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