imtoken下载安装ios|fdg

作者: imtoken下载安装ios
2024-03-07 18:40:14

氟代脱氧葡萄糖_百度百科

葡萄糖_百度百科网页新闻贴吧知道网盘图片视频地图文库资讯采购百科百度首页登录注册进入词条全站搜索帮助首页秒懂百科特色百科知识专题加入百科百科团队权威合作下载百科APP个人中心氟代脱氧葡萄糖播报讨论上传视频氟代衍生物收藏查看我的收藏0有用+10本词条由“科普中国”科学百科词条编写与应用工作项目审核。氟代脱氧葡萄糖是2-脱氧葡萄糖的氟代衍生物。通常简称为18F-FDG或FDG。FDG最常用于正电子发射断层扫描（PET）类的医学成像设备：FDG分子之中的氟选用的是属于正电子发射型放射性同位素的氟-18，从而成为18F-FDG。在向病人（患者，病患）体内注射FDG之后，PET扫描仪可以构建出反映FDG体内分布情况的图像。接着，核医学医师或放射医师对这些图像加以评估，从而作出关于各种医学健康状况的诊断。中文名氟代脱氧葡萄糖外文名Fludeoxyglucose化学名称2-氟-2-脱氧-D-葡萄糖简称18F-FDG或FDG类别氟代衍生物最常用于正电子发射断层扫描（PET）类的医学成像设备目录1简介2历史3作用机理与代谢命运4临床应用5生产与配送手段6质量保证▪常规性质量检验▪追溯性质量检验7参见简介播报编辑氟代脱氧葡萄糖是2-脱氧葡萄糖的氟代衍生物。通常简称为18F-FDG。 [3]18F-FDG最常用于正电子发射断层扫描（PET）类的医学成像设备：18F-FDG分子之中的氟选用的是属于正电子发射型放射性同位素的氟-18，从而成为18F-FDG。在向病人（患者，病患）体内注射18F-FDG之后，PET扫描仪可以构建出反映18F-FDG体内分布情况的图像。接着，核医学医师或放射医师对这些图像加以评估，从而作出关于各种医学健康状况的诊断。历史播报编辑二十世纪70年代，美国布鲁克海文国家实验室（Brookhaven National Laboratory）的Tatsuo Ido首先完成了18F-FDG的合成。1976年8月，宾夕法尼亚大学的Abass Alavi首次将这种化合物施用于两名正常的人类志愿者的身上。其采用普通核素扫描仪（非PET扫描仪）所获得的脑部图像，表明了18F-FDG在脑部的浓聚。 [1]作用机理与代谢命运播报编辑作为一种葡萄糖类似物，18F-FDG将为如脑、肾脏以及癌细胞等葡萄糖高利用率细胞所摄取。在此类细胞内，磷酸化过程将会阻止葡萄糖以原有的完整形式从细胞之中释放出来。葡萄糖之中的2位氧乃是后续糖酵解所必需的；因而，18F-FDG与2-脱氧-D-葡萄糖相同，在细胞内无法继续代谢；这样，在放射性衰变之前，所形成的18F-FDG-6-磷酸将不会发生糖酵解。结果，18F-FDG的分布情况就会很好地反映体内细胞对葡萄糖的摄取和磷酸化的分布情况。在18F-FDG发生衰变之前，18F-FDG的代谢分解或利用会因为其分子之中2'位上的氟而受到抑制。不过，18F-FDG发生放射性衰变之后，其中的氟将转变为18O；而且，在从环境当中获取一个H之后，18F-FDG的衰变产物就变成了葡萄糖-6-磷酸，而其2'位上的标记则变为无害的非放射性“重氧”（heavy oxygen，oxygen-18）；这样，该衰变产物通常就可以按照普通葡萄糖的方式进行代谢。 [1]临床应用播报编辑在PET成像方面，18F-FDG可用于评估心脏、肺脏以及脑部的葡萄糖代谢状况。同时，18F-FDG还在肿瘤学方面用于肿瘤成像。在被细胞摄取之后，18F-FDG将由己糖激酶（在快速生长型恶性肿瘤之中，线粒体型己糖激酶显著升高）加以磷酸化，并为代谢活跃的组织所滞留，如大多数类型的恶性肿瘤。因此，18F-FDG-PET可用于癌症的诊断、分期和治疗监测，尤其是对于霍奇金氏病、非霍奇金氏淋巴瘤、结直肠癌、乳腺癌、黑色素瘤以及肺癌。另外，18F-FDG-PET还已经用于阿尔兹海默病的诊断。在旨在查找肿瘤或转移性疾病的体部扫描应用当中，通常是将一剂通常为5至10毫居里，或者说200至400兆贝克勒的18F-FDG溶液迅速注射到正在向病人静脉之中滴注生理盐水的管路当中。此前，病人已经持续禁食至少6小时，且血糖水平适当较低。在给予18F-FDG之后，病人必须等候大约1个小时，以便18F-FDG在体内充分分布，为那些利用葡萄糖的器官和组织所摄取；在此期间，病人必须尽可能减少身体活动，以便尽量减少肌肉对于这种放射性葡萄糖的摄取（当我们所感兴趣的器官位于身体内部之时，这种摄取会造成不必要的伪影）。接着，就会将病人置于PET扫描仪当中，进行一次或多次一系列的扫描；这些扫描可能要花费20分钟直至1个小时的时间每次PET检查，往往只会对大约体长的四分之一进行成像。 [1]生产与配送手段播报编辑医用回旋加速器（medical cyclotron）之中用于产生F-18的高能粒子轰击条件会破坏像脱氧葡萄糖或葡萄糖之类的有机物分子，因此必须首先在回旋加速器之中制备出氟化物形式的放射性F-18。这可以通过采用氘核轰击氖-20来完成；但在通常情况下，F-18的制备是这样完成的：采用质子轰击富O水（O-enriched water，重氧水），导致O之中发生(p,n)核反应（中子脱出，或者说散裂（spallation）），从而产生出具有放射性核素标记的氢氟酸（hydroF-18luoric acid，HF-18）形式的F-18。接着，将这种不断快速衰变的F-18（18-氟化物，18-F-18luoride）收集起来，并立即在“热室（hot cell）（放射性同位素化学制备室）”之中，借助于一系列自动的化学反应（亲核取代反应或亲电取代反应），将其连接到脱氧葡萄糖之上。之后，采取尽可能最快的方式，将经过放射性核素标记的18F-FDG化合物（F-18的衰变限定其半衰期仅为109.8分钟）迅速运送到使用地点。为了将PET扫描检查项目的地区覆盖范围拓展到那些距离生产这种放射性同位素标记化合物的回旋加速器数百公里之遥的医学分子影像中心，其中可能还会使用飞机空运服务。最近，用于制备18F-FDG，备有自屏蔽及便携式化学工作站的现场式回旋加速器，已经伴随PET扫描仪落户到了偏远医院。这种技术在未来具有一定的前景，有望避免因为要将18F-FDG从生产地点运送到使用地点而造成的忙乱.。 [2]质量保证播报编辑常规性质量检验澄明度pH值滞留系数放射化学纯度活度除菌滤器完整性检测追溯性质量检验无菌试验内毒素检测K2.2.2含量检测乙醇含量检测乙腈含量检测 [1]参见播报编辑葡萄糖穴醚核医学放射药理学乙腈亲核取代反应亲电取代反应新手上路成长任务编辑入门编辑规则本人编辑我有疑问内容质疑在线客服官方贴吧意见反馈投诉建议举报不良信息未通过词条申诉投诉侵权信息封禁查询与解封©2024 Baidu 使用百度前必读 | 百科协议 | 隐私政策 | 百度百科合作平台 | 京ICP证030173号京公网安备110000020000

