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Medical Diagnosis > Lecture one (Radiology Principles), Exam 1 > Flashcards

Lecture one (Radiology Principles), Exam 1 Flashcards

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1
Q

Who is on the radiology team?

A
  • Radiologist
  • Diagnostic Medical Physicist
  • Radiology Assistant
  • Radiology Nurse
  • Radiology Technologist-> do the actually imaging
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2
Q

What are the ethical principles of radiology?

A
  • Respect for Autonomy
    – Must obtain consent (esp. Pregnancy and children)
  • Beneficience
  • Nonmaleficence
  • Justice
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3
Q
  • What is the most important factors when approaching an image?
  • What is the goal of imaging?
A
  • The history of the present illness (HPI) is byfar the most important factor when approaching an image
  • Goal of imaging is to combine subjective history and objective exam findings to reach a diagnosis
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4
Q

When was xrays discover and by who?

A

1895 and Wilhelm Konrad Rontgen

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5
Q

What is “x-ray light kills”?

A
  • William Rollins; 1901,demonstrated that guinea pigs died from overexposure to x-rays
  • Lower doses caused death to the fetus of aguinea pig
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6
Q

⭐️

A
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7
Q

What are the primary exposure factors?

A
  • mA (milliamperes; current)
  • S (time in seconds)
  • kVp(kilovolt peak; difference in potential)
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8
Q

What is the x-ray beam consisted of?

A

remember that the x-ray beam is HETEROGENEOUS – it will consist of photons of different wavelengths (low/inter/high energy)

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9
Q

When is the penetrating power for x-ray higher?

A

The shorter the wavelength and the higher the frequency of a photon

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10
Q

What is mAs?

A

controls the amount (quantity) of radiation coming out of the x-ray tube
* mA X s =mAs

Increase the time –> increase production of electrons –> increase exposure.

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11
Q

What affects the QUALITYor
PENETRATING POWER of the beam?

A

Kilovoltage (kVp)

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12
Q

Which ones have high, normal and low kvp?

A

IncreasekVpif you want to see more bone.

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13
Q

What is a better technique for the patient with kvp and mAs

A

A high kVp, low mAs technique is better for the patient than a low kVp, high mAs. (Remember that kVp controls the penetrating power of the beam. A higher kVp will reduce the number of soft energy x-ray photons entering the patients’ tissues).

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14
Q

What levels of kVp is needed for soft tissue vs bone?

A
  • ST: low
  • Bone: high
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15
Q

High or low kVp?

A

high
* look how dark the lungs are and all the bones we can see

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16
Q

T/F: CTa of the chest and BRCA1 mutation has the same chance for breast cancer development

A

True

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17
Q

What does high kVp, low mAs look like and what about low kVp and high mAs?

A
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18
Q

How do radiation burns happen?

A

Burn from the inside out

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19
Q
  • Who is at higher risk of adverse affects of radiation?
  • What can block out the softer more harmful rays?
A
  • X-ray machine operators, not patients, are at a higher risk of the adverse affects of radiation exposure
  • Metals such as gold, lead, and aluminum blocked out the softer more harmful rays

Gold is most effective mechanical method of radiation protection. Lead is used instead because its cost effective.

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20
Q

What is the ideal combination of kilovoltage and milliamperes per second when evaluating soft tissues on an XRay?
1. High kVp, high mAs
2. Low kVp, highmAs
3. HighkVp, low mAs
4. LowkVp, low mAs

A
  1. LowkVp, low mAs
    * 1. High kVp, high mAs will be for bone
    * 2. Low kVp, highmAs will be for deep tissue since high mAs
    * 3. HighkVp, low mAs
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21
Q

UNITS OF MEASURE

  • What is R (roentgen)?
  • What is Rad (radiation absorbed dose)?
  • What is Rem (Rad equivalent man)?
A
  • R (roentgen) – the amount of radiation measured in dry air
  • Rad (radiation absorbed dose) – the amount of energy transferred to an object by any type of radiation
  • Rem (Rad equivalent man) – refers to the absorbed dose of any radiation that has the “same biological effect” as one rad of x- radiation

R=rad=rem

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22
Q

What cells are the most radiosenitive? What about low sensitivity?

