Test 1 Flashcards by Assante Diaz

• Examples of ionizing radiation for imaging:

X-rays
• Computed Tomography (CT)
• Bone Mineral Density scans (DEXA

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“Reflective” imaging:Examples

Ultrasonography (sound waves)

• MRI (radio frequency waves)

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Emitted energy imaging examples?

radionuclide scans (bone scans, tagged RBC scan)

Thallium scans (functional cardiac imaging)

Positron emission tomography (PET) scan

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The longer the wavelength the?

lower the energy

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X-rays are generally in the wavelength range of

10-9

to 10-11 meters (.1-10 angstroms)

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The shorter the wavelength, the

higher the

energy

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Air, appears ? on the final x-ray image.

black

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Bone therefore appears ? on the final x-ray image.

white

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Fat is more dense than air, but far less dense than bone, so fat tissue appears
? on the final x-ray

dark gray

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Water, which is the major component of soft tissue is much more dense than air or
fat, but less dense than bone, so water will appear ?

whitish gray

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Substances that absorb x-rays are called

radiopaque

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Radiopaque substances will appear ? on the x-ray images.

white

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Substances that allow more x-rays to pass through are called ?

radiolucent

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• Radiolucent substances will appear ? on the final x-ray images.

darker

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something further away on xray appears

larger (magnified)

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the body part of interest needs to be

closest to the film or detector

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objects closer to the film or detector will be

sharper and better defined

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objects farther away from film or detector will be s

blurred, or have less precise edge

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One structure may obscure another by eliminating contrast at the edges, a
phenomenon called

“silhouette sign”

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• Exposure depends on two things:

energy of the x-ray and exposure time

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higher kVp means higher energy of the x-rays,

• Milliamps,(mA): corresponds to the quantity of x-rays produced

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how to control scatter?

KVP, grids, air gap

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X-rays are excellent tools for

Fractures and dislocations

infections

neoplasmsw

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• Some organs are known to be more sensitive to radiation effects than others:

Thyroid
• Breast tissue
• Gonads and reproductive organs
eyes, skin, bone marrow, and
vascular structures

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Lesions involving new bone formation | • Increased density (radiopaque)

Blastic lesions Reactive bone from any process • Reparative phase after a bony injury

fracture naming conventions

site (distal, proximal, midshaft Extent • Complete, incomplete, comminuted Type • spiral, transverse, buckle or torus • Alignment and displacement of fracture fragments * Direction of fracture lines * Special features * Associated abnormalities

how does cortical bone heal?

• Large hematoma, external callous, fluid matrix, periosteal sleeve

how does cancellous bone heal?

• Internal callous, better vascularity usually, faster healing

promotes healing?

good immobilization - growth hormone - thyroid hormone - calcitonin - insulin - vitamins A&D - hyaluronidase - electric currents - oxygen - physical exercise - young age

retard healing

- motion - corticosteroids - anticoagulants - anemia - radiation - poor blood supply - infection - osteoporosis - osteonecrosis - comminution - old age

Expected Fracture Healing Times metacarpal

4-6 wk

Expected Fracture Healing Times metatarsal

4-8 wk

Expected Fracture Healing Times distal radius (extraarticular)

6-8 wk

Expected Fracture Healing Times distal radius (intrarticular)

6-10 wk

Expected Fracture Healing Times humeral shaft

12 wk

Expected Fracture Healing Times femoral shaft

12 wk

Expected Fracture Healing Times radius and ulnar shaft

16 wk

Expected Fracture Healing Times tibial shaft

16-24 wk

Expected Fracture Healing Times femoral neck

24 wk

Expected Fracture Healing Times femoral neck

24 wk

Epiphysis remains intact | • Prognosis is good with treatment

• Salter-Harris Types I and II

Epiphysis is injured • Prognosis is poorer, therefore repair must be more precise to prevent growth abnormality

• Salter-Harris Types III and IV

Crush injury • Usually occurs along with one of the types I-IV. • Prognosis poor even with repair.

type V

for salter harris injuries the test of choice for diagnosis is?

plain x-ray

The biggest advantage of CT over plain radiography is

markedly enhanced detail of | the final image, especially for soft tissue structures (compared to plain films)

• Although ? (see next section) is still the best modality for soft tissues

MRI

“Slice thickness” (thickness of the plane that is in focus) can be variable. For most CT images it is usually between

1-20 mm

can detect occult pneumothorax or effusion?

