3.0磁共振成像在丘脑底核靶点定位中的应用研究

目的:探讨3.0T磁共振成像(magnetic resonance imaging,MRI)在丘脑底核(subthalamic nucleus,STN)靶点直视定位的可行性及其临床效果。方法:采用不同场强的MRI技术对23例帕金森病患者进行STN靶点定位脑深部电极植入术。采用T2加权扫描,层厚2 mm,间隔0.5 mm,TE 150～200 ms,TR 4000～5000 ms,FOV33 cm2。结果:术前3.0TMRI能清晰可视STN等重要结构,能够在直视下STN靶点直接定位。3.0T组术中均出现微毁损效应,临床效果满意,术后MRI复查显示电极均位于相关靶点内。结论:3.0TMR能清晰显示STN结构的低信号区,可直视靶点定位,电极位置准确可靠。     

Effect of subthalamic nucleus deep brain stimulation on balance in Parkinson’s disease: A static posturographic analysis

BackgroundThe effect of subthalamic deep brain stimulation on balance in Parkinson’s disease remains unclear.ObjectiveTo evaluate the effect of subthalamic nucleus stimulation on balance in Parkinson’s disease using posturography.Methods16 patients (9 women) who underwent subthalamic deep brain stimulation [mean age 59.6 years (46–70); mean disease duration 15.6 years (7–25); mean duration of subthalamic stimulation 32.1 months (3.0–69.6)] and 13 healthy age-matched controls were evaluated using a static posturography analysis. Patients were assessed under four conditions: 1) off medication/off stimulation; 2) off medication/on stimulation; 3) on medication/off stimulation and 4) on medication/on stimulation in ten experimental paradigms, some reproducing common situations of daily living. The displacement of the centre of pressure was analyzed using 14 posturographic parameters. The Mann-Whitney test was used to compare patients with controls. The Wilcoxon signed rank test was used to compare patients under different clinical conditions.ResultsPatients off medication/off stimulation showed larger and more rapid displacements of the centre of pressure than controls in most paradigms (p < 0.05), particularly when performing a dual task. Subthalamic stimulation alone reduced the lateral excursion and anterior-posterior velocity of the centre of pressure in quite stance paradigms (p < 0.05). Subthalamic stimulation combined with antiparkinsonian medication did not induce statistically significant changes in posturagraphic measures in any experimental paradigm.ConclusionsAlthough subthalamic stimulation alone may induce some positive effect on balance, subthalamic stimulation in addition to antiparkinsonian medication, which is the usual treatment in clinical practice, did not modify balance as assessed by static posturography in patients with Parkinson’s disease.     

MR perfusion imaging in human brain using the UNFAIR technique. Un-inverted flow-sensitive alternating inversion recovery.

Pulsed arterial spin labeling magnetic resonance techniques have been developed recently to estimate cerebral blood flow (CBF). Flow-sensitive alternating inversion recovery (FAIR) is one such technique that has been implemented successfully in humans. Un-inverted FAIR (UNFAIR) is an alternative technique in which the flow-sensitive image is acquired following inversion of all spins outside the slice of interest, and the control image is acquired without any spin labeling. This approach is potentially more efficient than FAIR since the UNFAIR control image is entirely flow independent and need only be acquired once. Here, we describe implementation of the sequence on a clinical 1.5 T magnetic resonance system. Both FAIR and UNFAIR perfusion-weighted images were obtained from six normal volunteers. Wash-in/wash-out curves measured in cortical gray and white matter were practically identical for the two techniques, as predicted by our model.     

