小动物Look-Locker反转恢复成像在快心率状态下同时产生T1图、电影和反转恢复准备图像:初始研究

目的开发一种可以综合评估快心率小动物的心脏功能和组织特性的MR成像方法。材料与方法所有动物研究均经当地动物伦理委员会批准。在临床3.0T MR设备中应用小动物Look-Locker反转恢复成像(SALLI),使用70mm螺线管线圈。     

MR合成反转恢复成像中反转时间对心肌延迟强化定量精度的影响

正摘要目的探讨MR合成反转恢复成像中反转时间(TI)对心肌梗死(MI)病人心肌延迟强化(LGE)定量精度的影响。方法对53例疑似既往MI发作的病人行1.5 T心脏     

脂肪抑制液体衰减反转恢复序列评估髌周滑膜炎的诊断准确性:初步结果及与增强MR成像的比较

<正>摘要目的确定脂肪抑制(FS)液体衰减反转恢复(FLAIR)MR成像与增强(CE)T_1加权MR成像评估髌周滑膜炎的一致性。材料与方法经机构伦理委员会批准,并免除知情同意。33例膝痛病人行3 T MR成像。成像方案包括常规临床序列、FLAIR FS序列(反转时间:2 200 ms)和CE T_1加权成像。在所有序列上评估滑膜可见性、滑膜厚度和5个髌周区     

建立MRI监测胆道内局部试剂运送技术:应用猪的可行性研究

目的研究MR成像监测胆管内运送钆莫特沙芬(MGd)进入猪胆总管(CBD)壁的可行性。材料与方法动物实验获机构动物保护和使用委员会批准。首先,采用不同浓度的MGd,T1加权MR成像对比剂、化疗药物及细胞标记物的混合物,对人胆管癌细胞进行处理。然后,使用共焦显微镜检     

小鼠肺癌模型的建立与MR成像

目的:观察应用小动物线圈对小鼠移植型肺癌模型MR成像的效果.方法:采用1.5T MRI仪结合小鼠专用线圈对23只小鼠肺癌A549细胞株模型进行成像.结果:①肿瘤大小:直径2～3mm 16只,直径3～4mm7只.②肿瘤数量:单个瘤体21例,两个瘤体2例.③肿瘤部位:腋下21例,侧腹壁2例.④肿瘤强化:轻度～中度强化23例.结论:小鼠肺癌模型适合用小动物线圈MR成像,对小肿瘤或早期肿瘤的研究有价值.     

周围神经修复:在神经断伤鼠模型利用gadofluorine M增强MRI监测种植间充质干细胞的壳聚糖神经导管

目的利用MR成像观察组织工程化构建植入术后鼠神经修复的纵向变化,并确定能否利用gadofluorine M增强MR成像或神经T2值测量监测使用组织工程化构建增强神经再生。材料与方法所有实验协议经机构动物使用和保护委员会批准。组织工程构建是通过在壳聚糖神经管中种植     

肝脏液体衰减反转恢复序列最佳参数的选择及临床应用

目的:探讨液体衰减反转恢复(FLAIR)序列肝脏扫描的最佳参数及临床应用价值。方法:体外实验组将6组不同血红蛋白浓度液体和5组不同浓度的肝囊肿穿刺液埋于载体中,经0.5 T超导MR机行T2WI及FLAIR序列(TR6000 ms,TE 100 ms,TI 1500/1700/1900 ms)扫描,检测并分析相同病灶在T2WI及不同TI值的FLAIR成像的信号强度。结果:体外实验结果显示FLAIR成像随液体蛋白浓度(≥1.64 g/dl)升高和TI值延长其信号呈逐渐升高趋势,优选参数FLAIR成像(TI 1700 ms)可鉴别肝囊肿与肝血管瘤(P<0.05)。结论:FLAIR成像可初步判定液体蛋白含量,优选参数的FLAIR成像结合常规SE序列可提高肝脏病变的鉴别诊断。     