FDG代谢增高就一定是恶性肿瘤么? - 知乎

FDG代谢增高就一定是恶性肿瘤么? - 知乎首页知乎知学堂发现等你来答切换模式登录/注册癌症增高发育生物学代谢FDG代谢增高就一定是恶性肿瘤么?关注者24被浏览12,271关注问题写回答邀请回答好问题 2添加评论分享3 个回答默认排序爱递募未来关注　　FDG代谢增高不一定就是癌症，也有可能是炎症感染、结核等疾病造成的。FDG是氟代脱氧葡萄糖，如果其代谢增高，则表示PET/CT检查中显示组织器官对葡萄糖的摄取增高，可能与恶性肿瘤细胞的代谢活跃度明显增高有关。但除了恶性肿瘤，其它高代谢的疾病，比如炎症感染、结核等，也有可能造成FDG代谢增高。　　FDG中文名称是氟代脱氧葡萄糖，是放射性同位素氟标记的葡萄糖，是PET-CT检查最常用的放射性药物。肺部FDG代谢增高是指在PET-CTT检查中显示组织器官对葡萄糖的摄取增高的意思，葡萄糖是人体能量供应的主要来源，几乎所有的组织器官都会从血液中摄取葡萄糖来供能，尤其是代谢活跃的组织器官。身体组织局部FDG代谢增高说明局部代谢比较旺盛，临床出现肺部FDG代谢增高，除肿瘤外还可见于局部的感染炎症反应，也可以引起局部组织代谢增高改变。　　恶性肿瘤的诊断可能通过影像学检查，包括CT、核磁共振，还有像PET-CT可以做出初步诊断，但是并不能完全确诊，还需要结合肿瘤标志物有没有升高，以及能不能取到明确的病理。如果能取到病理活检，才是确诊的依据。如果恶性肿瘤发现之后能手术治疗，也是争取做手术根治的。发布于 2022-11-17 11:16赞同 4添加评论分享收藏喜欢收起瑞祥谈肿瘤关注 FDG是一种葡萄糖类似物。临床上静注后被用来作为PET-CT检查常用的放射性示踪剂，当组织局部代谢异常升高时，FDG会特异性的识别聚集，再经断层扫描，就会发现病变的部位，大小，数量。而且PET-CT可以多维度扫描成像，故漏诊率很低。临床常被用来评估肿瘤的临床分期，有无远处转移和手术指征以及治疗后疗效的评估。很多文献提供的数据诊断准确率非常高，甚至达90%以上。个人临床经验感觉有夸张的成份。高分化恶性肿瘤，软组织外伤，慢性骨髓炎，隐性骨折等情形同样可以显示放射性的浓聚区，易造成误诊。因此，临床工作一定要结合病史，尽可能的采用一元论解释影像学诊断，才能提高确诊率。发布于 2022-07-25 10:26赞同 4添加评论分享收藏喜欢收起

放射性葡萄糖——2-氟18-2-脱氧葡萄糖 - 知乎

放射性葡萄糖——2-氟18-2-脱氧葡萄糖 - 知乎首发于多知道点切换模式写文章登录/注册放射性葡萄糖——2-氟18-2-脱氧葡萄糖LifeChem华中科技大学理学硕士我们经常谈“核”色变，因为切尔诺贝利和福岛第一核电站事件让我们仍心有余悸。大量研究已经表明，长时间暴露在电离辐射中会导致癌症。但你是否知道具有放射性的分子却经常被用到癌症检测和治疗中？正电子发射断层扫描（Positron Emission Tomography, PET）是最常见的医学成像技术之一，可用于临床前和临床中。PET 成像依靠将少量的放射性化合物或 "放射性示踪剂 "注射到病人体内来实现。通过检测示踪剂在体内的放射性衰变，其分布、吸收和新陈代谢情况就可以实时显示出来。肿瘤学中最广泛使用的放射性示踪剂是一种葡萄糖类似物，称为2-氟18-2-脱氧葡萄糖（2-[18F]fluoro-2-deoxyglucose，简称为氟-18 FDG），其结构中C2位置的羟基被放射性同位素氟-18取代。FDG由Pacák及其同事于1968在查尔斯大学（当时属于捷克斯洛伐克）首次合成。随后在20世纪70年代，布鲁克黑文国家实验室的科学家利用高活性的亲电氟源——氟-18氟气，成功地合成了氟-18标记类似物。70年代后期，在宾夕法尼亚大学，氟-18 FDG被用于健康人类志愿者中，实现了脑部葡萄糖代谢可视化。重要的是，除了脑部，其他具有高葡萄糖吸收的组织，如含有癌症肿瘤的组织，可以相当有效地检测到。和葡萄糖一样，氟-18 FDG被细胞吸收并被己酮酶磷酸化，这一过程通常标记即将代谢的葡萄糖分子。然而，与葡萄糖不同的是，用氟原子取代C2位置的羟基意味着，氟-18 FDG不能被细胞机制代谢掉。这种行为上的差异意味着，当越来越多的氟-18 FDG输送到细胞中时，它会逐渐累积，而不是被清除掉。此外，由于癌细胞消耗的葡萄糖量比正常细胞多，所以PET成像在临床肿瘤学中是一种非常敏感的诊断工具。在Hamacher和同事于1986年开发了更可靠而高产的氟-18 FDG合成路线后，PET成像被广泛采用。该方法涉及到保护的葡萄糖衍生物与氟-18标记氟的亲核取代，至今该方法基本未变。亲核的氟-18氟化物由质子轰击富含氧-18的水在回旋加速器中制成，以水溶液的形式出现。由于氟化物具有很高的水合能，围绕着它的水分子外壳削弱了其反应性。Hamacher的方法采用了Kryptofix 222——一种双环笼状化合物——作为相转移催化剂，这不仅增加了氟离子的亲核性，也提高了其在有机溶剂中的溶解性。与亲电的氟-18氟气相比，使用亲核的氟-18氟化物的一个主要好处是它的高比活度，这意味着只需将少量的放射性同位素注射到病人体内，就可以实现可视化。氟-18仍然是PET成像中最受欢迎的放射性同位素，其中氟-18 FDG的应用占到了9成。因此，你可能会思考，是什么使氟-18在所有可使用的放射性核素中如此特别？对于PET成像，氟-18具有几个优势，其中理想的半衰期也许是最突出的特点。氟-18的半衰期约为110分钟，其衰变速度对于典型的PET扫描来说是合理的，因其稳定时间足够长，所以放射性示踪剂可以很容易地在现场或附近设施中合成。除了肿瘤学，氟-18 FDG还可用于心脏疾病、炎症情况以及癫痫的诊断中。另外，氟-18 FDG在神经科学方面也有应用，特别是针对中枢神经系统的药物开发。目前在临床上使用的其他氟-18标记的放射性示踪剂，包括用于骨骼成像的氟-18NaF和用于帕金森病患者多巴胺能神经末梢可视化的氟-18 FDOPA。目前，越来越多的研究专注于开发可应用于氟-18放射性标记的后期亲核氟化方法。随着新的合成方法被采用并应用于放射化学实验室中，放射性药物市场将发生怎样的变化将是一件有趣的事情。原文见 https://doi.org/10.1038/s41557-022-00920-5发布于 2022-04-23 07:10放射性元素葡萄葡萄糖赞同 53 条评论分享喜欢收藏申请转载文章被以下专栏收录多知道点科研人物、基本

