Intro to Imaging

Question 1

XRays

• How they pass through tissue
• How they create an image

Answer 1

-Depends on energy of Xray & density of tissue; higher density is more likely to absorb Xray

• Xrays that pass completely through to film = dark spaces –> air
• Xrays that are blocked & don’t reach the film = white –> metal

Question 2

5 Basic Radiographic Densities

Answer 2

Air
Fat
Fluid/soft tissue
Bone/mineral
Metal

Question 3

CT Scan

• Mechanism
• Images
• Contrast dye
• Uses

Answer 3

• 64 multi-slice CT can produce images quickly
• Each rotation of the scanner provides a picture of a thin slice of the organ or area “cuts”; saved as a group
• Contrast dye may be utilized to enhance visualization; PO, IV, rectally e.g P.E
• CT fluoroscopy can be used to guide a Bx needle or other instrument; used carefully d/t significant radiation

Question 4

Head CT scan indications

Answer 4

Tumors
Intracranial bleeds
Edema
Skull fx
Vasculature

Question 5

Spine CT indications

Answer 5

• Cervical, thoracic, lumbar fx (intrarticular fx): can leave spinal collar on
• Compression fx
• Dislocation
• Tumors
• Abscesses
• Cysts

Question 6

Chest CT indications

Answer 6

Lung Ca
P.E
Aneurysm (aortic)
Spread of Ca (METs to lymph nodes)
May/not require contrast

Question 7

Abdominal CT indications

Answer 7

Cysts/ Abscesses
Infection
Tumors
Aneurysm (AAA)
Enlarged lymph nodes
Foreign objects
Bleeding
Diverticulitis
IBD
Appendicitis (usually seen 1st w/ U/S)
Obstruction
Kidney stones (don't need contrast; can measure)
Pancreatitis
Spleen
Gallbladder, bile ducts (only if U/S unavail)
Adrenals

Question 8

Pelvic CT indications

Answer 8

Usually always ordered in combo w/ abdominal CT
Uterus, ovaries (cysts), fallopian tubes
Prostate gland, seminal vesicles
Arteries, veins

Question 9

Extremity CT Indications

Answer 9

Fx (non-union type)
Joint effusion
Tumors
Dislocation
Cysts/ abscesses

Question 10

CT Angiography

• Images
• ID points
• Method
• Risks

Answer 10

• 2D, 3D pictures of vessels & organs
• IDs obstruction, embolism, thrombosis, dissection, CAD, vessel stenosis, AV malformation
• Done by injecting radiopaque dye IV: usually accessed via femoral artery to look at arteries and/or jugular vein to look at veins
• Risks: allergic rxn (dye), stroke, thrombosis/ embolism, cardiac arrhythmias, kidney damage (dye), hypoTN, pericardial effusion; C/I for people w/ kidney damage (Cr > 1.8) for people w/ dye allergy

Question 11

Mammography

• Use
• Limitations

Answer 11

• Diagnostic/ screening tool to examine breast

- 7 % false (+) rate; called back for further testing: cone down views

Question 12

Nuclear Medicine Scanning

• Method
• Uses
• Examples

Answer 12

• Small amount of low level radioactive material to produce imagines not well-seen with standard Xrays: via injection or drinking solution several hrs or 1 day before scan
• Tumors, infections, fx, organ function
• Whole body scan: bone-related pathologies i.e. stress fx, lesions, infections, METs
• Myocardial perfusion scan: non-invasive evaluation of CAD (overall risk for an event)
• Hepatobiliary scan: for gallbladder dz
• VQ scan: for P.E. (CT angiography preferred)
• Thyroid scan: usine iodine to eval hyperthyroidism
• Parathyroid scan: for adenomas

Question 13

SPECT

• Method
• Uses

Answer 13

• Nuclear imaging: radioactive substance + camera that creates 3D pictures
• Assists in analyzing fxn of internal organs: monitoring brain DOs (dementia, seizures, vascular blockages, encephalitis), CV dz, bone DOs (healing), cancer progression

Question 14

PET Scan

• Method
• Uses: most helpful

Answer 14

• Uses small amts of radioactive material; nuclear med
• Used to diagnose or treat many dz incl CANCERS, CV dz, G.I, endocrine, neurological DOs
• Can pinpoint molecular activity w/in body to ID dz in early stages, determine response of pts to interventions: monitoring tumors (esp pulmonary)

