摘要:
In imaging using 2-dimensional selective excitation pulses, regardless of applications thereof, a technique for obtaining a high quality image is provided.In the technique, a 2-dimensional selective excitation sequence is carried out while changing a coefficient for determining the cylinder diameter of a region excited by the 2-dimensional selective excitation sequence and a time difference for determining an offset position.The obtained excitation region and a desired region are compared with each other, and the coefficient and time difference with which the obtained excitation region and the desired region match each other are determined to be the optimum ones.The determination processing may be performed as an initial adjustment, may be performed according to need in each imaging, or may be performed on a per-application basis.
摘要:
A high-quality image is obtained using a two-dimensional selective excitation method even if the static magnetic field is not uniform. Therefore, non-uniformity of a static magnetic field of a region to be focused in particular in a selective excitation region excited by 2DRF is measured, and a result of the measurement is reflected in an imaging sequence using the 2DRF. For example, a resonance frequency of magnetization obtained from the measurement result is set as an irradiation frequency of the 2DRF. In addition, a shim gradient magnetic field is applied so as to correct the non-uniformity of the magnetization obtained from the measurement result. These are applied only in the imaging sequence using the 2DRF, and an irradiation frequency and a shim gradient magnetic field set in a conventional method are used in other imaging sequences.
摘要:
In imaging for labeling only the fluid of a specific region, a high-quality image is acquired in a short time. In order to achieve this, the optimal number of segments N is determined from the flow velocity V and the size φ of a specific region to be labeled when performing imaging by labeling only the fluid of the specific region using a two-dimensional selective excitation pulse as a pre-pulse. In addition, the k-space ordering is determined according to the arrival timing of the fluid to the imaging region. In addition, the optimal flip angle (FA) is determined depending on the type of pre-pulse.
摘要:
An MRI apparatus and a two-dimensional excitation adjustment method capable of performing appropriately two-dimensional excitation of a region, in which materials with different resonance frequencies are present, according to imaging conditions are provided. In order to do so, when performing the two-dimensional excitation of a two-dimensional excitation region of an object formed by a first material with a first resonance frequency and a second material with a second resonance frequency, an irradiation frequency of a high-frequency magnetic field for the two-dimensional excitation is set on the basis of the imaging conditions related to the two-dimensional excitation and the first and second resonance frequencies so that desired regions of the first and second materials are excited in a two-dimensional manner.
摘要:
Disclosed is a technique which allows easy optimization of imaging conditions in imaging using two-dimensional excitation as a pre-pulse. To this end, a parameter which specifies the excitation region of the two-dimensional excitation is shifted, a value (optimum value) when a predefined index is ideal for each application to be applied is decided in a subsequent main imaging sequence, and the optimum value is set to the value of the parameter, whereby optimization is performed. A two-dimensional excitation pre-pulse which is excited under optimum excitation conditions is used to optimize the parameter in the main imaging sequence.
摘要:
In imaging using 2-dimensional selective excitation pulses, regardless of applications thereof, a technique for obtaining a high quality image is provided.In the technique, a 2-dimensional selective excitation sequence is carried out while changing a coefficient for determining the cylinder diameter of a region excited by the 2-dimensional selective excitation sequence and a time difference for determining an offset position.The obtained excitation region and a desired region are compared with each other, and the coefficient and time difference with which the obtained excitation region and the desired region match each other are determined to be the optimum ones.The determination processing may be performed as an initial adjustment, may be performed according to need in each imaging, or may be performed on a per-application basis.
摘要:
An object is to enhance usability of parameter check when an imaging parameter is changed in multistation imaging, and easily obtain a desired image with high quality. In the multistation imaging, it is determined in a lump before imaging whether an image having desired quality is obtained by using the changed value of the imaging parameter, and the result is presented to an operator. The determination is executed in the order of “possible or impossible” determination of execution of imaging itself and “possible or impossible” determination of combination of obtained images. When it is determined that it is impossible to execute the imaging itself, the determination processing is finished. At this time, a recommended value may be presented.
摘要:
In imaging for labeling only the fluid of a specific region, a high-quality image is acquired in a short time. In order to achieve this, the optimal number of segments N is determined from the flow velocity V and the size φ of a specific region to be labeled when performing imaging by labeling only the fluid of the specific region using a two-dimensional selective excitation pulse as a pre-pulse. In addition, the k-space ordering is determined according to the arrival timing of the fluid to the imaging region. In addition, the optimal flip angle (FA) is determined depending on the type of pre-pulse.
摘要:
An MRI apparatus and a two-dimensional excitation adjustment method capable of performing appropriately two-dimensional excitation of a region, in which materials with different resonance frequencies are present, according to imaging conditions are provided. In order to do so, when performing the two-dimensional excitation of a two-dimensional excitation region of an object formed by a first material with a first resonance frequency and a second material with a second resonance frequency, an irradiation frequency of a high-frequency magnetic field for the two-dimensional excitation is set on the basis of the imaging conditions related to the two-dimensional excitation and the first and second resonance frequencies so that desired regions of the first and second materials are excited in a two-dimensional manner.
摘要:
A high-quality image is obtained using a two-dimensional selective excitation method even if the static magnetic field is not uniform. Therefore, non-uniformity of a static magnetic field of a region to be focused in particular in a selective excitation region excited by 2DRF is measured, and a result of the measurement is reflected in an imaging sequence using the 2DRF. For example, a resonance frequency of magnetization obtained from the measurement result is set as an irradiation frequency of the 2DRF. In addition, a shim gradient magnetic field is applied so as to correct the non-uniformity of the magnetization obtained from the measurement result. These are applied only in the imaging sequence using the 2DRF, and an irradiation frequency and a shim gradient magnetic field set in a conventional method are used in other imaging sequences.