CT has to use contrast to see ?

vascular

``` Slit length determines the width of the section to be imaged in relation to the long axis of the whole part being imaged. In other words, this determines how wide a slice through the body is obtained on a given CT scan. • Think of it as if the body is being sliced into pies. • Slit length determines how thick each entire pie is. ```

Shorter slit length results in narrower pies, meaning there is higher discrimination (you can see the pie filling better)

Slit width determines the size of the slice of tissue plane imaged with each beam of x-rays. • In other words, how wide or narrow are the slices in each pie. •

Again, smaller width usually means more detail, because the pie slices are narrower, but also means more slices per pie (images per slice) and therefore more radiation exposure

(x-ray absorption or transmission) of each pixel is averaged by the computer from the multiple images that contain the spot that corresponds to that pixel.

attenuation

average attenuation is called the ???, and is | applied to each of the pixels that make up the final image

"attenuation coefficient"

• This is a "grayness" scale that extends from -1000 to +1000

• Hounsfield scale:

• ? density is assigned a value of -0-, and defines the midpoint of the scale

Water

• ? is the least radiodense substance, and is assigned a value of -1000

Air

• Very dense ? is the most dense, and is assigned a value of +1000

bone

A bone window, for example, may set water (0 Hounsfield units) as completely black, and shades of gray for everything above it.

Likewise a lung window may set water (0 Hounsfield units) as completely white, allowing better grayness discrimination for less dense structures as seen in the lungs

• With contrast, CT is excellent for visualizing details of vascular structures • CT angiography is the test of choice for ?

pulmonary embolus detection

Excellent modality for detecting fresh blood in tissue spaces (fresh blood has an extremely high Hounsfield coefficient, but this decreases as clot formation progresses ) • Non contrast CT is the test of choice for detecting

intracranial bleeding

non contrast CT Also excellent for

soft tissue hematomas

non contrast CT Also excellent for

soft tissue hematomas

• CT is excellent for observing fine detail in areas with high contrast:

Soft tissue masses in lungs • Pneumothorax in lungs • Calcification in muscle or brain, etc..

("wobbles") about the axis of its magnetic vector, the way that a spinning top precesses as it spins

precesses

• It must be the EXACT frequency (energy level).

Larmor frequency

• This released energy is referred to as their ??, and this can be measured.

echo

This return to original state is referred to as

which represents the return to | longitudinal equilibrium with the external magnetic field (parallel/antiparallel)

``` When these transverse (xy plane) vectors reach a certain percentage of their original state (67% to be exact), this is designated as. ```

• T2 is far more dependent on the local environment than T1

• T2 is always shorter than T1

represents decay from high energy state to low energy state, and is a function of loss of energy

is often referred to as the thermal relaxation time or spin | lattice relaxation time.

though is not a return to a resting energy state, but a loss of phase coherence between adjacent protons

is sometimes called the spin-spin relaxation | time.

time to repetition | • The time between subsequent RF pulses which are given in sequence

TR=

time to echo | • Time from application of a radiofrequency pulse to peak echo signal

• ?? will be longer in tissue that contains more water.

?? weighting uses shorter TR and TE, causing tissue with more water to appear darker, and tissue with less water to appear brighter

bone marrow is much whiter on

CSF T1?

