- Poster presentation
- Open Access
Do we need to consider motion artefacts other than swallowing in carotid artery imaging?
© Chan et al; licensee BioMed Central Ltd. 2009
- Published: 28 January 2009
- Carotid Artery
- Wall Imaging
- Carotid Artery Wall
- Respiratory Movement Artefact
- Head Support
Recent advances in carotid artery wall imaging have seen a transition from 2D to more efficient 3D imaging  without sacrificing image quality . A disadvantage of 3D scans is their longer time to complete the acquisition, making them more susceptible to motion artefacts, particularly swallowing  and bulk head motion during the long 3D acquisition time. Respiratory movement artefact is controversial , but Boussel  demonstrated its detrimental effect on carotid wall imaging, using real-time transaxial cines. However, during quiet supine respiration, breathing is predominantly diaphragmatic resulting in the greatest carotid movement in the head-foot direction. We used a novel high temporal resolution interleaved approach to study carotid artery movement in all directions, over the typical 3D scan duration, for a true representation of the potential problem for 3D imaging.
This study aimed to measure bulk respiratory and swallowing motion affecting carotid artery imaging and investigates optimal head support for carotid work.
During a swallow event, there was variable movement of carotid artery in all 3 directions. To measure swallowing motion the position measurements were compared between smoothed (20-cycle running average, swallows filtered out) and unsmoothed motion traces. Examining all the scans, the greatest movement was predominantly in the head-foot direction with average movement of 3.5 mm (SD 1.8, range 1.6–6.2 mm). Left-Right movement was greater in comparison to Antero-Posterior, 2.8 mm (SD 1.4, range 0.9–6.2 mm) and 1.7 mm (SD 1.5, range 0.6–5.1 mm), respectively.
The amount of movement during quiet respiration was calculated between smoothed and unsmoothed traces excluding swallow events. The largest average movement was in the head-foot direction 1.4 mm (SD 0.6, range 0.6–3.2 mm), with substantially less movement in the LR 0.9 mm (SD 0.5, range 0.3–2.4 mm) and AP 0.5 mm (SD 0.3, range 0.1–1.1 mm).
Although no obvious difference in head motion was measured between the different head supports, individuals reported that the vac-lok™ pillow was more comfortable and offered greater neck support.
We have shown that respiratory motion previously regarded as insignificant may be large enough to contribute to blurring and ghosting of 3D carotid images. Involuntary head motion even in motivated volunteers during 3D imaging times is clearly an issue for 3D imaging reliability, as is swallowing motion in some subjects. These motion artefacts can corrupt the entire 3D sequence and affect wall imaging and plaque characterisation.
This article is published under license to BioMed Central Ltd.