肺功能成像:傅里叶分解MRI和SPECT/CT对猪肺的定性对比研究

目的对比研究实验动物采用傅里叶分解(FD)非增强MR成像的肺通气(VM)和肺灌注加权成像(QW)时与临床上标准化的SPECT/CT的差异。材料与方法该研究由当     

大鼠眼循环的高分辨力三维磁共振微血管成像

摘要目的开发高空间分辨力MR微血管成像技术对大鼠的眼循环进行成像。方法动物实验由机构动物保护委员会批准。使用11.7T磁共振设备定制的小圆形表面线圈,分别在注射单晶氧化铁纳米颗粒(MION)前、后,对8只大鼠眼行MR微血管成像(分辨率为84μm×84μm×84μm或42μm×42μm×84μm)。MR微血管成像测量分别在空气、氧气和混合氧吸入情况下进行。     

应用MR成像控制的聚焦超声制造骨高热:控制策略和药物给予

目的评估应用MR成像控制的聚焦超声制造高热及热敏脂质体实现影像引导下对骨给药的可行性。材料与方法实验经动物保护机构委员会批准。在MR测热法闭环温度控制下,应用聚焦超声在9只兔子大腿的骨肌交界面的直     

Cardiorespiratory and hemodynamic responses to inversion and inversion with sit-ups

Eighteen men were studied during 15 minutes of inversion to determine the effects of 4 sit-ups per minute for 5 minutes on the cardiorespiratory system. Systolic blood pressure, diastolic blood pressure, ventilation, oxygen uptake, and METS increased significantly from preinversion/standing (A) to inversion (B). Arterial blood pressure increased from 122/81 mmHg to 142/99 mmHg during the first 5 minutes of inversion. Oxygen uptake increased from 341 ml.min-1 to 456 ml.min-1. Heart rate decreased significantly from (A) to (B). Double product, frequency of breaths, and tidal volume were not significantly changed from (A) to (B). Blood pressure, double product, ventilation, frequency of breaths, oxygen uptake, and METS increased significantly from the first 5 minutes of inversion (B) to the second 5 minutes of inversion with sit-ups (C). Arterial blood pressure increased from 142/99 mmHg (B) to 163/104 mmHg (C). The diastolic value remained significantly increased following the muscle strengthening exercise. Double product increased from 104 (B) to 126 (C), and oxygen uptake increased from 456 ml.min-1 (B) to 565 ml.min-1 (C). Following inversion/sit-ups (C), oxygen uptake decreased significantly during the third 5 minutes of inversion (D). Systolic blood pressure was also significantly decreased at (D) following the sit-ups. Upon returning to the standing position (E) versus the third 5 minutes of inversion (D), arterial blood pressure decreased significantly from 151/108 mmHg (D) to 123/84 mmHg (E). The postinversion/standing (E) blood pressure was nonsignificantly different from the preinversion/standing (A) blood pressure as was also the case with heart rate, double product, and tidal volume. Ventilation, frequency of breaths, oxygen uptake, and METS were still significantly increased during (E) versus (A). These data illustrate the influence of muscular exercise on the cardiorespiratory system during full -90 degree inversion. The increase in blood pressure is no cause for concern, and the assumed dangerous effects of full inversion have been overestimated.     

Echo-planar spin-echo and inversion pulses

The echo-planar k-space trajectory can be used as the basis for any two-dimensional selective pulse. The main application is spectral-spatial pulses, which must be based on the echoplanar trajectory. In this paper we show how echo-planar spinecho (EPSE) pulses may be designed.     

Continuous inversion angiography

A subtractive time-of-flight technique for magnetic resonance anglography is described. In this approach, the arterial supply to an organ is inverted in a steady-state fashion by applying off-resonance irradiation in the presence of a linear magnetic field gradient. An angiogram is formed by subtracting an image acquired with arterial inversion from a control image acquired with no arterial inversion. A single coil is used to apply both the inversion and observation pulses. Intracranial angiograms obtained from normal volunteers using a two-dimensional projective implementation of this technique at 1.5 T illustrate excellent small vessel detail and background suppression.     