A
  • High: Reproductive cells (immature, rapidly dividing cells aka uterus, testes and breast), white blood cells (specifically lymphocytes), , thyroid, skin, liver
  • Low: Muscle, nerve, and cortical bone have highly specialized cells therefore not enough power to penetrate so no CT or ray (ex. ACL tear, you get an MRI)
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23
Q

What is the difference between genetic and somactic effects? ⭐️

A
  • Genetic effects – molecular effects; damage to DNA molecules can cause mutations in the offspring – passed to offspring
  • Somatic effects (physical effects/response) – cellular effects; describes biological damage to the individual (e.g. burns, hair loss, cancer) but is not passed to the offspring – happens to individual
    only

CANCER IS SOMATIC

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23
Q

What do you need to test for in females between 6-60 before an x-ray?

A

Pregnancy

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24
Q

What are embryologic effects?
What is the most radiosensitive period during pregnancy?

A
  • Embryologic effects – those that effect the embryo or fetus during its development
  • First trimester – most radiosensitive period;the most severe effects occur during the firstsix weeks (1st6 weeks especially)
  • Sensitivity decreases during the second andthird trimesters
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25
Q

What are the four ways to reduce radiation exposure?

A

1)Reduce the time of radiation exposure
2)Increase the distance from the radiation source - best
3)Provide radiation shielding between the individual and the radiation source.
4)Collimate(focus) the radiation beam. This has been shown to cut radiation inhalf.

2 and 3 are most important

Medical exposure to the patient is not counted because itis considered to benecessary for diagnostic purposes.

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26
Q
  • What is the most effective method of radiation protection?
  • What is the inverse square law?
A
  • Distance
  • The inverse square law: The intensity of the beam inversely proportional to the square of the distance.
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27
Q
  • For shielding, what is the most commonly used?
  • Who should you always shield?
  • What is beam restriction?
A
  • Shielding – lead is the metal most commonly used in diagnostic radiology forradiation protection
  • Shield ALL patients of childbearing age,and ALL pediatrics (if possible)
  • Beam restriction (another method of shielding) – the collimator is the best devicefor restricting the primary beam

Gold is best for shielding but too expensive

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28
Q

National Council on Radiation Protection and Measurements (NCRP) :
* When was it introduced and why?

A
  • Initially introduced in 1950 to limit radiation exposure of gonads and to limit potential genetic mutations
  • Changes in technology, automatic exposure control, and factors affecting the coverage of actual shielding led to the change
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29
Q

Radiation exposure can be conceptualized as what?

A

conceptualized as absorbed dose and effective dose.
* Effective dose differs based on tissue composition for each organ
* The effective dose is measured in Sieverts (Sv)

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30
Q
  • What is BERT?
  • When does it increase?
A

Background equivalent radiation time (BERT)
* Compared to the background radiation to which the entire population is exposed every day from natural radioactive substances in the air, soil, and environment.

Increases with altitude
* A single commercial roundtrip transcontinental flight in the U.S. is associated with an effective dose of 0.05 mSv (i.e. the equivalent of 2.5 chest x-rays).

BERT AND REM ARE THE SAME

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31
Q

Fill in ⭐️

A
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32
Q
  • What is Rem and sievert (Sv)?
  • What are the conversions of these valves to get mSv?
A
  • Rem = convention method of radiation absorbed dose measurement (used in theUS)
  • Sievert (Sv)= Standard International (SI)unit of measure
  • 1Sv= 100 rem or 1 rem = 0.01Sv= 10 mSv
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33
Q

What does one CXR, CT abd, pelvis CT equal in rem or bert?

A

1CXR = 0.01 rem or6 days in BERT

CT Abd and Pelvis CT = 1 rem
* equivalent to 500 chest xrays or 4.5 years of background radiation

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34
Q

What is the ALARA concept?

