Method and apparatus for volumetric projection rendering using reverse
ray casting
    1.
    发明授权
    Method and apparatus for volumetric projection rendering using reverse ray casting 失效
    使用反射射线投射的体积投影渲染的方法和装置

    公开(公告)号:US5226113A

    公开(公告)日:1993-07-06

    申请号:US844983

    申请日:1992-02-28

    IPC分类号: G06T17/00

    CPC分类号: G06T17/00

    摘要: A method for providing a volumetrically-rendered projection image using reverse ray casting, uses the steps of: acquiring, from an object volume of interest, a set of data sampled from each volume element (voxel) therein responsive to a selected characteristic of that object volume; storing the data for each object voxel in a corresponding data volume element; scanning sequentially through each data voxel within the data volume corresponding to the object volume of interest; projecting each scanned data voxel to an image plane, at a solid angle determined from the solid angle at which the object volume is viewed; storing a value for each image plane pixel, responsive to a selected criteria, from the values of all projected data voxel values impingent upon that image plane pixel; and then scaling the dimensions of each image plane pixel responsive to the dimensions of the corresponding object volume shape, and the involved projection solid angle, to correct for anisotropy.

    摘要翻译: 使用反射射线投射提供体积绘制的投影图像的方法使用以下步骤:从感兴趣的对象体积中获取从每个体元素(体素)采样的一组数据,其中响应于该对象的所选特征 卷; 将每个对象体素的数据存储在对应的数据量元素中; 依次扫描与感兴趣的物体体积相对应的数据体内的每个数据体素; 将每个扫描的数据体素以从观察对象体积的立体角度确定的立体角投影到图像平面; 响应于所选择的标准,从撞击该图像平面像素的所有投影数据体素值的值存储每个图像平面像素的值; 然后响应于相应的对象体积形状的尺寸和所涉及的投影立体角来缩放每个图像平面像素的尺寸,以校正各向异性。

    Apparatus and methods for magnetic resonance (MR) imaging of cavities
using fluids polarized at low temperatures
    2.
    发明授权
    Apparatus and methods for magnetic resonance (MR) imaging of cavities using fluids polarized at low temperatures 失效
    使用在低温下极化的流体对空腔进行磁共振(MR)成像的装置和方法

    公开(公告)号:US5617859A

    公开(公告)日:1997-04-08

    申请号:US537574

    申请日:1995-10-02

    IPC分类号: A61B5/055

    CPC分类号: A61B5/055

    摘要: A magnetic resonance (MR) active invasive device system employs a small, high-field polarizing magnet, and a large magnetic resonance (MR) imaging magnet for the purpose of generating MR images of selected body cavities. A subject is positioned in a large low-field MR imaging magnet. A substance, intended to be used as a contrast agent is first cooled, and then passed through the small high-field polarizing magnet where it becomes highly polarized. The substance is then heated to physiologic temperatures, vaporized, and introduced into the subject through a transfer conduit as a vapor. Radiofrequency (RF) pulses and magnetic field gradients are then applied to the patient as in conventional MR imaging. Since the vapor is highly polarized, it can be imaged even though it has a much lower density than the surrounding tissue.

    摘要翻译: 磁共振(MR)有源侵入性装置系统采用小型高场极化磁体和大型磁共振(MR)成像磁体,用于产生选定体腔的MR图像。 受试者位于大型低场MR成像磁体中。 首先将要用作造影剂的物质冷却,然后通过小型高场极化磁体,在其中高度极化。 然后将物质加热至生理温度,蒸发,并通过作为蒸气的转移导管引入受试者。 然后将射频(RF)脉冲和磁场梯度应用于患者,如在常规MR成像中。 由于蒸气是高度极化的,所以即使其具有比周围组织低得多的密度,也可以成像。

    Method for simultaneously obtaining three-dimensional NMR angiograms and
stationary tissue NMR images
    3.
    发明授权
    Method for simultaneously obtaining three-dimensional NMR angiograms and stationary tissue NMR images 失效
    同时获得三维核磁共振血管造影和固定组织NMR图像的方法

