CT - Chapter 3 Flashcards

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1
Q

What are reasonable measures to avoid contrast-induced nephropathy?

A
  • Calculating CrCl to ensure it is > 60 mL/min
  • Calculating contrast does based on:
    • weight
    • scan duration
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2
Q

What is the current recommendation for CCTA and asymptomatic patients?

A

No role

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3
Q

What are the benefits of using a timing bolus over bolus tracking?

A
  • decreased risk of false start or delay
  • identification of contrast dilution problems
  • chance to coach / observe the patient before the scan
  • ensures adequacy of IV line
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4
Q

What is the major disadvantage of timing bolus over bolus tracking?

A

need for slightly more time/contrast media (10-20 mL)

  • two injections
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5
Q

What is the effective radiation dose (mSv) of:

  • Cardiac NH3-PET/CT with and without myocardial stress performed with either adenosine or dobutamine
A

4-8 mSv

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6
Q

Which of the following is not considered an appropriate use of CCTA?

  • Evaluation of pulmonary vein anatomy prior to RF ablation for A-fib
  • Noninvasive coronary vein mapping prior to placement of BiV PPM
  • Assessment of RV morphology in suspected ARVD
  • Evaluation of CAD in patients with NSVT or syncope
A

Evaluation of CAD in patients with NSVT or Syncope

  • NSVT or Syncope evaluation is considered uncertain
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7
Q

What are contraindications to BB prior to CCTA?

A
  • Asthma or active bronchospasm
  • 2nd or 3rd degree heart block
  • AS with a MG 50 mmHg
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8
Q

What factors should be considered in performing CCTA on an obese patient?

A

Image noise will be high –> all controllable patient factors should be as favorable as possible for scanning

  • Additional complications (may warrant another test)
    • complicated post-revascularization anatomy
    • uncontrollable high HR or irregular rhythm
  • Scans require larger volumes of contrast:
    • renal function
    • IV access (small IV in hand vs. AC or forearm)
  • Higher radiation dose required
    • risk-benefit ratio
    • younger and female patients (may be innappropriate)
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9
Q

What is the treatment recommendations for CCTA in Hyperthyroidism?

A

Contraindicated

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10
Q

What is the best choice for contrast agent?

  • 58 year old male with atypical chest pain
  • GFR 45 mL/min/m2
A

Iodixanol (Visipaque)

  • iso-osmolar contrast agents may reduce the incidence of contrast-induced nephropathy compared to the traditional low-osmolar or high osmolar contrast-agents
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11
Q

What is the recommended course of action?

  • undergoing workup for Grave’s disease and scheduled for diagnostic thyroid scitigraphy
  • equivocal stress test and scheduled to undergo CCTA for exertional chest pain
A

Delay CCTA until after thyroid scintigraphy

  • Iodinated contrast is contraindicated prior to thyroid scintigraphy
    • carries the risk of precipitating thyrotoxicosis in hyperthyroid patients
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12
Q

What is the cause of nausea/vomiting in CCTA?

What is the next best step?

A
  • usually caused by first pass of a high osmolar contrast agent and self-limiting
  • Therapy –> “waiting” 1-2 miutes
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13
Q

Describe the difference in image quality between:

  • stainless steel stents
  • tantalum-made stents
A

stainless steel stents provoke less beam hardening artifacts

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14
Q

Which one of the following patients would be MOST appropriate to refer for a CCTA?

  • 40 year old woman with reurrent atypical chest pain
  • 35 year old man with A-fib
  • 38 year old man with recurrent angina pectoris and former kidney transplant
  • 58 year old man with chest pain, elevated cardiac enzymes and ST-Elevation
A

40 year old woman with recurrent atypical chest pain

  • due to her low pre-test probability
  • A-fib is not optimal due to irregular R-R intervals
  • Prior kidney trasplant:
    • MPI would be better due to high probability of severe coronary calcifications
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15
Q

What is the recommendation for cardiac CT in evaluation of cardiac masses?

