异常灌注评分法评价肺血栓栓塞症患者治疗效果的价值

目的 分析异常灌注评分法对肺血栓栓塞症（PTE）疗效的评估价值。方法 选择明确诊断为急性PTE的患者46例，在治疗前及治疗后14d行肺灌注显像，2位核医学科医师分别对肺灌注显像图进行定性分析，随后采用异常灌注评分法和Parker创建的肺段评分法进行肺灌注显像结果判读，比较两者在判读结果方面的一致性及其相关性，并比较2种方法所示的治疗后灌注改善率。结果 2位医师对左肺灌注结果判读的一致性为100％（Kappa值为1．0），对右肺灌注结果判读的一致性为91．3％（Kappa值为0．69）。治疗前后2种灌注评分结果均有较高度的一致性（Kappa值分别为0．657和0．665，P均〈0．001）。在治疗前和治疗后通过2种评分方法所计算的联合评分均呈显著正相关（r值分别为0．770和0．771，P均〈0．001）。肺灌注改善率在2种评分方法之间无显著差异（P=0．128）。结论 异常灌注评分法判读简单，是评价PTE治疗效果的较好方法。     

Concerns for medical radiation programs in Australian universities

The Australian higher education system is in a state of great change. The Federal education minister, Dr Brendan Nelson, has indicated that he intends to continue introducing far-reaching reforms that will impact significantly on how universities conduct teaching and research. The future allocation of government funding for university programs, including those in medical radiation, will have a significant effect on how those programs are delivered and could even determine whether programs remain viable. There will be a financial imperative for academic departments to strengthen research activity and to obtain funding from non-government sources, such as full-fee paying students, in order to generate enough income to cover program delivery. Medical radiation education in Australia is also facing many other challenges. Some of these are longstanding, such as the high cost of medical radiation program delivery, poor levels of research activity and difficulty in recruiting and retaining academic staff. Other problems have arisen recently, such as increased competition for students and a critical shortage of available training placements in clinical practice. The aim of this paper is to raise and explore these issues from a university perspective.     

Prediction and Detection of Secondary Hemorrhages after Thrombolytic Therapy in Ischemic Stroke

Abstract It is well established that thrombolytic therapy increases the risk of secondary intracerebral hemorrhage in ischemic stroke patients. However, the term “intracerebral hemorrhage” (ICH) covers a wide spectrum from tiny spots of blood to massive space-occupying hematoma. We will review the etiology and clinical consequences of secondary hemorrhage after thrombolysis in ischemic stroke patients and discuss the ability of magnetic resonance imaging (MRI) to predict this phenomenon. MRI is a highly sensitive tool for detection of hemorrhagic transformation after ischemic stroke. The definitions of a so-called symptomatic hemorrhage after ischemic infarction differ considerably and will also be described. Attributing a causal relationship of a clinical deterioration to a secondary hemorrhage is not easy and should be only addressed when it exceeds at least 30% of the infarct volume. In other patients, secondary hemorrhage might be regarded as side effect of reperfusion within the region with the most severe perfusion deficit. Cerebral microbleeds (CMBs) are a frequent finding in patients with leukoaraiosis and appear to be a general marker of various types of bleeding- prone small vessel disease and a predictor of recurrent vascular events. Current data do not support the hypothesis that the detection of CMBs is a useful diagnostic criterion for the exclusion of patients with CMBs from thrombolytic therapy. However, an increased risk for the rare patients with numerous CMBs can not be ruled out.      