A

radiation workers are to keep exposures As Low As Reasonably Achievable

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35
Q
  • What are the occupational dose limits for radiation? Rest of population? ⭐️
  • Who sets the rules?
A

Occupational dose limits are set by the National Council on Radiation Protection
* 5 rems (0.05 Sv)per year is the total dose limit for radiation workers
* 0.5 rems (0.005 Sv)per year is the total dose limit forthe rest of the population

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36
Q

What are two most common types of monitoring devices for radiation?

A

Thermoluminescent dosimeters
* contains small chips of lithium fluoride
* Change every 3 months

Film Badges
* piece of film similar to that of dental film within a plastic holder
* Change every 4 weeks

TLD are reusable and are more precise in low doses

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37
Q

What are the different films for image production? (3)

A
  • Roll film introduced – cellulose nitrate base coated with
    silver halide emulsion (Kodak)
  • Cellulose nitrate – highly flammable
  • Cellulose acetate – tended to wrinkle; gets moldy
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38
Q

What is the latent and manifest image?

A
  • Before the radiographic film is developed, the image, which cannot yet be seen is known as the latent image
  • The actual radiographic image that is visualized after the film is processed is called the manifest image, or the visible image
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39
Q
  • What are screen flim sensitive to?
  • What is the difference between slow and high speed screens?
A
  • Screen film is sensitive to fluorescent light from crystals in the intensifying screens
  • Slow speed screens have smaller crystals, result in greater detail; commonly used for extremity work. Disadvantage: increased patient exposure
  • High speed screens – large crystals; therefore decreased patient exposure. Disadvantage: less detail

Low kVp+longer time= pretty picture

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40
Q

What is image production-density controlled by?

A
  • mAs
  • kVp
  • Film-screen combination
  • Filtration
  • Tissue thickness
  • Processing
  • Fog
  • Artifacts
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41
Q

Label the types of tissue/fluid/material in our bodies

A
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42
Q

X-rays:
* Based on what?
* What do radiopaque(radiodense) structes appear as?
* Radiolucent structures appear what?
* What do other structures appear as?

A
  • Based on selective absorption of the x-ray beam
  • Radiopaque (radiodense) structures appear white
  • Radiolucent structures appear black
  • Other structures appear as different shades of gray based on their ability to absorb radiation
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43
Q

What is a fluroscopy?

A

Mobile x-ray tube that generates a continuous, adjustable x-ray beam, allowing for real-time visualization of anatomic structures

producure you do real time

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44
Q

What are different ways of using contrast?

A
  • Arteriograms/Venograms – Intra-arterial or intravenous
    contrast material used
  • Ingested contrast
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45
Q

Before you give contrast what do you need to check?

A

Kidney function so BUN and creatinine levels

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46
Q

What do you use for chest x-ray contrast?

A

Intravenous

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47
Q

Constrast ultilization includes a variety of procedures, give examples

A

Includes a variety of procedures in which the vascular or GI system is imaged by x-ray during the injection or ingestion of a radiopaque water- soluble contrast material

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48
Q

What are the most commonly used agents that result in increased attenuation of the x-ray beam.

A

iodine and barium

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49
Q
  • Intravascularly administered agents are iodinated, how does it get eliminated?
  • What are the cutoff for creatine level?
A

Intravascularly administered agents are iodinated, gets excreted through kidneys
* Various facilities interpret ACR guidelines differently; contrast cutoff for creatinine level may range from 1.4-1.7, and may require radiologist approval

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50
Q

When should iodinated contrast should be avoided?

A

Iodinated contrast should be avoided for two months before administration of iodine 131
– Reduces uptake of I-131 and makes it ineffective

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51
Q
  • What are the three different oral contrast?
  • What are the Characteristics?
A

Barium Sulfate
* Non-water soluble
* Avoid in suspected perforations due to peritonitis

Gastrografin
* Water-soluble
* Does not coat mucosa as well as Barium

Air

52
Q

What is Iodinated Contrast Media (ICM)?

A

injectable, water- soluble agents, classified as high osmolality and
low osmolality agents

53
Q

More severe reactions occur with what type of injectable contrast?

A

With high osmolar (ionic) contrast agents (1st generation): Omnipaque, Isovue, Optiray

54
Q

What injectable contrast have reduced risk of severe reactions?