用18F-FDG PET研究双侧丘脑底核电刺激对帕金森病神经功能网络的影响

目的 应用18F-FDG PET显像研究双侧丘脑底核(STN)深部脑电极刺激(DBS)对晚期帕金森病(PD)患者神经功能网络的影响.方法 5例晚期PD患者行双侧STN DBS植入术.DBS术后6个月,每例PD患者分别于"开"(处于DBS刺激状态)、"关"(停止DBS刺激状态)状态下行18F-FDG PET静息显像,并对每例患者进行统一PD量表(UPDRS)运动评分.通过统计参数图2(SPM2)软件对图像结果进行数据分析,了解双侧STNDBS对脑葡萄糖代谢尤其是神经功能网络的影响.结果 双侧STN DBS使PD患者豆状核(苍白球)、双侧丘脑、小脑及远隔顶叶皮质的葡萄糖代谢降低,中脑及脑桥的葡萄糖代谢升高,"开"和"关"状态下PD相关模式(PDRP)评分分别为2.12±15.24及4.93±13.01,差异有统计学意义(P＜0.05);且随着临床症状的改善,PDRP评分呈下降趋势.结论 双侧STN DBS能够明显改善晚期PD患者的临床症状,其机制可能是通过调节整个神经网络实现.     

经枢椎椎弓根内固定钉道轨迹的术前三维CT重建

目的 探讨术前CT三维重建经枢椎椎弓根螺钉内固定钉道轨迹的方法及其临床意义。方法 用GE LightSpeed 16 Pro螺旋CT对15具枢椎完整成人干燥标本进行扫描，扫描完成后内插重建为层厚0．6mm、层距0．3mm，在ADW4．2软件上采用容积再现（volume rendering，VR）及多平面重建（multiple planar reformatting，MPR）技术重建和分析图像。在图像工作站中模拟不同方法（方法A：进钉点为下关节突根部的中垂线，出至上关节突与齿突交界处；方法B：进钉点为下关节突背侧的头内1／4处，平行于狭部轴线至上关节突下缘）和不同直径的经枢椎椎弓根钉固定，观察虚拟螺钉在骨性通道中的通行情况，并将钉道参数结果应用于干燥枢椎标本的实际椎弓根内固定。结果 螺钉的轨迹可以从多方位、多角度以及任意轴面上得到动态观察，2具3侧标本的横突孔内侧壁和上关节突下方骨壁菲薄，明显不适于行椎弓根内固定。方法A与B两种钉道轨迹参数比较，二者的钉道长度相近（P〉0．05），方法A的上倾角度和内倾角度大于方法B（P〈0．05，0．01），方法A的骨性通道中可容纳虚拟螺钉的直径明显小于方法B（P〈0．05）。结论 本研究可以模拟经枢椎椎弓根钉固定的不同进钉点、螺钉的不同直径和不同安全角度，并动态观察螺钉的轨迹是否完全在骨性结构内通行，在临床治疗和科研中有较大的应用价值。     

丘脑底核电刺激治疗帕金森病时发音信号的动态分析

 目的 探讨丘脑底核(STN)DBS治疗PD发音障碍的效应.方法 19名PD患者,在服药和未服药状态下,开和关闭DBS,记录声音文件.用扰动和非线性动态分析方法进行分析.结果 t检验显示:植入双侧、左侧和右侧DBS的PD受试者在服药和未服药状态下,分析数值指标在DBS开和关之间没有显著的差异.结论 提示STN DBS对PD患者的周期性和非周期性发音障碍都没有显著改善.     

MR of the brain using fluid-attenuated inversion recovery (FLAIR) pulse sequences.

PURPOSE: Results from conventional T2-weighted spin-echo sequences were compared with those obtained using fluid attenuated inversion recovery (FLAIR) pulse sequences in order to assess their relative merits in detecting disease. METHODS: Forty adult patients with suspected disease of the brain were examined with spin-echo sequences (TE = 20 and TE = 80), and results were compared with FLAIR sequences of several types with inversion times of 1800-3000 msec and echo times of 130-240 msec. Scans were assessed by two radiologists for lesion number, conspicuity, and extent. RESULTS: A total of 48 lesions or groups of lesions were recognized with both sequences. In 22 instances, more lesions were seen with FLAIR sequences, and, in the remaining 26, equal numbers were seen. In 42 lesions, conspicuity was better with FLAIR sequences, equal in five and worse in one cystic lesion. Lesion extent was better assessed in 28 of the 48 cases with FLAIR sequences and equally well seen in the remainder. CONCLUSION: By virtue of their long echo time and relative freedom from cerebrospinal fluid artifact FLAIR sequences provide high sensitivity to a wide range of disease. The basic sequence is easy to implement but is relatively time consuming.     