原发性肝癌的彩色多普勒及三维血流能量成像特征及其临床意义

目的:探讨三维血流能量成像(3D-CPA)和彩色多普勒血流成像(CDFI)的临床应用价值。方法:对47例原发性肝癌的病灶进行二维、CDFI及3D-CPA的检查,比较CDFI及3D-CPA显示肿瘤瘤内或瘤周血流多普勒信号丰富程度及血管分布类型,并检测肿瘤的血流参数。结果:3D-CPA显示肿瘤血流分布丰富程度及血管分布类型与CDFI均有显著性差异(均P<0.05),CDFI均可探及肿瘤的搏动性动脉血流,其中,收缩期峰值血流速度(PSV)为43~157cm/s,阻力指数(RI)为0.49~0.82,大于0.65者45例。结论:3D-CPA结合彩色多普勒血流参数的检测可作为临床评价原发性肝癌血供及血管分布的常规检查方法。     

精神分裂症首次发病患者的磁共振弥散张量显像研究

目的探讨从未用过药的精神分裂症首次发病(以下简称首发)患者的重要白质及部分灰质区的磁共振弥散张量显像(DTI)的特点。方法选取9例首发精神分裂症患者(患者组)及9名年龄、性别、受教育程度与患者组相配对的健康者,应用DTI成像技术检测脑额颞交界处、内囊等白质区和颞中回灰质、中央前回、中央后回等灰质区的各向异性(FA)、表观扩散系数(ADC)及双侧海马体积。结果患者组及对照组组内左右两侧兴趣区FA值及ADC值的差异无统计学意义(P>0.05);患者组与对照组各感兴趣区FA值差异无统计学意义(P>0.05),但患者组颞中回灰质(8.655×10-9)、中央前回(7.816×10-9)、中央后回(7.855×10-9)ADC值高于对照组(分别为7.428×10-9,6.921×10-9,7.013×10-9;P=0.049,0.009,0.005);两组内及组间双侧海马体积比较,差异均无统计学意义(P>0.05)。结论首发精神分裂症患者与健康者DTI参数之间没有明显区别。     

磁共振成像在肝移植术后并发症诊断中的应用

目的探讨磁共振成像在肝移植并发症诊断中的价值。方法回顾分析11例肝移植术后发生并发症者的磁共振检查影像资料。结果11例患者术后出现皮肤和巩膜黄染、发热以及尿黄等症状，丙氨酸转氨酶、天冬氨酸转氨酶、γ-谷氨酰转移酶和胆红素升高．经B型超声波检查不能明确原因，采用磁共振（MRI、MRA和MRCP）检查，明确肝动脉吻合口狭窄1例；肝动脉闭塞2例；下腔静脉吻合口狭窄及血栓形成各1例；胆管吻合口狭窄4例，其中1例伴胆汁瘤形成；肝门水平非吻合口狭窄6例；肝坏死2例；肝包膜下血肿及右肾上腺出血各1例；均显示不等量的右侧胸腔积液、腹腔积液及肝门部水肿。结论磁共振一次检查可显示肝内外的多种结构，能为肝移植术后并发症的诊断提供丰富的肝脏、血管、胆道以及肝外结构的图像信息。     

鼻咽癌颈静脉孔侵犯的影像学表现及临床分析

[目的]探讨鼻咽癌颈静脉孔侵犯的临床和影像学特征及临床意义。[方法]回顾性分析8例初治和4例复发鼻咽癌伴颈静脉孔侵犯者的临床表现、CT及MRI特征。[结果]12例中,5例表现为Ⅸ￣Ⅺ颅神经均麻痹的颈静脉孔综合征,7例仅表现为Ⅸ颅神经麻痹。12例,有10例合并舌下神经管受累,3例有一侧的胸锁乳突肌及斜方肌萎缩,2例有一侧舌肌萎缩。CT及MRI显示鼻咽癌颈静脉孔侵犯主要有3种途径,分别为:①鼻咽病变通过茎突后间隙直接蔓延(4例,包括1例茎突后间隙复发);②转移淋巴结直接侵犯(4例,其中2例为咽后淋巴结转移,2例为颈动脉鞘淋巴结复发);③颈静脉孔骨性结构直接破坏(4例,其中1例为单纯颈静脉孔复发)。[结论]鼻咽癌可通过直接蔓延、咽后和颈动脉鞘区转移淋巴结侵犯及骨质直接破坏侵犯颈静脉孔,临床上出现Ⅸ￣Ⅺ颅神经一支或多支均麻痹。CT和MRI,尤其是MRI对于病变的诊断、病变范围的确定和放射治疗计划的制定有非常大的作用。     

Optimizing the efficiency of high-field multivoxel spectroscopic imaging by multiplexing in space and time.

