Training presentation for nuclear medicine technologists on myocardial perfusion imaging basics

1. Myocardial Perfusion Imaging SPECT
Basics
Imaging and Protocol Basics

2. Indications of MPI
 Detection of CAD
 Assessing functional significance of coronary
stenosis
 Evaluating prognosis and risk stratification
 Assessing medical therapy of CAD
 Assessing cardiac viability

3. Coronary Artery Disease
 Cardiovascular disease is the leading cause of death
in the United States
 Accounts for nearly 1 million deaths, half of which are the
result of CAD
 CAD is a condition in which the heart does not
receive enough blood
 Caused by accumulation of plaques in the coronary
arteries
 Causes stenosis of the lumen of the vessels
 Decreases ability of the walls of the affected vessels to
contract which inhibits cardiac function
 Occlusion of the vessels can also be caused by thrombus
or embolus in a coronary artery or an artery spasm

4. Risk Factors CAD
 High cholesterol
 High blood pressure
 Cigarette smoking
 Obesity
 Diabetes
 Sedentary lifestyle
 Family history of CAD
 Gender (more prevalent in males)

5. Symptoms of CAD
 Angina pectoris
 Transient pain or discomfort resulting from a temporary lack of
oxygen and nutrients to the heart muscle
 Myocardial Infarction
 A portion of the heart muscle dies resulting from inadequate
blood flow
 Changes the electrical activity of the heart
 Decreases contractility of heart in fibrous area
 Difficulty breathing
 Weakness
 Dizziness
 Perspiration
 CAD progresses over time and a person may be
asymptomatic in the early stages of the disease

6. Manifestations of CAD
 Before reaching > 70-80% vessel occlusion CAD
may have little or no effect on resting heart function
 When demands of the heart muscle are increased
diseased vessels cannot produce adequate blood
flow
 Coronary reserve: the ability to increase coronary
blood flow when needed
 Decreases in CAD due to increased metabolic demands
of the diseased vessels
 Patients with severe CAD will usually have
homogeneous resting regional myocardial blood flow
 Diminished blood flow at stress because of the
inability to increase blood flow when needed

7. Treatment of CAD
 Drug therapy
 Nitroglycerin
 Relaxes smooth muscle causing blood vessels to dilate
 Beta blockers
 Depress cardiac function and decrease cardiac output
 Cholesterol-lowering drugs
 Clot-dissolving agents
 Low-fat diet
 Exercise

8. Treatment of CAD
 CABG (coronary artery bypass graft)
 Blood vessels from one part of the body are used to
bypass a blocked region of a coronary artery to improve
blood supply to the affected area of the heart muscle
 PTCA (percutaneous transluminal coronary
angioplasty)
 Lumen of a stenotic vessel is dilated
 Atherectomy
 Obstructive plaque or thrombus is removed sing lasers or
mechanical devices
 Intracoronary stents

9. Patient Prep MPI Stress Test
 NPO 4 hours prior to test
 No caffeine within 24 hours
 Restrict cardiac medication if possible
 Consent for stress
 Pregnancy consent
 Skin prep/lead placement 12 lead EKG
 IV placement

10. Contraindications
 Pregnancy
 Food within 4 hours of stress study
 Caffeine within 24 hours (for pharmaceutical stress)
 Bronchospasm or severe obstructive lung disease
(for pharmaceutical stress)
 Hypotension (BP < 90)
 Xanthine-containing drugs

11. Protocols
 One-day
 Rest Thallium 3-5mCi/Stress Sestamibi or Tetrofosmin 20-
40mCi
 Rest Sestamibi or Tetrofosmin 10-15mCi/Stress
Sestamibi or Tetrofosmin 30-45mCi
 Two-day
 Stress Day 1
 25-45mCi Sestamibi or Tetrofosmin
 Rest Day 2 (if needed)
 25-45mCi Sestamibi or Tetrofosmin

12. Imaging Protocols maiCAM180
 Rest 30-40 seconds/step
 Stress 20-30 seconds a step
 16/32 steps 32/64 projections
 64x64 matrix
 Non-circular orbit
 Limiting patient motion is essential during acquisition
for quality images
 Movement can appear differently on upright imaging
systems than supine

13. Processing
 Set reconstruction limits on both
Rest and Stress cine data
Segami Mirage 5.715b is used for
demonstration purposes

14. Processing
 Reorient slices to appropriate angles

15. Processing
 Apply mask and post filtering if necessary

16. Reconstruction and Review Basics: Slice
Display
Planes of the heart that are
reconstructed in MPI are:
Horizontal Long Axis (HLA)
Short Axis (SA)
Vertical Long Axis (VLA)
Reconstructed data is viewed at
rest and stress, and the
corresponding planes and slices
are compared.
Intensity/color changes between
the two can represent ischemic
changes.
Count deficient areas that are
shared between the two can
represent fixed defects.

17. Reconstruction and Review Basics: Slice
Display

18. Reconstruction and Review Basics: Volume
Data
 3-D view of the heart that can be viewed from all
angles
 Gated data can be viewed as cine volume data to
assess wall motion
 Surface of the heart can be viewed separately or
simultaneously in both systole and diastole

19. Reconstruction and Review Basics: Volume
Data

20. Reconstruction and Review Basics:
Quantification
 Largely developed by Cedars Sinai Medical Center
(Los Angeles, CA) and Emory University (Atlanta,
GA)
 Polar Map or Bull's-eye of the left ventricle of the
heart
 Left ventricle is sliced from apex to base and
displayed in concentric ring; this allows the
visualization of the left ventricle in a comprehensive
image, rather than multiple images as with slice
displays

21. Reconstruction and Review Basics:
Quantification

22. References
 Nuclear Cardiac Imaging: Terminology and Technical
Aspects; Crawford and Husain; 2003; SNM
 Diagrams taken from Nuclear Cardiac Imaging:
Terminology and Technical Aspects; Crawford and
Husain; 2003; SNM
 Nuclear Cardiac images taken from MAI Demo
database using Cedars Sinai and Segami Mirage
processing applications