Siemens Aktiengesellschaft

Xiao Dong Zhou

Cheng Ni

Ke Wang

Qiang He

De He Weng

Guo Li

Yiu-Cho Chung

Marc Beckmann

Yong Ming Dai

For magnetic resonance imaging (MRI), a dynamic frequency drift correction method for binomial water excitation method includes collecting the reference one-dimensional navigation signal by an MRI device; acquiring one current one-dimensional navigation signal after scanning N images, wherein N is a positive integer; calculating the frequency drift according to the reference one-dimensional navigation signal and the current one-dimensional navigation signal; calculating and setting the initial phase of the next radio frequency signal by the MRI device according to the frequency drift. The method provides real-time calculation of the main magnetic field frequency drift according to the one-dimensional navigation signal during the scanning period and corrects the phase of the radio frequency signal to ensure that the direction of the gradient field is always perpendicular to the plane formed by the spinning of fat protons, so there is only water signal remaining after excitation so that water images can be obtained.

Dynamic frequency drift correction method in magnetic resonance imaging

A method for reducing magnetic resonance temperature measurement errors, which is used for the high-intensity focused ultrasound device for monitoring magnetic resonance imaging includes obtaining a magnetic resonance phase diagram as a reference image before the high-intensity focused ultrasound device heats the heating area; obtaining another magnetic resonance phase diagram as a heating image during or after the heating process of the high intensity focused ultrasound device; calculating the temperature changes in the heating area according to said heating image and reference image. The method further includes measuring the magnetic field changes caused by the position changes of the ultrasonic transducer of said high-intensity focused ultrasound device, and then compensating for the temperature changes according to said magnetic field changes. The present invention can significantly reduce the temperature errors caused by the position changes of the ultrasonic transducer.

Method for reducing magnetic resonance temperature measurement errors in a magnetic resonance monitored HIFU treatment

A method for magnetic resonance imaging, in which a magnetic resonance imaging device employs a multi-echo imaging sequence, includes the steps of: applying, to one of the multiple echoes, a first number of steps of phase encoding, applying a readout gradient, and collecting the data of this echo to reconstruct an anatomical image; and applying, to another one of the multiple echoes, a second number of steps of phase encoding, applying a readout gradient, and collecting the data of this echo to construct a temperature image. The method is capable of obtaining at the same time both a temperature image with high time resolution and an anatomical image with high spatial resolution.

Method for magnetic resonance imaging

A method for reducing errors in the measurement of temperature by magnetic resonance, for use in magnetic resonance imaging-guided HIFU equipment, includes acquiring an MR phase image, as a reference image, before heating an area to be heated with the HIFU equipment; acquiring another MR phase image, as a heated image, during or after the heating by the HIFU equipment; and calculating the temperature change in the heated area according to said heated image and said reference image; and making compensation to said temperature change according to the change in the magnetic field caused by the position change of an ultrasonic transducer in said HIFU equipment. The method can reduce significantly the temperature errors resulting from the position changes of the ultrasonic transducer.

Magnetic resonance thermometry method

In a method for automatically selecting a region of interest covering a heated area, in the context of high intensity focused ultrasonic technology during acquisition of magnetic resonance data, phase data of a scanned area are acquired, and a heated area is identified in the scanned area according to the phase data acquired. An image is reconstructed and displayed, and in the displayed image a region of interest covering the heated area is automatically demarcated according to a predetermined size of said region of interest that covers and is larger than the heated area. The method causes the heated area to be automatically and completely included in the region of interest; and eliminates the instability of a manual selection of the region of interest.

Method for automatically selecting region of interest covering heated area

In a method and apparatus for accelerating MR temperature imaging used in MR-monitored high intensity focused ultrasound (HIFU) therapy, temperature changes are determined at the focus of the ultrasound during MR temperature imaging; determining the ideal acceleration rate needed for data sampling according to the temperature changes at said focus is determined, the variable-density (VD) data sampling in k-space is adjusted according to the determined ideal acceleration rate, and the data obtained from sampling are reconstructed to form an image. The capability of accelerating MR temperature imaging with both good temporal resolution and good spatial resolution is improved by determining the acceleration rate according to temperature changes at the ultrasound focus and by adjusting the VD data sampling of k-space and thereby the benefits of good flexibility, feasibility and stability are achieved.

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Shenzhen, China

Xiao Dong Zhou