Vector flow imaging in abdominal aortic aneurysms: Feasibility of blood speckle tracking with adaptive clutter filtering

Objective Test the impact of clutter filtering and feasibility of ultrasound blood speckle tracking (BST) to evaluate flow patterns in abdominal aortic aneurysms. Methods Data were acquired for 7 patients diagnosed with an abdominal aortic aneurysm with minor intraluminal thrombus (ILT) volume, and 6 patients having substantial ILT volume, of which 10 patients were included in the assessment. A multi-observer assessment was done to tune and compare the performance of clutter filtering based on singular value decomposition (SVD) and polynomial regression, prior to BST. The quality of the resulting vector flow images was assessed in a second multi-observer assessment. Results After selecting a suitable filter threshold for each patient recording, only two out of 10 measurements had remaining clutter in the spectrograms during systole, and in one case during diastole. During systole, for 8 out of 10 patients 80% of the lumen area or more was deemed to have physiologically correct vector flow imaging (VFI) estimates. During diastole, this was only the case for 2 patients. For 4 patients, this percentage was lower than 50% during diastole. Conclusion During systole, BST can be applied to get accurate VFI results in the abdominal aortic aneurysm. Quantifying the lower velocity flow during diastole was less successful.