    公开(公告)号:US4918386A

    公开(公告)日:1990-04-17

    申请号:US288849

    申请日:1988-12-23

    CPC分类号: G01R33/56308 G01R33/56316

    摘要: A method for simultaneously obtaining a three-dimensional nuclear magnetic resonance (NMR) angiographic image of moving spins associated with fluid flow in a region of a living organism sample, and a three-dimensional NMR image of stationary tissue in the same sample region, by immersing the sample in a main static magnetic field; nutating, in an excitation subsequence of each of a plurality of NMR sequences, the nuclear spins and the generating a flow-encoding magnetic field gradient selected to cause a resulting NMR response echo signal from the spin of a moving nucleus to be different from the NMR response echo signal from the spin of a substantially stationary nucleus. The acquired response data is processed to provide at least one of (1) a difference data set from which response data obtained from stationary nuclei has been substantially removed, (2) a summation data set from which response data obtained from moving nuclei has been substantially removed, and (3) a set of phase data indicating direction of flow for flow amplitudes obtained in set (1), in order to generate both an angiographic image lying in a selected plane in a three-dimensional volume, and an image of stationary tissue in the same plane.

    Apparatus and methods for magnetic resonance (MR) angiography using
hydrogen polarized at low temperatures
    4.
    发明授权
    Apparatus and methods for magnetic resonance (MR) angiography using hydrogen polarized at low temperatures 失效
    在低温下使用极化极化的磁共振(MR)血管造影术的装置和方法

    公开(公告)号:US5611340A

    公开(公告)日:1997-03-18

    申请号:US537571

    申请日:1995-10-02

    IPC分类号: A61B5/055

    CPC分类号: A61B5/055

    摘要: A magnetic resonance (MR) active invasive device system employs a small, high-field polarizing magnet, and a large low-field magnetic resonance (MR) imaging magnet for the purpose of generating MR angiograms of selected blood vessels. A subject is positioned in a large low-field MR imaging magnet. A catheter is inserted into the patient at or near the root of a vessel tree desired to be imaged. A hydrogen gas is first cooled and condensed into a liquid state, and then passed through the small high-field polarizing magnet where it becomes highly polarized. A contrast fluid is then made by chemically combining the polarized hydrogen with oxygen to obtain highly polarized water. The water is then heated to physiologic temperatures and, if desired, made more physiologically compatible with the addition of substances such as salts. The physiologically conditioned polarized fluid is then introduced into the subject through the catheter. Radiofrequency (RF) pulses and magnetic field gradients are then applied to the patient as in conventional MR imaging. Since the fluid has a larger longitudinal magnetization than tissue which has not passed through the polarizing magnet, the fluid produces a much larger MR response signal than other tissue resulting in the vessel tree being imaged with excellent contrast.

    摘要翻译: 磁共振(MR)主动侵入性装置系统采用小型,高场极化磁体和大型低场磁共振(MR)成像磁体,以产生选定血管的MR血管造影。 受试者位于大型低场MR成像磁体中。 在期望成像的血管树的根部处或附近将导管插入患者体内。 首先将氢气冷却并冷凝成液态,然后通过小型高场极化磁铁,在其中高度极化。 然后通过将偏振氢与氧化学组合来获得高极化水来制造造影剂。 然后将水加热至生理温度,并且如果需要,与物质例如盐的添加相比更具生理学相容性。 然后通过导管将生理调节的极化流体引入受试者。 然后将射频(RF)脉冲和磁场梯度应用于患者,如在常规MR成像中。 由于流体具有比没有通过偏振磁体的组织更大的纵向磁化强度,所以流体产生比其它组织大得多的MR响应信号,导致血管树以优异的对比度成像。

    Magnetic resonance (MR) angiography using a faraday catheter
    5.
    发明授权
    Magnetic resonance (MR) angiography using a faraday catheter 失效
    使用法拉第导管进行磁共振(MR)血管造影

    公开(公告)号:US5419325A

    公开(公告)日:1995-05-30

    申请号:US264282

    申请日:1994-06-23

    摘要: A magnetic resonance (MR) angiography system employs a Faraday catheter for generating MR angiograms of selected blood vessels. A subject is first placed in a polarizing magnetic field. The Faraday catheter is then inserted into a selected blood vessel of the subject at or near the root of a vessel tree desired to be imaged. An MR imaging pulse sequence is then applied to the subject to obtain image information from the region containing the desired vessel tree. Fluid inside the Faraday catheter is shielded from the RF pulses of the MR imaging sequence allowing the fluid to be in a relaxed state, while tissue outside the Faraday catheter is on a steady-state. As the fluid exits the catheter, and before it reaches steady-state, it produces an increased MR response signal causing the desired vessel tree to be imaged.

