CN105433945A - Bone mineral density detection equipment and detection method - Google Patents

Abstract

Translated fromChinese

本发明公布了一种基于磁共振T₂弛豫时间谱的骨密度检测设备和检测方法，基于磁共振T₂弛豫时间谱检测骨密度，包括计算机控制终端、单板磁共振控制器单元、信号放大及开关控制单元和磁体单元；本发明首先测量骨骼中水分子磁共振横向弛豫衰减信号，然后通过数学反演方法得到相应的T₂弛豫时间谱，再通过分析T₂弛豫时间谱上的各峰值确定骨小梁之间孔隙的结构特征，最后通过回归分析数据处理方法得到生物的骨密度数据；本发明可应用于骨质疏松症的鉴别，具有快速、无损分析测定骨密度，评价骨质量等功能，具有对生物体完全无害，设备结构简单、体积小、重量轻，测量精度高、操作简便、测量方法可重复性强等优点。

The invention discloses a bone density detection device and detection method based_on magnetic resonance T2 relaxation time spectrum, which detects bone density based_on magnetic resonance T2 relaxation time spectrum, including a computer control terminal, a single-board magnetic resonance controller unit, Signal amplification and switch control unit and magnet unit; the present invention first measures the magnetic resonance transverse relaxation decay signal of water molecules in bones, and then obtains the corresponding_T2 relaxation time spectrum by mathematical inversion method, and then analyzes the_T2 relaxation time The peaks on the spectrum determine the structural characteristics of the pores between the trabeculae, and finally obtain the biological bone density data through the regression analysis data processing method; the present invention can be applied to the identification of osteoporosis, and has rapid and non-destructive analysis to measure the bone density , Evaluating bone quality and other functions, it has the advantages of being completely harmless to organisms, simple equipment structure, small size, light weight, high measurement accuracy, easy operation, and strong repeatability of measurement methods.

Description

Translated fromChinese

一种骨密度检测设备和检测方法A kind of bone density detection equipment and detection method

技术领域technical field

本发明属于磁共振技术领域，涉及生物骨密度检测，尤其涉及一种基于磁共振T₂弛豫时间谱的骨密度检测设备和检测方法。The invention belongs to the technical field of magnetic resonance and relates to biological bone density detection, in particular to a bone density detection device and detection method based_on magnetic resonance T2 relaxation time spectrum.

背景技术Background technique

骨骼是人体中最基本也最为重要的生理结构之一。随着年龄的增长，人们大都存在骨量流失的情况；如果骨量流失特别严重，就会发生骨质疏松症。骨质疏松症不仅会增加骨折的风险，还会造成多种并发症，严重威胁着人类健康。Bones are one of the most basic and important physiological structures in the human body. As people age, most people lose bone mass; when bone loss is severe, osteoporosis occurs. Osteoporosis not only increases the risk of fractures, but also causes various complications, which seriously threaten human health.

一般来说，骨质疏松症患者的骨骼结构没有特别明显的变化，变化比较显著的是骨骼的质量(Quality)。为了将骨骼的质量(Quality)定量化，一般选取骨矿物质密度BMD(BoneMineralDensity)作为衡量骨质量的参数。现行测量BMD数据的主要方法有单光子吸收测定法、双能X射线吸收测定法、定量CT法和超声波测定法。Generally speaking, the bone structure of patients with osteoporosis has no particularly obvious changes, and the more significant changes are in bone quality. In order to quantify bone quality, BMD (Bone Mineral Density) is generally selected as a parameter to measure bone quality. The current main methods for measuring BMD data include single-photon absorptiometry, dual-energy X-ray absorptiometry, quantitative CT and ultrasound.

单光子吸收测定法由于准确度低、重复性差，已经逐渐淘汰。大多数情况下，采用双能X射线吸收测定法测定骨密度BMD数据。双能X射线吸收测定法，又称DEXA(DualEnergyX-rayAbsorptiometry)，其基本原理是根据透过组织的两束不同能量的X线光束里电子数目以及能量的减少，来定量分析透过组织的厚度与密度。DEXA是现行的主流诊断方法，技术成熟且其测定的骨密度数据可以在一定程度上反映骨骼质量的好坏。但是不同厂家的产品、不同操作员去测量，骨密度数据存在差异性。更严重的是该方法存在一定剂量的X射线辐射，对于人体有一定损伤，不宜频繁测量，骨密度数据的跨时间比较受到限制。Single photon absorptiometry has been phased out due to its low accuracy and poor reproducibility. In most cases, bone density (BMD) data are determined using dual-energy X-ray absorptiometry. Dual energy X-ray absorptiometry, also known as DEXA (DualEnergyX-rayAbsorptiometry), its basic principle is to quantitatively analyze the thickness of the tissue according to the reduction of the number of electrons and the energy in the two X-ray beams of different energies that pass through the tissue and density. DEXA is the current mainstream diagnostic method, the technology is mature, and the bone density data measured by it can reflect the bone quality to a certain extent. However, there are differences in the bone density data of products from different manufacturers and different operators. What's more serious is that there is a certain dose of X-ray radiation in this method, which will cause certain damage to the human body, so it is not suitable for frequent measurement, and the comparison of bone density data across time is limited.

定量CT的方法又称QCT(QuantityComputedTomography)，可以在现有的计算机断层扫描仪上改进实现，但是需要新增专用的软件。与DEXA不同，它测量的是体积的骨密度数据(g/cm³)，是真实的密度数据。但是QCT的辐射剂量高于DEXA，且设备庞大、费用昂贵，难以推广。The method of quantitative CT is also called QCT (Quantity Computed Tomography), which can be improved and implemented on the existing computer tomography scanner, but it needs to add special software. Different from DEXA, it measures the volumetric bone density data (g/cm³ ), which is the real density data. However, the radiation dose of QCT is higher than that of DEXA, and the equipment is huge and expensive, so it is difficult to promote.

超声测定的方法实际上测量的不是骨密度数据，而是根据测量的声波的声速值SOS(SpeedofSound，单位：m/s)和宽带超声波衰减值BUA(BroadbandUltrasoundAttenuation，单位：dB/MHz)经过计算得到定量超声波骨强度QUS(QuantityUltrasoundStiffness)数据。QUS测量方法与DEXA测量方法相比，不存在电离辐射，对身体无害。但是经过试验对比，QUS数据与DEXA测得的BMD数据相比，相关性较低，准确性无法保证，只具有一定的参考价值，很难用于临床测量诊断。The method of ultrasonic measurement actually does not measure bone density data, but is calculated based on the measured sound velocity value SOS (Speed of Sound, unit: m/s) and broadband ultrasonic attenuation value BUA (Broadband Ultrasound Attenuation, unit: dB/MHz) Quantitative ultrasonic bone strength QUS (QuantityUltrasoundStiffness) data. Compared with the DEXA measurement method, the QUS measurement method does not have ionizing radiation and is harmless to the body. However, after experimental comparison, the correlation between QUS data and BMD data measured by DEXA is low, and the accuracy cannot be guaranteed. It only has a certain reference value and is difficult to be used for clinical measurement and diagnosis.

近几年随着磁共振成像技术的不断发展，由于其具有完全无创、精确度高等特点越来越受到医学领域的重视。磁共振成像技术在骨科中的应用发展尤其迅速，主要应用于骨骼创伤、骨肿瘤和软组织病变等方面的鉴别与诊断。但是，现有的磁共振成像设备和方法采集回波时间较长，不能够采集到极短回波时间下的骨组织信号，较少应用于对骨密度的检测中。In recent years, with the continuous development of magnetic resonance imaging technology, it has been paid more and more attention in the medical field because of its characteristics of complete non-invasiveness and high precision. The application of magnetic resonance imaging technology in orthopedics has developed rapidly, and it is mainly used in the identification and diagnosis of bone trauma, bone tumors and soft tissue lesions. However, the existing magnetic resonance imaging equipment and methods take a long time to collect echoes, cannot collect bone tissue signals under extremely short echo times, and are seldom used in the detection of bone density.

发明内容Contents of the invention

为了克服上述现有技术的不足，本发明提供一种基于磁共振T₂弛豫时间谱的骨密度检测设备和检测方法，通过设计磁共振硬件设备缩短设备回波时间至超短回波时间UTE(Ultra-shortEchoTime，范围即回波时间短于100微秒)，能够采集到T₂弛豫时间极短的骨组织信号，再经过数学反演得到T₂弛豫时间谱等数据，进一步将T₂弛豫时间谱与定量测定的骨密度数据相结合，最终达到正确测量骨密度的目的。In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a bone density detection device and detection method based_on magnetic resonance T2 relaxation time spectrum, and shortens the echo time of the device to the ultra-short echo time UTE by designing the magnetic resonance hardware device (Ultra-short EchoTime, the range is that the echo time is shorter than 100 microseconds), which can collect bone tissue signals with extremely short T₂ relaxation time, and then obtain T₂ relaxation time spectrum and other data through mathematical inversion, and further convert T₂ The relaxation time spectrum is combined with the quantitatively determined bone density data to finally achieve the purpose of correctly measuring bone density.

