BLADE技术在3.0T磁共振克服关节扫描中运动伪影上的临床应用

目的:探讨在3.0T磁共振成像过程中,刀锋伪影较正(BLADE)技术在克服关节扫描中运动伪影方面的的的临床应用.方法:20例行四肢关节MR扫描检查的患者(肩关节10例,腕关节10例),在常规行T2WI常规扫描中出现不同程度的运动伪影,然后引入BLADE技术,扫描T2WI.,以能否清晰显示韧带肌腱而无重影为标准,对比常规序列扫描来评价BLADE技术在消除关节扫描过程中图像运动伪影方面的价值.结果:常规T2扫描出现运动伪影,用BLADE技术序列扫描出来的图像运动伪影消失,对比度明显提高.结论:应用BLADE技术进行扫描可以有效消除病人细微运动造成的运动伪影,获得高分辨率无伪影具有临床诊断价值的理想的图像.     

棉铃虫单核衣壳核多角体病毒解螺旋酶基因的序列分析

对棉铃虫单核衣壳核多角体病毒（Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus,HaSNPV）基因组中EcoR I-N片段进行序列分析,获得了完整的解螺旋酶基因（hel）,其开放阅读框大小为3762bp,编码一个分子量为146kD的蛋白质。在hel起始密码子ATG上游50位有强晚期启动子转录起始信号ATAAG,在－112位和－189位存在两个TATA box,但未发现早期转录信号CAGT。其在终止密码子下游第12位有一PolyA终止信号AATAAA。在其它真核或原解螺旋酶中存在的7个保守基元（Ⅰ、Ⅰa、Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ）,只有5个（Ⅰ、Ⅰa、Ⅱ、Ⅲ、Ⅳ）在杆状病毒中保守。同源性比较发现,HaSNPV解螺旋酶的氨基酸序列与甜菜夜蛾核多角体病毒（Spodoptera exigus MNPV,SeMNPV）的解螺旋酶具有最高的同源性（66％）,与Xestia c-nigrum颗粒体病毒（XcGV）解螺旋酶的同源性最低（43％）。HaSNPV解螺旋酶基因是第一个报道的单粒包埋核多角体病毒的解螺旋酶基因。     

Balance—FFE序列在胆管磁共振检查中的应用

目的：探讨磁共振平衡式稳态自由进动梯度回波序列（Balance—FFE）在胆管疾病中的应用价值。方法：92例胆管病变患者均进行了冠状面的Balance—FFE序列扫描和磁共振胰胆管造影（MRCP）。将Balance-FFE的图像和3DMRCP像及MRCP原始图像对病变的显示率进行X。检验。结果：胆管系统在Balance—FFE序列中呈明显高信号,并能直接显示胆管结石和胆管狭窄,还能显示胆管外病变和胰腺病变,对周围淋巴结的显示也比较清楚。经x^2检验,Balance—FFE序列和MRCP原始像对胆管系统病变的显示没有统计学意义（P〉0．05）,而3DMRCP像对病变的显示能力不如Balance．FFE序列和MRCP原始像,对胆道病变的显示能力具有统计学意义（P〈0．05）。结论：Balance-FFE序列对胆道病变能清晰显示,成像速度快,图像信噪比高,伪影较少,与MRCP结合能提高对胆管系统病变的诊断率,因此Balance-FFE序列应作为胆管疾病磁共振扫描的常规序列,可作为MRCP序列的有效补充。     

