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Published on: September 22, 2023
The influence of heart rate, slice thickness, and calcification density on calcium scores using 64-slice
Jaap M Groen1, Marcel J Greuter, Bernhard Schmidt
1Department of Radiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. j.m.groen@rad.umcg.nl
Insights
Higher heart rates and thicker slices increase variability in coronary artery calcium (CAC) scores. Reducing heart rate below 70 bpm and using thinner slices on 64-slice MDCT improves CAC scoring accuracy and reproducibility.
Area of Science:
- Cardiovascular Imaging
- Radiology
- Medical Physics
Background:
- Coronary artery calcium (CAC) scoring is crucial for cardiovascular risk assessment.
- Accurate CAC scoring depends on optimal imaging parameters.
- Factors like heart rate and slice thickness can influence CAC score variability.
Purpose of the Study:
- To investigate the impact of heart rate, slice thickness, and calcification density on CAC score absolute values and variability.
- To assess these influences using 64-slice multidetector computed tomography (MDCT).
Main Methods:
- Artificial arteries with varying calcification densities were scanned using a moving cardiac phantom on a 64-slice MDCT.
- Scans were performed at rest and varying heart rates (50-110 bpm).
- Images were reconstructed at multiple slice thicknesses (0.6-3.0 mm), and calcium was quantified using Agatston, volume, and mass scores.
Main Results:
- CAC scores varied with heart rate, calcification density, and slice thickness; higher heart rates (>60 bpm) caused score increases (HDC) or decreases (LDC).
- Thinner slices resulted in higher CAC scores, while thicker slices increased score variability.
- Score variability escalated with heart rate, particularly for low-density calcifications and thicker slices.
Conclusions:
- Cardiac motion, calcification density, and slice thickness significantly affect CAC scoring.
- Increasing heart rates alter CAC scores differently based on density, while higher rates and thicker slices increase variability.
- Reducing heart rate (<70 bpm) and utilizing thinner slices on 64-slice MDCT enhance CAC scoring reproducibility.
Objective:
The purpose of this study was to investigate the influence of heart rate, slice thickness, and calcification density on absolute value and variability of calcium score using 64-slice multidetector computed tomography (MDCT).
Methods And Materials:
Three artificial arteries containing each 3 lesions with varying density were scanned using a moving cardiac phantom at rest and at 50 to 110 beats per minute (bpm) at 10-bpm intervals on a 64-slice MDCT. Images were reconstructed at slice thicknesses (increment) of 0.6 (0.4), 0.75 (0.5), 1.5 (1.5), and 3.0 (3.0) mm. The amount of calcium was expressed as an Agatston score, volume score, and equivalent mass.
Results:
Absolute coronary artery calcium (CAC) scores decreased [average -37% for low density calcification (LDC)] or increased [average +32% for high density calcification (HDC)] at heart rates over 60 bpm depending on slice thickness and scoring method. Thinner slice thicknesses yielded higher CAC scores. Variability of the CAC scores increased with increasing heart rates especially for low density calcifications (8% at rest vs. 50% at 110 bpm). Variability also increased for thicker slices (average 6% for 0.6 mm vs. 18% for 3.0 mm). Variability was lower for HDC compared with LDC (approximately 5% for HDC vs. 27% for LDC at 70 bpm, averaged over all methods and slice thicknesses).
Conclusion:
CAC-scoring is strongly influenced by cardiac motion, calcification density, and slice thickness. CAC scores increase for high density calcifications and decrease for low density calcifications at increasing heart rates. Heart rate should be reduced on 64-slice MDCT to obtain a lower degree of variability of CAC-scoring, preferably below 70 bpm. A thinner slice thickness further enhances the reproducibility.
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