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clinical medicine II exam 2 > pulmonary diagnostic imaging > Flashcards

pulmonary diagnostic imaging Flashcards

1
Q

What is the benefit of using US and/or MRI imaging in pulmonary diagonistics

A

no ionizing radiation

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2
Q

which diagnostic imagining is often the initial study to evaluate respiratory symptoms

A

chest xray

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3
Q

describe the inherent contrast of chest xray

A
  • air in lungs is black
  • soft tissue (light grey)
  • bone (nearly white)
  • metal (white)
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4
Q

what are the chest xray views? which two are used most often?

A
  • PA
  • Lateral
  • AP: (anything on anterior part of chest is magnified)
  • Decubitus
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5
Q

silhoutette sign

A

when you see a nice silhouette of heart border

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6
Q

How is the lateral view chest xray taken

A
  • taken from right to left so that the heart does not appear abnormally large
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7
Q

when is is appropriate to order a decubitus CXR

A
  • suspect pleural effusion
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8
Q

benefits of CXR

A
  • non-invasive
  • low radiation exposure (0.1 mSv)
  • inexpensive
  • widely available
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9
Q

what do you look for on CXR when you suspect pneumothorax

A

look for edge of pleura as a light line that has advanced inward toward heart

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10
Q

what condition does this wedge shaped sign suggest

A

Hampton’s hump -> pulmonary infarct

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11
Q

Computed tomography (CT scan) takes what kind of pictures

A

cross sectional images (slices) through the body

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12
Q

Why would you order a CT

A
  • clarify abn CXR
  • characterize pulmonary nodules
  • detection and staging of primary and metastatic lung neoplasms
  • evaluate suspected mediastinal or hilar masses
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13
Q

What are the various types of CT scans

A
  1. conventional
  2. helical
  3. high resolution
  4. low dose CT
  5. CT angiography
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14
Q

conventional CT scan

A
  • 10 mm slice
  • “step and shoot:
  • 25-30 min
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15
Q

helical CT

A
  • continuous
  • < 5 min
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16
Q

high resolution CT (HRCT)

A
  • better detail
  • 1 mm slice
  • used to figure out what is going on with lung tissue; ex: chronic lung diseases
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17
Q

multi_detector CT

A
  • also called multislice CT
  • 4-620 slides
  • conventional or helical scans
  • very fast; higher radiation
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18
Q

what are the benefits of CT

A
  • fast
  • real-time imaging
  • can be performed even if patient has implantable device
  • less expensive and sensitive to patient movement than MRI
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19
Q

what contrast is used in CT

A
  • iodine
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20
Q

why is constrast used

A

to enhance differences in densities of various structures

21
Q

does the following require CT with or without contrast:

Masses, CA, metastatic disease, obstructive processes, PE or dissection

A

CT chest with contrast

22
Q

does the following require CT with or without contrast:

pulmonary fibrosis; interstitial lung disease; follow up of known pulmonary nodules

A
  • CT chest without contrast
    • pulmonary fibrosis; interstitial lung disease: use HRCT
23
Q

risk of CT

A
  • radiation exposure 8 mSv
  • increased CA risk
  • pregnancy exposure
  • body habitus > 450 lbs
24
Q

CT chest and CT chest with contrast can be approximated to have the radiation exposure equivalent to how many plain chest xrays

A
  • CT chest: 80
  • CT chest with contrast: 150
25
Q

why should CTs be avoided in pediatric patients

A
  • more radiosensitive than adults
    • increased risk of leukemia and brain tumors with CT scans
26
Q

what are the risks of getting a CT with contrast

A
  • allergic reaction
    • w/in 5-60 min of administration
    • risk factors: prior reaction, asthma, atopy (NOT shellfish allergy)
    • can pretreat with prednisone and benadryl
  • contrast induced nephropathy
27
Q

which imaging modality should you use cation with in patients taking metformin (Glucophage)