MRI动态增强扫描在子宫恶性肿瘤分期中的价值

目的探讨MRI动态增强扫描诊断子宫恶性肿瘤分期的价值。方法选取2016年11月～2017年11月我院收治的经病理确诊为子宫恶性肿瘤患者43例,所有患者术前给予横断面T1WI、横断面T2WI、矢状面T2WI STIR、Gd-DTPA动态增强矢状面、常规横断面以及矢状面T1WI增强扫描,分析动态增强扫描与常规序列扫描的肿瘤图像、结合带及子宫肌层情况,评估MRI动态增强扫描诊断子宫恶性肿瘤分期的价值。结果 MRI动态增强扫描图像可见子宫结合带和子宫肌层显示良好,且未见明显侵犯;DCE-MRI(动脉晚期)可见子宫后下方结合带部分毛糙,并累及浅肌层。43例子宫恶性肿瘤患者中,术后病理Ⅰ期36例,其中Ⅰa期6例,Ⅰb期25例,Ⅰc期5例;Ⅱ期5例;Ⅲ期2例。4例子宫内膜间质肉瘤患者均为Ⅱ期。术后病理检测诊断子宫内膜癌Ⅰa期和Ⅱ期准确率均高于常规序列组(P0.05);常规序列扫描与动态增强扫描诊断Ⅰb期和Ⅱ期的准确率比较,差异有统计学意义(P0.05)。结论 MRI动态增强扫描诊断子宫恶性肿瘤有显著价值,能够清晰显示子宫恶性肿瘤范围和组织侵犯情况,对手术前分期以及治疗措施的选择有指导意义。     

乳腺MR检查的常见伪影及解决方案

目的:分析乳腺MR检查中的常见伪影,探讨合理的解决方案,以提高乳腺MR图像质量及诊断准确性。方法:随机抽取我院100例行乳腺MR检查的图像资料,观察图像中出现的各种伪影及其表现,分析其产生的原因和影响因素。结果:乳腺MR图像的影像细节显示能力较强,图像质量与扫描技术关系密切,影响图像质量的常见伪影有:硬件相关伪影、图像处理相关伪影、运动相关伪影。结论:加强MR设备的使用管理,选择合理的扫描序列及参数,做好乳腺MR扫描的检查前准备及扫描,有助于提高乳腺病变的检出率。     

小分子G蛋白Rap1 shRNA表达载体的构建和鉴定

应用RNA干扰（RNA interference,RNAi）技术抑制Rap1基因的表达,构建RaplshRNA（small hairpin RNA．shRNA）表达载体,观察其对小鼠肝脏细胞中RaplmRNA和蛋白表达的干扰作用．根据小鼠RaplmRNA的全序列．设计了3种Rap1 siRNA序列（Rap1 siRNA1、Rap1 siRNA2、Rap1 siRNA3）和阴性对照序列（HK）;采用克隆技术,将其插入带有报告基因绿色荧光（EGFP）的pGenesi1－3载体,构建RaplshRNA表达载体：经双酶切和测序证实Rap1 siRNA表达载体克隆构建成功,插入片段测序结果与合成的siRNA结果一致：昆明小鼠40只,体重18～20g,随机分成4组：I组（转染HK组）、Ⅱ组（转染RaplshRNAl组）、Ⅲ组（转染RaplshRNA2组）、Ⅳ组（转染Rap1 shRNA3组）．于0、16、24h腹腔内注射Rap1 shRNA2．0－2．5mg／kg（用PBS稀释至1mL）：48h后收集小鼠肝脏．用显微荧光、定量RT—PCT、免疫组化检测小鼠肝细胞中Rap1 shRNA的转染率、Rap1基因表达以及蛋白质表达水平．I组、Ⅱ组、Ⅲ组、Ⅳ组小鼠肝脏细胞体内转染率均大于60％．Ⅱ组、m组、Ⅳ组的RaMmRNA表达、Rap1蛋白表达均降低．其中Rao1 shRNA1干扰效果最佳．     

外阴阴道假丝酵母菌病的阴道清洁度观察

目的观察外阴阴道假丝酵母菌病阴道清洁度的情况。方法用湿片法进行阴道分泌物检查,随机选取1000例念珠菌阳性分泌物,对其阴道清洁度进行观察。结果1000例念珠菌阳性分泌物中,阴道清洁度Ⅳ度有606例,阴道清洁度Ⅲ度有279例,阴道清洁度Ⅱ度有82例,阴道清洁度Ⅰ度有33例。结论虽然大多数念珠菌阳性分泌物（88．5％）阴道清洁度异常（Ⅲ～Ⅳ度）,但仍然有少数念珠菌阳性分泌物（11．5％）阴道清洁度属于正常（Ⅰ～Ⅱ度）。这一结果应有助于临床妇产科医生在为患者做常规妇检、在外观性状上对阴道分泌物作判断时采取更加谨慎的态度。     

