1. John N. Hamaty D.O. Second year student module
Nuclear Cardiology
John N. Hamaty D.O.
Second year student module

2. Nuclear cardiology has been an active clinical discipline for more than two decades.
Indirect measure of coronary perfusion to the myocardium.
Utilized for the assessment of functional categories as well as prognosis and risk.

3. Instrumentation Scintillation (gamma) camera
Collimation (focusing Lens)
Computer (principal component)-processor

5. Spect Imaging Single-photon emission computed tomography
Planar images obtained over 180 degree arc
Three planes-
A) short axis
B) Horizontal
C) Vertical

6. Myocardial perfusion imaging
Allows RELATIVE distribution of myocardial blood flow
Absolute quantification is not feasible with spect
PET scanning is only absolute test

7. Myocardial perfusion imaging
Most important clinical application of myocardial perfusion imaging is in conjunction with stress testing for evaluation of ischemic heart disease

8. Stress testing
Objective is to “stress” the heart via treadmill or pharmacologic testing
Alterations in heart rate, O2 consumption and blood pressure effect uptake of the nuclear agent.
Goal heart rate is 85% of predicted based on age (220-age) then 85% is target.
Sensitivity/Specificity is 85% with nuclear/echo augmentation

9. Myocardial perfusion imaging
Demonstrated that findings on stress images reflect the hemodynamic and functional significance of coronary artery stenosis and thus provide important prognostic information.

10. Radiopharmaceuticals
Thallium-201
Technetium-99

11. Thallium-201 Cyclotron produced Doses of 3-4 mCi
Initial myocardial accumulation is proportional to myocardial blood flow.
Continuous exchange of Tl takes place across the cell membrane.

12. Thallium-201 Energy requiring (Na-K-Atp-ase)
Cell re-accumulation of Tl gives effective half-life in heart of 7.5 hours.
Unique property because it allows early and late imaging after injection

13. Thallium-201
Images immediately after injection reflect the flow dependent initial distribution and thus regional myocardial blood flow-Ischemia

14. Thallium-201
Images taken after a delay of 2-24 hours reflect the distribution of the potassium pool and hence allow for detection of
Myocardial Viability

15. Myocardial Viability
Detection of living cells despite hypo-akinesis of ventricular contractility
Stunned myocardium
Hibernating myocardium

16. Technetium-99 Emmits Gamma rays at 140 kev Half-life is 6 hours
Slow body clearance
30 mCi
Initial distribution is similar to Tl and is proportional to regional blood blow

17. Technetium-99M
Difference is tech extraction from the heart is greater (65%) and redistribution is much less than Tl.
Because the intracellular retention is relatively fixed over time, no significant redistribution occurs.

18. Technetium-99M
Since no significant redistribution occurs, the myocardial blood flow at the time of injection is “frozen” over time and imaging can occur hours later.

19. Technetium-99M
This also allows for assessment of wall motion and ejection fraction. Since image is “fixed” for a period of time, we can look at systolic and diastolic function. Allows greater sensitivity in detection of infarcted and ischemic myocardium.

20. Gated spect imaging
This has increased the sensitivity and specificity of interpretation due to detection of breast/diaphram artifact.
Chamber size and right ventricular function can also be assessed

21. Dual isotope imaging
Utilizing an “Hybrid” of imaging proticals, two injections of rest thallium and stress tecnetium
Greater patient throughput
Allows for viability testing
Comparing apples and oranges(two different agents)