18F-FDG是什么？18F-FDG怎么标记病灶【高尚医学影像】 - 知乎

18F-FDG是什么？18F-FDG怎么标记病灶【高尚医学影像】 - 知乎切换模式写文章登录/注册18F-FDG是什么？18F-FDG怎么标记病灶【高尚医学影像】高尚医学影像医疗质量为本，品质呵护健康当我们去做PET/CT检查的时候，会接触到一个很特殊的字样：18F-FDG。18F-FDG是什么？其实它是一种放射性显像剂，更专业的名称是正电子发射性药物。一般做PET/CT之前，都要注射18F-FDG到体内才能完成检查。因其是21世纪中很重要且常用的显像剂，所以被誉为“世纪分子”。走进18F-FDG18F-FDG全称氟[18]脱氧葡糖注射液，是一种有正电子核素标记生物分子。它主要由两个部分组成，一个是18F，一个是FDG。18F是具有放射性的核素，它是由被加速的具有一定能量的粒子束轰击靶原子核转变而成的。18F可以发射正电子，因此又被称为“正电子核素”。可以把它看作是“追踪器”。FDG是葡萄糖类似物，它是用来让体内病变器官产生葡萄糖代谢的。可以把它看作“诱捕器”。18F-FDG结构式18F-FDG怎么标记病灶在了解18F-FDG标记病灶的原理之前，我们先来了解一下人体能量的主要来源。大脑和心脏通过对食物中的脂肪酸、糖类（主要是葡萄糖）进行吸收消耗，进而产生ATP，ATP再为人体供能。当大脑和心脏代谢脂肪酸与糖类的时候，耗氧量会较大。也就是说，大脑和心脏是人体耗氧比较多的器官。如果在缺氧的情况下，消耗的方式就会从脂肪酸变成厌氧糖代谢。当18F-FDG注射到人体内，因为它是一种类似葡萄糖的物质，所以人体会把它视为葡萄糖。从而大脑、心脏会把它当成糖类利用起来，18F-FDG会被磷酸化为氟[18F]脱氧葡糖-6-磷酸盐。这时，这种物质会聚集在大脑和心脏。但当体内有肿瘤的时候，这种物质不单单聚集在大脑和心脏里，还会聚集在肿瘤所在之地。因为恶性肿瘤细胞生长得快速且无序，导致周围的血管生长变得迟缓，局部组织相对缺氧。而在缺氧的情况下，消耗方式从脂肪酸变成厌氧糖代谢，肿瘤细胞就需要更多的葡萄糖（约是正常细胞的十倍），厌氧糖解速率也更高。所以18F-FDG作为葡萄糖类似物，发挥着“诱捕器”的作用，也会大量集聚到恶性肿瘤所在的地方，供它代谢。问题来了，18F-FDG找到病灶后，又是怎么让我们“看”到恶性肿瘤所在的地方？答案就在18F-FDG的18F上。PET设备扫描的原理，就是扫出γ射线所在之处。像上面说过的，18F可以作为“追踪器”，它衰变后放出的正电子很快就与周围的电子结合释出γ射线，就像信号一样。这时PET设备就可以感应γ射线并呈现它所在位置，让我们能看到病灶所在的地方。作为符合国家GMP规范的正电子放射性药物研发、生产的高新技术企业，回旋医药一直致力于研发、生产以18F-FDG为基础的多种正电子放射性药物，在正电子断层显像诊断放射性药物及其制备方、亚氨基酸类PET显像剂及其制备方法与应用等方面获得了相关专利证书，并获得多项正电子药物相关的企业资质证书。回旋医药生产的18F-FDG，除了可以用于肿瘤的PET成像，还可以发现冠状动脉疾病、癫痫等多种疾病的病灶，用途广泛。18F-FDG为疾病诊断与治疗提供丰富信息与应用价值，大大提高了疾病诊断决策的精准性与便利性，“世纪分子”的称号当之无愧。高尚医学影像科技集团有限公司(简称高尚医学影像）初创于2003年，是以独立第三方医学影像诊断中心为核心的多元化协同发展的综合型医疗机构。高尚医学影像集二十年数十家大型分子影像诊断中心之大成，立足广州,布局全国。广东高尚医学影像诊断中心是2017年经卫生健康委员会批准成立的早期独立第三方医学影像诊断中心。集团计划3年内全国布局20家独立影像诊断中心，广州、昆明、西安、厦门、武汉、成都、合肥中心已正式运营，上海、长沙、重庆、郑州等多家在建。各中心配置有西门子新一代PET/CT、PET/MR（选配）、双源CT、1.5T和3.0TMR、数字化X线摄影系统、乳腺DR、新一代GE彩色超声以及法国EOS X射线影像采集系统。高尚医学影像汇集了一支包括教授、主任医师和博士组成的团队，并按照影像亚专业聘请各省主委级教授，领衔学科建设、质量控制、疑难病会诊、临床特色项目创新和科研教学等医教研并进，同时开展常规远程会诊以及多学科疑难病会诊等医学影像诊断服务，致力于形成四个完整体系的建设：影像亚专业分组诊断体系；重大疾病早期诊断体系；疑难病多学科会诊体系；质量控制和培训体系。高尚医学影像是同时拥有独立影像中心与正电子药物制药的影像集团，以其特有的优势，根据不同疾病的影像诊断对分子影像示踪剂的不同需求，生产提供匹配的特异性示踪剂，为分子影像对疑难疾病的精准诊断提供保障。匠心影像，传承高尚！高尚医学影像以匠心品质、精益求精的工匠精神，以厚德尚医、传承百年为志向，执行严谨的医疗质量管理体系，不断提升自身的诊断能力；以合理齐全高水平的医师团队为基础，以高质量的诊断能力为抓手，力求成为业界颇具影响力和公信力的专业影像诊断机构，打造成国内外知名的医学影像诊断品牌。发布于 2022-08-31 09:57PET/CT赞同 6添加评论分享喜欢收藏申请

FDG-PET成像（氟脱氧葡萄糖-正电子体层扫描成像）简介与原理-CSDN博客

FDG-PET成像（氟脱氧葡萄糖-正电子体层扫描成像）简介与原理

最新推荐文章于 2024-03-04 22:00:00 发布

lolisky

最新推荐文章于 2024-03-04 22:00:00 发布

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图像处理

本文链接：https://blog.csdn.net/lolisky/article/details/128757384

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因为要做医学图像相关工作涉及此方面，需要补习一下基础知识，在这里记录一下以便复习回顾。

PET（正电子体层扫描）简介与原理

PET全称为：正电子发射型计算机断层显像（Positron Emission Computed Tomography），是核医学领域比较先进的临床检查影像技术。

PET的大致方法是：将某种物质，一般是生物生命代谢中必须的物质，如：葡萄糖、蛋白质、核酸、脂肪酸等标记上短寿命的放射性核素（如18F，11C等），注入人体后，通过对于该物质在代谢中的聚集，来反映生命代谢活动的情况，从而达到诊断的目的。

这些放射性核素在衰变过程中释放出正电子，一个正电子在行进十分之几毫米到几毫米后遇到一个电子后发生湮灭，从而产生方向相反（180度）的一对能量为511KeV的光子（based on pair production）。这对光子，通过高度灵敏的照相机捕捉，并经计算机进行散射和随机信息的校正。经过对不同的正电子进行相同的分析处理，我们可以得到在生物体内聚集情况的三维图像。

PET优点： PET是唯一可在活体上显示生物分子代谢、受体及神经介质活动的新型影像技术，现已广泛用于多种疾病的诊断与鉴别诊断、病情判断、疗效评价、脏器功能研究和新药开发等方面。

（1）灵敏度高。PET是一种反映分子代谢的显像，当疾病早期处于分子水平变化阶段，病变区的形态结构尚未呈现异常，MRI、CT检查还不能明确诊断时，PET检查即可发现病灶所在，并可获得三维影像，还能进行定量分析，达到早期诊断，这是其它影像检查所无法比拟的。（2）特异性高。MRI、CT检查发现脏器有肿瘤时，是良性还是恶性很难做出判断，但PET检查可以根据恶性肿瘤高代谢的特点而做出诊断。（3）全身显像。PET一次性全身显像检查便可获得全身各个区域的图像。（4）安全性好。PET检查需要的核素有一定的放射性，但所用核素量很少，而且半衰期很短（短的在12分钟左右，长的在120分钟左右），经过物理衰减和生物代谢两方面作用，在受检者体内存留时间很短。一次PET全身检查的放射线照射剂量远远小于一个部位的常规CT检查，因而安全可靠。

FDG-PET成像

最近各医院主要使用的物质是氟代脱氧葡萄糖，简称FDG。其机制是，人体不同组织的代谢状态不同，在高代谢的恶性肿瘤组织中葡萄糖代谢旺盛，聚集较多，这些特点能通过图像反映出来，从而可对病变进行诊断和分析。

PET-CT成像

PET-CT基本原理是利用PET和CT联合成像，通过引入放射性核素进行显像，然后再使用CT解剖结构进行联合诊断。其显像主要引入的显像剂包括代谢物、葡萄糖、氨基酸、蛋白质及多肽等元素，属于综合分子显像技术。PET-CT主要应用于肿瘤、神经系统及心血管疾病和心肌代谢诊断。临床较多应用于肿瘤诊断与治疗，或放射治疗靶区的更换和一些高端体检等项目。

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FDG-PET成像（氟脱氧葡萄糖-正电子体层扫描成像）简介与原理

