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Published on: January 4, 2013
Effect of black blood MR image quality on vessel wall segmentation
J B Thomas1, B K Rutt, H M Ladak
1Imaging Research Labs, John P. Robarts Research Institute, University of Western Ontario, London, Canada.
Abstract:
Black blood MRI has become a popular technique for measuring arterial wall area as an indicator of plaque size. Computer-assisted techniques for segmenting vessel boundaries have been developed to increase measurement precision. In this study, the carotid arteries of four normal subjects were imaged at seven different fields of view (FOVs), keeping all other imaging parameters fixed, to determine whether spatial resolution could be increased at the expense of image quality without sacrificing precision. Wall areas were measured via computer-assisted segmentation of the vessel boundaries performed repeatedly by two operators. Analysis of variance (ANOVA) demonstrated that the variability of wall area measurements was below 1.5 mm(2) for in-plane spatial resolutions between 0.22 mm and 0.37 mm. An inverse relationship between operator variability and the signal difference-to-noise ratio (SDNR) demonstrated that semi-automatic segmentation of the wall boundaries was robust for SDNR >3, defining a criterion above which subjective image quality can be degraded without an appreciable loss of information content. Our study also suggested that spatial resolutions higher than 0.3 mm may be required to quantify normal wall areas to within 10% accuracy, but that the reduced SNR associated with the higher resolution may be tolerated by semi-automated wall segmentation without an appreciable loss of precision.
Insights
Black blood MRI precisely measures arterial plaque size. Higher spatial resolution improves accuracy without sacrificing measurement precision, even with reduced image quality.
Area of Science:
- Medical Imaging
- Cardiovascular MRI
- Biomedical Engineering
Background:
- Black blood MRI is crucial for assessing arterial wall area and plaque burden.
- Computer-assisted segmentation enhances the precision of vessel boundary measurements.
- Optimizing spatial resolution in MRI is key for accurate plaque quantification.
Purpose of the Study:
- To evaluate the impact of spatial resolution on the precision of arterial wall area measurements using black blood MRI.
- To determine the threshold for signal difference-to-noise ratio (SDNR) in maintaining measurement robustness.
- To assess if higher spatial resolution can be used without compromising measurement accuracy.
Main Methods:
- Carotid arteries of four normal subjects were imaged at varying fields of view (FOVs).
- Computer-assisted segmentation was performed repeatedly by two operators to measure wall areas.
- Analysis of variance (ANOVA) assessed measurement variability across different spatial resolutions.
Main Results:
- Wall area measurement variability remained below 1.5 mm(2) for resolutions between 0.22 mm and 0.37 mm.
- Semi-automatic segmentation proved robust for signal difference-to-noise ratios (SDNR) >3.
- Higher spatial resolutions (>0.3 mm) may be needed for 10% accuracy in normal wall area quantification.
Conclusions:
- Spatial resolution can be increased in black blood MRI without sacrificing measurement precision.
- Semi-automatic segmentation tolerates reduced signal-to-noise ratio (SNR) at higher resolutions, maintaining precision.
- Image quality can be subjectively degraded above SDNR >3 without significant information loss.