本发明提供的技术方案是：The technical scheme provided by the invention is:

一种骨密度检测设备，所述检测设备基于磁共振T₂弛豫时间谱检测骨密度，包括计算机控制终端1、单板磁共振控制器单元2、信号放大及开关控制单元3和磁体单元4，所述计算机控制终端1连接单板磁共振控制器单元2，单板磁共振控制器单元2与信号放大及开关控制单元3相连接，信号放大及开关控制单元3和磁体单元4相连接；所述计算机控制终端1用于控制整套设备系统的工作流程，同时接收并处理所述单板磁共振控制器单元2采集的信号，得到T2弛豫时间谱；所述单板磁共振控制器单元2用于产生磁共振序列并采集得到原始磁共振信号；所述信号放大及开关控制单元3用于放大采集到的信号和控制射频线圈的开关；所述磁体单元4用于保持检测区域环境的恒温和构建区域静磁场。A bone density detection device, the detection device detects bone density based on magnetic resonance T2 relaxation time spectrum, including a computer control terminal₁ , a single-board magnetic resonance controller unit 2, a signal amplification and switch control unit 3 and a magnet unit 4 , the computer control terminal 1 is connected to the single-board magnetic resonance controller unit 2, the single-board magnetic resonance controller unit 2 is connected to the signal amplification and switch control unit 3, and the signal amplification and switch control unit 3 is connected to the magnet unit 4; The computer control terminal 1 is used to control the workflow of the entire equipment system, and simultaneously receives and processes the signal collected by the single-board magnetic resonance controller unit 2 to obtain a T2 relaxation time spectrum; the single-board magnetic resonance controller unit 2 is used to generate a magnetic resonance sequence and acquire the original magnetic resonance signal; the signal amplification and switch control unit 3 is used to amplify the acquired signal and control the switch of the radio frequency coil; the magnet unit 4 is used to maintain the detection area environment Constant temperature and construction of regional static magnetic field.

上述骨密度检测设备中，进一步地，所述单板磁共振控制器单元2包括频率合成及激励信号发射部分5和数字检波及数字信号处理部分6；所述信号放大及开关控制单元3包括低噪声前置放大器7、射频放大器8、射频开关9和Q-switch开关10；所述频率合成及信号发射激励部分5产生磁共振激励信号序列，经过射频放大器8传输至射频线圈，此时射频开关9为信号激励状态；射频线圈在信号序列激励样本后经射频开关9及Q-switch开关10的共同控制，切换至信号采集状态，采集得到原始磁共振信号；所述原始磁共振信号经低噪声前置放大器7放大后，由数字检波与数字信号处理部分6进行预处理后传输回计算机控制终端1，由计算机控制终端1处理所述信号得到T2弛豫时间谱，作为检测得到的最终数据结果。In the above-mentioned bone density detection equipment, further, the single-board magnetic resonance controller unit 2 includes a frequency synthesis and excitation signal transmitting part 5 and a digital detection and digital signal processing part 6; the signal amplification and switch control unit 3 includes a low Noise preamplifier 7, radio frequency amplifier 8, radio frequency switch 9 and Q-switch switch 10; Described frequency synthesis and signal emission excitation part 5 produce magnetic resonance excitation signal sequence, transmit to radio frequency coil through radio frequency amplifier 8, at this moment radio frequency switch 9 is the signal excitation state; after the signal sequence excites the sample, the radio frequency coil is jointly controlled by the radio frequency switch 9 and the Q-switch switch 10, and is switched to the signal acquisition state, and the original magnetic resonance signal is acquired; the original magnetic resonance signal is passed through a low-noise After the preamplifier 7 is amplified, it is preprocessed by the digital detection and digital signal processing part 6 and then transmitted back to the computer control terminal 1, and the signal is processed by the computer control terminal 1 to obtain the T2 relaxation time spectrum as the final data result of the detection .

上述骨密度检测设备中，进一步地，所述单板磁共振控制器单元2将多个高度集成的电子芯片集成在一块电路板上，用于实现磁共振测量功能；本发明实施例中，所述电路板的尺寸为"220mm×100mm"，极大地简化了磁共振设备的结构，使得设备具有便携性和可移动性；多个高度集成的电子芯片主要包括德州仪器(TI)生产的数字信号处理(DSP)芯片LF2407、ALTERA公司生产的现场可编程门阵列FPGA(Field－ProgrammableGateArray)芯片EP3C55F484C8、FPGA的供电芯片(型号为TPS74401)、FPGA的配置芯片EPCS16和数模转换(DA)芯片AD9742。In the above-mentioned bone density detection equipment, further, the single-board magnetic resonance controller unit 2 integrates a plurality of highly integrated electronic chips on one circuit board to realize the magnetic resonance measurement function; in the embodiment of the present invention, the The size of the above-mentioned circuit board is "220mm×100mm", which greatly simplifies the structure of the magnetic resonance equipment, making the equipment portable and mobile; multiple highly integrated electronic chips mainly include digital signal produced by Texas Instruments (TI) Processing (DSP) chip LF2407, field programmable gate array FPGA (Field-Programmable GateArray) chip EP3C55F484C8 produced by ALTERA company, FPGA power supply chip (model TPS74401), FPGA configuration chip EPCS16 and digital-to-analog conversion (DA) chip AD9742.

上述骨密度检测设备中，进一步地，所述单板磁共振控制器能够缩短设备回波时间至超短回波时间UTE(Ultra-shortEchoTime，范围即回波时间短于100微秒)，能够采集到T₂弛豫时间极短的骨组织信号。In the above bone density detection equipment, further, the single-board magnetic resonance controller can shorten the equipment echo time to ultra-short echo time UTE (Ultra-short EchoTime, the range is that the echo time is shorter than 100 microseconds), and can collect Bone tissue signals with extremely short relaxation times to_T2 .

上述骨密度检测设备中，进一步地，Q-switch开关10是带有线圈品质因子切换开关(Q-switch)，通过该Q-switch开关可以使线圈在激励信号发射与磁共振信号接收两种工作模式之间快速转换，极大缩短磁共振信号采集时间，从而采集到骨骼组织本身极短衰减时间的磁共振信号。In the above-mentioned bone density detection device, further, the Q-switch switch 10 is provided with a coil quality factor switching switch (Q-switch), and the coil can be operated in both excitation signal transmission and magnetic resonance signal reception through the Q-switch switch. Rapid switching between modes greatly shortens the acquisition time of magnetic resonance signals, so that magnetic resonance signals with extremely short decay times of the bone tissue itself can be collected.

上述骨密度检测设备中，进一步地，所述磁体单元4包括温控装置11、永磁体12与发射和接收用线圈13；所述永磁体12提供主频为10.71MHz的磁场；所述永磁体12是一种开放式的可移动磁体，样品口径达120mm，不仅适用于各种小动物的骨组织测量，而且适用于人体前臂骨组织等测量对象体积较大的情况，满足多种条件下的测量需求。In the above-mentioned bone density detection equipment, further, the magnet unit 4 includes a temperature control device 11, a permanent magnet 12, and a coil 13 for transmitting and receiving; the permanent magnet 12 provides a magnetic field with a main frequency of 10.71 MHz; the permanent magnet 12 is an open movable magnet with a sample diameter of 120mm, not only suitable for bone tissue measurement of various small animals, but also suitable for large-volume measurement objects such as human forearm bone tissue, satisfying various conditions Measurement needs.