A new strategy to yield information from the maximum number of voxels, each at the optimum signal-to-noise ratio (SNR) per unit time, in MR spectroscopic imaging (MRSI) is introduced. In the past, maximum acquisition duty-cycle was obtained by multiplexing in time several single slices each repetition time (TR), while optimal SNR was achieved by encoding the entire volume of interest (VOI) each TR. We show that optimal SNR and acquisition efficiency can both be achieved simultaneously by multiplexing in space and time several slabs of several slices, each. Since coverage of common VOIs in 3D proton MRSI in the human brain typically requires eight or more slices, at 3 T or higher magnetic fields, two or more slabs can fit into the optimum TR (approximately 1.6 s). Since typically four or less slices would then fit into each slab, Hadamard encoding is favored in that direction for slice profile reasons. It is demonstrated that per fixed examination length, the new method gives, at 3 T, twice as many voxels, each of the same SNR and size, compared with current 3D chemical shift imaging techniques. It is shown that this gain will increase for more extensive spatial coverage or higher fields.     

Real‐time RF pulse adjustment for B0 drift correction

Although the magnetic field of an MR scanner is very stable under little or no load, it can become less stable under heavy‐duty cycle conditions, such as in diffusion tensor imaging (DTI). Uncorrected, such field drifts lead to an apparent image shift along the phase‐encoding direction and decreasing effectiveness of fat saturation pulses. A method is presented to adjust the center frequency of all RF pulses and the receiver in real time during the acquisition. No data postprocessing or changes to the sequence timing are necessary. In vivo acquisitions were performed to assess the prolonged effectiveness of fat saturation. Field drifts of approximately 2.5 Hz/min were measured and corrected during DTI acquisitions at b‐values of up to 3000 s/mm². The effectiveness of fat saturation diminished over the duration of an 18‐min acquisition when the drift was left uncorrected. The proposed method corrects for apparent image shift and ensures continuously effective fat saturation over the duration of an acquisition. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.     

晚期肝硬化肝脏MR灌注成像的灌注量化分析

目的:使用动态增强MR成像技术获得的肝灌注系数(HPI),评价其在反映肝移植前晚期肝硬化患者肝脏血供特点中的价值。方法:使用1.5T MR扫描仪对100例正常肝脏组和57例晚期肝硬化患者移植前的受体肝脏进行快速团注对比剂(Gd-DTPA)后的斜冠状断面单层2D SPGR序列的MR灌注成像检查,比较对照组和肝硬化组门静脉和肝实质的时间-信号强度变化曲线(TIC)特点及峰值时间。根据腹腔干水平腹主动脉和门静脉主干的TIC为参照设置时间参数,计算受检者肝脏实质动脉期和静脉期的正增强系数(PEI)。设定肝灌注系数(HPI)=动脉期PEI/(动脉期PEI 门脉期PEI)×100%。对两组受检者HPI进行统计分析,根据HPI的受试者工作特性曲线(receiver operator characteristiccurve,ROCcurve)选择诊断肝硬化的HPI参考标准。结果:对照组及肝硬化组门静脉曲线峰值时间分别为(38.66±4.14)s和(55.51±5.31)s,P<0.01;肝实质TIC峰值时间分别为(56.24±4.47)s和(81.39±7.02)s,P<0.01;对照组及肝硬化组肝实质的HPI分别为(18.9±3.5)%和(26.4±5.5)%,P<0.01;应用HPI>21.6%为诊断肝硬化的标准,敏感度为86%,特异度为85%,阳性预测值为77%,阴性预测值为91%,诊断符合率为85%。结论:MR灌注成像技术可以在活体状态下无创分析肝内血供,此技术可用于评估晚期肝硬化患者肝移植前肝脏内的血流灌注。