    摘要翻译: 磁共振(MR)血管造影系统采用法拉第导管来产生选定血管的MR血管造影。 首先将被摄体置于极化磁场中。 然后将法拉第导管插入受试者的选定血管中,该血管中希望成像的血管树根部处或附近。 然后将MR成像脉冲序列应用于受试者以从包含所需血管树的区域获得图像信息。 法拉第导管内的流体与MR成像序列的RF脉冲屏蔽,允许流体处于松弛状态,而法拉第导管外的组织处于稳态。 当流体离开导管并且在其达到稳定状态之前,其产生增加的MR响应信号,从而使所需的血管树成像。

    Tracking system to monitor the position of a device using multiplexed
magnetic resonance detection
    7.
    发明授权
    Tracking system to monitor the position of a device using multiplexed magnetic resonance detection 失效
    跟踪系统监视使用复用磁共振检测的设备的位置

    公开(公告)号:US5353795A

    公开(公告)日:1994-10-11

    申请号:US989283

    申请日:1992-12-10

    摘要: A tracking system employs magnetic resonance signals to monitor the position of a device such as a catheter within a subject. The device has a receiver coil which is sensitive to magnetic resonance signals generated in the subject. These signals are detected in the presence of magnetic field gradients and thus have frequencies which are substantially proportional to the location of the coil along the direction of the applied gradient. Signals are detected responsive to applied magnetic gradients to determine the position of the device in several dimensions. Sensitivity of the measured position to resonance offset conditions such as transmitter frequency misadjustment, chemical shift and the like is minimized by repeating the process a plurality of times with selected amplitudes and polarities for the applied magnetic field gradient. Linear combinations of the data acquired responsive to the different applied magnetic field gradients are computed to determine the position of the device in three orthogonal dimensions. The position of the device as determined by the tracking system is superimposed upon independently acquired medical diagnostic images.

    摘要翻译: 跟踪系统采用磁共振信号来监测被检体内诸如导管之类的装置的位置。 该装置具有对受试者中产生的磁共振信号敏感的接收器线圈。 在存在磁场梯度的情况下检测这些信号,因此具有与沿施加的梯度方向的线圈位置基本成比例的频率。 响应于所施加的磁梯度检测信号以确定装置在几个维度中的位置。 通过用所施加的磁场梯度的选定幅度和极性重复该过程多次来最小化测量位置对谐振偏移条件(例如发射机频率误调整,化学位移等)的灵敏度。 计算响应于不同施加的磁场梯度采集的数据的线性组合,以确定装置在三个正交尺寸中的位置。 由跟踪系统确定的设备的位置叠加在独立获取的医学诊断图像上。

    Apparatus and methods for magnetic resonance (MR) angiography using
fluids polarized at low temperatures
    8.
    发明授权
    Apparatus and methods for magnetic resonance (MR) angiography using fluids polarized at low temperatures 失效
    使用在低温下极化的流体进行磁共振(MR)血管造影术的装置和方法

    公开(公告)号:US5626137A

    公开(公告)日:1997-05-06

    申请号:US537572

    申请日:1995-10-02

    IPC分类号: A61B5/055

    CPC分类号: A61B5/055

    摘要: A magnetic resonance (MR) active invasive device system employs a small, high-field polarizing magnet, and a large, possibly low-field magnetic resonance (MR) imaging magnet for the purpose of generating MR angiograms of selected blood vessels. A subject is positioned in a large MR imaging magnet. A catheter is inserted into the patient at or near the root of a vessel tree to be imaged. A fluid, intended to be used as a contrast agent is first cooled and frozen, and then passed through the small high-field polarizing magnet where it becomes highly polarized. The frozen fluid is then heated and melted to physiologic temperatures and introduced into the subject through the catheter. Radiofrequency (RF) pulses and magnetic field gradients are then applied to the patient as in conventional MR imaging. Since the fluid has a larger longitudinal magnetization than tissue which has not passed through the polarizing magnet, the fluid produces a much larger MR response signal than other tissue, resulting in vessel tree images with excellent contrast.