A

Low osmolar (nonionic) contrast agents have a reduced risk of severe reactions (2nd gen): Renografin, Hypaque Conray

55
Q
  • What is The single most important risk factor for an adverse reaction?
  • Why have low-osmolality ICM have not replaced the older injection?
A
  • the type of contrast agent chosen for injection
  • The reason that low-osmolality ICM have not completely replaced the older higher-osmolality ICM is their higher cost and the gaps of insurance coverage for the low osmolar compounds which are considerably more expensive.
56
Q

What are the idiosyncratic characteristics? ⭐️

A
  • Unpredictable
  • Usually within 20 minutes
  • Independent of dose amount or rate of injection
  • Can occur with less than 1ml injection
  • Prior sensitivity testing is of no value
  • Symptoms can progress change from mild to severe

Allergic and didn’t know

57
Q

What are the non- idiosyncratic characteristics? ⭐️

A
  • Non-idiosyncratic
  • These can occur rapidly after injection
  • Usuallyhave metallic taste in mouthand possibly nausea, vomiting
  • Bradycardia, hypotension andvasovagal reactions
  • Unattended these reactions can lead to vascular collapse and death
58
Q

What is a mild and severe types of adverse reaction?

A

Mild
* Not allergic-like response to injection including, nausea, vomiting, sensation of warmth or flushing
* Usually do not require treatment; observe for 30 minutes

Severe
* Rare, but are rapid and progressive. Can develop into seizures, AMS, and cardiac arrest

59
Q

Low yield

What is a moderate adverse reaction?

A

Typically not life-threatening, but include urticaria, bronchospasms,
angioedema, vasovagal reactions. Can progress quickly.

60
Q

Rooms in which contrast material is administered should be stocked with what?

A
  • With appropriate basic and advanced life support and monitoring equipment and drugs.
  • The equipment should be regularly checked.
61
Q
  • History of reactions or allergies may require pretreatment with what?
  • What is the typical prep?
A

steroids or anti-histamines

Typical Steroid prep:
* 50mg Prednisone PO 13hrs prior to exam
* 50mg Prednisone PO 7hrs prior to exam
* 50mg Prednisone PO 1hrs prior to exam
* 50mg Benadryl PO 1hr prior to exam

62
Q

Radiocontrast Nephrotoxicity

  • What are risk factors for radiocontrast nephrotoxicity?
  • What are preventions?
  • What may also offer a small benefit?
A
  • Preexisting renal insufficiency, diabetes, volume depletion, and severe CHF are risk factors
  • Prevention in high-risk patients includes IV hydration before, during, and after the study (NOT CHF)
  • Nonionic contrast agents may also offer asmall benefit in these patients
63
Q
  • What are the third generation of contrast that reduces nephrotoxicity?
  • What medicine interacts with contrast?
A
  • Third generation agents are available: iodixanol (Visipaque), reduces nephrotoxicity
  • Metformin and contrast interaction (withhold 48hrs before and after radiocontrast)
64
Q

What are the two types of angiography?

A
  • Arteriography (arteriograms)
  • Venography(venograms)
65
Q
  • The arterial system is usually opacified by what?
  • Can image any what?
  • What is the “gold standard” in imaging of the arterial system?
A
  • The arterial system is usually opacified by a contrast injection into a percutaneously placed small caliber catheter, usually placed into the femoral artery
  • Can image any major artery (e.g. carotid arteriogram, femoral arteriogram)
  • Angiography (arteriography) remains the “gold standard” in imaging of the arterial system
66
Q

Which of the following findings will prevent you from administering IV contrast?
1. Creatinine of 1.8
2. O2 Saturation of 93% on Room Air
3. Chronic use of Metformin (Glucophage)
4. Flushing upon prior administration of contrast

A
  1. Creatinine of 1.8
67
Q

What is arthography?

A

Uses positive contrast (e.g. an iodinated contrast agent) or negative contrast (air) to demonstrate joint abnormalities that are notnormally evident on plain films

68
Q

What are the Advantages and Disadvantages of Utilizing radiography?