A

CT with contrast

  • hold medication for 48 hours after exam
  • recheck creat/BUN before restarting
  • can cause lactic acidosis
28
Q

what is contrast induced nephropathy

A
  • serum creatinine increase > 25% form baseline or > 0.5 mg/dL
    • usually reversible
    • best treatment is prevention
    • caution with impaired kidney function
      • creat > 1.5 mg/dL or GFR < 60
29
Q

when should you check renal function prior to iodine contrast

A
  • age > 60 yo
  • history of renal disease
    • dialysis, single kidney, kidney transplant, renal CA, renal sx
  • h/o HTN treated with medication
  • h/o DM
  • taking metformin
30
Q

which imaging modiality assess vasculature in the body

A

angiography

  • CT-> CTA
  • MRI-> MRA
  • xray with catheter
31
Q

which imaging modality should be used for suspected PE, aortic dissection, superior vena cava syndrome; or vascular malformation

A

CT pulmonary angiography (CTPA)

32
Q

risks and limitations of CTPA

A
  • can miss sub-segmental PEs
  • allergy to contrast
  • nephrotoxicity from contrast
  • radiation exposure: 10-15 mSv
  • body habitus > 450 lbs
33
Q

what imagining modality is the gold standard in evaluation of PE

A

direct pulmonary angiography

34
Q

describe direct pulmonary angiography technique

A
  • catheter inserted into right femoral or internal jugular vein -> Rt heart -> pulm arteries
    • dye injected; xrays taken
  • used if V/Q scan or CTPA are inconclusive and high clinical suspicion
  • invasive and expensive
35
Q

risks of direct pulmonary angiography

A
  • bleeding or hematoma at insertion site
  • heart arrhythmia
  • allergic reaction to contrast
  • impaired kidney function
  • radiation exposure (5 mSv)
36
Q

benefits of using MRI over CT

A
  • no bone artifact as with CT
  • no ionizing radiation
37
Q

the following indicate evaluating with what imaging

hilar or mediastinal densities, sulcus tumors, possible cysts and lesions of chest wall; allergy to iodinated contrast or renal disease (GFR <30)

A

MRI

38
Q

functio of Magnetic resonancy angiograph

A
  • high quality images of many blood vessels
    • less detailed view of lung parenchyma and diminished spatial resolution compared to CT
39
Q

what is the contrast material used for MRI and MRA

A

Gadolinium

40
Q

limitations/risk of MRI/MRA

A
  • patient must remain still
  • claustrophobia
  • body habitus
  • risk of nephrogenic systemic fibrosis ( GFR <15 ml/min)
41
Q

contraindications of MRI/MRA

A
  • pacemaker or defibrillator
  • metal in eye
  • clips used in brain aneurysms
  • cochlear implant
42
Q

when is V/Q scan used

A
  • to evaluate for PE
  • for pre-op assesment prior to lung resection
43
Q

how does V/Q scan work

A

emitted radiation is captured by external detectors in 2 phases

  1. IV phase: technetium-99m labeled to human albumin is injected and follows distribution of blood flow -> perfusion
  2. inhalation phase -> radio labeled xenon gas demonstrates distribution of ventilation
44
Q

test of choice for diagnosis of PE in pregnant women

A

V/Q scan

45
Q

benefits of V/Q scan

A
  • allergic reaction is rare
  • low dose radiation 2-2.5 mSv
46
Q

which imaging is the acquisition of physiologic images based on the detection of radiation emitted from FDG (radioactively labeled glucose) which is injected into patient

A

positron emission tomography (PET)

47
Q

where does FDG (radioactively labeled glucose) accumulate

A
  • is tissues/organs with high metabolic activity (cancer cells***)
    • PET scan most often used to detect CA
48
Q

in a PET scan, patient is scanned and measurements of the uptake are made in standardized uptake value (SUV). and SUV > X raises the possibility of malignancy

A

SUV > 2.5

49
Q

limitations of PET scan

A
  • radiation exposure 14 mSv
  • false results occur with metabolic imbalances
  • radioactive substance decays quickly
  • high cost

clinical medicine II exam 2 (7 decks)

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