维生素C和E合用对应激和非应激中华鳖幼鳖生长、肝脏维生素C和E以及血清皮质醇含量的影响

为探讨维生素C (VC)和维生素E (VE)联用对应激和非应激中华鳖幼鳖的生长、肝脏VC 和VE 以及血清皮质醇含量的影响 ,作者使用了 5组饵料 ,VC 和VE 的添加量依次为 0和 0mg/kg (对照组 )、 2 5 0和 5 0mg/kg (实验Ⅰ组 )、2 5 0 0和 5 0mg/kg (实验Ⅱ组 ) ;2 5 0和 2 5 0mg/kg (实验Ⅲ组 ) ;2 5 0 0和 2 5 0mg/kg(实验Ⅳ组 )。中华鳖幼鳖的生长、肝脏VC 和VE以及血清皮质醇分别通过特定生长率、高压液相色谱法和放免法来测定。结果实验Ⅰ -Ⅳ组中华鳖的特定生长率明显高于不加VC 和VE的对照组 ,但实验Ⅰ -Ⅳ组间没有明显不同。非应激中华鳖肝脏VC 和VE的含量随饵料中VC 和VE 含量的增加而明显升高 ,并且实验Ⅱ -Ⅳ组肝脏VC 和VE都明显高于对照组和实验Ⅰ组。酸应激后 ,对照组和实验组中华鳖肝脏VC 和VE都有下降的趋势 ,但无显著差异 ;应激后实验Ⅱ -Ⅳ组肝脏VC 和VE均明显高于对照组 ,实验Ⅳ组明显高于其它 4组。血清皮质醇的含量在实验Ⅰ -Ⅳ组间没有明显不同 ,实验Ⅰ -Ⅲ组与对照组相比虽有降低的趋势但没有变化 ,实验Ⅳ组则明显低于对照组。酸应激后 ,对照组血清皮质醇明显升高 ,其他 4组虽有升高的趋势 ,但没有明显变化。应激后实验Ⅰ -Ⅳ组血清皮质醇的含量均明显低于对照组 ,实验Ⅰ -Ⅳ组间没有明显     

口腔内金属材料对磁共振检查的影响

检测口腔内常用金属材料在磁共振检查时是否有伪影和伪影的严重程度。对２１种口腔内常用金属材料做了磁共振成像测试,磁共振仪磁场强度为１．５Ｔ,所用序列是梯度回波。铸金片、银汞合金、银尖等９种材料无伪影;钛合金和金属烤瓷成品有轻度伪影;牙用固位钉、椿钉等１０种材料有严重伪影。部分口腔内金属材料会引起严重伪影,影响图象质量,所以在做口腔颌面部和服部磁共振成像时,须引起重视。     