Question 15

Ultrasound

• Method
• Benefits
• Imaging of choice

Answer 15

• High freq. sound waves to visualize soft tissue: muscle, blood vessels, internal organs
• No radiation, can be done bedsite (starting a central line, PICC line; fluid evaluation)
• Test of choice for: gallbladder dz, DVT, soft tissue FBs & cysts, hemoperitoneum, pericardial tamponade, cardiac valve/pump fxn, fetal development, uterine/ovarian dz, arterial blood flow (femoral, subclavian), breast cysts

Question 16

MRI

• Method
• Common uses

-NOTHING METALLIC CAN BE IMAGED

Answer 16

• Magnetic field pulses to develop pictures or organs/ structures: NO RADIATION; takes longer
• Common in orthopedics for tendon, ligament, meniscus, muscle injury; evaluating arthritis, tumors, stress rxns, stress fx/ infection in bones; CAN be used in pregnancy
• In spine: disc dz, nerve impingement, stenosis, abscesses/tumors
• Aneurysm, cerebral hemorrhage, nerve injury; damage d/t stroke
• Used with contrast to ID obstruction in blood flow through vessels, dissection, aneurysm, AV malformation (MRA)
• Tumors of breast, lung, abd, ovaries/uterus

Question 17

Fluoroscopy

• Method
• Risk
• Uses

Answer 17

• Uses Xray to obtain REAL TIME images of internal structures (can move limb around)
• Biggest risk = radiation exposure
• Barium enemas/ swallow tests, orthopedic surgery (fx fixation/ reduction) angiography, feeding tube placement, pacemaker/defibrillator/resynchronization device implantation

Question 18

Radiation Dosage, effect

• Highest risk modalities
• Consequences

Answer 18

• CT scan & upper G.I. barium swallow with SBF = 2 biggest doses of radiation
• 5 CT studies of head, neck, chest, abdomen across pt’s lifetime exposes pt to ~50mSv = associated increased cancer risk; dosing is cumulative
• 1,000-10,000 mSv: radiation sickness –> death

Question 19

Contrast

• Function
• Routes
• Uses
• Risks, reactions

Answer 19

-Produces bright white outline of structure
-IV or PO
-Barium Sulfate: oral/ rectal contrast for tract imaging
-IV contrast (usually iodinated):
Angiography/Venography; urography, visualizing changes in tissue on CXR, CT, MRI
-Risk of severe reactions: C/I for pts w/ shellfish allergy; MC for IV contrast; RENAL FAILURE can be exacerbated, BUN/CRT w/ calculated CrCl is needed before contrast can be given!!
-Reaction types: laryngeal edema (stridor) anaphylaxis, severe hypotension, cardiac arrest; transient renal failure

Question 20

Ordering Tests

• Tips
• Appropriateness Criteria

Answer 20

• Know what you’re looking for before ordering it; if it won’t change your plan, don’t order it!!
• American College of Radiology provides evidence-based guidelines for appropriate imaging tests for each circumstance
• Call radiologist for guidance PRN

Question 21

Extremity Fxs

• 7 involving diaphysis
• 4 involving epiphysis

Answer 21

• Transverse
• Oblique
• Spiral
• Comminuted (>2 pieces, irregularly-shaped)
• Segmental (>2 pieces, similarly-shaped sections)
• Torus (cortex didn’t allow fx to break through – kids)
• Greenstick (only one cortex is broken)

Avulsed
Impacted
Displaced
Angulated
Rotated -- should be described in relation to proximal portion of bone

Question 22

Hip Fractures

• 2-4 parts
• 6 major types

Answer 22

• Subcapital neck fx: just underneath head
• Transcervical neck fx: right through surgical neck
• Intertrochanteric fx: right through both trochanters
• Subtrochanteric fx: below both
• Greater trochanteric fx
• Lesser trochanteric fx – evulsion (tx as tolerated)

Question 23

Proximal Tibial Fractures

-6 major types

Answer 23

• Type I (wedge/ split) easiest to fix using screws
• Type II: split depression
• Type III: central depression (screws, plates etc.)
• Type IV: medial condyle (comminuted)
• Type V: biocondyler
• Type VI: biocondylar with shaft involvement

Question 24

Pediatric Fractures

-SUDAC and Types I-V

Answer 24

-Shifted (tender at growth plate) = type I
Up (above plate) = II
Down (below plate) = III
Across (both above and below plate) = IV
Compressed (plate obliterated) = V