Topic 8 Nuclear Medicine Applications
• Nuclear Cardiology
• Single Photon Emission Computed Tomography
Nuclear Cardiology
• Data Acquisition Methods• Analysis of Multi-gated Blood Pool Images• Quantitative Data Analysis• First Pass Cardiac Studies• Data Reformatting Methods for First Pass Studies• Planar Quantification of Myocardial Perfusion
List Mode Acquisition
Dynamic Sorting
Abnormal Heart Beat
Abnormal Heart Beat
Counts Losses
• Count losses at last a few frames: – Abnormal heart beat: too long or too short.
• Count losses at first several frames: – delayed gating owing to– ECG gate is delayed in sending trigger or– Computer is delayed in reacting trigger
Comparison of Heart Beat
Buffered Gating Method
Multi-Window Buffered Gating
Delayed Gating
Analysis of Multiple Gated Blood Pool Images
• Cine display: – pinpoint regions of abnormal wall contraction
• Low counts per image:– poor count statistics– Spatial smooth (on frame)– Temporal smooth (from one frame to next)– Count normalisation (last a few frames are
normalised to the total counts in first frame)
Temporal Smoothing
Quantitative Data Analysis
• Left ventricular ROI:
• Volume curve
• Functional images
• Phase analysis
• Amplitude analysis
Quantitative Data Analysis
• Region of Interest: ED, ED, Bkg.– Ejection Fraction=(ED-EDBkg)-(ES-ESBkg)/(ED-EDBkg)
• Volume Curve:– Time activity curve: 3 point smooth etc
• Functional images – Functional parameters on pixel to pixel basis.
– Stroke volume images: Diastolic -Systolic
– Paradox images: Systolic - Diastolic
Construction of Volume Curve
Stroke Volume Image
Paradox Image
Paradox Image
Phase and Amplitude Analysis
• Phase Analysis– Pixel-to-pixel
– Time activity curve
– Fourier Analysis
• Results of Phase Analysis– Amplitude (magnitude of contraction)
– Phase angle (relative position)
• Amplitude Analysis– maximum count difference=>stroke volume image
Activity of Atrium and Ventricle
Phase Analysis
Phase Image
Amplitude and Phase Images
First Pass Cardiac Studies
• Data acquisition technique– List or Frame: 0.5 second per image
• Data reformat
• Ventricular function evaluation– EF, Ventricle size, wall motion similar to multiple gated studies
• Detection of Intra-cardiac shunts– Left to right shunt: Qs=Qp-Qsk; (Qp/Qs)>1.3
– Right to left shunt: some activity goes directly into the left ventricle without first passing through the lung.
Data Reformat• Reformatting ECG gated data
– Select frames that bolus starts and fading.(~ 5 to 15 cardiac cycles)
– select R-R range
– Sort counts into respective frames
• Reformatting Non-ECG gated data– Reformat into a series of 1 sec frames; ROI on left ventricle;
– Reframe from appearance to exiting; Time activity curve,
– select 4-6 frames in the down slope for reformatting
– Divide each frame into 16 equal segments and repeat for all.
• Reformatting dynamic frames– add several frames to increase statistics
Data Reformat
First Pass by Rapid Dynamics
Detection of Intra-cardiac Shunts
Right to Left Shunt
201Tl Myocardium Perfusion
Single Photon Emission Computed Tomography
• Instrumentation
• Mathematics of Transverse Image Reconstruction
• Physical Factors Affecting the Quality of the SPECT images
• Quality Assurance of the SPECT system
A Dedicated SPECT System
Rotational SPECT Camera
Step-and-Shot Acquisition
Activity Profile
Simple Backprojection
Image of Simple Backprojection
Filtered Backprojection
Filtered Backprojection
Image of Filtered Backprojection
The Ramp Filter
Modified Ramp Filter
Image with Ramp Filter
Butterworth Window
Ramp + Butterworth
Image with Ramp+Butterworth
Over-Smooth Filter
Over-Smoothed Image
Over-Smooth on Low Counts
Iterative Reconstruction
Sampling Criteria: Aliasing
Attenuation Correction Map
Body Contour
Scatter Reduction -Asymmetric Window
Spatial Resolution vs Distance
Distances vs Positions
Non-Circular Orbit
Triple Head Camera
Centre of Rotation
Dimension of a Pixel
Five Point Sources - Axes Centring
Gated SPECT