Wall Motion Studies P1 Flashcards
Poor labeling can:
lead to increased free 99m-TcO4- and increased body background
Increased 99m-TcO4 is due to
- too little stannous
- methyldopa
- hydralyzine
- tinning time too short
Increased body background is due to:
- Too much stannous
- heparin
- doxorubicin
- carrier 99m-TcO4-
Other issues caused by poor labeling
- quinidine
- iodinated contrast
- prior transfusion
- transplantation
Describe gating in LVEF studies
- The acquisition begins with the r-wave on the patients ECG, which corresponds to end-diastole
- One cardiac cycle is divided into multiple frames or bins of equal duration
- Data from each frame are acquired and stored separately
- When the image is processed, the data from each frame or bin are summed
- Each bin must have sufficient countsto produce a quality image, insufficient counts may produce a flashing or streaking artifact
How are the frames represented post acquisition
Cine
What is a tolerance window?
- A window created based on the patients R-to-R interval
- Usually set to no larger than 20%
- Beats outside the tolerance window are not included in the final image
What occurs as the tolerance window increases
- The greater the winow, the greater the number of irregular beats are accepted
- negatively affects the LVEF and the resolution of the final images
What are the most common gating problems
- Heart rhythm
- Skeletal muscle
- Pacemakers
- Electrical interferance
Describe list mode
- Less commonly used
- Every detected photon is logged with its x,y,x postion
- energy level
- high temporal resolution
- allows for retrospective processing
Describe Frame mode
- Most commonly used is buffered frame mode
- Two sets of frames, one used for acquisition, one used as a buffer frame prior to storage
- Frames switch roles
- Criteria set prior to image start
- Beats must fall within acceptance window
- Less memory required than list mode
What are the different views
- LAO 45
- Steep LAO 70
- Anterior
LAO 45
- 5-15 degree caudal tilt
- Adjusted for best ventricle separation
- Septal, inferoapical, and posterolateral walls visualized
Steep LAO 70
- Left arm raised or lowered
- Apical, inferior, and inferobasal walls visualized
Anterior
- Detectors parallel to patient
- Inferior, apical, and anterolateral walls visualized
What kinds of filters are used?
- Spatial
- Temporal
- Background subtraction
Explain hypokinesis
- Decreased contraction or wall motion in a region of the heart
- Caused by: coronary artery disease, cardiomyopathy, hypertension, and valvular heart disease
- indicates ischemia, heart failure, or myocardial damage
Explain Hyperkinesis
- Increased or exaggerated contraction of a heart segment
- Compensation for hypokinesis in other areas
- indicates ischemia, heart failure, or stress conditions
Explain dyskinesis
- Paradoxical or abnormal outward movement of a segment of the heart wall during systole instead of normal contraction
- Indicates damagedor scarred heart muscle, leading to reduced LVEF
Explain Akinesis
- complete absence of movement in a segment of the heart wall during ystole
- Caused by thickening, severely damaged or infarcted heart muscle
- Associated with severely reduced ejection fraction and heart function decline
- Indicates dead myocardium
What is tardokinesis
- delayed contraction of a segment of the heart wall during systole
- Reduced ef and heart failure symptoms
- left ventricular dysynchrony
- LBBB, cardiomyopathy, post-myocardial infarction scarring, and ventricular pacing
What are some means of quantitative analysis
- Ejection fraction
- Global and regional EF
- Phase: Data on when motion occured
- Amplitude: Data on degree of motion
Explain ejection fraction
Ejection Fraction (EF) is the percentage of blood pumped out of the left ventricle with each heartbeat. It is a key measure of heart function.
◦ % EF = (net ED - net ES/net ED) x 100%
- Tac generated
- Background ROI
🔹 Normal EF Values:
✅ 55-70% – Normal
⚠ 40-54% – Mild dysfunction
❌ <40% – Reduced function (heart failure risk)
🚀 >70% – Hyperdynamic (can be due to high output states)
Stroke volume
SV (Stroke Volume): Blood ejected per beat.
End diastolic volume
EDV (End-Diastolic Volume): Total blood in the left ventricle before contraction.
What are some reasons why an EF would have inaccurate values
◦ Gate
◦ Shape TAC
◦ Net ventricular counts < 6,000
◦ Overestimation @ ED = High EF
◦ Underestimation @ ES = High EF
Explain the influence of ROI selection on Processing quality
◦ Over/underestimation EF
◦ Spleen or aorta in background ROI
◦ Atrium in LV
◦ Exclusion of part of LV
Can you explain the stress MUGA patameters
*Fasting 3-4 hrs
*Off meds affecting HR
*12-Lead
*16 time bins
*Length of scan @ each level
*Only one image @ each level
*Recovery image
Explain SPECT MUGA parameters
*Gating: 8 or 16 time bins
*Only one view needed
*Absolute EF
*Absolute volumes
*RVEF and LVEF
*Patient compliance
*Processing software
