This document discusses various imaging modalities used in orthopedics, including their mechanisms and uses. It covers conventional x-rays, computed tomography, magnetic resonance imaging, ultrasound, nuclear medicine techniques like PET and bone scintigraphy, and bone densitometry. X-rays remain a commonly used first-line test due to low cost and radiation exposure. CT provides cross-sectional imaging while MRI enables excellent soft tissue contrast without radiation. Emerging techniques like PET allow functional imaging of disease processes. Overall, selecting the appropriate imaging modality depends on the diagnostic question and each has advantages and limitations for orthopedic applications.

1. Presenter: Dr. Bijay Mehta
Moderator: Dr. Kuldip Mangal Joshi

2. INTRODUCTION
 IMAGING MODALITIES REMAINS A KEYSTONE
IN DIAGNOSING ORTHOPAEDIC CONDITIONS
 HISTORY DATES BACK TO 1895 –DISCOVERY OF
XRAY
 USEFUL IN DIAGNOSIS, STAGING AS WELL AS
FOR MANAGEMENT PURPOSES

3. IMAGING MODALITIES
1. Xray(Plain Radiograph)
2. Ultrasonography
3. Computed Tomography
4. Magnetic Resonance Imaging
5. Bone scan / scintigraphy
6. Single Photon Emission Computed Tomography(SPECT)
7. Positron Emission Tomography
8. Bone Mineral Densitometry

4. X Ray(Plain Film Radiography)
 High energy electromagnetic radiation
 wavelength ranging from 0.01 to 10 nanometers
 Penetrates the tissue producing images based on the
density/absorption of tissue
 Produced by Xray tube
 Absorbed by film after passing through a medium

5.  Denser the tissue, greater xray attenuation and brighter
the image
 Discovered by WK Roentgen in 1895
 Most commonly used as 1st line investigation
 Produce 2 D images
 “One view is no view”
 Generally at least 2 views are used
 Inexpensive

6. Rule of 2
 2 views
 2 joints
 2 sides
 2 occasions
 2 Sites
 Most commonly used views- Anteroposterior and
Lateral Views

7. Special views
Scapula Stryker Notch view, Scapular Y view
Shoulder Y view, Axillary View, Hill Sachs View,
Elbow Coyle view
Wrist Carpal tunnel view
Hand Ball catcher view
Pelvis Inlet/Outlet View
Acetabulum Judet – iliac/ obturator oblique view
Ankle Mortise view
Calcaneum Harris axial view

8. Radiographic Interpretation
 Should be done in a sequence- preferably- the patient-
the bone- the soft tissues- the joint
 The patient- confirm name,age and history
 The bone- shape, change in density, fracture or
localized change
 The soft tissues- Any soft tissue shadows
 The Joint-the joint space, shape , Erosions

9. Uses in orthopedics
 Fracture / dislocation/ subluxation
 Soft tissue shadows
 Evaluation of implants
 Guiding image in cases of closed reduction
 Identifying infections/Tumors

10. Fracture /Dislocations

11. Union vs Consolidation
Union Consolidation
Incomplete Repair Complete Repair
Ensheathing callus is calcified Callus is ossified
Attempted angulation is painful painless
Xray- fracture line still visible
with callus around it
Fracture line obliterated and
crossed by bony trabeculae

12. Infections
 During 1st week- No xray
abnormalities
 2nd week- Periosteal Reactions
 Later- patchy rarefaction of
metaphysis and bone
destruction
 Chronic osteomyelitis-
Sequestrum, Involucrum may
be seen

13. Fluoroscopy
 Uses X-rays to obtain real-time moving images

14. Uses
1. Arthrography (visualization of a joint or joints)
2. To asses joint stability
3. During Intraop Imaging
4. Biopsy guidance

15. Computed Tomography
 Discovered by Sir Godfrey Hounsfield in 1974
 Produces transaxial cutting images through specific
planes
 Emission of X radiation from X ray tube within
machine k/a Gantry in an arc of 180 degree
 Cutting slice usually 5 – 10 mm but variable slice can
be used according to requirements

