- Meeting abstract
- Open Access
1052 The settling properties of slow flow blood demonstrated using SWI
© Haacke et al; licensee BioMed Central Ltd. 2008
- Published: 22 October 2008
- Deep Venous Thrombosis
- Phase Image
- Slow Flow
- Cardiac Gating
- Hematological Finding
For some time now it has been possible to measure oxygen saturation with susceptibility weighted filtered phase imaging. However, when the subject has slow flow this method often fails. We postulate that this is due to the settling of blood in some veins when the flow is slow.
To demonstrate that blood separates into at least two separate components, hematocrit and plasma, and possible a third layer which is a mixture of both.
We use an SWI sequence to obtain both magnitude and phase images. High resolution scans are used (with a resolution of 0.5 mm × 0.5 mm in-plane, 2 mm slice thickness) in a transverse plane to image the calf. No cardiac gating is performed. The phase images are filtered using a 64 × 64 central k-space homodyne filter. In six cases, the TR was 60 ms and the TE was 40 ms, in three cases, the TR was 20 ms and the echo time 10 ms. Scan times were 8 minutes for the shorter TR and 64 slices and 12 minutes for the longer TR and 32 slices. No parallel imaging was used. A total of 9 volunteers were scanned with an age range of 18 to 56. One patient was scanned in both the supine and prone position. The rest were scanned in the supine position.
The separation of the blood into different layers after only 20 minutes has major implications. The more dense hematocrit sinks as the blood flow from certain vessels seems to be naturally reduced and shunted to other vessels. The implications of this to deep venous thrombosis are that blood settling may serve as a risk factor or predictor. This remains to be validated, but the separation of the blood is already in itself a major new rheological, hemodynamic and hematological finding.
This article is published under license to BioMed Central Ltd.