四种苏丹红染料对小鼠体内血液的影响

目的探讨苏丹红对小白鼠血液和组织器官的影响。方法取小鼠连续12 d腹腔注射不同剂量苏丹红Ⅰ、Ⅱ、Ⅲ、Ⅳ（0、40、80、160 mg/kg）,末次给药24 h后采集血样,用血细胞分析仪检测血常规指标,毛细血管法测定凝血时间,剖腹取主要器官称重,计算脏器系数。结果苏丹红Ⅰ和Ⅱ组血液红细胞数明显减少,而苏丹红Ⅲ和Ⅳ组不明显,苏丹红不同剂量之间比较,低剂量苏丹红Ⅰ和高剂量苏丹红Ⅱ组比苏丹红Ⅲ和Ⅳ组血液红细胞数变化明显;苏丹红Ⅰ和Ⅱ组血液血红蛋白含量明显降低,而苏丹红Ⅲ和Ⅳ组血红蛋白含量变化不明显。四种不同剂量苏丹红组小鼠血液中血小板数量减少,随着剂量增加小鼠血液凝固时间延长。随着苏丹红剂量增加,苏丹红I和II组小鼠血液白细胞数比对照组明显增加,苏丹红Ⅲ和Ⅳ组白细胞数有增加趋势但差异不显著。与对照组比较,苏丹红组小鼠血液白细胞数明显增加、而淋巴细胞和单核细胞显著减少。随着苏丹红注射剂量增加,肾脏和脾脏脏器系数较对照组明显增大,肝脏脏器系数变化不明显。结论苏丹红对小鼠血液细胞、血红蛋白、血小板和凝血时间以及组织器官都有不同程度影响。     

CT与MRI对肝硬化背景下小肝癌检出率的比较

目的:分析比较CT与MR对肝硬化背景下小肝癌检出情况,探究CT与MR在肝硬化背景下小肝癌的诊断价值。方法:选择2010年6月~2015年6月期间,我院收治确诊为肝硬化背景下小肝癌患者91例为研究对象,病理及临床相关方法确诊102个病灶,其中小肝癌69个和微小肝癌33个,患者均在不同时期或序列下行多排螺旋CT与MRI检查,分析比较两者对小肝癌和微小肝癌的检出率。结果:多排螺旋CT检查发现肝癌小病灶91个,其中66个小肝癌,25个微小肝癌;MRI检查发现95个病灶,小肝癌67个,微小肝癌28个;69个小肝癌病灶,检出率最高的为CT动脉期(92.75%)与LAVA动脉期(92.75%),检出率最低的为CT平扫(76.81%);33个微小肝癌病灶,检出率最高为LAVA动脉期(75.76%),检出率最低的为LAVA平衡期(36.36%);CT平扫、门静脉期、动脉期、平衡期、MRI-IN-PHASE、LAVA平衡期、LAVA平扫对小肝癌的检出率显著高于对微小肝癌的检出率(P0.05);CT对小肝癌的检出率显著高于微小肝癌的检出率(P0.05),MRI对小肝癌与微小肝癌的检出率无显著差异(P0.05);MRI与CT对小肝癌的检出率不存在差异(P0.05),但MRI对微小肝癌的检出率显著高于CT(P0.05)。结论:MRI-LAVA的动脉期序列对小肝癌病灶与微小肝癌病灶的检出率最高;CT与MRI在对小肝癌的检出率不存在差异,但MRI对微小肝癌的检出具有更明显的优势。     

Optimizing MRI sequences and images for MRI-based stereotactic radiosurgery treatment planning

AimDevelopment of MRI sequences and processing methods for the production of images appropriate for direct use in stereotactic radiosurgery (SRS) treatment planning.BackgroundMRI is useful in SRS treatment planning, especially for patients with brain lesions or anatomical targets that are poorly distinguished by CT, but its use requires further refinement. This methodology seeks to optimize MRI sequences to generate distortion-free and clinically relevant MR images for MRI-only SRS treatment planning.Materials and methodsWe used commercially available SRS MRI-guided radiotherapy phantoms and eight patients to optimize sequences for patient imaging. Workflow involved the choice of correct MRI sequence(s), optimization of the sequence parameters, evaluation of image quality (artifact free and clinically relevant), measurement of geometrical distortion, and evaluation of the accuracy of our offline correction algorithm.ResultsCT images showed a maximum deviation of 1.3 mm and minimum deviation of 0.4 mm from true fiducial position for SRS coordinate definition. Interestingly, uncorrected MR images showed maximum deviation of 1.2 mm and minimum of 0.4 mm, comparable to CT images used for SRS coordinate definition. After geometrical correction, we observed a maximum deviation of 1.1 mm and minimum deviation of only 0.3 mm.ConclusionOur optimized MRI pulse sequences and image correction technique show promising results; MR images produced under these conditions are appropriate for direct use in SRS treatment planning.     