16. Views/ Scans
 Sagittal
 Coronal
 Transverse/Axial

17. Advantages
 Cross sectional image
 No hindrances by overlying soft tissues
 Superior contrast resolution
 Detection of even early calcification
 3D reconstruction

18. Disadvantages
 Radiation exposure
 Soft tissues aren’t delineated properly
 Cost

19. Recent advances
 3 dimensional CT
 Real time multiplanar reconstruction
 High resolution CT
 Dynamic CT/ contrast enhanced

20. Uses
 Fractures/subluxation/dislocations requiring
transaxial/ 3D reconstruct like carpal/ tarsal/ tibial
plateau/calcaneal/pelvic

22. Spinal trauma

23. Spinal canal stenosis

24. CT guided biopsy

25. Magnetic Resonance Imaging
 Felix Bloch and EM Purcell discovered
 Paul C Lauterbur and Peter Mansfield won Nobel prize
for 3D MRI

26. Mechanism

28. TR and TE
 The repetition time (TR) is the length of time between
corresponding consecutive points on a repeating series
of pulses and echoes
 The echo time (TE) represents the time from the
center of the RF-pulse to the center of the echo

29.  T1 weighted image
 Longitudinal relaxation time
 Short TR and short TE
 return of protons back to equilibrium after application
and removal of the RF pulse
 Good anatomic detail- sharp / well defined
 Fat- bright ; Fluid – dark
 Contrast Enhanced MRI are T1 weighted

30.  T2 weighted image
 Transverse relaxation time
 Long TR and long TE
 Associated loss of coherence or phase b/w individual
protons immediately after application of RF pulse
 Evaluation of pathological process/ sensitively detect
edema
 Fat – bright ( fatty tissue/ bone marrow)
 Fluid – brighter ( CSF/ fluid)

31. T1 Vs T2 images

32. STIR (Short Tau Inversion Recovery)
 Highly water sensitive
 Timing of pulse sequence to supress signal from fatty
tissue
 Used to null the signal from fats

33. FLAIR ( Fluid Attenuated Inverse Recovery)
 Used to null the signal from water/ CSF

34. Utilities
 Spine
 PIVD
 Cord compression

38.  Knee
 ACL injury
 PCL injury

40.  Hip
 AVN
 Occult Fractures

41.  Shoulder

42.  Ankle

43. Advantages
 No risk of radiation
 Clear soft tissue visualisation

44. Disadvantages
 Expensive
 Patient must lie still
 Claustrophobic

45. Ultrasonography
 Sound frequency more than 20 KHz
 Uses based on intensity of USG
 High intensities(1-2 W/cm2)-for therapy/ operative
 Low intensities( 50mW/cm2)- diagnostics

46. Uses
 Deep seated cystic lesions
 DDH
 Rotator cuff injuries
 Soft tissue masses

47.  Advantages
 No radiation
 Cost effective

48. Positron Emission Tomography(PET)
 Advanced Nuclear Medicine technique that allows
functional imaging of disease process
 Uses positron emitting isotopes with short half lives
 Most commonly used is 18-fluoro-2-deoxy –D-
glucose(18FDG)
 Measures the consumption rate of glucose by different
tissues
 Useful in oncology to identify occult malignant tumors
and stage them

49. Bone Mineral Densitometry
 Used in identifying osteoporosis and osteopenia
 Techniques used- Radiographic Absorptiometry(RA),
Quantitative CT(QCT), Quantitaive US(QUS), DEXA
 Most commonly used technique-Dual Energy Xray
Absorptiometry(DEXA scan)

50. DEXA scan
 Uses low dose xray beams of two different beams to
distinguish density of soft tissue and bones
 Measures xray absorption by bones (esp hip and spine
) and compares with age and sex matched
population(Z score) and also to peak adult bone mass(
T score)
 According to WHO- T score <-1.5- osteopenia and T-
score <- 2.5 -osteoporosis

51. References
 Clinical Orthopedics Diagnosis 3rd edition
 Apley and Solomon’s System of Orthopaedics and
Trauma, 10th Edition
 Radiopedia
 Radiography masterclass

52. Thank You