本发明还提供一种利用上述骨密度检测设备进行骨密度检测的方法，首先测量骨骼中水分子磁共振横向弛豫衰减信号，然后通过数学反演方法得到相应的T₂弛豫时间谱，再通过分析T₂弛豫时间谱上的各峰值确定骨小梁之间孔隙的结构特征，最后通过回归分析数据处理方法得到生物的骨密度数据；该方法包括如下步骤：The present invention also provides a method for bone density detection using the above-mentioned bone density detection equipment. First, the magnetic resonance transverse relaxation attenuation signal of water molecules in the bone is measured, and then the corresponding_T2 relaxation time spectrum is obtained by a mathematical inversion method, and then Determine the structural characteristics of the pores between the trabecular bone by analyzing each peak value_on the T2 relaxation time spectrum, and finally obtain biological bone density data through a regression analysis data processing method; the method includes the following steps:

1)将一组测量样本置于所述骨密度检测设备的磁场中心位置进行测量，得到每组测量样本的原始磁共振信号，作为每组测量样本的自旋回波数据；1) placing a group of measurement samples at the center of the magnetic field of the bone density detection device for measurement, and obtaining the original magnetic resonance signal of each group of measurement samples as the spin echo data of each group of measurement samples;

本发明实施例中，具体通过采用自旋回波脉冲序列进行测量得到的自旋回波信号数据，以消除主磁场不均匀性的影响；In the embodiment of the present invention, the spin echo signal data obtained by measuring the spin echo pulse sequence is used to eliminate the influence of the inhomogeneity of the main magnetic field;

2)将测得的自旋回波数据进行数学反演处理，得到T₂弛豫时间谱；₂ ) Mathematically inverting the measured spin echo data to obtain the T2 relaxation time spectrum;

3)将T₂弛豫时间与生物骨密度之间存在的线性对应关系通过标线公式(式4)表示：₃ ) Express the linear correspondence between the T2 relaxation time and the biological bone density through the marking formula (Formula 4):

BMD＝K·T₂+C(式4)BMD＝K·T₂ +C (Formula 4)

式4中，BMD为骨密度(BoneMineralDensity，g/cm²)；T₂为被测样品皮质骨的T₂弛豫时间数据，单位为μs；K为常数，单位为g/(cm²﹒μs)；C为常数，单位为g/cm²；K值和C值随着生物种类不同、性别不同、年龄不同取值不同。将不同样本的T₂弛豫谱与双能X射线骨密度仪测定得到的相应骨密度数据进行回归分析，得到式4中的K值和C值；In formula 4, BMD is the bone density (BoneMineralDensity, g/cm² ); T₂ is the T₂ relaxation time data of the cortical bone of the tested sample, the unit is μs; K is a constant, the unit is g/(cm² ·μs ); C is a constant, and the unit is g/cm² ; the values of K and C vary with different biological species, genders, and ages._The T2 relaxation spectrum of different samples and the corresponding bone density data measured by dual-energy X-ray absorptiometry are subjected to regression analysis to obtain K value and C value in formula 4;

4)根据式4计算得到检测骨密度，完成骨密度检测。4) Calculate the detected bone density according to formula 4, and complete the bone density detection.

上述骨密度检测方法，进一步地，步骤2)将测得的自旋回波(CPMG)数据进行数学反演处理，得到T₂弛豫时间谱；所述数学反演采用文献《核磁共振弛豫信号的多指数反演》(王为民，李培，叶朝辉，中国科学A，2001:，31(6)：730-736)记载的变换反演算法。The above-mentioned bone density detection method, further, step 2) carries out mathematical inversion processing to the measured spin echo (CPMG) data, obtains T₂ Relaxation time spectrum; Described mathematical inversion adopts literature " nuclear magnetic resonance relaxation signal The transformation inversion algorithm recorded in "Multi-exponential Inversion" (Wang Weimin, Li Pei, Ye Chaohui, Chinese Science A, 2001:, 31(6): 730-736).

本发明中，采用的变换反演算法为如下具体过程：In the present invention, the transformation inversion algorithm that adopts is following specific process:

由于骨骼中存在不同大小的孔隙，而不同大小孔隙对应的T₂弛豫时间长短不同，因此，本发明中测量得到的自旋回波信号y(t)是一系列单个孔隙自旋回波信号的叠加，如公式11所示：Since there are pores of different sizes in the bone, and the T2 relaxation times corresponding to pores of different sizes are different, therefore, the spin echo signal y(t₎ measured in the present invention is the superposition of a series of single pore spin echo signals , as shown in Equation 11:

$y\left(t\right)={\Σ}_i{f}_i\·\exp (-\frac{t}{T_{2i}})+\mathrm{\ϵ}\left(t\right),t=n\·\mathrm{\τ}$(式11)$\mathrm{the\; y}\left(t\right)={\Σ}_i{f}_i\·\exp (-\frac{t}{T_{2i}})+\mathrm{\ϵ}\left(t\right),t=\mathrm{no}\&Center\; Dot;\mathrm{\τ}$ (Formula 11)

式11中，f_i为第i类孔隙在总孔隙中所占的份额；T_2i为第i类孔隙的T₂弛豫时间；τ为回波间隔时间；ε(t)为随机噪声序列。通过求解出各类孔隙的T₂弛豫时间T_2i以及各类孔隙在总孔隙中所占的份额f_i，即可得到相应的T₂弛豫时间谱。In Equation 11, f_i is the share of pores of type i in the total pores; T_2i is the T₂ relaxation time of pores of type i; τ is the echo interval time; ε(t) is a random noise sequence. The corresponding T₂ relaxation time spectrum can be obtained by solving the T₂ relaxation time T_2i of various types of pores and the proportion f_i of each type of pores in the total pores.

为了求解上述方程式11，先做目标函数如下式12：In order to solve the above equation 11, the objective function is first made as the following equation 12:

${\mathrm{\χ}}^2={\Σ}_{i=1}^n{\[y_i-{\Σ}_{j=1}^m(f_j\·m_{ij})\]}^2+\mathrm{\λ}\·{\Σ}_{j=1}^m{f}_j=\left|\right|y-Mf|{|}^2+\mathrm{\λ}\·|\left|f\right|{|}^2$(式12)${\mathrm{\χ}}^2={\Σ}_{i=1}^{\mathrm{no}}{\[{\mathrm{the\; y}}_i-{\Σ}_{j=1}^m(f_j\·m_{ij})\]}^2+\mathrm{\λ}\·{\Σ}_{j=1}^m{f}_j=\left|\right|\mathrm{the\; y}-mf|{|}^2+\mathrm{\λ}\·|\left|f\right|{|}^2$ (Formula 12)

式12中，M＝[m_ij]＝[exp(-t_i/T_2j)]，m_ij＝exp(-t_i/T_2j)；λ为平滑因子；f＝(f₁,f₂,…,f_m)^T为幅度；χ²为相应的目标函数；y_i为选取的n维时域中第i维对应的磁共振信号；y为式11中的y(t)，即测得的自旋回波信号；f_j为m维T2空间域中第j维对应的孔隙在总孔隙中所占的份额。对幅度f的第k个分量求极值(k＝1,2,…,m)并使其等于0可得式13：In Formula 12, M=[m_ij ]=[exp(-t_i /T_2j )], m_ij =exp(-t_i /T_2j ); λ is the smoothing factor; f=(f₁ , f₂ , ..., f_m )^T is the amplitude; χ² is the corresponding objective function; y_i is the magnetic resonance signal corresponding to the i-th dimension in the selected n-dimensional time domain; y is y(t) in formula 11, that is, the measured The spin echo signal of ; f_j is the share of the pores corresponding to the jth dimension in the total pores in the m-dimensional T2 space domain. Calculate the extremum (k=1,2,...,m) of the kth component of the amplitude f and make it equal to 0 to obtain formula 13:

(M^TM)·f+λI_m×m·f＝M^T·y(式13)(M^T M) f+λI_m×m f=M^T y (Formula 13)

式13中，I_m×m为m×m阶单位矩阵；对式13做线性变化，令f＝M^T·c，即可使m维的T₂空间域的解变换到n维时域空间来解，将此变换带入式13，并选择合适的λ值，即可通过式14求出方程式11的最小二乘解：In Equation 13, I_m×m is the unit matrix of m×m order; linearly change Equation 13, let f=M^T c, the solution of m_- dimensional T2 space domain can be transformed into n-dimensional time domain space To solve, put this transformation into Equation 13, and choose the appropriate value of λ, the least squares solution of Equation 11 can be obtained by Equation 14:

$\hat{f}=M^T\·{(M\·M^T+{\mathrm{\λI}}_{n\×n})}^{-1}\·y$(式14)$\hat{f}=m^T\·{(m\·m^T+{\mathrm{\λI}}_{\mathrm{no}\×\mathrm{no}})}^{-1}\&Center\; Dot;\mathrm{the\; y}$ (Formula 14)

式14中，为n维幅度值的解；n的个数即为布点数，对应n个T₂弛豫时间值。In formula 14, is the solution of the n-dimensional amplitude value; the number of n is the number of distribution points, corresponding to n T₂ relaxation time values.

在本发明实施例中，采用上述变换反演算法，选取适合的平滑因子为λ＝0.05，反演时间范围1～10000μs，布点数100，布点方法采用以10为底的log布点方式，进行数学反演处理，得到T₂弛豫时间谱。In the embodiment of the present invention, the above transformation and inversion algorithm is adopted, the suitable smoothing factor is selected as λ=0.05, the inversion time range is 1 to 10000 μs, and the number of distribution points is 100. Inversion processing is performed to obtain the_T2 relaxation time spectrum.