Gd-DTPA-enhanced short repetition time and short inversion time inversion recovery magnetic resonance imaging. Experimental and clinical assessment

To suppress both water and fat signal while retaining the high signal of Gd-DTPA enhancement, magnetic resonance imaging (MRI) of phantoms and 28 patients with mass lesions was done using short repetition time (TR) and short inversion time inversion recovery (STIR) sequences. Optimal STIR pulse sequences of 500 to 1000/80-100/20-30 (TR/TI/TE) were determined by an experimental study. In most instances, a signal bandwidth of +/- 8 kHz was used to increase the signal-to-noise ratio. The authors measured image contrast between lesions and adjacent fatty tissue and compared postcontrast STIR and T1-weighted spin-echo (T1-W SE) images. When the signal intensity of a lesion is 80% of adjacent fatty tissue on postcontrast T1-W SE, short TR STIR images provide better tumor delineation.     

Multiple-readout selective inversion recovery angiography

We have developed a variation of selective inversion recovery (SIR) angiography that allows us to obtain a collection of several angiograms within the same acquisition time previously required to obtain a single image. In basic SIR, a single readout is performed after the tagging inversion pulse. In multiple-readout SIR, a succession of readout pulses is applied following the inversion pulse. By varying the gradients appropriately during the successive readouts, we can obtain a set of multiple projection-angle angiograms, or, by appropriately spacing the readouts throughout the cardiac cycle, we can obtain a set of time-resolved angiograms. This technique allows us to obtain additional spatial or temporal information without increasing total scan time. A sequence of increasing flip-angle read pulses is used to maintain a constant signal level across the images. A trade-off exists between SNR and the number of images acquired.     

A new adiabatic inversion pulse

Adiabatic pulses play an important role in magnetization inversion in the presence of RF field inhomogeneity. In this work the authors present an efficient adiabatic inversion pulse that is able to selectively invert magnetization over a large frequency bandwidth in a short time. The pulse is constructed in two steps: (i) the optimal trajectory is determined and (ii) the optimal rate of motion along that trajectory is determined. The resulting pulse enables separately controlling and trading off the pulse duration against the transition width. The superiority of this pulse over the well known sech/tanh adiabatic pulse is demonstrated in a scenario where a large bandwidth should be inverted at a short time using limited B₁ amplitude.     

MR imaging of uterine inversion

Inversion of the uterus is a postpartum complication that is an obstetric emergency. This report describes a case of inversion of the uterus in which clinical evaluation was inconclusive, and magnetic resonance (MR) of the pelvis revealed findings virtually pathognomonic of incomplete inversion of the uterus with far greater conspicuity than on corresponding ultrasound. The MR findings directly resulted in earlier therapeutic intervention with a possible decrease in morbidity.     

Sonographic and MR features of puerperal uterine inversion

Puerperal uterine inversion is a rare and potentially life-threatening complication of a mismanaged third stage of labour. Early diagnosis is mandatory for proper management of the patient. Complete uterine inversion is a clinical diagnosis. However, incomplete uterine inversion is difficult to identify and warrants further workup. Sonographic evaluation, although a bedside procedure, may be confusing. The conspicuity of findings is much greater on MR examination than on ultrasound. Only a few diagnostic imaging findings in uterine inversion have been described in previous reports. We present the case of a 26-year-old woman who had a full-term vaginal delivery and presented after 20 days with acute urinary retention and mild vaginal bleeding. She was diagnosed as a case of neglected subacute incomplete uterine inversion. Both greyscale and Doppler sonographic and MR features of the case are described with an emphasis on better delineation of uterine and adnexal anatomy on MR imaging.