A
  • Advantages: Widely available, cheap, causes low dose exposure
  • Disadvantages: no 3D images, inferior to MRI or CT, especially in non-skeletal imaging
69
Q
  • In tomography, how is the image made up?
  • What is body section radiography?
  • X-ray source moves how? What does this show?
A
  • Image is made with both the x-ray tube and the film moving at the same time
  • The effect is the ability to image different slices of the body, aka Body Section Radiography
  • X-ray source moves in one direction as the film is moved in the opposite direction, thus showing detail in a predetermined plane of tissue while blurring or eliminating detail in other planes
70
Q

What plane of movement is the predominate plane for CT? ⭐️

A

Transverse

71
Q

What is a Cat scan?

A
  • Aka Computed Axial Tomography (CAT scan)
  • X-ray tube and detectors move around the patient, computer provides axial tomograms of the patien
72
Q

What scan is used for smokers and lung cancer?

A

Helical CT scan

73
Q

Computed Tomography:
* Good or bad contrast resoultion?
* Cross-sectional images in mostly the _ plane?
* Excellent for imaging what?

A
  • Excellent contrast resolution
  • Cross-sectional images in mostly the axial plane
  • Excellent for imaging cortical bone

Prettier than x-ray but does the same thing

74
Q

What type of scan is this?

A

ct with reconstruction

75
Q

When can artifacts be seen?
What are the typical causes?

A

Artifacts can be seen in conventional, computed, and direct radiography.

Typical causes are:
* Patient Motion
* Dust particles
* Foreign Bodies

76
Q
  • What do you not irradiate in a women in the first trimester of pregnacy?
  • What should you do instead if possible?
  • What should you limit?
A
  • Do not irradiate the abdomen, pelvis,lumbar spine, or hips of a woman in the firsttrimester of pregnancy, unless it is clearlymedically indicated
  • Whenever possible defer the examination orchoose as alternative imaging modality (forexample, ultrasound or MRI)
  • Limit the number of images or views obtained tothose required to ensure adequate care whenevaluating a pregnant woman with modalities thatuse ionizing radiation
77
Q

If the abdomen or pelvis of a pregnant patient isaccidentally irradiated, what needs to happen?

A

the radiology department needs to be notified. The Radiation Safety Officer can estimate the radiation dose to the fetus

78
Q

What are the CT Strengths and Weaknesses?

A
  • Strengths: Accurate, 3D reformation ability, Ability to combine with PET
  • Weaknesses: Radiation exposure, Contrast reactions, Nephrotoxicity, Air embolism, Contrast extravasation
79
Q
  • What disease states do you essentially never have IV contrast?
  • What disease states do you almost always use IV contrast?
  • What are disease states that you may or may not use contrast?
A
  • Essentially always without IV contrast: Bony abnormalities, FBs, Pneumonia
  • Almost Always with IV contrast: Soft Tissue Trauma
  • Maybe: PE, Aortic Dissections,Renal Stones
80
Q
  • What disease states do you only use IV contrast?
  • What do disease states for oral contrast?
A
  • With IV contrast Only: Cellulitis, Mass, Infection (excluding pneumonia), Inflammation, Soft Tissue non-trauma
  • With oral contrast: Most Bowel abnormalities
81
Q

MRI:
* What are patients placed in?
* What is directed into the patients?
* The radiowaves interact with what? What does this do?

A
  • Patient is placed in a magnetic field
  • Radiowaves are directed into the patient
  • The radiowaves interact with hydrogen atoms in the patient’s FAT and WATER molecules
  • Hydrogen atoms (protons) which are small magnets themselves, align themselves with the magnetic field.
  • Radiowaves are then released from thepatient and detected by a receiver
  • A computer analyzes the data to reconstructan image
82
Q

MRI:
* What is not used?
* What is the image not based on?
* What terms do not apply?

A
  • X-rays are NOT used in MRI!
  • The image is NOT based on selective absorption!
  • The terms radiopaque and radiolucent do NOT apply!
83
Q

MRI:
* MRI is based on?
* A strong signal will appear as what?
* A weaker signal will appear as what?
* No signal will appear as what?