上述骨密度检测方法，进一步地，步骤3)所述标线公式具体是通过最小二乘法进行线性拟合得到。In the above bone density detection method, further, the marking formula in step 3) is specifically obtained by performing linear fitting by the least square method.

上述骨密度检测方法为快速测量方法，测量所需时间小于0.5分钟。The above bone density detection method is a rapid measurement method, and the time required for measurement is less than 0.5 minutes.

与现有技术相比，本发明的有益效果是：Compared with prior art, the beneficial effect of the present invention is:

本发明通过设计磁共振硬件设备，缩短设备回波时间至超短回波时间UTE(Ultra-shortEchoTime，范围即回波时间短于100微秒)，能够采集到T₂弛豫时间极短的骨组织信号，再经过适当的数学反演得到T₂弛豫时间谱等数据，进一步将T₂弛豫时间谱与定量测定的骨密度数据相结合，最终达到正确测量骨密度的目的。The present invention shortens the equipment echo time to ultra-short echo time UTE (Ultra-short EchoTime, the scope is that the echo time is shorter than 100 microseconds₎ by designing magnetic resonance hardware equipment, and can collect bones with extremely short T2 relaxation time._The T2 relaxation time spectrum and other data are obtained through appropriate mathematical inversion, and the_T2 relaxation time spectrum is further combined with the quantitatively determined bone density data to finally achieve the purpose of correctly measuring bone density.

本发明提供检测设备及其检测方法首先测量骨骼中水分子磁共振横向弛豫衰减信号，然后通过数学反演方法得到相应的T₂弛豫时间谱，再通过分析T₂弛豫时间谱上的各峰值确定骨小梁之间孔隙的结构特征，最后通过回归分析数据处理方法得到生物的骨密度数据；本发明可应用于骨质疏松症的鉴别，具有快速、无损分析测定骨密度，评价骨质量等功能，与常规的使用X射线测量方法的设备相比，具有对生物体完全无害，设备结构简单、体积小、重量轻，测量精度高、操作简便、测量方法可重复性强等优点。The invention provides a detection device and a detection method thereof. Firstly, the magnetic resonance transverse relaxation decay signal of water molecules in the bone is measured, and then the corresponding_T2 relaxation time spectrum is obtained through a mathematical inversion method, and then the T2 relaxation time spectrum is analyzed by analyzing the_T2 relaxation time spectrum. Each peak value determines the structural characteristics of the pores between the trabecular bone, and finally obtains the biological bone density data through the regression analysis data processing method; Quality and other functions, compared with conventional equipment using X-ray measurement methods, it has the advantages of being completely harmless to organisms, simple in structure, small in size, light in weight, high in measurement accuracy, easy to operate, and highly repeatable in measurement methods. .

附图说明Description of drawings

图1是磁共振自旋回波(CPMG)测量序列时序图。Figure 1 is a timing diagram of a magnetic resonance spin echo (CPMG) measurement sequence.

图2是本发明实施例中的超短回波生物骨骼磁共振弛豫谱测量设备的结构框图；Fig. 2 is a structural block diagram of the ultrashort echo bio-skeleton magnetic resonance relaxation spectrum measurement device in the embodiment of the present invention;

其中，1—计算机控制终端1；2—单板磁共振控制器单元；3—信号放大及开关控制单元；4—磁体单元；；5—频率合成及激励信号发射部分；6—数字检波及数字信号处理部分；7—低噪声前置放大器；8—射频放大器；9—射频开关控制；10—Q-switch开关；11—温控装置；12—永磁体；13—发射和接收用线圈。Among them, 1—computer control terminal 1; 2—single-board magnetic resonance controller unit; 3—signal amplification and switch control unit; 4—magnet unit; 5—frequency synthesis and excitation signal transmission part; 6—digital detection and digital Signal processing part; 7—low noise preamplifier; 8—radio frequency amplifier; 9—radio frequency switch control; 10—Q-switch switch; 11—temperature control device; 12—permanent magnet; 13—coil for transmitting and receiving.

图3是本发明提供的磁共振T₂谱检测骨密度方法的流程框图。Fig.₃ is a flow chart of the method for detecting bone density by magnetic resonance T2 spectrum provided by the present invention.

图4是本发明实施例中12月龄大鼠股骨典型样本T₂弛豫时间谱。Fig. 4 is the T₂ relaxation time spectrum of a typical sample of a 12-month-old rat femur in an embodiment of the present invention.

图5是本发明实施例中12月龄大鼠股骨T₂弛豫时间-平均骨密度最小二乘法拟合直线。Fig. 5 is a straight line fitted by the least squares method of the T2 relaxation time of the₁₂ -month-old rat femur and the average bone density in the embodiment of the present invention.

具体实施方式detailed description

下面结合附图，通过实施例进一步描述本发明，但不以任何方式限制本发明的范围。Below in conjunction with accompanying drawing, further describe the present invention through embodiment, but do not limit the scope of the present invention in any way.

本发明提供一种用于骨密度测量的设备与检测方法，用于提升骨密度数据测量的准确性、可重复性和安全性，使得检测数据能够更为准确的反映骨骼质量的好坏，并减少对医务人员和病患的放射危害。The present invention provides a device and detection method for bone density measurement, which are used to improve the accuracy, repeatability and safety of bone density data measurement, so that the detection data can more accurately reflect the quality of bone, and Reduce radiation hazards to medical staff and patients.

本发明通过设计磁共振硬件设备，缩短设备回波时间至超短回波时间UTE(Ultra-shortEchoTime，范围即回波时间短于100微秒)，能够采集到T₂弛豫时间极短的骨组织信号，再经过适当的数学反演得到T₂弛豫时间谱等数据，进一步将T₂弛豫时间谱与定量测定的骨密度数据相结合，最终达到正确测量骨密度的目的。The present invention shortens the equipment echo time to ultra-short echo time UTE (Ultra-short EchoTime, the scope is that the echo time is shorter than 100 microseconds₎ by designing magnetic resonance hardware equipment, and can collect bones with extremely short T2 relaxation time._The T2 relaxation time spectrum and other data are obtained through appropriate mathematical inversion, and the_T2 relaxation time spectrum is further combined with the quantitatively determined bone density data to finally achieve the purpose of correctly measuring bone density.

T₂弛豫时间又称横向弛豫时间，是氢原子发生自旋-自旋弛豫时，横向磁化矢量分量(即磁化矢量在三维坐标系中x、y方向的分量)由最大值衰减至0所需的时间。弛豫期间磁化强度矢量的横向分量M_x、M_y，如式1和式2所示：_The T2 relaxation time, also known as the transverse relaxation time, is when the hydrogen atom undergoes spin-spin relaxation, the transverse magnetization vector component (that is, the magnetization vector in the x, y direction components in the three-dimensional coordinate system) decays from the maximum value to 0 time required. The transverse components M_x , M_y of the magnetization vector during relaxation are shown in Eq. 1 and Eq. 2:

$M_x\left(t\right)=M_x\left(0\right)sin\left({\mathrm{\ω}}_{0}t\right)e^{-t/T_2}$(式1)$m_x\left(t\right)=m_x\left(0\right)\mathrm{the\; s}i\mathrm{no}\left({\mathrm{\ω}}_{0}t\right)e^{-t/T_2}$ (Formula 1)

$M_y\left(t\right)=M_y\left(0\right)cos\left({\mathrm{\ω}}_{0}t\right)e^{-t/T_2}$(式2)$m_{\mathrm{the\; y}}\left(t\right)=m_{\mathrm{the\; y}}\left(0\right)co\mathrm{the\; s}\left({\mathrm{\ω}}_{0}t\right)e^{-t/T_2}$ (Formula 2)

式1和式2中，T₂为弛豫时间；M_x和M_y分别为弛豫期间磁化强度矢量的横向分量；M_x(0)和M_y(0)分别为t＝0时磁化强度矢量的横向分量；t为从T₂弛豫开始时(t＝0)所经历的时间；ω₀为磁化矢量分量的拉莫进动频率。In formulas 1 and 2, T₂ is the relaxation time; M_x and My_y are the transverse components of the magnetization vector during relaxation, respectively; M_x (0) and_My (0) are the magnetization at t=0 The transverse component of the vector; t is the time elapsed from the beginning of T₂ relaxation (t=0); ω₀ is the Larmor precession frequency of the magnetization vector component.