PET全称为：正电子发射型计算机断层显像（Positron Emission Computed Tomography），是核医学领域比较先进的临床检查影像技术。PET的大致方法是：将某种物质，一般是生物生命代谢中必须的物质，如：葡萄糖、蛋白质、核酸、脂肪酸等标记上短寿命的放射性核素（如18F，11C等），注入人体后，通过对于该物质在代谢中的聚集，来反映生命代谢活动的情况，从而达到诊断的目的。这些放射性核素在衰变过程中释放出正电子，一个正电子在行进十分之几毫米到几毫米后遇到一个电子后发生湮灭，从而产生。

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MRI to FDG-PET: Cross-Modal Synthesis Using 3D U-Net for Multi-modal Alzheimer’s Classification摘要方法数据集预处理网络结构实验分类实验

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18F-FDG-PET-CT with little value in different diagnosis between pulmonary malignancy and amyloidosis

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18F-FDG-PET-CT在区分肺部恶性疾病与淀粉样变方面意义不大，刘明辉，宋作庆，肺淀粉样变的发病率很低,常常由于缺乏对这种疾病的广泛认识而被误诊。PET-CT在区分肺恶性肿瘤和肺淀粉样变作用仍不清楚。在此，我�

使用PET成像的非稀疏无限核学习来自动识别阿尔茨海默氏病

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最近，将多核学习机（MKLM）引入计算机辅助痴呆识别和病理学进展跟踪的研究中。尽管其良好的性能，特别是在使用异构数据的情况下，这种学习模式及其变体通常利用L1范数约束，该约束会促进稀疏解，这可能会导致潜在的重要信息丢失。在本文中，我们提出了一种非稀疏的无限核学习机（NS-IKLM），用于从正常对照中自动识别阿尔茨海默氏病。在我们的方法中，修改后的约束条件用于促进非稀疏解决方案，并且在学习过程中会自动调整内核参数。已对选自阿尔茨海默氏病神经创动倡议（ADNI）队列的一组FDG-PET图像进行了评估，对所提出的算法进行了评估。我们的结果表明，提出的非稀疏NS-IKLM能够以相对较低的计算成本实现令人满意的痴呆症识别。

一个有关PET及其成像原理的PPT

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给那些PET的初学者，让你对PET有一个基本的了解

FDG-PET定量指标可靠性和判别准确性仿真 (2008年)

06-17

正电子发射断层成像中内在的随机噪声导致基于其图像的定量指标具有波动性。通过计算机模拟逼真的肺癌和炎症组织的氟代脱氧葡萄糖([18F]2-fluoro-2-deoxy-D-glucose，FDG)代谢动力学曲线，研究不同定量指标的可靠性和判别准确性。结果表明，对动态成像运用Patlak方法求得的净摄入率具有最高的可靠性；双时成像求得的保留指数可靠性最低，但相对于标准摄入值依然能更有效地判别肿瘤的良恶性；通过增加双时成像中第二帧扫描时间，可提高保留指数的可靠性和判别准确率。

淀粉样蛋白PET和18F-FDG-PET对阿尔茨海默病和其他痴呆的诊断研究

cc1609130201的博客

02-14

762

在正在进行的研究中，正在确定适当地向患者和家属披露检查结果的背景。2019年进行的一项大型前瞻性多中心试验(IDEAS)，包括超过16000名参与者，显示根据所谓的适当使用标准选择的患者中的淀粉样蛋白PET导致相关比例(约60%的患者)的管理发生变化，这有力地证明了该方法在相应人群中的应用。如果临床和结构成像信息都倾向于特定的诊断(例如，在具有典型海马萎缩的记忆显性特征的患者中)，在有痴呆家族史或APOE ε4基因型的患者中，或者如果诊断的结果很差，这意味着它们不会影响患者的治疗，则可以停止进一步的检查。

SPECT、PET、CT与MRI成像原理及其特点的比较转载

weixin_30646315的博客

06-19

1388

SPECT的基本原理SPECT是利用放射性同位素作为示踪剂，将这种示踪剂注入人体内，使该示踪剂浓聚在被测脏器上，从而使该脏器成为γ射线源，在体外用绕人体旋转的探测器记录脏器组织中放射性的分布，探测器旋转一个角度可得到一组数据，旋转一周可得到若干组数据，根据这些数据可以建立一系列断层平面图像。计算机则以横截面的方式重建成像。正电子发射计算机扫描（Positron Emision Tomograph...