BLACK

CSF T2

WHITE

• Fat T1

white

Fat T2

black/dark gray

CNS gray matter T1

dark gray

CNS gray matter T2

light gray

Cns white matter T1

light gray

Cns white matter t2

dark gray

Cns white matter t2

dark gray

soft tissue edema t1

dark

soft tissue edema t2

light

acute stroke t1

dark

actue stroke t2

light

T1 shows usefulness for?

acute hematoma fat yellow marrow lipoma

T2 shows useful for

chronic hematoma fluid/edema soft tissue tumors

bone marrow is seen well on

MRI

• This is an imaging technique that can assess function as well as anatomy

PET scan

• Usually, Fluorine-18 labeled Fluorodeoxyglucose

PET SCAN

is used, usually in conjunction with a CT scan, to detect metabolically active disorders, such as: • Cancer or metastases, • Or to assess metabolic activity of tissue • CNS in Alzheimer's • Cardiac blood flow in certain types of ischemic heart disease

pet scan

-Sound waves are transmitted through the structure, and not reflected back to the sound transducer. • Area will appear black on the image • Most air or fluid filled structures such as cartilage or joint effusions

anechoic

structures with low level echos. • These appear gray on the final image, and include muscle, synovium, nerve structures

hypoechoic

denser structures that are more reflective of sound waves • Appear bright or white on the USG image • Bone, tendon, foreign bodies, areas of calcification

hyperechoic

acoustic “void” that appears behind a very reflective object

shadowing

Occurs where highly curved surfaces distort or block sound transmission • Gallbladder, long bone diaphyses, intermuscular interfaces

refractile/critical angle

Useful for cyst identification

ultrasound

useful for real time vascular imaging | • Carotid, cardiac, peripheral arteries as well as veins

ultrasound

• Real time localization of fluid and abscesses in ED- cardiac tamponade, pleural effusions, ascites • in clinic- joint effusions, abscesses

ultrasound

Distends joint capsule • Helps mobilize capsolabral sleeve • Highlights cartilage defects

Arthrography-

• Screening recommended for those with risk factors for osteoporosis

Bone Mineral density imaging

Less than 2.5 standard deviations below mean= high fractures risk, with treatment recommended

• DEXA: Dual Energy X-ray Absorptiometry

• Useful for detecting metastatic cancer and for staging primary tumors and for fracture age

bone scan

Complex regional pain syndrome (RSD) | • Metabolic bone abnormalities such as Paget disease

bone scan

• C1 does not have a vertebral body.

Stabilization of C1 depends on: • Transverse ligament • Facet articulations with C2.

• There is no intervertebral disk between C1 and C2

• The transverse ligament of C1 is anchored to the odontoid

American College of Radiology (ACR) Guideline to the Performance of Spine Radiography: Indications for imaging:

* Pain or neurologic symptoms * Spinal trauma * Surgical planning * Previous surgery, follow-up or suspected complications * Neoplastic (benign and malignant) lesions * Congenital anomalies * Previously detected abnormality * Alignment abnormalities * Infection * Arthropathy * Degenerative disorders * Spine instability or limitation of motion * Osteoporosis

Complete cervical series should include: | • Routine:

* AP * Lateral * Open mouth odontoid views

* Complete cervical series should include: | * Trauma patients:

* AP * Open mouth odontoid * Cross-table lateral before moving the patient * If the spine cannot be adequately examined, obtain CT or MRI

c-spine • When assessment of the neural foramina is necessary.

• Bilateral oblique views

c-spine• Assessment of the facets, particularly following trauma

• Pillar views

c-spine• When assessment of cervical instability is necessary

• Neutral, flexion, and extension lateral views

Oblique views are done whenever there is any suspicion for

neuroforaminal | stenosis

With lateral views, it is absolutely necessary to see | • If not the view is inadequate:

all 7 cervical vertebrae, and the | superior end plate of T1

•??? is usually the image of choice to visualize C7-T1.

