detail & soft tissue calcification
• Invaluable tool in pre operative planning in secondary fracture
management
• Routinely used for vertebrae , acetabulum , tibial plataeu , ankle & foot
injuries - complex ( intraarticular fractures ) & fracture dislocations
• Assessment of bone tumours ( size & spread )
• Can be employed for guiding soft tissues & bone biopsy

20. LIMITATIONS OF CT SCAN
• Provides relatively poor soft – tissue contrast
when compared with MRI
• Major diadvantage is - high radiation exposure

21. MAGNETIC RESONANCE IMAGING (
MRI )
• Provides superb soft tissue contrast , distinguishing
different soft tissues eg. Ligaments , tendons ,
muscle & hyaline cartilage
• Utilizes Non – Ionizing radiation
• Contraindicated in patients with pacemakers &
possible metallic foreign body

22. MRI PHYSICS
Patient’s body placed in a strong magnetic field
Body’s protons ( having + charge ) align themselves along
this
strong magnetic field
Spinning protons further excited by radiofrequency
pulses
spinning positive charges induce their own small
magnetic field , & also produce a signal as they relax (
slow down ) at different
rates

23. • Proton density map is recorded from these signals and
plotted in x, y , z coordinates
• T1 weighted ( T1W) images - high spatial resolution & good
anatomical looking pictures
• T2 weighted ( T2W ) images - physiological characterstics of
tissue
• Proton density ( PD) images - balanced / intermediate – are
combination of T1 & T2 images
• Fat suppression sequences - assessing soft – tissues & bone
marrow
oedema

24. CONTRAST ENHANCED – MRI
• Enhancement by intravenous contrast – active blood supply &
leaky cell membrane
• INDIRECT ARTHROGRAPHY
Gadolinium compounds – Intravenous – secreted through joint
synovium - into joint effusion
No additional distension of the joint
• DIRECT ARTHROGRAPHY
Dilute gadolinium ( 1:2000 concentration ) solution directly
punctured into joints under image guidance
Distention of joint capsule occurs

25. CLINICAL APPILICATIONS OF MRI
• Ideal for non – invasive imaging of the musculoskeletal system - excellent
anatomical detail , soft tissue contrast & multiplanar capability
• MRI of hip , knee , ankle , shoulder & wrist is common - can detect early
changes of bone marrow oedema & osteonecrosis
• MRI Knee - for meniscal tears & cruciate ligament injuries
• Fat suppresion sequences – extent of perilesional oedema & IV contrast –
active part of the tumour ( it distinguish vascular from avascular tissues
• Direct MRI arthrography - distent joint capsule
diagnose labral tears in shoulder & hip
ankle – assess integrity of the capsular ligaments

27. LIMITATIONS OF MRI
• Conventional radiographs & CT are more
sensitive to
SOFT TISSUE CALCIFICATION & OSSIFICATION
as compared
to MRI

28. DIAGNOSTIC ULTRASOUND
High frequency sound waves by TRANSDUCER
penetrate into soft tissues
some waves are reflected back - registered as electric signals
and display images on a screen
• Image produce , depend upon reflective surface & soft tissue interface
• Different tissues display varying echogenicity
Fluid –filled cyst - echo free
fat - highly echogenic
semi solid organs – varying degree of echogenicity
• REAL TIME display gives dynamic image – more useful than static image

29. CLINICAL APPLICATIONS
• Identify hidden cystic lesions – haematomas ,
abcesses , popliteal cysts & arterial aneurysms
• Detect intra- articular fluid , synovial effusions
& monitor ‘ irritable hip ‘
• Use to detect tendinitis & partial or complete
tears
• For guiding needle placement in diagnostic &
therapeutic joint & soft – tissue injections

30. DOPPLER ULTRASOUND
• Blood flow detected – principle of change in
sound frequency – material moving – towards or
away from USG transducer
• Abnormal increased blood flow – areas of
inflammation / aggressive tumours
• Different flow rates – different colour

31. RADIONUCLIDE IMAGING
• Photon emission by radionuclide taken by
specific tissues – recorded by gamma camera -
reflects physiological activity of that tissue
• Radiopharmaceutical used – 2 components
chemical compound – metaboloic uptake
in target tissue

32. ISOTOPE BONE SCAN
• Bone imaging - technetium – 99 m – ideal isotope
short half life – 6 hrs
rapidly excreted in urine
• Technetium – labelled hydroxymethylene
diphosphonate ( 99mTc-HDP) given intravenously
& recorded at 2 stages
1) Early perfusion phase - isotope in blood stream
– reflecting local

34. • 4 types of abnormality seen
1) Increased activity in perfusion phase -
inflammation , fracture , high
vascular tumour , regional
sympathetic dystrophy
2) Decreased activity in perfusion phase – local
vascular insufficiency
3) Increased activity in the delayed bone phase –
fracture , implant

35. CLINICAL APPLICATIONS
• Diagnosis of stress fracture /undisplaced
fracture
• Detection of a small bone abcess or osteoid
osteoma
• Investigation of loosening or infection around
prostheses

36. ADVANTAGE & DISADVANTAGE
• ADVANTAGE
whole body can be imaged for multiple sites
of pathology ( occult metastasis , multifocal
infection )
provides physiological activity of examined
tissues

37. OTHER RADIONUCLIDE
COMPOUNDS
• GALLIUM - 67
concentrates in inflammatory cells – identify
hidden infection
• INDIUM – 111 – LABELLED LEUCOCYTES
distinguish sites of active infection from
chronic inflammation

38. SINGLE – PHOTON EMISSION
COMPUTED
TOMOGRAPHY ( SPECT )
• SPECT - bone scan – images are recorded &
displayed in all 3 orthogonal planes ( coronal ,
sagittal & axial plane )
spatial localization of pathology

39. POSITRON EMISSION TOMOGRAPHY (
PET )• Positron – emitting isotopes - short half life –
produced by cyclotron
• M/C used – 18 – fluro – 2 – deoxy – D – glucose (
18 – FDG )
measures rate of consumption of
glucose
• Malignant tumours metabolize glucose faster
than benign tumours

40. BONE MINERAL DENSITOMETRY
• Bone mineral density measurement – widely used in
oseoporosis & increased risk of osteoporotic fractures
• Various techniques developed
RADIOGRAPHIC ABSORPTIOMETRY ( RA )
QUANTITATIVE COMPUTED TOMOGRAPHY ( QCT )
QUANTITATIVE ULTRASONOMETRY ( QUS )
DUAL ENERGY X- RAY ABSORPTIOMETRY ( DEXA ) – M/C
accepted

41. • RA - conventional radiographic equipment – bone density in
phalanges
• QCT – trabecular bone density in vertebral bodies
• QUS - measures bone mineral density in peripheral skeleton
( wrist & calcaneum )
• DEXA - columnated low – dose X ray beams to distinguish bone density from
soft tissue
• Advantage of DXA – develop huge international database – express bone mineral
density in comparison to age & sex matched population. (Z-score) and peak adult
bone mass (T score)
• According to WHO, T score <-1- osteopenia & T-score <-2.5 – osteoporosis.

43. THANK YOU