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Published byDulcie Cunningham Modified over 9 years ago
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Phantom to test MUGA software Bill Thomson, Joe O’Brien Nigel Williams
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Not New! Phantom developed some years ago need to test amplitude and phase component not designed for ejection fraction
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Normal / Abnormal MUGA scan
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Single Harmonic Fourier At each pixel position, we fit a curve based on first term of Fourier series a + b.sin( t) + c.cos( t) = A.sin( t + ) the first harmonic is a sinusoid function with the fundamental frequency and a phase angle .
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Sum of Cos and Sin terms + =
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Sum of Cos and Sin terms + =
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Sum of Cos and Sin terms Frequency does not change phase change only + =
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Sum of Cos and Sin terms Frequency does not change phase change only + =
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Single harmonic Fourier fit A For each pixel, A Amplitude functional image extent of change Phase functional image timing
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Amplitude and Phase zAmplitude how much movement zPhase onset of contraction 15% threshold (from amplitude) histogram of phase in - whole image ED L ventricle region
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Test Procedure zNeed to input sinusoid terms zwant amplitude range 0 - 100% zwant phase values 0 - 360
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Sinusoid shape A A
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A A
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Curves generated
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rotating plane phantom
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Amplitude and phase
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Phase direction note 90 degree shift in phase angle Phase should follow the phantom Phase is actually going in opposite direction
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Change of ED ROI
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Effect of change in ED position
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Different ROI position
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Phantom for EF curve creation Perimeter of phantom based on EF curve similar effects seen shows robust Fourier fit at low ejection fraction and counts
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Previous work - different processor Area of LV was delayed phase shows early contraction!! phase was reversed
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Previous work - different processor Area of LV was delayed phase shows early contraction!! phase was reversed Corrected program
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Higher Harmonic testing 1st harmonic
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Higher Harmonic testing 1st harmonic 2nd harmonic
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Higher Harmonic testing 1st harmonic 3rd harmonic 2nd harmonic
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3 Harmonic phantom
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3 harmonic phantom Fourier curve fit tries to fit first EF type component only
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3 harmonic phantom, different ROI
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3 harmonic fit to noisy data
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Issues Phase angle appears to run in wrong direction Will not affect aneurism detection Amplitude and phase dependent on ROI Fourier fits to CDBS curve Time to Peak Fill is based on Fourier curve Suggest use 4 harmonic fit routinely
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