NUCLEAR CARDIOLOGY Flashcards
What is nuclear cardiology?
A field of cardiology that uses radioisotopes to assess myocardial perfusion and myocardial function.
What is myocardial perfusion imaging (MPI)?
A noninvasive imaging method that utilizes radioisotopes to assess regional myocardial blood flow, function, and viability.
What imaging techniques can be used in MPI?
- Single-photon emission computed tomography (SPECT)
- Positron emission tomography (PET)
What happens during the stress portion of an MPI test?
Exercise increases myocardial demand or a pharmacologic agent is used to produce vasodilation in the coronary vascular bed.
How does a normal blood vessel respond to stress during MPI?
A normal vessel can increase coronary blood flow up to four times its baseline.
What is a perfusion defect?
An area of reduced radiotracer uptake in the myocardium.
What differentiates a fixed defect from a reversible defect in MPI?
A fixed defect occurs during both stress and rest, while a reversible defect is present only during stress.
What are the uses of myocardial perfusion imaging?
- Diagnose coronary artery disease (CAD)
- Localize and quantify ischemia
- Determine infarct size
- Risk stratification
- Assess residual ischemia after revascularization
- Assess myocardial viability
What is the sensitivity and specificity of MPI compared to stress echocardiography?
Sensitivity: 85% vs. 75%; Specificity: 79% vs. 88%.
What are the two main radiopharmaceutical agents used in MPI SPECT?
- Thallium-201 (Tl-201)
- Technetium-99m (Tc-99m)
What is the half-life of Thallium-201?
73 hours.
What is a key characteristic of Thallium-201 in MPI?
Myocardial redistribution after initial uptake.
What is the half-life of Technetium-99m?
6 hours.
What is the importance of Technetium’s short half-life?
It reduces radiation exposure to the patient.
What are the stress modalities for myocardial perfusion imaging?
- Exercise-induced
- Pharmacologic
What are common forms of exercise used in stress testing?
- Treadmill
- Bicycle
- Isometric handgrip
What is a major contraindication for exercise stress testing?
Severe aortic stenosis or decompensated heart failure.
What is the sum difference score (SDS) in MPI?
The difference between summed rest score (SRS) and summed stress score (SSS), representing the amount of ischemia.
Fill in the blank: A _______ defect suggests the presence of ischemia.
reversible
True or False: A fixed defect always indicates myocardial scar.
False.
What is the method used for semiquantitative analysis of perfusion defects?
Scores from 0 to 4 are assigned to each segment based on severity.
What does a score of 0 indicate in semiquantitative evaluation?
Normal count.
What does a score of 4 indicate in semiquantitative evaluation?
Absence of uptake.
What is dobutamine used for?
Diagnose CAD, assess risk for those who cannot exercise
CAD stands for coronary artery disease.