在实际测量中，由于主磁场总存在一定的不均匀性，M_x、M_y的衰减极大地加快，相应的T₂弛豫时间变为如式3所示：In the actual measurement, due to the inhomogeneity of the main magnetic field, the attenuation of M_x and My_y is greatly accelerated, and the corresponding T₂ relaxation time becomes As shown in formula 3:

$\frac{1}{{T_2}^{*}}=\frac{1}{T_2}+\frac{1}{T_{2m}}$(式3)$\frac{1}{{T_2}^{*}}=\frac{1}{T_2}+\frac{1}{T_{2m}}$ (Formula 3)

式3中，T_2m是由于主磁场不均匀性引起T₂弛豫时间变化的部分；T₂为真实的T₂弛豫时间；为T_2m和T₂共同作用下测量到的T₂弛豫时间。为了消除主磁场不均匀性的影响，采用自旋回波脉冲序列进行测量。图1是磁共振自旋回波(CPMG)测量序列时序图，如图1所示，该测量序列的过程是：In formula 3, T_2m is the part of T₂ relaxation time change caused by the inhomogeneity of the main magnetic field; T₂ is the real T₂ relaxation time; T₂ relaxation time measured under the joint action of T_2m and T₂ . In order to eliminate the influence of the inhomogeneity of the main magnetic field, a spin-echo pulse sequence is used for the measurement. Figure 1 is a timing diagram of a magnetic resonance spin echo (CPMG) measurement sequence, as shown in Figure 1, the process of the measurement sequence is:

(1)在长为TR的恢复时间内，在时间t＝0时发射一个90°射频脉冲；(1) Transmitting a 90° RF pulse at time t=0 during a recovery time of length TR;

(2)在t＝τ＝TE/2时发射一个180°射频脉冲，由于横向磁化矢量分量先聚相后散相，此时在接收线圈中将出现一个幅值先增长、后衰减的磁共振信号(即自旋回波信号)，该信号在t＝2τ＝TE时间处出现最大值；(2) When t=τ=TE/2, a 180° radio frequency pulse is transmitted. Since the transverse magnetization vector component gathers phase first and then separates phase, there will be a magnetic resonance whose amplitude first increases and then decays in the receiving coil signal (i.e. spin echo signal), the signal has a maximum value at t=2τ=TE time;

(3)每隔时间2τ发射一个180°射频脉冲，共重复n次(n＝1,2,3……，n的数值可以自选)，即得到一组信号幅值不断减小的自旋回波信号。(3) A 180° radio frequency pulse is emitted at intervals of 2τ, repeated n times in total (n=1, 2, 3..., the value of n can be selected by oneself), that is, a set of spin echoes with decreasing signal amplitudes is obtained Signal.

通过对上述过程测量得到的自旋回波信号进行数学反演即可求得T₂弛豫时间谱，通过T₂弛豫时间谱可以得到不同样品组分对应的T₂弛豫时间分布。The T₂ relaxation time spectrum can be obtained by mathematical inversion of the spin echo signal obtained from the above process measurement, and the T₂ relaxation time distribution corresponding to different sample components can be obtained through the T₂ relaxation time spectrum.

动物包括人类的股骨主要成分为皮质骨，其基本特征为骨小梁组成的孔隙状结构。而骨小梁之间的孔隙中存在少量结合水和自由水。不同孔隙大小中的水分子发生表面弛豫时的T₂弛豫时间不尽相同，大孔隙对应的T₂弛豫时间较长，小孔隙对应的T₂弛豫时间较短。通过将常规骨密度测量数据与T₂弛豫时间谱值数据进行对比分析，就可实现用T₂弛豫时间谱来反映被测样本的骨密度大小的目的。实际应用中，通过将常规骨密度数据与T₂弛豫时间谱上约在300～500μs之间的峰值数据进行对比分析，就可用T₂弛豫时间来反映被测样本的骨密度大小。The main component of the femur of animals including human is cortical bone, and its basic feature is the porous structure composed of bone trabeculae. However, there is a small amount of bound water and free water in the pores between bone trabeculae. The T₂ relaxation time of water molecules in different pore sizes is different when surface relaxation occurs, the T₂ relaxation time corresponding to large pores is longer, and the T₂ relaxation time corresponding to small pores is shorter. By comparing and analyzing the conventional bone density measurement data with the T₂ relaxation time spectrum value data, the purpose of using the T₂ relaxation time spectrum to reflect the bone density of the measured sample can be achieved. In practical applications, by comparing and analyzing the conventional bone density data with the peak data_on the T2 relaxation time spectrum between 300 and 500 μs, the_T2 relaxation time can be used to reflect the bone density of the tested sample.

本发明采用T₂弛豫时间谱测量和分析方法，提供了用于生物骨密度测量的完备装置和骨密度分析方法，包括：_The present invention adopts the measurement and analysis method of T2 relaxation time spectrum, and provides a complete device and bone density analysis method for biological bone density measurement, including:

1)一种超短回波时间磁共振测量装置，该装置主要包括一个测量口径120mm、主磁场频率10MHz的可移动式永磁体、高速线圈品质因子切换开关和高度集成的小型单板磁共振控制器；1) An ultra-short echo time magnetic resonance measurement device, which mainly includes a movable permanent magnet with a measurement aperture of 120mm and a main magnetic field frequency of 10MHz, a high-speed coil quality factor switch and a highly integrated small single-board magnetic resonance control device;

图2为本发明提供的磁共振T₂弛豫时间分析测定生物骨密度的设备的结构图，包括计算机控制终端1、单板磁共振控制器单元2、信号放大及开关控制单元3和磁体单元4共计四个部分。其中，单板磁共振控制器单元2主要包括频率合成及激励信号发射部分5和数字检波及数字信号处理部分6。信号放大及开关控制单元3包括低噪声前置放大器7、射频放大器8、射频开关控制9和Q-switch开关10。磁体单元4包括温控装置11、永磁体12与发射和接收用线圈13。Fig.₂ is the structural diagram of the equipment for the magnetic resonance T2 relaxation time analysis and determination of biological bone density provided by the present invention, including computer control terminal 1, single-board magnetic resonance controller unit 2, signal amplification and switch control unit 3 and magnet unit 4 There are four parts in total. Among them, the single-board magnetic resonance controller unit 2 mainly includes a frequency synthesis and excitation signal transmitting part 5 and a digital wave detection and digital signal processing part 6 . The signal amplification and switch control unit 3 includes a low noise preamplifier 7 , a radio frequency amplifier 8 , a radio frequency switch control 9 and a Q-switch 10 . The magnet unit 4 includes a temperature control device 11 , a permanent magnet 12 and a coil 13 for transmitting and receiving.

上述测定生物骨密度的设备在工作时，计算机控制终端1控制整套系统的工作流程，单板磁共振控制器单元2负责磁共振序列的产生和信号的采集，信号放大及开关控制单元3用于实验室采集到的信号放大及射频线圈的开关控制作用，磁体单元4用于实验区域的恒温以及静磁场区域的构建。具体工作时，计算机控制终端下达指令，从单板磁共振控制单元中频率合成及信号发射激励部分产生磁共振激励信号序列，经过射频放大器传输至发射与接收用线圈，此时射频开关为信号激励状态；射频线圈在信号序列激励样本后经射频开关控制及Q-switch的共同控制，切换至信号采集状态，采集原始磁共振信号，经低噪声前置放大器放大原始信号后，由数字检波与数字信号处理部分预处理后传输回计算机控制终端，最终由计算机控制终端处理信号得到T₂弛豫时间谱，作为最终数据结果。When the above-mentioned equipment for measuring biological bone density is working, the computer control terminal 1 controls the workflow of the entire system, the single-board magnetic resonance controller unit 2 is responsible for the generation of magnetic resonance sequences and signal acquisition, and the signal amplification and switch control unit 3 is used for The signals collected in the laboratory are amplified and the switch control function of the radio frequency coil. The magnet unit 4 is used for the constant temperature of the experimental area and the construction of the static magnetic field area. During specific work, the computer control terminal issues instructions to generate a magnetic resonance excitation signal sequence from the frequency synthesis and signal emission excitation part of the single-board magnetic resonance control unit, which is transmitted to the transmission and reception coils through the radio frequency amplifier. At this time, the radio frequency switch is the signal excitation state; after the signal sequence excites the sample, the RF coil switches to the signal acquisition state through the RF switch control and the joint control of the Q-switch, and collects the original magnetic resonance signal. After the original signal is amplified by the low-noise preamplifier, the digital detection and digital The signal processing part is preprocessed and transmitted back to the computer control terminal, and finally the computer control terminal processes the signal to obtain the_T2 relaxation time spectrum as the final data result.

