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[Computer-assisted contour detection in a complete heart cycle by levocardiography with adaptive raster
Insights
This study introduces a computer-assisted method for detecting left ventricular contours in cineangiograms. The automated edge detection accurately calculates cardiac volumes and ejection fraction, minimizing operator interaction.
Area of Science:
- Cardiovascular Imaging
- Medical Image Analysis
- Computational Cardiology
Background:
- Accurate assessment of left ventricular function is crucial in cardiology.
- Manual contour detection in cineangiograms is time-consuming and operator-dependent.
- Automated methods are needed to improve efficiency and reproducibility.
Purpose of the Study:
- To develop and validate a computer-assisted method for automated edge detection of the left ventricle throughout the cardiac cycle.
- To assess the accuracy of calculated cardiac volumes and ejection fraction using the automated method compared to manual measurements.
Main Methods:
- Left ventricular cineangiograms were acquired and digitized.
- An operator-defined contour in the first frame was used to initialize an adaptive raster.
- A gradient-based method was employed to automatically track left ventricular contours across frames.
- Cardiac volumes and ejection fraction were calculated from the automated contours.
Main Results:
- The automated method successfully calculated systolic contours in 28/30 cases and diastolic contours in 26/30 cases with minimal operator interaction.
- Mean contour deviation ranged from -1.2 +/- 1.9 mm to 0.9 +/- 2.9 mm.
- High correlation (r=0.98-1.0) was found between computer-determined and manual volumes, with low standard errors (2.8-5.2 ml).
- Ejection fraction correlation was r=0.99 with a standard error of 1.9%.
Conclusions:
- The developed computer-assisted edge detection method provides accurate and reproducible measurements of left ventricular volumes and ejection fraction.
- This automated approach significantly reduces the need for manual operator intervention, enhancing efficiency in cardiac image analysis.
- The method shows high potential for clinical application in routine cardiovascular assessments.
Abstract:
A method for computer-assisted edge detection in a full heart cycle of the left ventricular cineangiogram is presented. Left ventricular cineangiograms were acquired in the 30 degrees RAO position on cinefilms with 50 frames/s. A selected heart cycle was digitized with a spatial resolution of 512 x 512 pixels and a grey-value range from 0 to 255. In the first frame of the heart cycle a raster was calculated from contour points marked by an operator. The raster was automatically adapted to the left ventricular contour in the following frames. The contour points were determined on the adaptive raster by a gradient method. The automatic calculation of all contours of the systolic contraction was possible in 28 of 30 cineangiograms, operator interaction was necessary in two cineangiograms. The calculation of the diastolic contours requested operator interaction in 4 of 30 cineangiograms. The mean deviation of the calculated from the true contours ranged from -1.2 +/- 1.9 mm to 0.9 +/- 2.9 mm. The correlation coefficients between volumes calculated from the computer-determined and manually drawn contours ranged from r = 0.98 to r = 1.0 at beginning of systole, midsystole, endsystole, middiastole, and enddiastole with a standard error of the estimate between 2.8 ml and 5.2 ml. A repeated automatic determination of the contours after an independent remarking of the starting points resulted in a linear correlation of the calculated volumes with a correlation coefficient of r = 1.0 and a standard error of the estimate between 1.3 ml and 4.7 ml. The correlation coefficient for the ejection fraction was r = 0.99 with a standard error of the estimate of 1.9%.(ABSTRACT TRUNCATED AT 250 WORDS)