An automated image registration-based method for assessing flow-mediated dilation showed negligible bias (0.05% FMD) and better reproducibility (CV 0.40%) compared to manual measurements.
Does an automatic image registration-based method improve the accuracy and reproducibility of brachial artery flow-mediated dilation measurements compared to manual assessment?
A novel automated image registration-based method for quantifying brachial artery FMD provides comparable accuracy and better reproducibility than manual measurements.
Absolute Event Rate: 0.05% vs 0.23%
Flow-mediated dilation (FMD) offers a mechanism to characterize endothelial function and, therefore, may play a role in the diagnosis of cardiovascular diseases. Computerized analysis techniques are very desirable to give accuracy and objectivity to the measurements. Virtually all methods proposed up to now to measure FMD rely on accurate edge detection of the arterial wall, and they are not always robust in the presence of poor image quality or image artifacts. A novel method for automatic dilation assessment based on a global image analysis strategy is presented. We model interframe arterial dilation as a superposition of a rigid motion and a scaling factor perpendicular to the artery. Rigid motion can be interpreted as a global compensation for patient and probe movements, an aspect that has not been sufficiently studied before. The scaling factor explains arterial dilation. The ultrasound sequence is analyzed in two phases using image registration to recover both transformation models. Temporal continuity in the registration parameters along the sequence is enforced with a Kalman filter since the dilation process is known to be a gradual physiological phenomenon. Comparing automated and gold standard measurements (average of manual measurements) we found a negligible bias (0.05%FMD) and a small standard deviation (SD) of the differences (1.05%FMD). These values are comparable with those obtained from manual measurements (bias = 0.23%FMD, SD(intra-obs) = 1.13%FMD, SD(inter-obs) 1.20%FMD). The proposed method offers also better reproducibility (CV = 0.40%) than the manual measurements (CV = 1.04%).
Frangi et al. (Sat,) conducted a other in Cardiovascular diseases. Automated image registration-based method for FMD assessment vs. Manual measurements was evaluated on Bias and standard deviation of differences in FMD measurements. An automated image registration-based method for assessing flow-mediated dilation showed negligible bias (0.05% FMD) and better reproducibility (CV 0.40%) compared to manual measurements.