2)一种用T₂弛豫时间谱分析测定骨密度数据的方法，可以正确拟合出骨密度-T₂弛豫时间定标线并应用于骨密度的测量和计算得到对应骨骼的骨密度。通过本发明提供的上述磁共振T₂弛豫时间分析测定生物骨密度的设备，采集得到T₂弛豫时间极短的骨组织信号(即原始磁共振信号)，再经过数学反演得到T₂弛豫时间谱等数据；本发明检测方法中，将T₂弛豫时间与生物骨密度之间存在的线性对应关系通过标线公式(式4)表示：₂ ) A method of measuring bone density data by T2 relaxation time spectrum analysis, which can correctly fit the bone density_- T2 relaxation time calibration line and apply it to the measurement and calculation of bone density to obtain the bone density of the corresponding bone . Through the above_- mentioned magnetic resonance T2 relaxation time analysis and determination of biological bone density equipment provided by the present invention, the bone tissue signal (ie, the original magnetic resonance signal₎ with a very short T2 relaxation time is collected, and then T2 is obtained through mathematical_inversion . Data such as relaxation time spectrum; In detection method of the present invention, the linear corresponding relation that exists between T2 relaxation time and biological bone density is represented by marking_formula (formula 4):

BMD＝K·T₂+C(4)BMD＝K·T₂ +C(4)

上式中，BMD为骨密度(BoneMineralDensity，g/cm²)，T₂(单位：μs)为被测样品皮质骨的T₂弛豫时间数据，K(单位：g/(cm²﹒μs))、C(单位：g/cm²)为常数。根据我们的研究结果，K值和C值随着生物种类不同、性别不同、年龄不同等因素有着不同的取值。在实际应用中，需要先定量测量一定样本量的生物骨组织的骨密度，然后采用回归分析得出生物所在组别的K值和C值，再根据式4测定得到骨密度。由于本测量方法安全无害，可以进行多次测量，从而方便使用者根据骨密度的大小来判定是否骨质疏松以及骨质疏松症发生和发展的过程。In the above formula, BMD is the bone mineral density (BoneMineralDensity, g/cm² ), T₂ (unit: μs) is the T₂ relaxation time data of the cortical bone of the tested sample, K (unit: g/(cm² μs) ), C (unit: g/cm² ) are constants. According to our research results, the K value and C value have different values depending on the biological species, gender, age and other factors. In practical application, it is necessary to quantitatively measure the bone density of a certain sample size of biological bone tissue, and then use regression analysis to obtain the K value and C value of the biological group, and then determine the bone density according to formula 4. Because the measurement method is safe and harmless, multiple measurements can be carried out, so that users can judge whether osteoporosis and the process of occurrence and development of osteoporosis according to the size of bone density.

图3是本发明实施例中用T₂弛豫时间谱分析测定生物骨密度方法的具体流程图，以下以大鼠离体股骨(但不限于股骨)骨密度测定为例(生物种类不限于大鼠)，详细说明本发明的T₂弛豫时间分析测定生物骨密度的方法及具体的工作过程。Fig. 3 is in the embodiment of the present invention with_T2Relaxation time spectrum analysis measures the concrete flow chart of biological bone density method, the following is an example (biological species is not limited to large) with rat isolated femur (but not limited to femur) bone density measurement Rat), describe in detail the method and specific working process of_T2 relaxation time analysis of the present invention to measure biological bone density.

步骤1)测量样本准备：取编号为1～10的12月龄卵巢摘除的大鼠离体股骨进行实验，其中1～5组为骨质疏松组，6～10组为对照组(骨质正常)；大鼠体长20cm，体重600克；Step 1) Preparation of measurement samples: The isolated femurs of 12-month-old rats with numbers 1 to 10 were subjected to the experiment, wherein groups 1 to 5 were the osteoporosis group, and groups 6 to 10 were the control group (normal bone mass). ); Rat body length 20cm, body weight 600 grams;

步骤2)测量仪器准备：打开超短回波生物骨组织磁共振弛豫谱测量设备，待设备温度恒定；选取添加弛豫试剂的水作为基本定标物，确定磁场偏置、增益大小、90°及180°脉冲长度等参数；Step 2) Measuring instrument preparation: turn on the ultrashort echo biological bone tissue magnetic resonance relaxation spectrum measuring equipment, and wait for the temperature of the equipment to be constant; select water with relaxation reagents as the basic calibrator, and determine the magnetic field bias, gain, 90 ° and 180° pulse length and other parameters;

步骤3)仪器参数选择：选取的具体测量参数为磁场主频10.71MHz(由永磁体12提供)，回波间隔时间TE＝100μs，扫描累加次数4次，恢复时间1000毫秒，采样点数1024个(上述参数数据对应于磁共振激励信号序列基本参数)。每次测量将一组(每组一根股骨)测量样本置于磁共振设备的磁场中心位置进行测量，得到每组对应的自旋回波数据(即原始磁共振信号)；Step 3) Instrument parameter selection: the specific measurement parameters selected are magnetic field main frequency 10.71MHz (provided by permanent magnet 12), echo interval time TE=100μs, scanning accumulation times 4 times, recovery time 1000 milliseconds, sampling points 1024 ( The above parameter data correspond to the basic parameters of the magnetic resonance excitation signal sequence). For each measurement, a group of measurement samples (one femur in each group) is placed in the center of the magnetic field of the magnetic resonance equipment for measurement, and the corresponding spin echo data (ie, the original magnetic resonance signal) of each group is obtained;

步骤4)定标数据处理：将测得的自旋回波数据通过设定的反演参数进行数学反演处理，得到T₂弛豫时间分布即T₂弛豫时间谱，附图4为本实验中三组典型的T₂弛豫时间谱。然后将不同样本的T₂弛豫谱与双能X射线骨密度仪测定得到的相应骨密度数据进行回归分析，得到标线公式(4)中的K值和C值；Step₄ ) Calibration data processing: the measured spin echo data is subjected to mathematical inversion processing through the set inversion parameters to obtain the T2 relaxation time distribution, that is, the T2 relaxation time spectrum, and Figure₄ is the experiment The typical T₂ relaxation time spectra of the three groups. Then the T2 relaxation spectrum of different samples and the corresponding bone density data that_dual -energy X-ray absorptiometry measures obtain carry out regression analysis, obtain the K value and the C value in the marking formula (4);

步骤5)骨密度测量：通过上述回归分析得到K值和C值；确定K和C值后，通过测量T₂弛豫时间谱；通过最小二乘法进行线性拟合得到标线公式；结合标线公式，即可以对其它大鼠股骨进行快速测量(测量时间小于0.5分钟)。具体操作步骤为：首先使用本发明测得相应大鼠样本的股骨T₂弛豫时间谱，取T₂时间谱中在300-500μs之间谱峰的峰值T₂弛豫时间，将相应样本的T₂弛豫时间与其用DEXA方法测得的骨密度数据对应，共测得10组样本。对测得的一一对应的T₂弛豫时间-骨密度数据进行最小二乘法线性拟合，可以得到相应的标线公式。Step 5) bone density measurement: obtain K value and C value by above-mentioned regression analysis; After determining K and C value, by measuring T₂ relaxation time spectrum; Carry out linear fitting by least square method to obtain marking line formula; Combine marking line formula, that is, other rat femurs can be quickly measured (measurement time is less than 0.5 minutes)._The specific operation steps are: at first use the present invention to measure the femur T2 relaxation time spectrum of the corresponding rat sample, get the peak T2_relaxation time of the spectrum peak between 300-500 μs in the T2 time spectrum, and take the_T2 relaxation time of the corresponding sample The T₂ relaxation time corresponds to the bone density data measured by the DEXA method, and a total of 10 groups of samples were measured. The corresponding marking formula can be obtained by performing least squares linear fitting on the measured one-to-one correspondence of T₂ relaxation time-bone density data.

T₂弛豫时间与生物骨密度之间存在线性对应关系，对应的标线公式为式4。There is a linear correspondence between the T2 relaxation time and the biological bone density, and the corresponding marking_formula is Equation 4.

如下表1中的数据，随着股骨骨密度的增加，其对应的在300～500μs之间的T₂弛豫时间峰值逐渐缩短。对于表1中的数据，采取最小二乘法进行线性拟合，所得标线公式如上述公式(4)所示。附图5为本实验中利用最小二乘法拟合出的定标直线的示意图。According to the data in Table 1 below, as the bone density of the femur increases, the corresponding peak T₂ relaxation time between 300 and 500 μs gradually shortens. For the data in Table 1, the least square method is used for linear fitting, and the obtained marking formula is shown in the above formula (4). Accompanying drawing 5 is the schematic diagram of the calibration straight line fitted by the least square method in this experiment.