Age-dependent 6kb deletion in human liver mitochondrial DNA.

Using PCR technique, restriction mapping and DNA sequencing, we analyzed liver mitochondrial DNA (mtDNA) of 2 stillborn babies and 62 Chinese subjects with non-liver disease from 27 to 86 years old. The results showed an age-dependent 6,063 bp deletion in the liver mtDNA of older subjects. We found a TAACAGAC sequence flanking the 5'-end breakpoint at 7,842 nucleotide position and an imperfect repeat sequence CAACATAC flanking the 3'-end breakpoint at 13,905 nucleotide position. The incidence of the deleted mtDNA was found to increase with age. The deleted mtDNA was not detected in the liver of the stillbirth or blood cells of all the subjects. This is the first account that an age-related 6,063 bp deletion occurs in the liver mtDNA of old humans. The occurrence of this and previously reported 4,977 bp deletions is consistent with our recent finding that liver mitochondrial respiratory functions decline with age and support the hypothesis that continuous accumulation of mtDNA mutations is an important contributor to ageing process in the human.     

MRI和螺旋CT增强在肝脏占位性病变诊断中的价值比较

目的:对比分析MRI和螺旋CT增强在肝脏占位性病变诊断中的价值。方法:以2012年7月-2016年5月我院收治的临床考虑为肝脏占位性病变70例患者为研究对象,将70例患者根据入组先后顺序分为两组,35例行增强CT扫描,35例行动态增强MRI扫描,比较两组患者的病理诊断结果、病灶个数及直径、增强CT及MRI的诊断结果和检查过程中的不良反应及耐受性。结果:CT增强组和MRI增强组的肝脏占位性病变的病理诊断、病变类型、分布及病灶个数(71 vs 70)、病灶直径(2.25±2.01 cm vs2.19±1.98 cm)比较差异均无统计学意义(P0.05);以病理诊断结果为金标准,MRI增强组的总诊断符合率为85.71%,CT增强组的总诊断符合率为77.14%,MRI增强组的总诊断符合率高于CT增强组,但差异无统计学意义(P0.05);CT增强组共发生2例不良反应,均为轻度恶心,MRI增强组未出现造影剂不良反应,CT增强组的不良反应发生率(5.71%vs 0.00%)及视觉模拟评分法(VAS)评分(1.25 0.96分vs 0.71 0.56分)均显著高于MRI增强组(P0.05)。结论:CT增强和MRI增强扫描对于肝脏占位性病变的诊断均具有较高的临床价值,其中MRI增强扫描的安全性和耐受性更高,临床医师可根据患者的经济状态、身体状态等因素的综合评估,选择合适的检查手段,必要时可两者联合检查,以提高诊断的准确性。     

The effects of the use of piezoelectric motors in a 1.5-Tesla high-field magnetic resonance imaging system (MRI).

PURPOSE: This paper presents the results of an experimental investigation with two different rotatory piezomotors in a closed 1.5 Tesla high-field MRI. The focus of the investigation was on testing the functionality of these motors within the MRI and to determining the image interference they caused. MATERIALS AND METHODS: To obtain a differentiated estimate of the interference the motors were tested in both the passive (turned off, i.e. without current flow) and active (turned on, i.e. with current flow) state during MRI scanning. Three different types of sequences were used for the test: Spin-Echo (SE), Gradient-Echo (GE) and Echo-Planar Imaging (EPI). A plastic container filled with a gadolinium-manganese solution was used for representation of the artefacts. The motors investigated were placed parallel to the container at predetermined distances during the experiment. RESULTS AND CONCLUSIONS: The results show that the motors investigated suffered no functional limitations in the magnetic field of the MRI but, depending on the type of motor, the measurement distance and the state of the motor, the motors had different effects on the sequence images. A motor in the off-state placed immediately next to the object to be measured mainly causes artefacts because of its material properties. If, on the other hand, the piezomotor is in the on-state images with strong noise result when the motor is immediately next to the object being measured. The images regain their normal quality when the motor is approximately at a distance of 1 m from the object being investigated. Driving the motor inside the MRI, therefore, is only to be recommended during the pauses in scanning: this delivers artefact-free images if minimal, motor-specific distances are kept to. With regard to the three different types of sequences it was determined that the SE sequence was the least sensitive and the EPI sequence the most sensitive to disturbance. The GE sequence showed only minimal differences to the SE sequence with regard to signal-to-noise ratios. Since it requires considerably shorter scan-times it can be considered to be the most effective type of sequence under these conditions.     

