CT - Chapter 3

Question 1

What are reasonable measures to avoid contrast-induced nephropathy?

Answer 1

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

Question 2

What is the current recommendation for CCTA and asymptomatic patients?

Answer 2

No role

Question 3

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

Answer 3

• 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

Question 4

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

Answer 4

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

• two injections

Question 5

What is the effective radiation dose (mSv) of:

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

Answer 5

4-8 mSv

Question 6

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

Answer 6

Evaluation of CAD in patients with NSVT or Syncope

• NSVT or Syncope evaluation is considered uncertain

Question 7

What are contraindications to BB prior to CCTA?

Answer 7

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

Question 8

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

Answer 8

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)

Question 9

What is the treatment recommendations for CCTA in Hyperthyroidism?

Answer 9

Contraindicated

Question 10

What is the best choice for contrast agent?

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

Answer 10

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

Question 11

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

Answer 11

Delay CCTA until after thyroid scintigraphy

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

Question 12

What is the cause of nausea/vomiting in CCTA?

What is the next best step?

Answer 12

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

Question 13

Describe the difference in image quality between:

• stainless steel stents
• tantalum-made stents

Answer 13

stainless steel stents provoke less beam hardening artifacts

Question 14

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

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

Relative contraindication

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

Question 17

What is the recommended evaluation of suspected pulmonary vein stenosis?

Answer 17

CT or MRI

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

Question 18

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

Answer 18

Cauliflower

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

Question 19

What is the most appropriate next step?

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

Answer 19

MPI

• CCTA will be limited due to calcium presence

Question 20

What is the recommendation for contrast study and Metformin?

Answer 20

Hold 48 hours before/after contrast administration?

and

obtain assessment of renal function prior to restarting metformin

Question 21

What is the patient’s cardiac risk?

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

Answer 21

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

Question 22

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

Answer 22

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

Question 23

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

Answer 23

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

Question 24

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

Answer 24

Myocardial perfusion SPECT

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

Question 25

Describe the findings and next best step:

Answer 25

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

Question 26

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

Answer 26

Dobutamine stress echo

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Question 27

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

Answer 27

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

Question 28

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

Answer 28

Not recommended

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