Parkinson disease: pattern of functional MR imaging activation during deep brain stimulation of subthalamic nucleus--initial experience

PURPOSE: To prospectively determine the pattern of functional magnetic resonance (MR) imaging activation at 3 T produced by deep brain stimulation (DBS) of subthalamic nucleus (STN) for treatment of Parkinson disease and to determine the safety of DBS electrode stimulation during functional MR imaging at 3 T. MATERIALS AND METHODS: Informed consent was obtained from all subjects participating in the study, and the study protocol was approved by the institutional review board at the Cleveland Clinic Foundation and was HIPAA compliant. After extensive phantom safety testing of DBS lead systems, five patients (three men, two women; mean age, 49.4 years +/- 14.5 [standard deviation]; range, 31-74 years) with percutaneously extended bilateral DBS electrodes placed in the STN for treatment of Parkinson disease were examined at 3 T on the 1st or 2nd postoperative day. Imaging consisted of a three-dimensional anatomic data set with leads disconnected and a blood oxygen level-dependent functional MR image with a single lead connected to the external pulse generator in the MR imaging control room by using stimulation parameters previously determined to produce optimal stimulation for alleviation of symptoms. A total of nine leads were tested with the functional MR imaging protocol. Subjects underwent neurologic examination immediately before and after MR imaging. RESULTS: All five patients completed the study without change in their neurologic examination and with activation seen in eight of nine electrodes stimulated. Activation was seen in the ipsilateral basal ganglia in all subjects and ipsilateral thalamus in six of the electrodes tested. Two of the electrode stimulations demonstrated additional activation in the STN and/or substantia nigra region adjacent to the electrode tip. For three electrode stimulations, activation was seen in the contralateral superior cerebellum. CONCLUSION: Therapeutically effective DBS of STN can be performed safely during functional MR imaging at 3 T and produces a consistent pattern of ipsilateral activation of deep brain motor structures.     

Phase-sensitive inversion recovery for detecting myocardial infarction using gadolinium-delayed hyperenhancement.

After administration of gadolinium, infarcted myocardium exhibits delayed hyperenhancement and can be imaged using an inversion recovery (IR) sequence. The performance of such a method when using magnitude-reconstructed images is highly sensitive to the inversion recovery time (TI) selected. Using phase-sensitive reconstruction, it is possible to use a nominal value of TI, eliminate several breath-holds otherwise needed to find the precise null time for normal myocardium, and achieve a consistent contrast. Phase-sensitive detection is used to remove the background phase while preserving the sign of the desired magnetization during IR. Experimental results are presented which demonstrate the benefits of both phase-sensitive IR image reconstruction and surface coil intensity normalization for detecting myocardial infarction (MI). The phase-sensitive reconstruction method reduces the variation in apparent infarct size that is observed in the magnitude images as TI is changed. Phase-sensitive detection also has the advantage of decreasing the sensitivity to changes in tissue T(1) with increasing delay from contrast agent injection.     

Signal suppression of normal liver tissue by phase corrected inversion recovery: a screening technique

A new pulse sequence characterized by simultaneous multislice spin echo (SE) and short inversion time (TI) with inversion recovery (STIR) acquisitions is demonstrated. For the STIR component, a repetition time of 1,000 ms and TI of 210 ms were chosen to suppress the signal from normal liver at 0.5 T and create a fast sequence suitable for screening purposes. Phase correction of the STIR with the SE's signal as a reference resulted in high contrast real IR images that were free of phase error artifact. In 13 min the entire liver could be imaged in 14 adjacent slices, each slice portrayed in an ensemble of four images: a T1-weighted SE image, IR real and modulus images, and a T1 map. Forty-one patients with liver pathology and 10 normal volunteers were examined with the sequence implemented on a commercially available 0.5 T imager (Gyroscan; Phillips). Images demonstrated high liver-lesion contrast and sensitivity to liver lesions. Lesions of less than 1 cm in diameter and lymphomatous lesions, commonly occult to magnetic resonance, were detected.     