A
  • The MR image is based on the strength ofthe radiofrequency signal emitted from thepatient
  • A strong signal will appear white (a highsignal intensity)
  • A weaker signal will appear gray (a lowsignal intensity)
  • No signal will appear black (no signal)
84
Q

How is the image created with MRI?

A
  • With the patient placed in the magnets radio frequencies are pulsed in. When energy is then released from the body, it is digitalized and used to create the image.
  • The information is collected from all radii thus allowing images to be created in anyplane i.e. axial, coronal or sagittal.
85
Q

What are MRI absolute contraindications?

A
  • Cardiac pacemakers
  • Automatic internal defibrillators
  • Cerebral aneurysm clips
  • Metal in eyes
  • Cochlear implants
  • Implanted infusion pumps
  • Penile prostheses
  • Shrapnel/foreign bodies
  • Tattoos with ferromagnetic dyes
  • Permanent cosmetics (i.e., eyeliner, lipliner, lip coloring)
86
Q

What are MRI safe devices?

A
  • Orthopedic prostheses made from paramagnetic metals
  • Surgical hemostasis clips (delay 2 to 3monthspost surgery)
  • Dental fillings, braces
  • IUD’s
87
Q
  • MRI allows for direct scanning in which planes?
  • What is T1 and T2?
A
  • MRI allows for direct scanning in the coronal and sagittal planes
  • In T1 weighted images, white matterappears white, gray matter appears gray,CSF appears black
  • In T2 weighted images, CSF appears white, fatty structures appear darker (SEES MORE DETAIL)
88
Q

If you have a patient that comes in with a brain bleed, what MRI scan should you do?

A

T2 since fluid will light up

89
Q

Which one is T1 and T2?

A
90
Q

MRI Basics

  • Protons process at a frequency that is directly proportional to what?
  • Varying B0allows what?
A
  • Protons process at a frequency that is directly proportional to the strength of B0
  • Varying B0 allows direct imaging in multiple slices and plains (as opposed to CT, in which imaging is dependent upon the position of the body part in the gantry)

TheB0inMRIrefers to the main staticmagnetic fieldand is measured inteslas (T).

91
Q

MRI Basics

  • During scanning, what is directed at the patient?
  • What is knocked out of alignment? What will happen?
A
  • During scanning, apulsed radio wave of aparticular frequency isdirected at the patient.
  • The hydrogen atoms are knocked out of alignment andwill “echo” the radio waveback when they realign with the magnetic field
92
Q
  • What is relaxation time?
  • What are the two relaxation times are recognized with MR scanning?
A

The time required for the atoms to realignis called the relaxation time.

Two relaxation times are recognized withMR scanning:
* T1 or longitudinal (spin-lattice) relaxationtime.
* T2 or transverse (spin-spin) relaxationtime

93
Q

How does T1 and T2 depend on the length?

A
  • TR (repetition time) – time between pulses we send to the patient
  • TE (echo time) - time for signal to come back
94
Q
  • What does TR control and is that longer or shorter?
  • What does TE control and is that longer or shorter?
A
  • TR controls T1 weighting. The shorterthe TR, the brighter those tissues with T1characteristics appear
  • TE controls T2 weighting. The LONGERthe TE, the brighter those tissues with T2characteristics appear
95
Q
  • T1 weighted images (short TR) is best for what?
  • T2 weighted images (long TE) is best for what?
A
  • T1 weighted images (short TR): best for normal anatomy; FAT and BONE MARROW (primarily fat) appear BRIGHT
  • T2 weighted images (long TE): best for pathology; WATER, EDEMA, ACUTE HEMORRHAGE appear BRIGHT
96
Q

With the proton density at play, what appears bright with MRI? What is it good for?

A
  • Proton density: FAT and WATER appear BRIGHT; good for tendon pathology
97
Q

What always appear black in MRI?

A

Tendons, ligaments, cortical bone, and air always appear black because of their lack of water content

98
Q

Fill in:
* T1 weighted images:
* T2 weighted images:
* Proton Density:

A
  • T1 weighted images: short TR; short TE
  • T2 weighted images: long TR; long TE
  • Proton Density: long TR; short TE
99
Q

What are most MRI contrast? What type of images are they on?