    摘要翻译: 磁共振(MR)主动侵入性装置系统采用小型,高场极化磁体和大型可能的低场磁共振(MR)成像磁体,用于产生选定血管的MR血管造影。 受试者位于大型MR成像磁体中。 在要成像的血管树的根部处或附近将导管插入患者体内。 首先将要用作造影剂的流体冷却并冷冻,然后通过小型高场极化磁体,在其中高度极化。 然后将冷冻的流体加热并熔化成生理温度并通过导管引入受试者。 然后将射频(RF)脉冲和磁场梯度应用于患者,如在常规MR成像中。 由于流体具有比没有通过偏振磁体的组织更大的纵向磁化强度,所以流体产生比其他组织大得多的MR响应信号,导致具有优异对比度的容器树图像。

    Imaging of interventional devices during medical procedures
    9.
    发明授权
    Imaging of interventional devices during medical procedures 失效
    在医疗过程中形成介入装置

    公开(公告)号:US5577502A

    公开(公告)日:1996-11-26

    申请号:US415409

    申请日:1995-04-03

    摘要: A tracking system monitors the position of a device within a subject and superimposes a graphic symbol on a diagnostic image of the subject. Registration of the tracked location with the diagnostic image is maintained in the presence of subject motion by monitoring subject motion and adjusting the display to compensate for subject motion. Motion monitoring can be performed with ultrasonic, optical or mechanical methods. The display can be adjusted by modifying the displayed location of the device or it can be adjusted by translating, rotating or distorting the diagnostic image.

    摘要翻译: 跟踪系统监视对象内的设备的位置并将图形符号叠加在被摄体的诊断图像上。 通过监视对象运动并调整显示以补偿被摄体运动,通过诊断图像对被跟踪位置的注册保持在受试者运动的存在下。 运动监测可以用超声波,光学或机械方法进行。 可以通过修改显示的设备位置来调整显示,也可以通过翻译,旋转或扭曲诊断图像进行调整。

    Magnetic resonance (MR) active invasive devices for the generation of
selective MR angiograms
    10.
    发明授权
    Magnetic resonance (MR) active invasive devices for the generation of selective MR angiograms 失效
    用于产生选择性MR血管造影的磁共振(MR)主动侵入性装置

    公开(公告)号:US5447156A

    公开(公告)日:1995-09-05

    申请号:US222053

    申请日:1994-04-04

    CPC分类号: G01R33/563 G01R33/34084

    摘要: A magnetic resonance (MR) active invasive device system employs a radio-frequency (RF) coil embedded in an invasive device for the purpose of generating MR angiograms of a selected blood vessels. A subject is first placed in a polarizing magnetic field. The invasive device is then placed into a selected blood vessel of the subject such that the RF coil of the invasive device is located at or near the root of a vessel tree desired to be imaged. The RF coil is then used to alter the nuclear spin magnetization of blood flowing within the vessel. This is done by employing an RF excitation signal to the coil at the Larmor frequency of the blood. The nutation of spin magnetization can change the amount of longitudinal spin magnetization or the Amount of magnetization in the transverse plane. Because the size of the radio-frequency coil in the invasive device is small, the change in spin magnetization is limited to blood flowing by the invasive device. An MR imaging pulse sequence is then applied to the subject to obtain image information from the region containing the desired vessel tree. The MR imaging pulse sequence is designed to selectively detect the blood whose spin magnetization has been changed by the MR-active invasive device. Since only blood which the magnetization has modified is detected with the imaging sequence, the vessel tree is imaged.

    摘要翻译: 磁共振(MR)有源侵入性装置系统采用嵌入在侵入性装置中的射频(RF)线圈,用于产生选定血管的MR血管造影。 首先将被摄体置于极化磁场中。 然后将侵入性装置放置在受试者的所选择的血管中,使得侵入性装置的RF线圈位于期望成像的血管树的根部处或附近。 RF线圈然后用于改变在血管内流动的血液的核自旋磁化。 这通过在血液的拉莫尔频率处对线圈采用RF激励信号来完成。 自旋磁化的章动可以改变纵向自旋磁化的量或横向平面中的磁化量。 由于侵入性装置中的射频线圈的尺寸小,所以自旋磁化强度的变化受限于由侵入性装置流动的血液。 然后将MR成像脉冲序列应用于受试者以从包含所需血管树的区域获得图像信息。 MR成像脉冲序列被设计成选择性地检测其自旋磁化已被MR活性侵入性装置改变的血液。 由于仅利用成像序列检测到磁化已经改变的血液,所以对血管树进行成像。