In vivo sodium magnetic resonance imaging of the human brain using soft inversion recovery fluid attenuation.

Sodium imaging with soft inversion recovery fluid attenuation, which may be advantageous for intracellular weighting, was demonstrated with cerebrospinal fluid (CSF) suppression in five healthy volunteers at 4.7 T. Long rectangular inversion pulses reduce the average power deposition in an inversion recovery sequence, allowing repetition time to be shortened and more averages acquired for a given scan length. Longer pulses also significantly reduce the "depth" of Mz inversion in environments with rapid T1 and T2 relaxation (i.e., brain relative to CSF). Phantom experiments and simulation show a marked SNR increase when using a 10-ms, rather than a 1-ms, rectangular inversion pulse. Images were acquired in 11.1 min with a voxel size of 0.25 cm3 and the SNR in CSF, which is typically approximately 3 times larger than in brain, was reduced to 23% of that in the brain tissue, which had an average SNR of 17.     

Diagnostic reliability and interobserver agreement in T1-weighted phase sensitive inversion recovery sequence for detection of cervical cord demyelinating plaques

Purpose

To evaluate the diagnostic reliability of PSIR sequence as compared to STIR in detection & counting of MS plaques in cervical cord and assess inter and intra-observer agreement.

Quantitative imaging of magnetization transfer using an inversion recovery sequence.

A new imaging method has been developed for quantitatively measuring magnetization transfer (MT). It uses a simple inversion recovery sequence, although one with very short (milliseconds) inversion times, and thus can be implemented on clinical imaging systems with little modification to existing pulse sequences. The sequence requires an inversion pulse with a length much longer than T(2m) (typically 10 micros) and much shorter than T(2f) (typically tens of ms) and 1/k(mf) (typically tens of ms), where T(2m) and T(2f) are the transverse relaxation times of the immobile macromolecular and free water protons, respectively, and k(mf) is the rate of MT between these populations. The resultant NMR signal is sensitive to MT when this inversion pulse affects the mobile and immobile proton pools to different degrees and by appropriate analysis of the signals obtained for different inversion times, quantitative information can be derived on the macromolecular content and exchange rates within the sample. The method has been used in conjunction with echo planar imaging to produce maps of the spatial distribution of the macromolecular content and MT rate in cross-linked bovine serum albumin. Comparisons between this method and other quantitative MT techniques are discussed.     

T1-Weighted MR imaging of the brain using a fast inversion recovery pulse sequence

The purpose of this paper was to develop and evaluate a fast inversion recovery (FIR) technique for T1-weighted MR imaging of contrast-enhancing brain pathology. The FIR technique was developed, capable of imaging 24 sections in approximately 7 minutes using two echoes per repetition and an alternating echo phase encoding assignment. Resulting images were compared with conventional T1-weighted spin echo (T1SE) images in 18 consecutive patients. Compared with corresponding T1SE images, FIR images were quantitatively comparable or superior for lesion-to-background contrast and contrast-to-noise ratio (CNR). Gray-to-white matter and cerebrospinal fluid (CSF)-to-white matter contrast and CNR were statistically superior in FIR images. Qualitatively, the FIR technique provided comparable lesion detection, improved lesion conspicuity, and superior image contrast compared with T1SE images. Although FIR images had greater amounts of image artifacts, there was not a statistically increased amount of interpretation-interfering image artifact. FIR provides T1-weighted images that are superior to T1SE images for a number of image quality criteria.     

Mapping of lateral geniculate nucleus activation during visual stimulation in human brain using fMRI

Functional magnetic resonance imaging has been successfully used to map the activation in the lateral geniculate nucleus (LGN) in both hemispheres as well as the primary visual cortex (V1) during a checkerboard visual stimulation. The average blood oxygenation level dependent (BOLD) change in LGN was less than that in V1. However, the BOLD temporal responses were similar between LGN and V1. The activation in the pulvinar nucleus during visual perception was also detected, and its activated location could be separated from LGN in 3D images. The LGN activation between intersubject and intrasubject multiple trials was compared. The results demonstrate that fMRI can reliably and robustly detect small subcortical nucleus activation in the human brain.     