A
  • Most are gadolinium enhanced to produce “positive” or enhanced contrast mostly on T1 weighted images.
  • T2 effects are negligible
100
Q

What are the types of contrast material for MRI? (3)

A

– Extracellular agents
– Blood Pool agents
– Hepatobiliary agents

101
Q
  • When are extracellar agents used for MRI contrast? What is the constrast name?
  • When are blood pool agents used for MRI contrast? What is the constrast name?
A

Extracellular agents
* Used in imaging of tumors, inflammation or magnetic resonance angiography (MRA). Gadodiamide (Omniscan)

Blood Pool agents
* Agent binds to albumin; used for MRA exclusively due to longer intravascular half-life.Gadofosveset trisodium (Ablavar).
* Gadolinium deposit disease

102
Q

When are hepatobilary agents used for MRI contrast? What is the constrast name?

A

Used in discrimination of focal hepatic lesions due to long-lasting enhancement of normal liver parenchyma at which point lesions will stand out as black spots in contrasted normal liver. Gadobenate (MultiHance)

103
Q

What other organ can be damaged form gadolinium administration?

A

Renal Impairment

104
Q

Nephrogenic System Fibrosis
* When does it present? What is the contrast that mostly causes it
* How does it present?
* What significant risks?

A
  • Presents 2-10 weeks following contrast, usually Omniscan
    * Thought to release most free gadolinium
  • Presents asacute to subacute onset of limb edema that is accompanied by cutaneous papules and plaques overlying fibrosis of the cutaneous and subcutaneous fat
  • Has significant mortality risks

YOU NEED TO CHECK INR AND CREATINE LEVELS (LIVER AND KIDNEY)

105
Q

What are the MRI bottomlines?

A
  • Expensive
  • Takes nearly an hour per study
  • But does not produce ionizing radiation
  • Excellent at imaging soft tissues
106
Q

If a patient comes in with bilateral flank pain and renal failure, their CT scan without contrast shows cystic lesions or fibroids on the kidneys, what procedure did they undergo prior?
1. Colonoscopy
2. Endoscopy
3. MRI of the brain with contrast
4. heart attack

A

MRI with contrast

107
Q

Does the “Air” appear differently on CT or Xray in terms of contrast?

A

no
* same with MRI vs x-ray

ALWAYS BLACK AIR

108
Q

Ultrasound:
* What is it based on?
* What does solid and cystic structures appear like?

A

Based on directing high frequency soundwaves into the patient, and recording themanner in whichsound is absorbed orreflected fromorgans and structures

Echogenicity
* Solid structures appear white (echogenic, orhyperechoic)
* Cystic structures appear black (echolucent,hypoechoic or anechoic)

109
Q

What is an option to detect flow with US?

A

Doppler

110
Q
  • What does sciatic nerve, adipose, muscles, veins, popliteal artery and bone look like with US?
A
  • Sciatic nerve (hyperechoic with stippled “honeycomb” structure)
  • Adipose tissue (hypoechoic)
  • Muscles (note the striations and hyperechoic fascial lines on muscle surfaces)
  • Vein (anechoic – partially collapsed under pressure to US transducer)
  • Popliteal artery (anechoic – pulsating)
  • Bone (hyperechoic rim with hypoechoic shadow below it)
111
Q

Which one is a cyst or solid using US?

A

Oneofthegreateststrengthsof ultrasound is its ability to differentiate cysts from solid lesions, making it a useful problem-solving tool for further evaluation of cystic lesions incidentally noted on CT.

112
Q

Duplex Ultrasonography:
* Clear fluid collections look like what?
* Not completely clear fluids (blood, pus, debris) will appear like what?
* Since vascular ultrasound does not require what, it is what?

A
  • Clear fluid collections produce no echoes at ultrasound, and are thus anechoic (black)
  • Not completely clear fluids (blood, pus, debris) will appear hypoechoic (gray), or anechoic
  • Since vascular ultrasound does not require injected contrast material, it is well tolerated by most patients (venous doppler has pretty much replaced venography in the imaging of DVT)
113
Q

What is the color of blood when going towards the doppler and away?

