Method for measuring and imaging fluid flow

A method for providing a high contrast MR image of arterial flow in living tissue using time-of-flight MR methods wherein the slice of tissue to be iamged is composed of a number of small volume elements of voxels, said method comprising the sequential steps of:

• (a) sensing the period of cyclic arterial flow velocity;
• (b) generating a first MR signal at a first time location corresponding to a time of slow flow within the period of cyclic arterial flow velocity;
• (c) generating a second MR signal at a second time location corresponding to a time of fast flow within the period of cyclic arterial flow velocity;
• (d) repeating steps (a), (b) and (c) to provide two full data sets for each voxel;
• (e) forming a MR image from each of said data sets;
• and
• (f) comparing said MR images to determine the arterial flow as represented by relatively enhanced areas in the images.

A non-invasive method employing MR for identifying flow within an artery of a living body, comprising the steps of:

• (a) positioning said body in a substantially homogeneous magnetic field;
• (b) sensing the cardiac cycle of said living body;
• (c) determining a slice of said living body for MR imaging including said artery;
• (d) determining the propagation delay from the start of a cardiac cycle, marked by a contraction of the heart, to the occurrence of a predetermined arterial flow condition in the slice to be images;
• (e) generating and detecting MR signals in said slice at two predetermined temporal locations of a cardiac cycle utilizing a flow-related enhancement method which is time adjsuted by an amount approximately equal to said propagation delay so as to accurately reflect the arterial flow rate in said slice during generation and detection of said MR signal;
• (f) creating imaging data from detected MR siganls for each temporal location;
• and
• (g) subtracting imaging data associated with one temporal location from the imaging data associated with the other temporal location.

A method for enhancing arterial flow in an MR image of a slice of living tissue, said method comprising the steps of:

• (1) generating a homogenous magnetic field through living tissue which includes said slice;
• (2) determining the cycle of said arterial flow associated with said living tissue;
• (3) generating a first series of RF pulses sequences for sequentially tagging and exciting selected new nuclei in said slice such that each of said RF pulse sequences in said first series is synchronized with said cycle of arterial flow so as to be initiated after the expiration of a first time delay related to the propagation delay of said cycle of arterial flow from an area of its determination to said slice;
• (4) adjusting the value of said first time delay such that any MR signal from the excited nuclei in said occurs during a time of slow arterial flow in the slice;
• (5) collecting the MR signals from said excited nuclei in said slice;
• and
• (6) creating imaging data from the MR signals collected in step (5).