News Column

Patent Issued for System for Non-Contrast Enhanced MR Anatomical Imaging

September 8, 2014

By a News Reporter-Staff News Editor at Cardiovascular Week -- According to news reporting originating from Alexandria, Virginia, by NewsRx journalists, a patent by the inventor Xu, Jian (New Hyde Park, NY), filed on February 2, 2011, was published online on August 26, 2014 (see also Siemens Medical Solutions USA, Inc.).

The assignee for this patent, patent number 8818491, is Siemens Medical Solutions USA, Inc. (Malvern, PA).

Reporters obtained the following quote from the background information supplied by the inventors: "Known systems employ ECG-gated (Turbo) spin echo (TSE) imaging for MR Angiography using an intrinsic contrast mechanism by exploiting differences in the velocity of arterial blood during a cardiac cycle. In this type of imaging, an MR signal from stationary tissue and non-pulsatile venous blood is canceled by image subtraction, while an MR signal from arterial blood is preserved. This is because, faster flowing blood has a low MR signal on TSE images due to de-phasing effects, while slow flowing blood has a higher signal. Known systems acquire two datasets during diastolic and systolic cardiac phase as illustrated in FIG. 1 corresponding to fast and slow flow periods of the cardiac cycle using ECG triggering. The datasets are subtracted and post processed using maximum intensity projection (MIP). The known systems employ readout methods including SPACE based readout (using a variable flip angle method) and Turbo Spin Echo readout including HASTE (Half Fourier Acquisition STE) as identified in FIG. 2.

"The readout direction of known systems for limb imaging, for example, is along the direction of blood flow i.e. longitudinally along a limb as illustrated in FIG. 3 because this is the longest dimension of the anatomy and ensures efficient data acquisition. In order to obtain adequate recovery of magnetization between successive RF (radio frequency) excitation pulses, data is typically collected in one or more cardiac cycles. Many k-space lines (typically k-space lines of an entire slice (partition)) need to be collected per echo train to image a 3D volume within a reasonable scan time as illustrated in FIG. 4. Specifically, FIG. 4 illustrates acquisition of a slice every two heart cycles. Further, in order to achieve a larger field of view (FOV) coverage, known MR systems typically use a coronal orientation together with a localization scan to find vessels prior to an MRA scan which is time-consuming and operator dependent.

"In known MR imaging systems, an entire 3D volume is excited with RF excitation fields over multiple cardiac cycles and typically two 3D datasets are acquired with one being acquired during a fast blood flow (e.g. systolic) cardiac period and another being acquired during a slow blood flow (diastolic) cardiac period. For example, known system perform imaging using a single shot SPACE or TSE sequence, with 80 partitions (slices) for 3D volume imaging, triggered by an RR waveform so that 160 RRs are needed, which is time consuming and therefore sensitive to respiratory motion disturbance. A system according to invention principles addresses the deficiencies of known MR imaging systems and related problems."

In addition to obtaining background information on this patent, NewsRx editors also obtained the inventor's summary information for this patent: "A system provides user friendly MR device operation with ECG triggering and Spin Echo sequence based Non Contrast Enhanced MR Angiography using transversal orientation acquisition and continuous patient table or electronic FOV movement to accelerate 3D image volume acquisition. A system for Non-Contrast Agent enhanced MR imaging, includes an MR image acquisition device. The MR image acquisition device acquires over multiple heart cycles, first and second datasets representing first and second image slabs individually comprising multiple image slices oriented substantially perpendicular in at least one axis to direction of vasculature blood flow, in response to a heart cycle synchronization signal. Within an individual heart cycle, a slice of a first image slab and a slice of a second image slab are acquired with one slice of one slab being acquired at a relatively fast blood flow portion of the heart cycle and the other slice of the other slab being acquired at a relatively slow blood flow portion of the heart cycle. An image data processor processes imaging datasets representing the first and second image slabs to provide first and second volume datasets representing a 3D volume imaged at the fast blood flow portion and the slow blood flow portion respectively and for providing a difference dataset representing an image difference between the first and second volume datasets and enhancing arterial blood flow. A display processor provides data representing an image showing the enhanced arterial blood flow."

For more information, see this patent: Xu, Jian. System for Non-Contrast Enhanced MR Anatomical Imaging. U.S. Patent Number 8818491, filed February 2, 2011, and published online on August 26, 2014. Patent URL:

Keywords for this news article include: Angiography, Cardiology, Siemens Medical Solutions USA, Siemens Medical Solutions USA Inc.

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Source: Cardiovascular Week

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