Prioritization of liver MRI for distinguishing focal lesions

Liver cancer is one of the leading causes of cancer-related mortality worldwide.Magnetic resonance imaging(MRI) is a non-invasive imaging technique that is often used by radiologists for diagnosis and surgical planning.Analysis of a large amount of liver MRI data for each patient limits the radiologist's efficiency and may lead to misdiagnoses.The redundant MRI data,especially from dynamic contrast enhanced(DCE) sequences,is also a bottleneck in transmitting the images via the internet or PACS for remote consultancy in a reasonable amount of time.This study included 25 patients(aged between 20 and 70years) with liver cysts(seven cases),hemangiomas(eight cases),or hepatic cell carcinomas(10 cases).DCE T1 WI MRI was performed for all the patients.The diagnosis reference included typical MRI findings and post-surgery pathology.The methods were as follows:(i) MRI sequence pre-processing based on large vessels variation level set method to remove non-liver parts from MRI images;(ii) human visual model features(luminance,motion,and contour) extraction and fusion;(iii) anomaly-based MRI ranking;and(iv) methods assessment with the 25 patients' DCE MRI data.The prioritization methods applied to the DCE images could automatically assimilate and determine the content of the medical images,identifying the liver cysts,hemangiomas,and carcinomas.The average uniformity between radiologists and prioritization with the proposed method was 0.805,0.838,and0.818 for cysts,hemangiomas,and carcinomas,respectively,which indicates that the proposed method is an efficient method for liver DCE image prioritization.     

Technical note: Unexpected external markers artifact in 3D k-space based parallel imaging turbo spin-echo magnetic resonance imaging

PurposeMRI for radiotherapy planning requires spatial referencing using immobilization devices and markers. Clinical images of a difficult-to-interpret artifact are presented, resembling a metastasis, which occurs when combining CAIPIRINHA k-space-based parallel imaging (PI), 3D distortion correction, and external markers.MethodsA 3D variable flip angle Turbo Spin Echo sequence was used on a 1.5 T and 3 T MRI using flexible and head and neck coils. Two types of markers were tested: Liquimark LM1 and Spee-D-Mark. A silicone oil phantom was used that represents low signal intensity, such as gray matter. 3D Fourier transforms were also used to show the issue’s origin.ResultsThe markers can appear in an unexpected region of a patient, not in the same original or reconstructed slice nor in a rectilinear direction in a slice, especially when using CAIPIRINHA acceleration with 3D distortion correction. The probability of occurrence was respectively 13% and 80% for distances of <=2 mm and >2 mm between marker and patient, for example when using thermoplastic masks. Clinical cases are shown where this semi-randomly occurring artifact appears post contrast only, and thus can be interpreted as metastases. The artifact did not appear when using compressed sensing acceleration.ConclusionMarkers used for radiotherapy MRI application can introduce additional artifacts that can be interpreted as metastases. However, other high signal intensity structures on the surface of a patient, such as the ear, can lead to an equivalent error.     