表112月龄大鼠的股骨密度数据及其对应的T₂弛豫时间_Femur bone density data and corresponding T2 relaxation time of table 112 months old rats

表2列出了12月龄大鼠股骨对应的K值和C值。根据所得相关系数可以判断，T₂弛豫时间谱中300～500μs之间的峰值与骨密度数据的相关程度很高，可以用式4的线性关系来描述二者的联系，从而可以看出采用T₂弛豫时间谱方法可以准确测定骨密度。Table 2 lists the K and C values corresponding to the femurs of 12-month-old rats. According to the obtained correlation coefficient, it can be judged that the peak value between 300 and 500 μs in the T2 relaxation time spectrum has a high degree of correlation with the bone density data, and the relationship between the_two can be described by the linear relationship of Eq. T₂ relaxation time spectrum method can accurately measure bone density.

表212月龄大鼠股骨密度-T₂弛豫时间拟合参数值Table 212 month old rat femur density-T₂ relaxation time fitting parameter value

组别groupK值(g/(cm²﹒μs))K value (g/(cm² ｜μs))C值(g/cm²)C value (g/cm² )相关系数R值Correlation coefficient R value12月龄12 months old-0.0005-0.00050.49500.49500.92550.9255

为验证所得标线公式的准确性，选取同一批编号为1～5的12月龄卵巢摘除大鼠离体股骨进行验证实验。首先测量得到5组样本的T₂弛豫时间谱，再根据上述实验测得的标线公式，计算得出相应的骨密度数据。如下表3中所示，BMD1为利用DEXA方法测得的大鼠股骨骨密度数据，T₂弛豫时间为利用本方法测得的相应弛豫时间数据，BMD2为利用定标线公式计算得出的骨密度数据，Δ为BMD2与BMD1的差值，误差比例为Δ占BMD2的百分比。根据误差比例，5组样本的误差比例绝对值均小于5％，可见本方法精度较高，故可以用该方法替代现有的DEXA方法准确测量骨密度数据。In order to verify the accuracy of the obtained marking formula, the same batch of 12-month-old ovariectomized rat femurs numbered 1-5 were selected for verification experiments. Firstly, the T₂ relaxation time spectra of the 5 groups of samples were measured, and then the corresponding bone density data were calculated according to the marking formula obtained in the above experiments. As shown in Table₃ below, BMD1 is the rat femur bone density data measured by the DEXA method, T2 relaxation time is the corresponding relaxation time data measured by this method, and BMD2 is calculated by using the calibration line formula Δ is the difference between BMD2 and BMD1, and the error ratio is the percentage of Δ in BMD2. According to the error ratio, the absolute value of the error ratio of the 5 groups of samples is less than 5%. It can be seen that the accuracy of this method is high, so this method can be used to replace the existing DEXA method to accurately measure bone density data.

表3BMD＝K·T₂+C骨密度计算公式验证数据Table 3 BMD=K·T₂ +C bone density calculation formula verification data

编号NumberingBMD1(g/cm²)BMD1(g/cm² )T₂弛豫时间(μs)T₂ relaxation time (μs)BMD2(g/cm²)BMD2(g/cm² )Δ(g/cm²)Δ(g/cm² )误差比例(％)Error ratio (%)110.26580.26584604600.26500.2650-0.0008-0.0008-0.30-0.30220.27340.27344254250.28250.28250.00910.00913.223.22330.28520.28524004000.29500.29500.00980.00983.323.32440.29550.29553703700.31000.31000.01450.01454.684.68550.30200.30204004000.29500.2950-0.0070-0.0070-2.37-2.37

需要注意的是，公布实施例的目的在于帮助进一步理解本发明，但是本领域的技术人员可以理解：在不脱离本发明及所附权利要求的精神和范围内，各种替换和修改都是可能的。因此，本发明不应局限于实施例所公开的内容，本发明要求保护的范围以权利要求书界定的范围为准。It should be noted that the purpose of the disclosed embodiments is to help further understand the present invention, but those skilled in the art can understand that various replacements and modifications are possible without departing from the spirit and scope of the present invention and the appended claims of. Therefore, the present invention should not be limited to the content disclosed in the embodiments, and the protection scope of the present invention is subject to the scope defined in the claims.

Claims (10)

