Blood flow measurements with magnetic resonance phase velocity mapping

Chatzimavroudis, George P.

doi:10.1016/j.measurement.2004.10.001

Cited by 5 publications

(2 citation statements)

References 66 publications

(94 reference statements)

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“…The negative velocities oppose the flow direction, some of which appeared upstream of the valve. Fluid behaviours such as this recirculation have a direct effect on cardiac function and are clinically referred to as valvular regurgitation [14]. Figure 6(a) and (b) show the velocity distribution profile for both configurations at 0.2 tube diameters downstream (notice the differing vertical scales).…”

Section: Resultsmentioning

confidence: 99%

MRI: a tool for measuring turbulent intensities in flow systems

Adegbite¹,

Kadem²,

Newling³

2011

Environmental Health and Biomedicine

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Understanding the fluid-structure interaction and fluid dynamics downstream of an obstruction is crucial in the design and fabrication of devices that find application in both medicine and industry. It is known that the fluid flow patterns downstream of an obstruction may be very complex and are three dimensional, including the formation of vortices, recirculating flow, flow separation and the onset of turbulence. The development of any such pattern of flow might be detrimental to the optimal performance of the flow system. In this work we have used the magnetic resonance imaging (MRI) technique to investigate flow dynamics downstream of an artificial heart valve. MRI is a naturally threedimensional, non-invasive technique that finds application in clinical, biomedical research and materials research. It has the capability to visualize the internal structure of materials and also to quantify mass transport properties. In this in vitro study, we have measured the turbulent diffusivity and velocity downstream of the valve in two configurations (fully opened and partially opened). Our particular implementation of the MRI measurement (known as SPRITE imaging) is unusually robust to fast turbulent flows and has been demonstrated effective at Reynolds numbers on the order 10 5 , much higher than possible with most conventional, clinical MRI techniques. The results showed a low turbulent diffusivity downstream of the fully opened valve configuration, while the turbulent diffusivity is higher downstream of the partially opened valve coupled with a high-velocity fluid jet and recirculating flow. There are distinct differences between the downstream velocity profiles of the two configurations, which have diagnostic implications.

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Section: Resultsmentioning

confidence: 99%

MRI: a tool for measuring turbulent intensities in flow systems

Adegbite¹,

Kadem²,

Newling³

2011

Environmental Health and Biomedicine

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“…It also promises a noninvasive quantification of the mechanical energy losses of blood as it flows through the connection. New rapid acquisition sequences show accuracy in quantifying flow [16].…”

Section: Determination Of the Density Of Ferromagnetic Particlesmentioning

confidence: 99%

A Complex of the Electromagnetic Biosensors with a Nanowired Pickup

Sklyar¹

2009

Journal of Sensors

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The proposal to measure the biosignal values of different origins with advanced nanosensors of electromagnetic quantities is justified when allowing for superconducting abilities of the devices. They are composed in full-scale arrays. The said arrays can be both implantable into ionic channels of an organism and sheathed on the sources of the electromagnetic emanation. Nanowired head sensors function both in passive mode for picking up the biosignals and with additional excitation of a defined biomedium through the same head (in reverse). The designed variety of bio-nanosensors allow interfacing a variety of biosignals with the external systems, also with a possibility to control the exposure on an organism by artificially created signals. The calculated signals lies in the range of to 5 V, molecules or magnetic beads, pH, and stream speed m/s, flow m/s, and haemoglobin concentration of . The sensitivity of this micro- or nanoscope can be estimated as (/√Hz) with SNR equal to . The sensitivity of an advanced first-order biogradiometer is equal to 3 fT/√Hz. The smallest resolvable change in magnetic moment detected by this system in the band 10 Hz is 1 fJ/T.

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