Changes in regional cerebral blood flow caused by deep-brain stimulation of the subthalamic nucleus in Parkinson's disease.

The aim of this study was to investigate the effect of deep-brain stimulation of the subthalamic nucleus (STN) on regional cerebral blood flow (rCBF) throughout the entire brain volume in patients with Parkinson's disease and to evaluate which of the brain areas showing an rCBF increase during STN stimulation related significantly to the improvement in motor function. METHODS: Ten consecutive Parkinson's disease patients (6 men, 4 women; mean age +/- SD, 59 +/- 8 y) with bilateral STN stimulators underwent 3 rCBF SPECT examinations at rest: the first preoperatively and the second and third postoperatively (follow-up, 4.8 +/- 1.4 mo) with STN stimulators on and off, respectively. The motor unified Parkinson's disease rating scale, the Hoehn and Yahr disability scale, and the Schwab and England activities-of-daily-living scale were used to evaluate the clinical state under each condition. Statistical parametric mapping was used to investigate rCBF during STN stimulation in comparison with rCBF preoperatively and with STN stimulators off. Also evaluated with statistical parametric mapping was the relationship between rCBF and individual motor scores used as covariates of interest. RESULTS: STN stimulation significantly changed rCBF in the right pre-supplementary motor area (pre-SMA), anterior cingulate cortex, and dorsolateral prefrontal cortex and in the medial Brodmann's area 8 (BA8) as defined in the atlas of Talairach and Tournoux (P < 0.05 corrected for multiple comparisons). The rCBF in these areas increased from the preoperative condition to the stimulators-on condition and decreased again after the stimulators were switched off. A significant correlation was detected between the improvement in motor scores and the rCBF increase only in the right pre-SMA and in the anterior cingulate motor area (P < 0.005, uncorrected). CONCLUSION: According to the topographic organization of the primate STN, our study shows that stimulation of the STN leads to rCBF increases in the motor (pre-SMA), associative, and limbic territories (anterior cingulate) in the frontal cortex. The significant correlation between motor improvement and rCBF increase in the pre-SMA and the anterior cingulate motor area reinforces the hypothesis that STN stimulation in parkinsonian patients can potentiate the cortical areas participating in higher-order aspects of motor control.     

Quantitative breath-hold monitoring of myocardial gadolinium enhancement using inversion recovery TrueFISP.

The purpose of this work was to develop and evaluate the accuracy of a breath-hold IR-TrueFISP acquisition capable of monitoring gadolinium (Gd) concentrations through T1 measurements in the left ventricular blood pool and segments of the myocardium over an extended duration. Measurements using a phantom were performed to assess the accuracy of the technique. Accurate T1 measurements in the expected range after contrast agent administration were obtained with several theoretical formulations. Accurate T1 values before the administration of the contrast agent were obtained only when the incomplete recovery of magnetization during the delay time (TD) between imaging segments was incorporated into the observed signal intensity calculations. T1 measurements over a 1-hr time period were performed in four subjects with known myocardial infarctions. In this small study, Gd differences between recent and old myocardial infarctions were observed.     

Comparison of inversion recovery preparation schemes for lipid suppression in 1H MRSI of human brain.

To reduce contamination from subcutaneous lipid regions in MR spectroscopic imaging (MRSI) of whole brain, lipid signals are often suppressed using T(1) nulling methods. If a range of lipid T(1) values is present, the suppression efficiency will be improved using multiple inversion recovery (MIR) preparation. This study compared single IR (SIR) and double IR (DIR) applied with a volumetric MRSI sequence at 1.5 T based on experimental measurement of lipid T(1) and T(2) relaxation rates. At short and medium echo times (TEs), an approximately 28-47% improvement in lipid suppression was achieved with DIR compared to SIR. However, it also led to a loss of 37-43% in signal-to-noise ratio (SNR) for metabolites. Thus, SIR appears to be the better choice for suppressing lipid signals and maintaining metabolite sensitivity.