A
  • Towards: Red
  • Away: Blue
114
Q
  • Why do might we use a arterial or venous duplex?
  • Color doppler can be useful for what?
A
  • Arterial duplex (for arterial occlusivedisease)
  • Venous duplex (for DVT and venousvalvularincompetence)
  • Color doppler, while notdiagnostic in itsown right, canprovide valuable informationwith regard toflow turbulence and variancein anatomic routes
115
Q

A patient comes in with red, warm, swollen leg. As a PA student, you believe it is a DVT. How will you determine it is a DVT with a color doppler?

A
  • If you place the doppler on the possible vein with DVT and their is no blood going away (blue) then that is a DVT
116
Q

If you see an artery and vein next to each other, how do you know which one is which?

A

Usually seearteryand vein next to it. If apply pressure with transducer – wall of vein is thin and iscompressible. Wall of artery is not. So, identify vessels by vein collapse.

117
Q

Contrast Enhanced Ultrasound (CEUS):
* How big are the contrast agents?
* Used rarely when?
* What does it enhance?
* Suppress the background tissue to highlight what?
* What are the only FDA approved agents?

A
  • Microbubble contrast agents that are smaller than RBCs.
  • Used rarely incardiac perfusion studies
  • Enhance the Doppler signal of flowing blood
  • Suppress the background tissue to highlight the signal from the blood pool
  • Optison and Definity are the only FDA approved agents
118
Q

What are the positives and negatives of US?

A
  • It is cheap, harmless and is widely available
  • Preferred initial intraabdominal study of choice in most pediatric/pregnant patients
  • Results vary based on technician
  • Limited scope for deep structure evaluation
119
Q

What are the two most important artifacts in US?

A

Echo of posterior enhancement
* Bright band extending from the posterior aspect of the weak attenuator
* Distinguishes cyst vs lesion

Shadowing
* Decreased posterior attenuation of highly reflective surface
* Helpful in stones identification

120
Q

You are evaluating a patient following MVC with suspected ligament injury. What imaging modality will best evaluate this pathology?
1. XRay
2. CT
3. Ultrasound
4. MRI

A
  1. MRI
121
Q
  • What is the most common metabolic disease? What is it due to?
  • What is Bone mineral density (BMD)?
A
  • Osteoporosis is the most common metabolic disease of bone. It is due to disturbances in bone remodeling that result in less bone tissue (matrix and mineral) per unit volume
  • Bone mineral density (BMD), the average concentration of mineral in a defined section of bone, is used to diagnose osteoporosis
122
Q
  • What is used to diagnose osteoporosis?
  • What allows the BMD to be estimated?
A
  • A BMD of the hip and spine using a central DXA machine is used to diagnose osteoporosis. Forearm is an alternative site.
  • The low-energy and high-energy photons are attenuated differently in bone and soft tissue, allowing BMD in g/cm2 to be estimated.
123
Q

How is bone density quantified using the DEXA scan?

A

Results quantified statistically, using T- and Z-scores.
* Osteoporosis is quantified as T-score of −2.5 or lower.
* Osteopenia is defined as T-scores between −1 and −2.5
* A T-score higher than −1 is considered normal.

124
Q
  • What is nuclear medicine based on?
  • What does increased and decreased uptake appears as?
A
  • Based on the accumulation/metabolism or “uptake” of an injected radioactive
    substance (radiotracer) by body tissues
  • Increased uptake (hots pots; appear black) or decreased uptake (cold spots; appear white)
125
Q

What are the four different nuclear medicine agents?

A
  • Technetium-99m (bone scan MDP), measures bone metabolism
  • Gallium-67 Citrate, measures inflammatory disorders (tumors)
  • Indium-111 Oxine WBC, for acute infections
  • Ceretec Labeled WBC
126
Q

Themeanoperating expense and charge per procedure:
* CT:
* X-ray and US:
* Nuclear medicine:
* MRI:

A
  • computed tomography (CT): $51 and $1565
  • x-ray and ultrasound: $55 and $410
  • nuclear medicine (NM): $135 and
    $1138
  • magnetic resonance imaging (MRI): $165 and $2048.
127
Q
A

Medical Diagnosis (16 decks)

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