MR imaging scan using ECG-prep scan

Abstract

An ECU-prep scan is used to set an optimum time phase in both systole and diastole of the heart. At each of the different time phases, an imaging scan is started to acquire a plurality of sets of echo data. An artery / vein visually separated blood flow image is produced from the echo data. The imaging scan uses a half-Fourier technique, for example. This provides high-quality blood flow images with shorter scan time, without injecting a contrast medium. Additionally, with a readout gradient pulse applied substantially parallel with a direction of slowly flowing blood, a scan is performed in synchronism with an optimally determined cardiac time phase. The readout gradient pulse has a dephasing pulse for enhancing differences in a flow void effect depending on blood flow velocities. This enables slow-speed flows, such as blood flows in the inferior limb, to be depicted without fail.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]Notice: More than one reissue application has been filed for the reissue of U.S. Pat. No. 6,801,800. The reissue applications are application Ser. No. 13 / 590,396 (the present application), which is a continuation reissue of Ser. No. 11 / 542,604, and Ser. No. 11 / 542,604, all of which are reissues of U.S. Pat. No. 6,801,800.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to magnetic resonance imaging (MRI) for internally imaging an object to be examined on the basis of a magnetic resonance phenomenon of nuclear spins of the object, particularly, to an MRI (magnetic resonance imaging) system and an MR (magnetic resonance) method capable of acquiring artery / vein visually separated images of the object without using a contrast medium.[0004]2. Description of the Related Art[0005]Magnetic resonance imaging is based on an imaging technique for magnetically exciting nuclear spins of an object located in...

AI Technical Summary

Benefits of technology

This approach allows for high-quality, shorter scan times to produce visually separated artery and vein images, enriching blood flow information and accurately depicting slower-speed flows without the need for contrast media, reducing patient burden and improving imaging efficiency.

Problems solved by technology

However, this contrast MR angiography needs an invasive treatment to inject the contrast medium.

First of all, mental and physical burdens on patients become large.

Second, examination cost of the contrast MR angiography is still expensive.

Third, there are some cases where a contrast medium cannot be injected into patients due to patient's physical characteristics.

However, when the TOF technique or phase contrast technique is used for obtaining MR images of a patient's pulmonary field or abdomen which depict flows of large vessels, such as the aorta, in their superior-inferior directions, it is required to scan slices located vertically to the flowing direction.

Thus, in the case that two-dimensional slice imaging is performed to acquire such axial images, it is impossible to obtain an image in which blood flows are directly reflected.

Three-dimensional image data spatially containing blood flows are therefore needed, but the number of slices increases which will cause an entire imaging time to be longer.

One drawback is that a longer scan time is still needed in total, because a three-dimensional scan should be performed two times. Another is that registration may be mistaken if the position of a patient's body moves between two times of scans, which is apt to deteriorate quality of blood flow images which will be produced by the subtraction.

Additionally, there may occur influence of positional shifts due to heartbeats, it was almost impossible to detect such slower-speed fluid flows by the conventional techniques.

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