Translated fromChinese

1.一种骨密度检测设备，所述检测设备基于磁共振T₂弛豫时间谱检测骨密度，包括计算机控制终端1、单板磁共振控制器单元2、信号放大及开关控制单元3和磁体单元4，所述计算机控制终端1连接单板磁共振控制器单元2，单板磁共振控制器单元2与信号放大及开关控制单元3相连接，信号放大及开关控制单元3和磁体单元4相连接；所述单板磁共振控制器单元2用于产生磁共振序列和采集得到原始磁共振信号；所述信号放大及开关控制单元3用于放大采集到的信号和控制射频线圈的开关；所述磁体单元4用于保持检测区域环境的恒温和构建区域静磁场；所述计算机控制终端1用于控制整套设备系统的工作流程，同时接收并处理所述单板磁共振控制器单元2采集待的信号从而得到T2弛豫时间谱。1. A bone density detection device, said detection device detects bone density based on magnetic resonance T2 relaxation time spectrum, including computer control terminal 1, single-board magnetic resonance controller unit₂ , signal amplification and switch control unit 3 and magnet Unit 4, the computer control terminal 1 is connected to the single-board magnetic resonance controller unit 2, the single-board magnetic resonance controller unit 2 is connected to the signal amplification and switch control unit 3, and the signal amplification and switch control unit 3 is connected to the magnet unit 4 connection; the single-board magnetic resonance controller unit 2 is used to generate a magnetic resonance sequence and acquire an original magnetic resonance signal; the signal amplification and switch control unit 3 is used to amplify the acquired signal and control the switch of the radio frequency coil; The magnet unit 4 is used to maintain the constant temperature of the detection area environment and build a static magnetic field in the area; the computer control terminal 1 is used to control the workflow of the entire equipment system, and at the same time receive and process the data collected by the single-board magnetic resonance controller unit 2. The signal thus obtained the T2 relaxation time spectrum.2.如权利要求1所述骨密度检测设备，其特征是，所述单板磁共振控制器单元2包括频率合成及激励信号发射部分5和数字检波及数字信号处理部分6；所述单板磁共振控制器单元2将多个高度集成的电子芯片集成在一块电路板上，用于实现磁共振测量功能。2. bone density detection equipment as claimed in claim 1, is characterized in that, described single-board magnetic resonance controller unit 2 comprises frequency synthesis and excitation signal transmission part 5 and digital wave detection and digital signal processing part 6; The magnetic resonance controller unit 2 integrates a plurality of highly integrated electronic chips on a circuit board to realize the magnetic resonance measurement function.3.如权利要求2所述骨密度检测设备，其特征是，所述电子芯片包括DSP芯片、FPGA芯片、FPGA的供电芯片、FPGA的配置芯片和DA芯片。3. The bone density detection device according to claim 2, wherein the electronic chip comprises a DSP chip, an FPGA chip, a power supply chip of the FPGA, a configuration chip of the FPGA and a DA chip.4.如权利要求1所述骨密度检测设备，其特征是，所述信号放大及开关控制单元3包括用于将所述原始磁共振信号进行放大的低噪声前置放大器7、用于将单板磁共振控制器单元2产生的磁共振激励信号序列传输至射频线圈的射频放大器8、射频开关9和Q-switch开关10；所述Q-switch开关10是带有线圈品质因子切换开关，通过所述Q-switch开关使得射频线圈在激励信号发射工作模式与磁共振信号接收工作模式之间快速转换。4. The bone density detection device according to claim 1, wherein the signal amplification and switch control unit 3 includes a low-noise preamplifier 7 for amplifying the original magnetic resonance signal, and a low-noise preamplifier 7 for amplifying the single The magnetic resonance excitation signal sequence generated by the board magnetic resonance controller unit 2 is transmitted to the radio frequency amplifier 8 of the radio frequency coil, the radio frequency switch 9 and the Q-switch switch 10; the Q-switch switch 10 is a switching switch with a coil quality factor, through The Q-switch enables the radio frequency coil to rapidly switch between the excitation signal transmitting mode and the magnetic resonance signal receiving mode.5.如权利要求1所述骨密度检测设备，其特征是，所述磁体单元4包括温控装置11、永磁体12与发射和接收用线圈13；所述永磁体12是一种开放式的可移动磁体，提供主频为10.71MHz的磁场。5. The bone density detection device according to claim 1, wherein the magnet unit 4 includes a temperature control device 11, a permanent magnet 12 and a coil 13 for transmitting and receiving; the permanent magnet 12 is an open The movable magnet provides a magnetic field with a main frequency of 10.71MHz.6.如权利要求5所述骨密度检测设备，其特征是，所述永磁体12的样品口径达120mm。6. The bone density testing device according to claim 5, wherein the sample diameter of the permanent magnet 12 is up to 120mm.7.一种利用权利要求1～6所述骨密度检测设备进行骨密度检测的方法，其特征是，包括如下步骤：7. A method for bone density detection using the bone density detection equipment described in claims 1 to 6, characterized in that it comprises the following steps:1)将一组测量样本置于所述骨密度检测设备的磁场中心位置，采用自旋回波脉冲序列进行测量，得到每组测量样本的原始磁共振信号，作为每组测量样本的自旋回波数据；1) Place a group of measurement samples at the center of the magnetic field of the bone density detection device, and use a spin echo pulse sequence to measure, and obtain the original magnetic resonance signal of each group of measurement samples as the spin echo data of each group of measurement samples ;2)将步骤1)得到的自旋回波信号数据通过数学反演，得到T₂弛豫时间谱；₂ ) the spin echo signal data obtained in step 1) is obtained by mathematical inversion to obtain the T2 relaxation time spectrum;3)将T₂弛豫时间与生物骨密度之间存在的线性对应关系通过标线公式式4表示，式4中的K值和C值通过将不同样本的T₂弛豫谱与双能X射线骨密度仪测定得到的相应骨密度数据进行回归分析得到；₃ ) The linear correspondence between the T2 relaxation time and the biological bone density is represented by the marking formula Equation 4, and the K value and C value in the formula₄ are obtained by combining the T2 relaxation spectra of different samples with the dual-energy X Regression analysis was performed on the corresponding bone density data obtained by X-ray bone absorptiometry;BMD＝K·T₂+C(4)BMD＝K·T₂ +C(4)式4中，BMD为骨密度(BoneMineralDensity，g/cm²)；T₂为被测样品皮质骨的T₂弛豫时间数据，单位为μs；K为常数，单位为g/(cm²﹒μs)；C为常数，单位为g/cm²；K值和C值随着生物种类不同、性别不同、年龄不同取值不同；In formula 4, BMD is the bone density (BoneMineralDensity, g/cm² ); T₂ is the T₂ relaxation time data of the cortical bone of the tested sample, the unit is μs; K is a constant, the unit is g/(cm² ·μs ); C is a constant, the unit is g/cm² ; the K value and C value are different with different biological species, different genders, and different ages;4)利用步骤2)得到的T₂弛豫时间谱，根据式4计算得到检测骨密度，完成骨密度检测。4) Using the T2 relaxation time spectrum obtained in step₂ ), calculate the detected bone density according to formula 4, and complete the bone density detection.8.如权利要求7所述骨密度检测方法，其特征是，步骤2)将测得的自旋回波数据进行数学反演处理，得到T₂弛豫时间谱；所述数学反演为变换反演算法，具体包括如下步骤：8. bone density detection method as claimed in claim 7, is characterized in that, step 2) carries out mathematical inversion process to the spin-echo data recorded, obtains T₂ relaxation time spectrum; Described mathematical inversion is transformation inversion The algorithm specifically includes the following steps:21)测量得到的自旋回波信号y(t)是一系列单个孔隙自旋回波信号的叠加，通过式11表示；通过求解式11得到相应的T₂弛豫时间谱；式11为：21) The measured spin echo signal y(t) is the superposition of a series of single pore spin echo signals, expressed by Equation 11_; the corresponding T2 relaxation time spectrum is obtained by solving Equation 11; Equation 11 is:$y\left(t\right)={\mathrm{\Σ}}_i{f}_i\·\exp (-\frac{t}{T_{2i}})+\mathrm{\ϵ}\left(t\right),t=n\·\mathrm{\τ}$(式11)$\mathrm{the\; y}\left(t\right)={\mathrm{\Σ}}_i{f}_i\·\exp (-\frac{t}{T_{2i}})+\mathrm{\ϵ}\left(t\right),t=\mathrm{no}\·\mathrm{\τ}$ (Formula 11)式11中，y(t)为自旋回波信号；f_i为第i类孔隙在总孔隙中所占的份额；T_2i为第i类孔隙的T₂弛豫时间；τ为回波间隔时间；ε(t)为随机噪声序列；In Equation 11, y(t) is the spin echo signal; f_i is the share of the i-type pores in the total pores; T_2i is the T2 relaxation time of the i-type pores_; τ is the echo interval time ;ε(t) is a random noise sequence;22)通过构建目标函数式12，求解式11：22) Solve formula 11 by constructing objective function formula 12:${\mathrm{\χ}}^2={\mathrm{\Σ}}_{i=1}^n{\[y_i-{\mathrm{\Σ}}_{j=1}^m(f_j\·m_{ij})\]}^2+\mathrm{\λ}\·{\mathrm{\Σ}}_{j=1}^m{f}_j=\left|\right|y-Mf|{|}^2+\mathrm{\λ}\·|\left|f\right|{|}^2$(式12)${\mathrm{\χ}}^2={\mathrm{\Σ}}_{i=1}^{\mathrm{no}}{\[{\mathrm{the\; y}}_i-{\mathrm{\Σ}}_{j=1}^m(f_j\&Center\; Dot;m_{ij})\]}^2+\mathrm{\λ}\&Center\; Dot;{\mathrm{\Σ}}_{j=1}^m{f}_j=\left|\right|\mathrm{the\; y}-mf|{|}^2+\mathrm{\λ}\&Center\; Dot;|\left|f\right|{|}^2$ (Formula 12)式12中，M＝[m_ij]＝[exp(-t_i/T_2j)]，m_ij＝exp(-t_i/T_2j)；λ为平滑因子；f＝(f₁,f₂,…,f_m)^T为幅度；χ²为相应的目标函数；y_i为选取的n维时域中第i维对应的磁共振信号；f_j为m维T2空间域中第j维对应的孔隙在总孔隙中所占的份额；y为自旋回波信号；In Formula 12, M=[m_ij ]=[exp(-t_i /T_2j )], m_ij =exp(-t_i /T_2j ); λ is the smoothing factor; f=(f₁ , f₂ , ...,f_m )^T is the amplitude; χ² is the corresponding objective function; y_i is the magnetic resonance signal corresponding to the i-th dimension in the selected n-dimensional time domain; f_j is the corresponding signal of the j-th dimension in the m-dimensional T2 space domain The proportion of pores in the total pores; y is the spin echo signal;23)对步骤22)中的幅度f的第k(k＝1,2,…,m)个分量求极值，并使其等于0，得式13：23) Get the extreme value of the k (k=1,2,...,m) component of the amplitude f in step 22), and make it equal to 0, get formula 13:(M^TM)·f+λI_m×m·f＝M^T·y(式13)(M^T M) f+λI_m×m f=M^T y (Formula 13)式13中，I_m×m为m×m阶单位矩阵；M＝[m_ij]＝[exp(-t_i/T_2j)]，m_ij＝exp(-t_i/T_2j)；λ为平滑因子；f＝(f₁,f₂,…,f_m)^T为幅度；y为自旋回波信号；In Formula 13, I_m×m is the unit matrix of order m×m; M=[m_ij ]=[exp(-t_i /T_2j )], m_ij =exp(-t_i /T_2j ); λ is Smoothing factor; f=(f₁ ,f₂ ,…,f_m )^T is the amplitude; y is the spin echo signal;24)对式13做线性变化，令f＝M^T·c代入式13，设定一值，通过式14求出方程式11的最小二乘解：24) do linear change to formula 13, make f=M^T c substitute into formula 13, set a value, obtain the least squares solution of formula 11 by formula 14:$\hat{f}=M^T\·{(M\·M^T+{\mathrm{\λI}}_{n\×n})}^{-1}\·y$(式14)$\hat{f}=m^T\&Center\; Dot;{(m\·m^T+{\mathrm{\λI}}_{\mathrm{no}\×\mathrm{no}})}^{-1}\·\mathrm{the\; y}$ (Formula 14)式14中，为n维幅度值的解；n的个数为布点数，对应n个T₂弛豫时间值。In formula 14, is the solution of the n-dimensional amplitude value; the number of n is the number of distribution points, corresponding to n T₂ relaxation time values.9.如权利要求7所述骨密度检测方法，其特征是，步骤3)所述标线公式具体通过最小二乘法进行线性拟合得到。9. The bone density detection method according to claim 7, characterized in that, the marking formula in step 3) is specifically obtained by linear fitting by the least square method.10.如权利要求7所述骨密度检测方法，其特征是，所述骨密度检测方法为快速测量方法，测量所需时间小于0.5分钟。10. The bone density detection method according to claim 7, characterized in that, the bone density detection method is a rapid measurement method, and the time required for measurement is less than 0.5 minutes.