A swimmers lateral view

??? should be obtained in trauma patients if a swimmers view is not available or attainable

SCIWORA-

Spinal Cord Injury Without Radiographic Abnormality | • Special case occurring in trauma patients, especially children

AP cervical spine films are obtained with patient sitting | or standing The X-ray beam directed toward

C-4 (about Adam’s | apple level)

AP C-SPINE is used to assess the anteroposterior portion | of

C3-C7.

AP Difficult to assess cartilage on this view, | ??? is better

lateral

hyperextend the neck | • May occasionally be done when an unobstructed view of the odontoid is absolutely required

Fuchs View

usually the most informative cspine | view

lateral

Straightening of the normal lordotic | curve may indicate ???, associated with occult injury

cervical muscle | spasm

Reversal of the lordotic curve, or | kyphosis may indicate???

an unstable injury

The atlanto-dens interval, ADI, (distance between the anterior ring of C1 and the odontoid process) must be no more than ???

3 | mm

• A wider ADI indicates ???

C1-C2 instability

Look for soft tissue swelling in the retropharyngeal tissue anterior to C2. • Normally, the soft tissue in this area is ???? in width.

< 7 mm

Similarly, look at the soft tissue in the retrotracheal space at C6-7 • Normal soft tissue thickness at this level is ???

<22 | mm

They are taken with the patient rotated 45 | degrees to the plane of the film/detector

Oblique views

• T- spine is a common location for

metastatic cancer

standard exams for thoracic spine?

AP | lateral

t-spine lateral view Technique similar to lateral CXR: | • Patient erect, arms elevated• X-ray focused at ?

T-6 level

•lumbar standard examination includes :

• AP and lateral (or PA and lateral)

In general clinical practice for most adults, five standard views are usually obtained: l-spine

``` AP • Lateral • Right and left obliques • Cone down sacral view • Oblique views ```

• lumbar AP X-ray beam directed at the ?

mid-abdomen

lumbar later view • X-ray beam directed toward

Particularly useful for evaluation of the zygoapophyseal joints • Best views to assess spondylolysis and spondylolisthesis.

oblique

oblique view l-spine Side-lying with knees & hips flexed and rotated 45 degrees • Beam directed toward L3

*only thing that moves is the patient

oblique view l-spine Side-lying with knees & hips flexed and rotated 45 degrees • Beam directed toward L3

*only thing that moves is the patient

Scotty dog eyes:

• Pedicles:

Scotty dog ears:

superior

• Scotty dog legs:

inferior

• Scotty dog tail:

superior process, | opposite side

• Scotty dog nose

Transverse process

scotty dog neck

par interarticularis

scotty dog wearing collar =?

spondylolysis

scotty dog decapitated?

spondylolisthesis

Sensitivity about 70%/specificity about 90% for fracture, OA and osteonecrosis of the HIP

CT is much more sensitive for fracture and osteonecrosis (approaching 100%)

test of choice to confirm osteonecrosis (specificity ~100%, but sensitivity only about 38%) of the HIP

MRI

American College of Radiography (ACR) recommends the following views for hip?

``` AP LATERAL (frog leg or true lateral) ```

American College of Radiography (ACR) recommends the following views for the pelvis?

American College of Radiography (ACR) recommends the following views for the femur?

ap | lateral

• Shows femoral head and neck and greater and lesser trochanters

FROG LEG

Inferior lip of the anterior surface of | acetabulum

radiographic u

ilioischial line, acetabular articular surface, and radiographic U sign

teardrop

Imaginary line formed along the inferior border of the superior pubic rami (superior border of the obturator foramen) and along the inferomedial border of the femoral neck

shenton's line

Same patient position as AP • X-ray tube angled about 30 degrees cranially for the hip?

ferguson view (pelvic inlet)

Technique is similar to Ferguson view, but x-ray tube is angled about 60 degrees

pelvic outlet

• AP view taken with patient in a 45 degree oblique position of the hip? Affected hip anterior gives better view of anterior column and posterior acetabular rim Affected hip posterior shows better visualization of posterior column and anterior acetabular rim

judet vidw

Test 1 Flashcards

(166 cards)