流水灯控制cdfa/fdgp

04-13

简单的电路板图尼莫克炅十分激动死的JFK老师就弄匿名访问OK看我二姐夫你们

X-CT MRI、PET三种成像的优缺点

影像干货 | 核医学（18）F-FDG PET/CT报告书写规范 - 知乎

影像干货 | 核医学（18）F-FDG PET/CT报告书写规范 - 知乎切换模式写文章登录/注册影像干货 | 核医学（18）F-FDG PET/CT报告书写规范伦琴医疗【关键词】核医学；操作规范；正电子发射断层显像/计算机体层摄影术；正电子发射断层显像术；体层摄影术，X线计算机【中图分类号】R714.5；R445.1【DOI】10.3969/j.issn.1005-5185.2021.01.001随着正电子发射计算机断层显像/计算机断层显像（positron emission tomography/computed tomography，PET/CT）临床应用的增加，氟-18标记氟代脱氧葡萄糖（flurodeoxyglucose，18F-FDG）PET/CT的诊断作用得到了临床的广泛认可。18F-FDG PET/CT报告是核医学医师与临床医师之间的主要沟通方式，报告的内容可以体现影像医师在医疗过程中的作用，作为制订诊疗方案的依据，并作为提供医疗服务的法定证据，用于证明医疗的必要性。因此，重视报告的质量非常必要。由于这种融合成像模式的复杂性，书写一份高质量的18F-FDG PET/CT报告具有一定的挑战性，需要影像诊断医师同时具备多种影像技术能力和一定的相关临床知识。近年来，美国核医学与分子影像学学会（Society of Nuclear Medicine and MolecularImaging，SNMMI）、欧洲核医学协会（EuropeanAssociation of Nuclear Medicine，EANM）以及中华医学会核医学分会分别发表了有关18F-FDGPET/CT用于肿瘤显像或感染与炎症显像的相关指导性文件，不同程度地阐述了对报告书写的要求[1-4]。然而，目前国内尚缺乏专门针对报告质量控制的参考标准。为了进一步提升18F-FDG PET/CT对临床诊疗工作的贡献，规范各医疗单位PET/CT报告书写内容，北京市核医学质量控制和改进中心组织来自北京市多家大型医院的专家，针对历年来核医学质量控制检查中所发现的问题，经过论证研讨，撰写了此《核医学18F-FDG PET/CT报告书写规范》，对报告所含要素、各要素书写内容及报告审核等方面提出具体的要求，供核医学医师实际工作参考。1 报告基本要素完整的18F-FDGPET/CT报告应包括受检者的基本信息、临床病史及检查目的、检查技术及操作过程、检查所见、检查意见等内容（表1）。书写时应注意行文简洁、条理清晰、用词规范、关键数据完整。2 报告中的各要素说明2.1 基本信息报告的基本信息应包括患者姓名、性别、年龄、身高、体重、病历号、送检科室，以及PET/CT检查的检查号、检查项目、检查日期、设备型号等。患者基本信息用以保证PET/CT报告的唯一性，便于患者复查时个人多次检查之间的对比，也有利于报告归档、存储、后期在随访及特殊查询时调用。建议使用电子病历系统的单位将上述信息尽可能通过信息化手段直接生成，减少人工二次操作错误，便于溯源。2.2 病史及检查目的对病史的描述应包括：疾病的诊断时间或主要症状表现及出现时间（未明确诊断情况下）、相关实验室/影像学/病理学检查结果、主要治疗过程以及可能对影像结果产生影响的药物使用情况及既往手术史等。上述信息可通过询问患者及家属、临床主管医师或查阅在线病历的方式获取。检查目的代表患者的适应证及检查需回答的主要临床问题。PET/CT检查前了解患者的临床病史和检查目的可提示检查的必要性，也有助于核医学医师提供准确、恰当的PET/CT报告。2.3 检查技术与程序由于设备、检查方案、患者自身条件等诸多因素会对PET/CT图像质量、标准摄取值（standardizeduptake value，SUV）测量值甚至影像判读结果产生影响，故报告中应对相应的检查技术及操作过程做如实的记录，这不仅可作为影像判读和后续附加检查的参考，还可作为影像质量的判断依据。记录内容应包括患者血糖水平、显像剂名称、注射活度、给药时间及给药途径、图像采集时间、辅助干预措施（如水化情况、利尿剂、镇静剂、胰岛素使用等）及扫描参数（采集模式、床速、床位数量、扫描范围）。额外增加的PET/CT显像方案（如延迟显像）亦应详细记录采集时间、范围、扫描速度等可能影响SUV值测量的显像条件；如在PET/CT检查中使用诊断CT及对比剂应记录。2.4 影像所见由于PET/CT为大视野成像，所获得的图像包括PET、CT及两者的融合图像，图像数据信息量大，为了避免病变遗漏，报告时建议按照采集范围从上至下或按照系统性病变的观察顺序对异常所见进行描述，并提供相应的图像。2.4.1 对病灶的描述应包含位置、大小、边界、显像剂摄取情况及相应的同机CT所见或其他近期解剖影像所见。病灶显像剂摄取情况可以视觉判断方式或半定量方式（以SUV值表示，其中至少包含最大SUV值）进行描述。病灶大小的测量可使用单个径线（注明短径或长径）或2~3个相互垂直径线描述，注意单位统一。对于随访患者，应注意显像剂摄取和病灶大小的测量方法与前次显像一致性。对于PET/CT检查前其他影像检查（如CT、MRI、超声）发现的病变（包括日期）应描述与之相对应的PET影像所见。2.4.2 对附加图像的要求报告中的主要异常所见均需附加相应的截图，并加以必要的标示和文字说明。所给图像应清晰显示病灶的影像特征性表现，与影像所见中的文字表述一致。2.5 影像诊断意见鉴于临床医师常习惯于首先阅读PET/CT报告的检查意见，故此部分在报告中最为重要。PET/CT检查意见的关键在于清晰简要，层次分明，避免重复影像所见或进行赘述讨论。要求如下：①影像诊断意见应按照临床诊疗意义排序，首先回答临床主要关注问题，如“是否发现了恶性病变”“病变累及范围及分期”“治疗后随访病变PET及CT的响应评估”等；对于不能明确诊断的病变提出鉴别诊断，并尽可能提出帮助明确病变性质的诊疗措施（如提示适宜的活检部位或有针对性的其他检查方法）。②影像诊断意见所使用的语言应尽可能清晰和明确，如“未见”“可排除”或“考虑为XX疾病”等确定性语言，以避免造成误解。③复诊PET/CT影像诊断应与之前检查（注明日期）对照，提出总体病变数目、大小及代谢的变化情况，并尽可能给出评估意见。3 报告的签发报告的书写人员首先应具备相应的执业资质，报告医师完成报告后应仔细检查报告中的所有文字及图像并签字/签章。报告审核是保证医疗质量的有效措施，审核重点在于报告的正确性与合理性，建议双审核，原则上由具有副高级职称及以上的核医学专业医师完成并签字/签章。当诊断困难时，报告审核医师有责任通过与临床进一步沟通了解患者的临床情况，复习相关疾病知识，并组织集体阅片，以保证报告的整体质量。4 报告范例PET/CT报告虽无固定的写法，不同中心也有各自的格式，但总体要求一致：即PET/CT的书写要做到客观全面、条理清晰、重点突出、逻辑性强、文字凝练、术语准确、解决临床实际问题。为使广大核医学医师在实际工作中有经验可以借鉴，特附PET/CT报告范例（图1、2）。说明资料来源：中国医学影像学杂志,2021,29(01)如果图频或者文字侵权，请后台联系删除编辑于 2022-08-09 17:34核医学干货分享影像科医生赞同 4添加评论分享喜欢收藏申请

How We Read Oncologic FDG PET/CT | Cancer Imaging | Full Text

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How We Read Oncologic FDG PET/CT

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Published: 18 October 2016

How We Read Oncologic FDG PET/CT

Michael S. Hofman

ORCID: orcid.org/0000-0001-8622-159X1,2 & Rodney J. Hicks1,2

Cancer Imaging

volume 16, Article number: 35 (2016)

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Abstract

18F-fluorodeoxyglucose (FDG) PET/CT is a pivotal imaging modality for cancer imaging, assisting diagnosis, staging of patients with newly diagnosed malignancy, restaging following therapy and surveillance. Interpretation requires integration of the metabolic and anatomic findings provided by the PET and CT components which transcend the knowledge base isolated in the worlds of nuclear medicine and radiology, respectively. In the manuscript we detail our approach to reviewing and reporting a PET/CT study using the most commonly used radiotracer, FDG. This encompasses how we display, threshold intensity of images and sequence our review, which are essential for accurate interpretation. For interpretation, it is important to be aware of benign variants that demonstrate high glycolytic activity, and pathologic lesions which may not be FDG-avid, and understand the physiologic and biochemical basis of these findings. Whilst FDG PET/CT performs well in the conventional imaging paradigm of identifying, counting and measuring tumour extent, a key paradigm change is its ability to non-invasively measure glycolytic metabolism. Integrating this “metabolic signature” into interpretation enables improved accuracy and characterisation of disease providing important prognostic information that may confer a high management impact and enable better personalised patient care.

Background

18F-fluorodeoxyglucose (FDG) PET/CT imaging has become a key modality for imaging patients with cancer [1]. The process of reviewing PET/CT studies involves integration of the metabolic findings from the FDG component combined with the anatomical information provided by the CT component. This is a modality with many patterns of structural, physiologic and biochemical abnormalities that transcend the boundaries previously isolated in the worlds of nuclear medicine or radiology in characterising pathological conditions, particularly including cancer. Whilst there is a wealth of literature addressing the utility of PET in a large array of malignancies, the art of how to review and interpret PET/CT is generally acquired like an apprentice and not well addressed in the literature. In this article, we detail our approach to reviewing a PET/CT study using the most commonly used tracer, FDG. Future articles in this series will address the use of other tracers pertinent to other cancers.AcquisitionPatient preparation is important in acquiring good quality studies and it is the responsibility of the PET specialist to ensure that appropriate protocols are in place to prevent non-diagnostic or suboptimal studies. Detailed discussion of acquisition parameters is beyond the scope of this review but includes preparation of diabetic patients, strategies to minimise brown fat activation, as well as prescription of the extent of the field-of-view and the positioning of the patient to address the clinical question. For example, we position the patient with their arms down for head and neck malignancies but with their arms up for thoracic cancers. It is also important to determine the methodology to be used for CT acquisition. This varies widely according to local practice and our approach is discussed in further detail later in this manuscript.An important aspect of interpretation is assessment of the technical adequacy of the study and ideally should be done before the patient leaves the department to enable repeat acquisition of any critical regions inadequately assessed on the initial examination.Optimal windowing of PET imagesIn any PET/CT study there are three discrete image sets that require display. These are the stand-alone PET data, the CT and the fused PET/CT images. Correct and consistent windowing is key to avoid both over- and under-interpretation of findings and to maintain the consistency required for accurate comparison of multiple studies. This also aids presentation of findings to referrers and patients.The primary data from PET has been traditionally displayed on a linear grey scale. This is because the human eye is adept at discerning subtle differences in contrast from white through grey to black. The lower threshold of this display should be set at zero (white) while the upper threshold needs to be manipulated to obtain consistent display of physiological and pathologic uptake. Consequently, the intensity of normal tissues should be within the lower-to-middle portion of the dynamic range while the upper range used to demonstrate the range of intensities that might exist in pathological processes characterised by high glycolytic activity. By maintaining a reasonable spectrum of grey shades for display of normal tissues it is possible to detect faint lesions in areas of low background activity, such as the lung.Our preference is to have the most intense voxels in the normal liver appearing just below the middle of the grey scale range, which will be a light to mid-grey (Fig. 1a). Use of a colour scale is required for superimposition of functional images over the CT. We prefer to use the "rainblow" colour scale that has low activity regions displayed in the blue-green range and higher intensity regions in the orange-red spectrum. With this colour scale, the liver will generally appear blue with flecks of green with adjusgment if not (Fig. 1). This corresponds to an upper SUV window threshold of 8–10 and will usually achieve an appropriate contrast, except in very large patients in whom this may make the liver too dark. This is because adipose tissue contributes to the weight correction of administered activity, which is used for SUV calculation, but does not itself take up FDG. This means that more FDG is available for uptake in other tissues, including the liver. However, this may be counteracted by deposition of fat in the liver in obese subjects. This will usually be apparent by virtue of increased relative uptake in the spleen, which is generally marginally less intense than the liver. The brain will usually be nearly black with this scaling. This is unless cortical glycolytic activity is reduced by metabolic processes, especially by hyperglycaemia, or neurological conditions such as dementia. In children requiring general anaesthesia during the uptake and scanning procedure, cortical activity can also be significantly reduced. There are also changes in the brain during childhood maturation [2].Fig. 1The PET window intensity is adjusted so that the liver appears light to mid-grey on the grey scale, corresponding to flecks of green in the liver on the rainbow colour scale. Despite the difference in SUVmax of the liver secondary to differences in weights of the two patients (a and b), the liver intensity this appears the same in both patientsFull size image

