Magnetic resonance elastography with guided pressure waves

Magnetic resonance elastography aims to non-invasively and remotely characterize the mechanical properties of living tissues. To quantitatively and regionally map the shear viscoelastic moduli in vivo, the technique must achieve proper mechanical excitation throughout the targeted tissues. Although it is straightforward, ante manibus, in close organs such as the liver or the breast, which practitioners clinically palpate already, it is somewhat fortunately highly challenging to trick the natural protective barriers of remote organs such as the brain. So far, mechanical waves have been induced in the latter by shaking the surrounding cranial bones. Here, the skull was circumvented by guiding pressure waves inside the subject's buccal cavity so mechanical waves could propagate from within through the brainstem up to the brain. Repeatable, reproducible and robust displacement fields were recorded in phantoms and in vivo by magnetic resonance elastography with guided pressure waves such that quantitative mechanical outcomes were extracted in the human brain.     

Temperature-controlled power modulation compensates for heterogeneous nanoparticle distributions: a computational optimization analysis for magnetic hyperthermia

Purpose: To study, with computational models, the utility of power modulation to reduce tissue temperature heterogeneity for variable nanoparticle distributions in magnetic nanoparticle hyperthermia.

Methods: Tumour and surrounding tissue were modeled by elliptical two- and three-dimensional computational phantoms having six different nanoparticle distributions. Nanoparticles were modeled as point heat sources having amplitude-dependent loss power. The total number of nanoparticles was fixed, and their spatial distribution and heat output were varied. Heat transfer was computed by solving the Pennes’ bioheat equation using finite element methods (FEM) with temperature-dependent blood perfusion. Local temperature was regulated using a proportional-integral-derivative (PID) controller. Tissue temperature, thermal dose and tissue damage were calculated. The required minimum thermal dose delivered to the tumor was kept constant, and heating power was adjusted for comparison of both the heating methods.

Results: Modulated power heating produced lower and more homogeneous temperature distributions than did constant power heating for all studied nanoparticle distributions. For a concentrated nanoparticle distribution, located off-center within the tumor, the maximum temperatures inside the tumor were 16% lower for modulated power heating when compared to constant power heating. This resulted in less damage to surrounding normal tissue. Modulated power heating reached target thermal doses up to nine-fold more rapidly when compared to constant power heating.

Conclusions: Controlling the temperature at the tumor-healthy tissue boundary by modulating the heating power of magnetic nanoparticles demonstrably compensates for a variable nanoparticle distribution to deliver effective treatment.     

Principles of pressure transducer function and sources of error in clinical use

The invasive measurement of physiological pressures is a common requirement in anaesthesia and intensive care medicine. From arterial blood pressure to intracranial pressure, these calculated variables give a swift graphical and numerical representation of a patient's current physiological status. This allows us to respond rapidly to conditions outside our preferred parameters and to carefully titrate treatment to target effects. These systems are, however, not infallible. An understanding of the principles of their function will promote appropriate use and an ability to recognize and react to sources of error. This article aims to furnish the reader with this level of understanding in order to inform their academic and clinical practice.     

完全型雄激素不敏感综合征2例临床特点及处理

雄激素不敏感综合征(androgen insensitivity syndrome,AIS)又称为睾丸女性化综合征(testicular feminization syndrome,TFS),是一种X连锁遗传病,是男性假两性畸形中较常见的类型,可分为完全型AIS和不完全型AIS,其原因主要是雄激素受体(androgen receptor,AR)基因的突变导致其对雄激素产生抵抗和不应答。本文回顾南京医科大学附属妇产医院2例CAIS患者的临床资料及诊疗过程,以期能进一步提高对该病的认知及诊治水平。     

磁共振结合高分辨率CT在中耳乳突炎患者术前评估中的临床应用

目的探讨磁共振结合高分辨率CT在中耳乳突炎患者术前评估中的临床应用。方法选取我院2018年11月~2020年12月接收患有中耳乳突炎的患者40例为研究对象,所有患者均采用磁共振以及高分辨率CT进行诊断检查,比较两组患者诊断后手术特征显示度。结果诊断后,磁共振联合高分辨率CT检查图像显示度高于单独使用磁共振或高分辨率CT诊断(P<0.05)。结论使用磁共振结合高分辨率CT对中耳乳突炎患者进行术前评估,显示度较高,提高诊断准确度,值得推广。     

基于1H-NMR植物代谢组学技术分析青海产区枸杞子的化学特征

目的:采用核磁共振氢谱(~1H-NMR)植物代谢组学技术比较青海产区枸杞子与其他产区(宁夏、甘肃、新疆、内蒙古)枸杞子的化学成分差异。方法:收集5个产区共97份枸杞子样本,其中青海61个样本,采用50%甲醇提取,检测~1H-NMR图谱,结合多元统计分析,对比青海产区枸杞子与其他产区枸杞子的化学差异性,并对各产区样本的枸杞多糖进行含量测定(以无水葡萄糖计),检测波长490 nm。结果:枸杞子的~1H-NMR图谱共检测到32个化学成分,多元统计分析表明青海产区枸杞子与其他产区样本相比,无明显分离趋势;青海产区枸杞子与宁夏产区相比,以及青海省6个不同地区的枸杞子相比,重叠样品较多,均不能显著分开。相似度结果表明,大多数样品的相似度0.85;化合物的单变量分析结果显示,除了蔗糖、葡萄糖、脯氨酸等个别代谢物在各产区样本中存在显著差异外,其余代谢物在各产区样品中的含量分布基本一致。青海与其他产区样本中枸杞多糖含量无显著性差异,且枸杞多糖含量与~1H-NMR指认的小分子化合物的相关系数处于-0.2～0.4。结论:采用~1HNMR植物代谢组学技术从整体化学组成上分析了青海产区枸杞子的化学特征,并结合枸杞多糖含量测定,显示青海产区枸杞子与其他产区枸杞子的化学差异较小。建立的基于~1H-NMR的枸杞子质量评价方法可为其质控水平提升及种植产区选择提供科学依据。     

脑血管疾病后Holmes震颤的临床、影像和电生理特点

目的 总结脑血管疾病后Holmes震颤的临床、影像和电生理特点。 方法 回顾性分析2015年8月-2019年8月就诊于首都医科大学附属北京天坛医院的4例脑血管疾病 所致Holmes震颤患者，对其临床、影像及电生理资料进行分析总结。 结果 4例患者中2例由高血压性脑出血引起，另外2例分别由脑动静脉畸形和脑海绵状血管瘤破裂 出血引起。Holmes震颤出现于原发病后1～24个月，表现为病灶对侧肢体震颤，以上肢多见。头颅MRI 检查显示2例患者病灶仅累及丘脑，2例同时累及丘脑和中脑。震颤分析显示静止、姿势、意向及持物 1000 g几种状态下震颤的峰频率均在2.6～3.8 Hz，意向状态震颤半宽功率高于静止状态。主动肌与 拮抗肌在静息时以同步收缩为主，姿势、意向和持物时以交替收缩为主。3例接受普拉克索治疗均有 不同程度缓解。 结论 Holmes震颤多由累及中脑、丘脑部位脑血管疾病引起，表现为2～4 Hz低频震颤，意向状态震 颤明显，部分患者多巴胺受体激动剂治疗有效。