A

Useful in the evaluation of cardiac masses

  • techniques which do not utilize ionizing radiation should be used first:
    • Echo
    • MRI
  • MRI offers excellent tissue characterization
  • CT imaging of RA is difficult becuase of inhomogeneous contrast caused by mixing of contrast-enhanced blood from SVC and non-enhanced blood from the IVC
    • usually delayed additional scan 30-60s after first-pass is advisable
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16
Q

What is the recommendation for performing CCTA with A-fib?

A

Relative contraindication

  • due to misregistration artifacts associated with irregular rhythms and
  • motion artifacts associated with rapid HR’s
17
Q

What is the recommended evaluation of suspected pulmonary vein stenosis?

A

CT or MRI

  • most sensitive modalities for detection of pulmonary vein stenosis
  • PV stenosis > 70% is considered to be severe
18
Q

What left atrial appendage morphology is associated with the highest incidence of embolic event?

A

Cauliflower

  • strongest association with embolic phenomena
  • likely due to its complex, irregular structure with variable lobes and short length
19
Q

What is the most appropriate next step?

  • 70 year old male with 1 month of exertional chest pain
  • CAC 2 years ago
A

MPI

  • CCTA will be limited due to calcium presence
20
Q

What is the recommendation for contrast study and Metformin?

A

Hold 48 hours before/after contrast administration?

and

obtain assessment of renal function prior to restarting metformin

21
Q

What is the patient’s cardiac risk?

  • 55 year old woman
  • CAC 450 ( > 90 percentile)
  • GXT: Equivocal
  • Pharmacologic SPECT-MPI: normal myocardial perfusion
A

High long-term cardiac risk

  • CAC is a better estimate for longer-term prognosis
  • because of its ability to detect varying degress of coronary atherosclerosis before the development of stress-induced myocardial ischemia
22
Q

Why is CAC a good marker for long-term prognosis?

A
  • its ability to detect varying degress of coronary atherosclerosis
  • before the development of stress-induced myocardial ischemia
23
Q

What contrast agent is most likely to cause late skin reactions?

A

Iodixanol (Visipaque)

  • defined as those occurring approximately 1-7 days after intravascular iodinated contrast exposure
  • Reactions include:
    • urticaria, rash, HA, fever, musculoskeletal pain, nausea and vomiting
24
Q

What is the next best step?

  • 47 year old man with CAC = 1,210
  • He reports doing regular exercise on his treadmill at home and is asymptomatic
A

Myocardial perfusion SPECT

  • likelihood of silent ischemia in an asymptomatic individual with a calcium score above 1,000 –> 15%
25
Q

Describe the findings and next best step:

A
  • CT findings:
    • anomalous LM from the right coronary sinus with an interarterial course
  • LHC followed by CABG
26
Q

What is the most appropriate diagnostic test?

  • 50 year old man presents with chest pain, SOB, and lower extremity claudication, which limits his ambulation
  • PMH: DM and Asthma
  • Meds: Metformin and beta-agonist inhaler
  • EKG with NSR, 80 bpm, no ST-T abnormalities
A

Dobutamine stress echo

27
Q

Which of the following patients does NOT qualify for CCTA?

  • 32 year old woman with a newly detected LBBB with asthma and glaucoma
  • 46 year old woman whose parents each had MI in their early 50’s
  • 44 year old man complaining of atypical chest pain, with non-conclusive bicycle test results and HR 82
  • 49 year old man scheduled for preoperative heart assessment, with chronic A-fib and prior hip surgery
A

49 year old man scheduled for preoperative heart assessment, with chronic A-fib and prior hip surgery

  • CCTA is not recommended prior to non-cardiac surgery
28
Q

What is the recommendation for CCTA to evaluate LAA thombus prior to cardioversion?

A

Not recommended

  • conflicting evidece for sensitivity of CT in the detection of thrombus
  • only moderate specificity