Decreased methylation of the major mouse long interspersed repeated DNA during aging and in myeloma cells

Sequences of DNA that hybridize on Southern blots with cloned EcoR1 1.3 kb (ER1) of long interspersed repeated sequence (L1Md) of mouse have been examined in genomic DNA of neonatal mice, livers and brains of adult mice (3, 10, 27, and 30 mo old), and the solid myeloma tumor MOPC-315. The isoschizomers Hpa II (CCGG or mCCGG) and Msp I (CCGG or CmCGG) were used to assess methylation. We found that the L1Md sequence is fully methylated in young animals but demethylated in myeloma. Demethylation of L1Md sequence also occurred in aged animals. By scanning the autoradiogram, we found that approximately 8% of the 10(4)-10(5) copies have been demethylated in 27-mo-old liver.     

Gibberellin Biosynthesis in Maize. Metabolic Studies with GA(15), GA(24), GA(25), GA(7), and 2,3-Dehydro-GA(9)

[17-(14)C]-Labeled GA(15), GA(24), GA(25), GA(7), and 2,3-dehydro-GA(9) were separately injected into normal, dwarf-1 (d1), and dwarf-5 (d5) seedlings of maize (Zea mays L.). Purified radioactive metabolites from the plant tissues were identified by full-scan gas chromatography-mass spectrometry and Kovats retention index data. The metabolites from GA(15) were GA(44), GA(19), GA(20), GA(113), and GA(15)-15,16-ene (artifact?). GA(24) was metabolized to GA(19), GA(20), and GA(17). The metabolites from GA(25) were GA(17), GA(25) 16alpha,17-H(2)-17-OH, and HO-GA(25) (hydroxyl position not determined). GA(7) was metabolized to GA(30), GA(3), isoGA(3) (artifact?), and trace amounts of GA(7)-diene-diacid (artifact?). 2,3-Dehydro-GA(9) was metabolized to GA(5), GA(7) (trace amounts), 2,3-dehydro-GA(10) (artifact?), GA(31), and GA(62). Our results provide additional in vivo evidence of a metabolic grid in maize (i.e. pathway convergence). The grid connects members of a putative, non-early 3,13-hydroxylation branch pathway to the corresponding members of the previously documented early 13-hydroxylation branch pathway. The inability to detect the sequence GA(12) --> GA(15) --> GA(24) --> GA(9) indicates that the non-early 3,13-hydroxylation pathway probably plays a minor role in the origin of bioactive gibberellins in maize.     

PTFOS: Flexible and Absorbable Intracranial Electrodes for Magnetic Resonance Imaging

Intracranial electrocortical recording and stimulation can provide unique knowledge about functional brain anatomy in patients undergoing brain surgery. This approach is commonly used in the treatment of medically refractory epilepsy. However, it can be very difficult to integrate the results of cortical recordings with other brain mapping modalities, particularly functional magnetic resonance imaging (fMRI). The ability to integrate imaging and electrophysiological information with simultaneous subdural electrocortical recording/stimulation and fMRI could offer significant insight for cognitive and systems neuroscience as well as for clinical neurology, particularly for patients with epilepsy or functional disorders. However, standard subdural electrodes cause significant artifact in MRI images, and concerns about risks such as cortical heating have generally precluded obtaining MRI in patients with implanted electrodes. We propose an electrode set based on polymer thick film organic substrate (PTFOS), an organic absorbable, flexible and stretchable electrode grid for intracranial use. These new types of MRI transparent intracranial electrodes are based on nano-particle ink technology that builds on our earlier development of an EEG/fMRI electrode set for scalp recording. The development of MRI-compatible recording/stimulation electrodes with a very thin profile could allow functional mapping at the individual subject level of the underlying feedback and feed forward networks. The thin flexible substrate would allow the electrodes to optimally contact the convoluted brain surface. Performance properties of the PTFOS were assessed by MRI measurements, finite difference time domain (FDTD) simulations, micro-volt recording, and injecting currents using standard electrocortical stimulation in phantoms. In contrast to the large artifacts exhibited with standard electrode sets, the PTFOS exhibited no artifact due to the reduced amount of metal and conductivity of the electrode/trace ink and had similar electrical properties to a standard subdural electrode set. The enhanced image quality could enable routine MRI exams of patients with intracranial electrode implantation and could also lead to chronic implantation solutions.