Chap 1 Basic Principles Flashcards
Five different imaging modalities
1) X-ray
2) Computed Tomography (CT)
3) Magnetic Resonance (MR)
4) Ultrasound (U/S)
5) Nuclear Medicine
X-rays are good for:
Bones and airspaces
X-rays are bad for:
Soft tissue and overlapping structures
X-ray film starts off:
White
X-ray film turns ____ when hit with ionizing radiation
Dark
What material makes film brighter?
Dense
Different shades of gray in an x-ray
Water density
Radiographic density: Darkest
Air
Radiographic density: Less dark
Fat
Radiographic density: Gray
Fluid
Blood
Soft tissue
Radiographic density: White
Bone
Radiographic density: Most white
Metal/Contrast
Two-dimensional representation of a three-dimensional object
X-ray
Used if patient is unable to stand or sit for a PA view
Lower quality than PA view
Back is placed next to film
Heart is magnified and borders are fuzzier
Anteroposterior
Usually taken in conjunction with a PA view
Allows viewing of structures behind the heart (mediastinum) and provides three-dimensional image
Lateral (LAT “side view”)
X-ray:
At an angle used mostly on limbs
Oblique (OBL)
Object that is closer to the film has sharper borders
Chest is placed next to the film thereby placing most of the important structures, such as heart and great vessels, closer to the film
Heart size is minimally magnified and borders are sharp
Posteroanterior (PA “back to front”)
Similar to x-ray: Shows black, white, gray depending on density
Multiple pulses (shots) -Radiation dose is high
CT
CT is good for:
Bone
Airspaces
Some soft tissue and overlapping structures (especially abdomen in trauma)
CT is bad for:
Some soft tissues (nerves, muscles, connective tissue)
Patients with retained metallic objects (causes artifacts)
CT X-ray tube is in the:
Housing
CT views:
Sagittal / Median
Coronal
Axial / Transverse / Cross-sectional
Uses electromagnetism and radio frequency properties
No exposure to ionizing radiation
Magnetic resonance (MR)
MR is good for:
Soft tissue (nerves, muscles, connective tissue, brain, joints)
MR is bad for:
People who cannot hold still or have ferrous metal in the body
Difference in CT and MR views
They’re identical
Uses sound waves (like SONAR)
No radiation, but can’t go very deep
Operator dependent
Image produced is a focused segment of the object
Ultrasound
U/S is good for:
Determining fluid vs solids
Abdominopelvic imaging (gallbladder, kidneys, uterus, testis)
Assessing blood flow (doppler)
U/S is bad for:
Things under bones (chest)
Air filled chambers
Deep things
Radioactive agent is given intravenously
Agent participates in physiologic processes while emitting radiation
Radiation is detected and is used to create an image showing the distribution of the agent within the body
Typical use is to detect stress fractures before being visible on x-ray
Nuclear medicine
Nuclear medicine is good for:
Detecting normal or abnormal physiologic processes
Nuclear medicine is bad for:
Showing less anatomic detail
U/S views
Longitudinal (sagittal)
Transverse (axial)
Pre-read:
Correct Patient
Correct date
Correct body part
Correct type
Image has the number of views expected
Check to see if any comparison films exist
What is used to assess technical adequacy?
RIP
- Rotation
- Inspiration
- Penetration
Look at the clavicles relative to the vertebral column
They should be equally spaced
If not properly aligned, structures will change in appearance which may mean abnormal
Rotation
Look at the ribs:
- Should be able to count 9-10 ribs
- Posterior ribs are easier to see (more horizontal and project from the spine)
Inspiration
Should see the ribs through the heart
Should barely see the spine through the heart
Should see pulmonary vessel near the edges of the lungs (lungs should not be completely black)
Penetration
Lung fields completely black
Suggests pneumothorax
Over-penetrated film
Soft tissue structures are obscured
Image appears bright suggesting consolidation (pneumonia)
Under-penetrated film
Chest X-ray:
ABCDE
Airway/Airspaces
Bones/Soft tissue
Cardiac Shadow
Diaphragm
Everything else
Order of reading a Chest X-ray
Pre-read
Technical adequacy of the film (RIP)
Systematic method (ABCDE)
Cardiothoracic ratio only applies to what?
PA film
Transverse diameter of the cardiac silhouette should not exceed __% of the transverse diameter of the thoracic cage
50%
Film that magnifies the heart
AP
Makes the heart horizontal and larger
Shallow inspiration
Upper right heart border
Superior vena cava
Lower right heart border
Right atrium
Left heart border (from the top)
Aortic arch
Pulmonary arteries
Left atrial appendage
Left ventricle
Dome shaped
Right side is always higher than left
Diaphragm
Diaphragm:
Dark and have sharp points like upside down cat ears
Costophrenic angles (sulcus)
Falls under “Everything Else”
Look for gastric bubble (left side)
Check for EKG leads, lines, tubings, and other missed items (four corners of the film)
Lateral chest film:
The spine should appear:
Brighter as it proceeds inferiorly
Retrosternal space should be:
Clear; Contains upper lungs
Retrocardiac space should be:
Clear; contains lower lungs
LAT:
Middle lobe projects over:
The cardiac silhouette
LAT:
Cardiac and diaphragmatic borders should be:
Sharp
Imaging should _______ a suspicion
Confirm (NO FISHING)
Imaging should _______ your treatment
Impact
Imaging “_________” should be avoided
“Just in case”
Your imaging request should include:
Relevant and brief patient history
Purpose for evaluation
18-year-old non-smoker with fever, cough, dullness to percussion at left lower lobe, course crackles. Please evaluate for pneumonia.
Is an example of what?
