Introduction to Imaging Flashcards
Why do PTs need to understand imaging
- Potential PCP
- Military model
- International
- Improved communication among health care providers
- Enhancing understanding of pathology for clinical decisions & goals
- Patient education
How do PTs use imaging knowledge?
- Organize & interpret relevant information
2. Use for diagnostic process - obtain history, perform systems review, and select and administer tests & measures
Reasons for overuse of imaging
- Accuracy & ease of use
- Malpractice fear
- Patient pressure
- Health care chaos
Plain films are fastest way to assess & first imaging modality requested for
- Fractures
- Bony alignment
- Arthritis
- Bone infections
- Cancer
Plain Film Appearances
Increased object radiodensity appears white and decreased object radiodensity appears dark
Plain Film ABCS
- Alignment
- Bone Density
- Cartilage
- Soft tissue
Bone Scan (Scintigraphy)
- Inject radiopharmaceutical and medication concentrates in increased area of function
- Bright spot = increased activity
- Good for detecting Bone cancer/mets, fracture, bone infections, metabolic disease (Paget’s)
CT - viewing of image
- Axial - your right is patient’s left
- Coronal - your right is patient’s left
- Sagittal - viewed left to right
Useful in diagnosing
- Cancer
- Cardiovascular disease
- Infectious disease
- Internal trauma
- Musculoskeletal disease
- Bone density
Advantages of CT Scan
- Good alternative for people who cannot due MRI due to metallic implants
- More readily available
- Less expensive
- Less problematic
- Quicker test time
Limitations of CT Scan
- MRI is more suitable to assess fine details of soft tissue - intervertebral discs, shoulder and knee, tissues with similar make up
- Images only in axial plane
- High radiation exposure
Myelogram
- Injection of contrast dye into subarachnoid space and radiograph taken after injection
- Used to assess spinal cord, nerve roots, meninges, and cysts
MRI use
- Diagnose broad range of diseases - cancer, heart disease, vascular disease, and musculoskeletal disorders
MRI T1
- Good anatomical detail
- Fluids dark and fat bright
MRI T2
- Good for detecting inflammation
- Water bright, fat dark
Structures that are black in all sequences on MRI
- Tendons
- Muscles
- Labrum
- Ligaments
Proton Density Imaging
- T1 & T2 properties
- Helpful with tendon, meniscus, ligament & cartilage
STIR
- Similar to T2 images
- Poor resolution
- Emphasizes structures that are fluid rich
Viewing of MRI
- Coronal - your right is pt’s left
- Axial - your right is pt’s left
- Sagittal - left to right on both sides of body
MRI Advantages
- Better able to assess soft tissue fine details
- MRI less likely to produce allergic reaction
- No exposure to radiation
- Better view o changes in bone marrow
- Different sequences increase change of disease process being picked up
MRI Limitations
- Pacemaker - will stop its function
- Any ferromagnetic implants
- Metal implants safe but distort image
- CT better for unstable patients
- Does not distinguish between tumor tissue and edema
Transient effects of strong magnetic field
- Dizziness
- Vertigo
- Nausea
- Concentration issues
2 categories of ultrasound imaging
Rehabilitative ultrasound imaging (RUSI) & diagnostic imaging
RUSI
- Used to evaluate morphology & behavior of muscles; assist in application of therapeutic interventions aimed at improving clinical outcomes through restoration of neuromuscular function; carry out basic, applied, & clinical rehab research
Things you can measure with ultrasound imaging
- Muscle length
- Muscle depth
- Muscle diameter
- Muscle cross-sectional area
- Muscle volume
- Muscle contraction/timing of contraction
- Tissue deformation with contraction
- Qualitative assessment of muscle/tissue density
- Muscle discontinuity/tears
Why ultrasound imaging?
- Safe
- Scans in real time
- Cost effective
- Portable
- Clinically accessible
- No ionizing radiation
Ultrasound imaging limitations
- Operator dependent
- Cost issue for clinics
- Limited evidence
- Limited training available
Curvilinear transducer - ultrasound
- Lower frequency (3.5-5MHz) –> deeper structures; sacrifice resolution
Linear transducer - ultrasound
- Higher frequency (7.5-10 MHz) –> superficial structures
Sonographic apperance
- Hyperechoic –> very bright
- Hypoechoic –> darker
- Anechoic –> black
Visible structures seen on ultrasound
- Muscle
- Bone
- Subcutaneous tissue
- Tendon/ligament
- Cartilage
- Nerve
- Blood vessels
Appearance of muscle tissue
hypoechoic
Appearance of bone/calcification
hyperechoic
Appearance of tendon
hyperechoic
Appearance of ligament
hyperechoic
Appearance of cartilage
Hyaline - hypoechoic; fibro - hyperechoic
Appearance of peripheral nerve
Individual fascicles - hypoechoic; surrounding connective tissue - hyperechoic
Appearance of epidermis and dermis
hyperechoic
Appearance of hypodermis
adipose tissue - hypoechoic; fibrous septa - hyperechoic
Fluoroscopy
X ray source and fluorescent screen; real time motion; various structures & systems
Why are fractures missed?
- Failure to order radiography
- Failure to recognize fractures on radiograph
- Subtle fractures that may not be evident on initial radiograph
- Presence of multiple injuries
- Inadequate patient history
What to look for in report of fracture
- Open vs. closed
- Complete vs. incomplete
- Alignment of fragments
- Direction of fracture
- Special features
- Associated abnormalities
- Special types
Fracture Classification Systems
- Salter-Harris
2. Weber fractures of the ankle
Fracture Healing - Primary bone
Direct contact between bone fragments with compression. ORIF; osteoclastic then osteoblastic activity; new bone growth at ends of fracture
Fracture healing - secondary bone
- No fixation
- Cast immobilization
- External fixation
- Some movement at fracture site
- Callous formation
- Three stages: Inflammatory, reparative, remodeling
Inflammatory phase of healing
- Hematoma forms –> inflammatory cells –> osteoclastic activity
- Lasts several weeks
Reparative phase of healing
- Chrondroblasts & fibroblasts enter hematoma and form callus matrix
- Osteoblasts enter callus matrix and form bony callus
- Delayed and non-union can occur here
Remodeling phase of healing
- Bony matrix more organized
- Reabsorbs less organized callous as organized structure is laid down
- Callous is reabsorbed and fracture is no longer visible
Factors affecting healing
- Degree of fracture
- Age
- Nutrition
- Systemic factors
- Hormones
- Vascular injury (AVN)
- Intra-articular
- NSAIDs
- Cipro
- XRT
- Smoking
Abnormal fracture repair
- Delayed union: longer than expected for age, site, severity of injury
- Mal-union: union in poor functional position
- Non-union: Shaft of long bones > 6 months, femoral neck > 3 months, sclerosis at both ends, pseudoarthritis final stage; forms = hypertrophic, atrophic, fibrous, pseudoarthritis, septic
Stress Fracture Common Areas
- Sacral
- Pubis
- Femoral neck
- Tibia
- Calcaneal
- Navicular
- Metatarsals
- Sesamoid
