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Temporal Fourier transform of digital angiograms for left ventricular regional wall motion analysis
K Katayama1, B D Guth, T F Widmann
1Department of Medicine, School of Medicine, University of California, San Diego, La Jolla.
Insights
Temporal Fourier transform analysis of cardiac images detects subtle left ventricular wall motion abnormalities caused by ischemia. This method accurately identifies ischemic regions and quantifies their severity, aiding in diagnosis.
Area of Science:
- Cardiovascular Imaging
- Biomedical Engineering
- Diagnostic Cardiology
Background:
- Myocardial ischemia causes subtle changes in left ventricular (LV) wall motion.
- Detecting these abnormalities early is crucial for timely intervention.
- Current imaging methods may not always capture minor functional deficits.
Purpose of the Study:
- To evaluate the efficacy of the first harmonic of a temporal Fourier transform in detecting LV regional wall motion abnormalities.
- To assess the sensitivity of this technique in identifying ischemia induced by coronary stenosis.
Main Methods:
- Six dogs underwent instrumentation with micromanometers, hydraulic cuff occluders, and sonomicrometers.
- Left ventricular images were acquired post-contrast injection.
- Time-intensity curves were analyzed pixel-by-pixel using temporal Fourier transform to generate functional images (phase and amplitude).
- Regional phase and amplitude values were correlated with percent wall thickening (%WTh).
Main Results:
- Phase values in the ischemic region significantly increased with all stenosis levels.
- Amplitude values significantly decreased at moderate and severe stenosis.
- Amplitude images clearly depicted the topographic location of ischemia.
- Phase and amplitude changes correlated significantly with reduced %WTh (phase vs. %WTh: r = -0.55; amplitude vs. %WTh: r = 0.71).
Conclusions:
- Quantitative functional images derived from temporal Fourier transform are sensitive to LV regional wall motion abnormalities.
- This technique can detect abnormalities across mild, moderate, and severe ischemia.
- The method shows promise for non-invasive assessment of ischemic heart disease.
Abstract:
To determine whether or not the first harmonic of a temporal Fourier transform, applied pixel-by-pixel on time-intensity curves, can detect the subtle wall motion abnormalities due to ischemia, 6 dogs were instrumented with a micromanometer in the left ventricles, a hydraulic cuff occluder around the circumflex coronary artery, and sonomicrometers on the inferior (ischemic) and anterior (non-ischemic) walls. Left ventricular images, obtained after contrast injection via the pulmonary artery, were compared with dimension signals in control and 3 progressive levels of coronary stenosis (Stenosis I, II and III). Normalized, digital functional images (512 x 512 matrix, 256 shades of gray/pixel) were divided into anterior, apical, and inferior areas to acquire regional mean phase (degrees) and amplitude (intensity units) values. After inducing stenosis, phase in ischemic region significantly increased at all 3 levels of stenosis, whereas amplitude significantly decreased at Stenosis II and III. However, amplitude images showed clearly the topographic site of ischemia. There was a progressive increase in phase and decrease in amplitude in ischemic areas as the percent wall thickening (%WTh) fell (phase vs. %WTh: r = -0.55, p less than 0.005; amplitude vs. %WTh: r = 0.71, p less than 0.001). Heart rate and peak systolic pressure showed no significant changes during stenosis. We conclude that quantitative functional images, generated from a temporal Fourier transform, are sensitive to the detection of left ventricular regional wall motion abnormalities during mild, moderate, and severe degrees of ischemia.