Good imaging request
Common issues in primary care:
Acute foot pain
Acute ankle pain
Acute knee pain
Lower back pain
Headache
Ankle series is indicated if:
Has pain in the malleolar zone
AND
Has bone tenderness at the posterior edge (6cm) of the lateral or medial malleolus
OR
Inability to bear weight both immediately after the injury and for four steps
Foot series is indicated if:
Has pain in the midfoot region
AND
Has bone tenderness at the base of the 5th metatarsal or the navicular
OR
Inability to bear weight both immediately after the injury and for four steps in the evaluation room
Initial imaging for stress fractures:
X-ray
Can show abnormalities before X-ray findings
Bone scan
What should you “Consider” for suspicion of stress fractures?
CT or MRI
Knee series is indicated if age is:
> 55
Knee series indicated if:
Isolated tenderness of the patella
Tenderness at the fibula head
Inability to flex the knee 90 degrees
Inability to bear weight
Preferred imaging for knee ligamentous injury
MRI
Knee:
What should you do while awaiting further evaluation?
Immobilize
Knee:
If plain radiographs are negative and you still suspect bony fracture, consider:
CT
Image the shoulder if:
Traumatic cause
Presence of pain
Loss of range of motion
Shoulder:
Plain films will be able to identify:
Fractures
Dislocations
Arthritis
AC joint or SC joint injuries
Preferred imaging for labral, ligamentous or rotator cuff injuries
MRI
Hand:
Type of radiograph is based on:
Physical examination & Mechanism of injury
Images for a fracture of the phalanx:
AP and true lateral views
Hand:
When the fracture involves or is close to the joint, what view is helpful?
Oblique
Hand:
If the fracture cannot be delineated because of superimposed digits, such as the base of the proximal phalanx, a radiograph of what must be obtained?
Entire hand
All metacarpal fractures require:
AP
LAT
Oblique
Hand fractures are described radiologically primarily by:
Location
Geometry
Comminution is present
The most precise method of describing hand fracture is to name:
Broken bone and finger involved
Anatomical sites for phalanges and metacarpals include:
Head
Neck
Shaft
Base
Fractures specifically involving the head of the distal phalanx
Tuft
Anatomical sites of scaphoid fracture are:
Tubercle
Waist
Proximal pole
Distal pole
Fractures involving the joint
Intra-articular
Views of the initial evaluation of patients with chronic wrist pain
PA
LAT
Oblique
Wrist:
PA view, wrist is held at what degree of rotation:
0 degrees (neutral)
Wrist:
Lateral view must be obtained with the wrist at what degree?
0 degrees
True lateral views show the ______ projected over the scaphoid tubercle
Pisiform
Wrist (LAT):
Scapholunate angle greater than ___ degrees suggests possible scapholunate instability
60
Wrist (LAT):
An angle of less than __ degrees suggests ulnar-sided wrist instability
30
Scaphoid view
Wrist in ulnar deviation
Clenched fist view to check:
Scapholunate joint space widening seen with ligament disruptions
Hamate fractures
Hook view
Radiocarpal joint is characterized by narrowing of the joint space and sclerosis of the articular surfaces
Osteoarthritis
Three articulations of the elbow:
Radiohumeral
Ulnahumeral
Radioulnar
Capitellum of the humerus with the radial head
Radiohumeral
Trochlea of the humerus with the trochlear notch of the ulna
Ulnohumeral
Radial head with the radial notch of the ulna
Radioulnar
Elbow:
Fractures most common in falls
Distal humerus
Radial head
Elbow:
View frequently used to better visualize the radial head
Oblique
Elbow:
Fracture is not seen but there is suspicion, what view can be performed?
Coyle’s
Elbow:
Even when a fracture cannot be identified, the presence of joint effusion in adults should be treated as:
Non-displaced radial head fracture
Elevated anterior fat pad
Sail sign
Elbow effusions are best seen on:
Lateral projection
Elbow:
Posteriorly, the pericapsular fat is usually hidden in the:
Olecranon groove and fossa
Dislocations of the elbow are named for:
The direction of the radius and ulna dislocate relative to the humerus
Ulnar collateral ligament is commonly found in:
Baseball pitchers
Lateral epicondylitis
Tennis elbow
Back pain:
Imaging is not indicated in the first __ weeks
4-6 weeks
Back pain:
Some reasons to get imaging before the 4-6 week mark:
Neurological findings (Cauda equina)
Constitutional findings
Trauma
Malignancy
Elderly
IV drug use, immunosuppression
Chronic steroid use
Nerve root irritation
Osteoporosis
Back pain, imaging:
Helpful for fractures or joint degeneration:
X-ray
Back pain, imaging:
Preferred in serious trauma:
CT
Back pain, imaging:
Imaging of choice with prior surgery, suspected infection, spinal cord injury, tumor, or cord compression
MRI
Headache, consider imaging if:
Head/neck trauma
Worse or new features (Abrupt onset of headache)
Thunderclap headache
Neurologic signs or symptoms
Headache radiating to the neck
Persistent positional headache
Temporal headache in older than 55 y/o
Suspect infection (cough, exertion, sexual activity)
Headache, imaging:
Preferred for trauma, to rule out hemorrhage, bone abnormalities, or prior lumbar fractures
CT
Headache, imaging:
Preferred for soft tissue causes such as tumors or vascular
MRI
Angulated fracture line
Obique
Runs perpendicular to the shaft of the bone
Transverse
Has a multiplanar and complex fracture line
Spiral
One bone is displaced over the other
Overriding
Fragments are separated by a gap
Distraction
Looks like a bump classified as incomplete fracture seen in children
Torus
Fractures by bending like a green twig classified as incomplete fracture seen in children
Greenstick
Have more than two fracture fragments
Comminuted