Under fasting conditions, glucose and its analogue, FDG, have facilitated uptake into the liver and therefore generally this organ has significantly higher activity than the blood. By definition, any structure with uptake more intense than that in the liver must also have facilitated FDG uptake and trapping. The advantage of using the liver as a reference tissue is also aided by this organ having rather low variability in metabolic activity [3]. It is, however, inappropriate to threshold for liver uptake if it is not deemed normal due to diffuse malignant infiltration, sarcoidosis, or fatty infiltration. This can be detected visually if there is marked discrepancy between liver and spleen intensity, although with sarcoidosis or lymphoma both can be increased. Our practice of thresholding the grey and colour scale to liver as detailed above results in similar image intensity to a fixed upper SUV threshold of 8 to 10. However, using the liver as a reference enables consistent windowing of images over a series of time-points within and between individuals and compensates for variations that might be caused by inaccuracies in SUV measurement between scans, issues related to dose calibration errors, extravasation of dose, different uptake periods or technical differences if rescanned on a different type of PET/CT device. When the liver is abnormal and cannot be used as a reference organ, we use the default SUV setting of an upper SUV threshold of 8. The same SUV threshold as that used for the whole body study should be applied when additional separate series are acquired (e.g. of the limbs) that do not encompass the liver.Since some disease processes can have extremely high SUV values, it may be necessary to increase the upper threshold to appreciate the dynamic range of glycolytic activity. This is particularly important in diseases where there can be considerable heterogeneity in disease. Follicular lymphoma, in which most lesions can have a SUVmax in excess of 10 but regions of high-grade transformation with corresponding values of >15, is a particular case in point. Standard thresholds provide a good representation of the extent of disease but using a higher upper threshold to display the images can help to identify the regions of likely transformation or different disease biology and can aid biopsy site selection (Fig. 2).Fig. 2This patient presented with suspected metastatic nasopharyngeal cancer. Initial workup with endoscopic ultrasound and biopsy of the subcarinal node was non-diagnostic with necrotic tissue. FDG PET/CT demonstrates very intense uptake at all sites with lower uptake in the subcarinal node, only evident when widening the PET window. The findings suggest a different tumour biology at this site with necrosis. When feasible, we recommend biopsy of the most FDG-avid lesion which likely represents the site of most aggressive disease and least likely to be non-diagnostic. In summary, the PET study windowed narrowly is primed for sensitivity whereas a wider window enables superior characterisationFull size image

This “rainbow” colour scale has relatively abrupt changes in colour, which enable easy differentiation of uptake intensity in the low, mid or high range. It is also a psychologically intuitive scheme with blue-green shades being cool colours whereas yellow-orange colours denote caution and reds, danger. Like a traffic light, we teach our referrers that these spectrums usually represent benign, equivocal and pathological findings, respectively. Clearly, this is an oversimplification, but it enables one to eyeball the PET image and decide if the uptake is of low, moderate or high metabolic activity.It should, however, be noted that this can be a dangerous scale to use if there isn’t a disciplined and consistent use of the threshold setting principles detailed above since it is easy to “dial” lesions in and out. We often see studies, particularly from practices that have more experience with CT than PET, that have clearly had the threshold altered to render them red, or not, depending on whether the reader considers them more, or less, likely to be malignant based on the CT characteristics. While this might be a reasonable approach to communicate the site of a lesion, it diminishes the power of PET to characterise disease based on the degree of its metabolic activity. To avoid the risks associated with this scale, some manufacturers set the default colour scale to a dichotomous range, such as blue-yellow or brown-gold (see Fig. 3). This does not carry the psychological power of the rainbow scale but can be useful for displaying sites of presumed disease against the background of CT while reducing the risk of false-positive results due to use of an inappropriate display threshold. The “rainbow” colour scale may also be difficult for individuals with colour blindness to interpret.Fig. 3Patient with metastatic colorectal carcinoma and hepatic metastasis. The fused image is presented in different colour scales. We recommend using the “rainbow” scale owing to the superior tumour-to-liver contrast compared to other commonly used colour mapsFull size image

We dislike colour scales with a continuous spectrum of a single colour, such as the commonly used “hot metal” scale, as these provide poor contrast between low and high intensity, and background CT images. The human eye is very sensitive in detecting differences of intensity within a grey scale but not so good within a single colour spectrum. Consequently, with “hot metal” or similar colour scales, it is difficult to qualitatively assess an image and know where the intensity of abnormality lies within in the spectrum. Moreover, the highest intensity on this scale is sometimes white, which is essentially uninterpretable when superimposed on a grey scale CT image.Standardised windows have been developed that set upper and lower levels for Hounsfield units that optimally display the range of densities pertinent for a particular tissue. We routinely review soft tissue, lung and bone windows but in appropriate situations will use other specialised windows. Just as the profession has imposed certain discipline in the use of standardised windows for use on CT, we believe that there should be greater harmonisation of display of PET images.PET/CT review sequenceInitial review of the images blinded to patient history or indication is valuable as it enables an unbiased assessment. The black-and-white cine maximum intensity projection (MIP) is foremost in this initial review. This enables a “gestalt” impression of the study. The reconstruction method of these images tends to suppress noise and highlight regions of increased activity. Furthermore, the brain can appreciate these images as being volumetric, especially when rotating. This particularly aids recognition of the shape of regions increased activity, and particularly whether they are spherical, tubular or geographic. For the importance of this, see “Rod’s Rules” in the introduction to the “How We Read” series [4]. With experience, key findings are often established within seconds by review of this series. By definition, this image is relatively insensitive to regions of reduced activity.Next, we review the coronal PET images and triangulate apparent abnormalities on other planes and the MIP image. It is important to review these images on a workstation that has capacity to triangulate findings in axial, coronal and sagittal planes. We find the coronal images particularly helpful for detecting small abnormalities, particularly within the lungs and subcutaneous tissue. Any lesions identified on the PET are then correlated with the CT images, reviewing soft tissue, lung and bone windows as appropriate to the location of the abnormality. We selectively review the non-attenuation corrected (NAC) series when there is uncertainty about possible reconstruction artefacts due to metallic objects or patient movement between PET and CT components. Finally, it is important to widen the PET window in order to review the brain, otherwise easily discernible abnormalities can be missed (see Fig. 4).Fig. 4Patient with diffuse large B cell lymphoma. On the standard windowing, no abnormality is readily identified in the brain (a coronal & axial slice, b MIP image). By increasing the upper SUV threshold, abnormal uptake becomes readily becomes visible (c MIP image, d coronal & axial slice). This corresponded to a MRI abnormality which was not reported prospectively but identified following targeted review after the PET scan. Changing the PET window so that abnormalities can be identified above physiologic brain activity should be a routine component of image reviewFull size image

