Inverse problems in magnetic resonance velocimetry: shape, velocity, and boundary condition inference

Duration: 9 mins 35 secs

Share this media item:

Embed this media item:

<iframe width="_width_" height="_height_" src="https://sms.cam.ac.uk/media/3338386/embed" frameborder="0" scrolling="no" allowfullscreen></iframe>

Choose size:

About this item

Available Formats

About this item

Inverse problems in magnetic resonance velocimetry: shape, velocity, and boundary condition inference's image

Description:	Although Magnetic Resonance Imaging provides velocity fields, these fields are noisy and do not show the boundaries clearly. We take this noisy data and infer the most probable velocity field and boundary shape by adding the constraint that the flow must obey the Stokes equations, continuity, and no slip boundary conditions at the wall.


Created:	2020-11-20 23:03
Collection:	Matthew Juniper conference presentations
Publisher:	University of Cambridge
Copyright:	Prof Matthew Juniper
Language:	eng (English)
Keywords:	MRI; Inverse Problems; Fluid Mechanics; Velocimetry;


Abstract:	Magnetic Resonance Velocimetry (MRV) is a non-intrusive experimental technique used for example in medical imaging and porous rock sampling. It provides 3D velocity data in a 2D or 3D box, usually with low signal to noise ratio. Given noisy MRV data, we wish to infer the most likely boundaries of a flow, the boundary conditions, and the velocity of the flow. We do this by assimilating the data into a qualititatively-accurate flow model, such as the Navier-Stokes equations with unknown uniform viscosity, thus rendering the model quantitatively accurate. The revised model is used to infer hidden quantities of the fluid or the flow, which cannot be measured directly (e.g. wall-shear stress). At the same time, we obtain a denoised and higher-resolution version of the original MRV signal. The above methodologies combine fluid mechanics with optimal control and Bayesian inference and can be further applied to other experimental techniques such as PIV.

Abstract:

Magnetic Resonance Velocimetry (MRV) is a non-intrusive experimental technique used for example in medical imaging and porous rock sampling. It provides 3D velocity data in a 2D or 3D box, usually with low signal to noise ratio. Given noisy MRV data, we wish to infer the most likely boundaries of a flow, the boundary conditions, and the velocity of the flow. We do this by assimilating the data into a qualititatively-accurate flow model, such as the Navier-Stokes equations with unknown uniform viscosity, thus rendering the model quantitatively accurate. The revised model is used to infer hidden quantities of the fluid or the flow, which cannot be measured directly (e.g. wall-shear stress). At the same time, we obtain a denoised and higher-resolution version of the original MRV signal. The above methodologies combine fluid mechanics with optimal control and Bayesian inference and can be further applied to other experimental techniques such as PIV.

Available Formats

Format	Quality	Bitrate	Size
MPEG-4 Video	1280x720	1.01 Mbits/sec	72.89 MB	View	Download
MPEG-4 Video	640x360	295.72 kbits/sec	20.76 MB	View	Download
WebM	1280x720	518.94 kbits/sec	36.49 MB	View	Download
WebM	640x360	202.45 kbits/sec	14.24 MB	View	Download
iPod Video	480x360	520.0 kbits/sec	36.50 MB	View	Download
MP3	44100 Hz	250.16 kbits/sec	17.80 MB	Listen	Download
Auto *	(Allows browser to choose a format it supports)