Only after completing review of the stand-alone PET images we review the fused PET/CT images. This is a quite different process to that of many practices where the transaxial CT is scrolled through and any structural abnormalities identified are then correlated with the fused PET/CT image. This is often the preferred method of experienced radiologists who are sometimes more comfortable reviewing the CT than looking at stand-alone PET images. This approach tends to then use FDG information as an alternative contrast agent rather than as the primary data of a PET/CT study. Those disposed to this method will also generally prefer to obtain a full diagnostic CT as part of the examination. The advantages and disadvantages of these differing methods will be discussed subsequently.As a final pass, we review the CT images sequentially on soft tissue, lung and bone windows to identify structural abnormalities not previously identified on PET review. Interpretation of structural abnormalities that are not associated with metabolic abnormality requires particular care and can give significant insights into the nature of pathological processes.Interpretation of PET/CTThe reader is directed to the initial article in this series, which details many of the principles that we use in formulating an impression of a scan, in reporting its findings and reaching a conclusion.Tumours grow as spheres: differentiating malignant from inflammatory aetiologyWhen high metabolic activity is present, one of the primary aims is to ascertain if the aetiology is malignant, benign or inflammatory. In early PET literature focusing on analysis of solitary pulmonary nodules, some researchers defined malignancy based on a SUVmax threshold of greater than 2.5 [5]. We contend that SUV analysis has virtually no role in this setting. Far more important than the SUVmax is the pattern rather than intensity of metabolic abnormality and the correlative CT findings. Our number one rule is that tumours grow as spheres, whereas inflammatory processes are typically linear and track along soft tissue boundaries such as pleural surfaces or fascial planes (see Fig. 5).Fig. 5This patient had suspicion of pelvic recurrence in the setting of prior surgical excision for rectal carcinoma. There was intense uptake in the known pre-sacral soft tissue thickening (a) and (c) (red arrow) with SUVmax of 11. The linear morphology on the coronal image (b) suggested this was more likely inflammatory than malignant. A separate linear tract of metabolic activity was also seen (green arrow) extending from the pre-sacral abnormality to the peri-anal region (not shown). All abnormalities resolved following antiobiotic therapy confirming inflammatory aetiologyFull size image

Occam's razor teaches us to look for a single cause that will explain all the findings on a particular study. One of the most challenging aspects of oncologic FDG PET/CT review, however, is to recognise all the patterns of metabolic activity that are not malignant and which consequently confound interpretation. Many benign and inflammatory processes are also associated with high glycolytic activity. Whilst some require further investigation, many have characteristic appearances that enable confident characterisation. A variety of potential pitfalls are detailed in Table 1, most of which do not require further investigation. Recognition of other pitfalls requires knowledge of the typical pattern of the various malignancies but is beyond the scope of this review. Future articles in the “How I Read” series will address the specific details of reading PET/CT in various cancers.Table 1 Patterns of uptake in benign neoplasms, post treatment changes and inflammatory processes which can mimic malignancyFull size table

Fig. 6Patient with prior lung malignancy presents for surveillance. The study demonstrates a typical appearance of inflammatory change post talc pleurodesis with intense multi-focal uptake evident throughout the pleural surface (a). On the axial PET/CT (b) and CT (c) the high focal uptake correlates with a site of talc on CT recognised by its high density. Such change can persistent for many years after pleurodesisFull size image

Fig. 7Patient with non-small cell lung cancer treated with curative intent radiotherapy. Post treatment restaging PET/CT demonstrated a complete metabolic response (a–d, c upper SUV threshold adjusted to liver background as detailed above, d upper SUV threshold of 5). Follow-up CT 9 months later demonstrated enlargement of multiple mediastinal nodes considered likely to represent malignant aetiology. Repeat PET/CT (e–i) demonstrated low-to-moderate uptake in these nodes. Given the symmetry of distribution in hilar and mediastinal nodes the aetiology was considered inflammatory, which was confirmed by resolution on follow-up. Thresholding the PET with a SUV threshold of 5 (h–i) might lead to erroneous description of intense uptake and interpretation as malignant in aetiologyFull size image

Fig. 8Appearance of physiologic adnexal uptake observed mid-cycle. Although the metabolic activity is high, on the rotating MIP images (a anterior and lateral) the activity is bilateral and curvilinear, characteristic of fallopian tube activity (b). Unilateral focal ovarian follicular activity is frequently seen in association with this findingFull size image

Commonality of “Metabolic Signature”The intensity of uptake in metastases usually parallels that in the primary site of disease. If not, another aetiology should be considered. For example, discordant low-grade activity in an enlarged lymph node in the setting of intense uptake in the primary tumour suggests it is unlikely malignant and more likely inflammatory or reactive. By CT criteria the enlarged node is ‘pathologic’ but the discordantly low metabolic signature further characterises this is as non-malignant since such a node is not subject to partial volume effects and therefore the intensity of uptake should be similar to the primary site. The exception is when the lymph node is centrally necrotic as a small rim of viable tumour is subject to partial volume effects with expectant lower intensity of uptake; integrating the CT morphology is therefore critical to reaching an accurate interpretation (see Fig. 9). Small nodes that are visualised on PET are conversely much more likely to be metastatic as such nodes are subject to partial volume effects.The exception to this rule is tumours with a propensity for tumour heterogeneity at different sites. In follicular lymphoma or chronic lymphocytic leukaemia, discordant sites of high metabolic activity can be a specific finding for transformed disease. In malignancies with a range of well- to poorly-differentiated phenotypes (particularly endocrine tumours), it is possible to visualise tumour heterogeneity with different grades of disease at varying sites. The combination of FDG and a more specific tracer, which visualises the well-differentiated disease can be very useful to characterise this phenomenon, e.g. radio-iodine imaging for thyroid cancer or somatostatin receptor imaging for neuroendocrine tumours [6].Move beyond lesion counting and size measurement to lesion characterisationThe classical PET/CT indications involve primary staging, therapeutic monitoring, detection of recurrence disease or surveillance. The ability to non-invasively measure glycolytic activity, defining what we refer to as the “metabolic signature”, however, is a key feature of FDG PET/CT that is overlooked by many reporters. For the majority of malignant processes, the intensity of metabolic abnormality correlates with degree of aggressiveness or proliferative rate. For a metastatic malignant process that demonstrates no or minimal metabolic abnormality, this is usually a marker of low proliferative rate and indolent phenotype. Applying conventional diagnostic imaging paradigms, a negative PET/CT study in a patient with biopsy proven malignancy would be considered false-negative. A more useful report, however, would highlight the powerful prognostic information this provides. Providing such prognostic information was formerly the domain of pathology; a report which ignores the intensity of metabolic abnormality is missing a key utility of FDG PET/CT. Descriptively, we define SUV < 5 as “low intensity”, 5–10 as “moderate”, 10–15 as “intense” and >15 as “very intense”. Documenting the actual SUV in the report can be useful to avoid ambiguity with qualitative statements that may be interpreted variably.Evolving literature suggests that intensity of uptake is an independent prognostic factor and in some tumour subtypes superior to histopathologic characterisation. Tumours with low uptake and commensurate indolent phenotype may include papillary thyroid cancer, neuroendocrine tumours, clear cell renal carcinomas and breast carcinoma. Each of these, however, can also demonstrate high intensity uptake commensurate with their spectrum of well- to poorly-differentiated phenotype, with the more aggressive phenotypes demonstrating high intensity uptake commensurate with their higher proliferative rate. PET can be used to guide targeted biopsy of the most intense site of metabolic activity.There are some important exceptions to this broad principle as detailed below:FDG negative but aggressive malignancyThe vast majority of aggressive malignant processes use aerobic glycolysis to derive a substantial amount of their energy, converting glucose to lactate by denying pyruvate access to the tricarboxylic acid cycle. This is termed the Warburg effect [7]. There, however, are a significant minority of tumours that utilise substrates other glucose such as glutamine or fatty acids as a source of the carbon atoms required for growth and proliferation. These allow glucose to be diverted into the pentose phosphate shunt pathway. The utility of FDG PET is diminished in this setting. This includes a subset of diffuse gastric adenocarcinomas, signet cell colonic adenocarcinomas and some sarcomas, particularly liposarcoma. Histologically, these are characterised by tumours with high proliferative rate but minimal GLUT-1 expression. There may be a role for other radiotracers such as fluorothymidine (FLT) or amino acid substrates in this setting.FDG PET/CT has a finite resolution. However, this continues to improve with each generation of PET technology. Apparent FDG uptake is reduced in small volume disease due to partial volume effects, and also in areas of subject to movement, mainly due to respiration. The apparent intensity of uptake in small pulmonary metastases will be reduced due to both these phenomena. New reconstruction algorithms such as point spread function modelling can significantly improve lesion contrast but may also significantly impact the SUV of small lesions. Attempts to harmonise the semi-quantitative analysis of PET data require methods to deal with differences introduced by reconstruction algorithms [8]. Reduction in activity owing to respiratory motion is most evident in the lung bases and also the dome of the liver. Acquiring images with respiratory gating can be useful [9] but with experience this can often be recognised visually. As previously alluded to, enlarged necrotic nodes with only a thin rim of tumour are also subject to significant partial volume effects and can thus appear FDG negative (Fig. 9). Similarly, some aggressive sarcomas or mucinous tumours can also appear PET negative when the signal from cancer cells is dominated by the low uptake in adjacent by extra-cellular matrix or mucin production.Fig. 9Patient with HPV-p16 positive cervical squamous cell carcinoma presents for staging. FDG PET (a) demonstrates subtle uptake in an enlarged right external node (b) which would be difficult to discern without knowledge of the CT findings. Correlation with prior contrast-enhanced CT (c) demonstrates the node has rim enhancement and central necrosis consistent with malignant aetiology. The rim of viable tumour is thin and below the resolution of PET imaging explaining the absence of significant uptake. Integration of CT morphology is critical in this case for accurate interpretationFull size image

Intense FDG uptake but indolent neoplasmSome tumours harbour mutations that result in defective aerobic mitochondrial energy metabolism, effectively simulating the Warburg effect. Due to these mutations and consequent inefficient oxidative phosphorylation, a high amount of glucose is required for ATP production. Mutations in subunits of succinate dehydrogenase (e.g. SDHB) found in patients with hereditary paraganglioma and pheochromocytoma highlight this phenomenon. These have intense uptake on FDG PET/CT despite often having low proliferative rate. Benign oncocytomas, such as parotid, thyroid Hurthle cell or renal oncocytomas also harbour mutations of mitochrondrial oxidative phosphorylation resulting in high FDG activity (see Fig. 10). Uterine fibroids, hepatic adenomas, fibroadenomas of the breast and desmoid tumours are benign or relatively benign lesions that can have quite high FDG-avidity.Fig. 10Three different patients with (a) Hurthle cell adenoma (thyroid oncocytoma), (b) renal oncocytoma and (c) Parotid Warthin’s tumour (parotid oncocytoma). Each has high SUVmax of 45, 22 and 35, respectively. In each case, the abnormality was present on imaging more than one year prior and unchanged in size. The very intense FDG uptake could be interpreted as suspicious for aggressive malignancy but the lack of temporal change was inconsistent with this. The lack of progression in a thyroid, renal or parotid lesion with very intense uptake is pathognomonic of benign oncocytomasFull size image

Beware the staging scan which is actually a response assessment scanMetabolic activity switches off rapidly following initiation of therapy. For example, following initiating of the tyrosine kinase inhibitor, imatinib, for treatment for gastrointestinal stromal tumours (GIST) metabolic activity changes from intense to negative within 24 hours. The same principle applies in a wide variety of circumstances so it is important to be aware whether or not the patient has commenced active therapy. Common examples where patients have commenced active therapy but the referrer is requesting “staging” includes hormonal therapy (eg. tamoxifen) in breast cancer, oral capecitabine in colorectal cancer or high dose steroids in Hodgkin’s lymphoma. In these setting, sites of disease may not be metabolically active confirming effectiveness of active therapy, but limiting the utility of PET to provide accurate staging. Accurate staging may not possible even shortly after treatment has commenced, a paradigm that is different from anatomic imaging where it takes some weeks for changes to occur. It is therefore critical to perform PET staging before commencement of anti-tumour therapy.Integration of CT dataIntegrating the anatomic information provided by CT is important for accurate PET/CT interpretation as it may increase the specificity and sensitivity of PET findings. Detailed knowledge of the anatomic appearance of pathologic, inflammatory and benign processes is therefore critical to correctly interpret PET/CT. For example, focal intense abnormality on PET alone indicative of residual or recurrent lymphoma, may be revised to fat necrosis when CT appearances are integrated [10]. Likewise, lack of uptake in a lymph node may be revised from benign to malignant when the CT appearances of contrast enhancement rim enhancement and necrosis are integrated.Many groups perform diagnostic CT studies with PET using a full-dose and contrast-enhanced acquisition including specialised regional protocols. In part, whether to perform this routinely depends on local practices, credentialing of reporting specialists, and reimbursement schemes. The potential advantage of routine diagnostic CT is improved anatomic localisation and definition, although we contend that low dose CT images reconstructed on modern generation devices usually provide sufficient detail with limited incremental value from “dedicated CT”. Moreover, patients have frequently already had a recent diagnostic CT, although this may diminish with increased utilisation of PET/CT as the first test rather than the last test. Without intravenous contrast, additional identification of typical oncologic complications such as pulmonary embolism or venous thrombosis cannot be identified. Nevertheless, if a “low dose CT” technique is utilised, it should not be considered “non-diagnostic” as it provides rich anatomic detail.There are, however, situations where the acquisition of contrast-enhanced CT is preferred or can be tailored based on findings on the whole body low dose PET/CT without contrast in order to clarify the nature or anatomical relations of FDG-avid foci. Situations where we advocate full-dose, contrast-enhanced CT include localisation of cervical lymph nodes in head and neck cancer in the absence of systemic metastasis, especially to define necrotic nodes, the evaluation of liver metastases suitable for resection and for definition of pancreatic lesions [11]. In other cases, specific interventions, such as use of hyoscine and water to distend the stomach [12] or respiratory gating to resolve the nature of lesions that are subject to respiratory blurring [9], can further enhance diagnostic accuracy. The objective should always to utilise the complementary strengths of each modality to provide accurate diagnostic information pertinent to the individual patient’s care with the minimum risk and greatest convenience. Sometimes this will involve a dedicated and individualised CT acquisition protocol but for other patients, a non-contrast, low-dose protocol will be sufficient. Despite the logistic impost, our preference is to determine the need for and acquisition parameters for contrast-enhanced CT based on immediate review of the whole-body study without contrast and then doing a detailed loco-regional assessment as an additional acquisition, including pharmacological intervention if this may aid the diagnostic process.When performing dedicated CT with higher dose and administration of intravenous/oral contrast may enable detection of abnormalities that are not FDG-avid, such as small hepatic or pulmonary lesions, many of these abnormalities are not malignant and represent incidental benign aetiology, thus potentially decreasing specificity. Just as integration of CT increases specificity of PET findings as discussed above, the converse can also be true. In malignancies which are known or expected to have high FDG uptake, we advise caution in reporting incidental findings on CT that are not FDG-avid as suspicious or malignant. Furthermore, equivocal abnormalities by CT criteria alone (e.g. an ovarian cyst) that would ordinarily mandate further investigation, may be characterised by the absence of FDG uptake as being extremely likely benign. The integration of PET to characterise incidental CT findings is important to decrease further investigations that may usually be mandated with CT alone. Over-sensitive reporting can lead to patient harm, or, worse still, might deny potentially curative treatment.Restaging studiesFor oncologic FDG PET/CT, comparison with prior studies is critical to answer the clinical question. If the study is performed as an “interim” restaging study after commencement of therapy but before completion, in order to reach a valid or clinically useful conclusion findings must be interpreted in the context of known changes that occur at a specific timing and type of therapy. The most well studied use of interim PET is in Hodgkin’s lymphoma where repeat PET after two cycles of ABVD-chemotherapy provides powerful prognostic information and may improve outcomes by enabling early change of management. The use of interim FDG PET/CT is now a well established technique in high grade lymphoma with standardised reporting criteria [13].In our experience, critical errors of interpretation can be made by comparison only with the prior study. For example, if PET/CT is performed too frequently, findings may be erroneously described as stable whereas comparison with the baseline study may clearly demonstrate regression or progression. Review of multiple serial MIP images over the course of therapies can enable rapid appreciation of changes not evident by comparison with the prior study. Knowledge of when treatment commenced is also critical for correct interpretation. For example, a restaging PET/CT performed 3 months after a baseline study demonstrating a “mixed response” with some lesions appearing larger and others smaller, could be better explained by progressive disease and subsequent response to therapy if it was known that therapy was only commenced 1 month prior to the restaging scan, with the initial scan therefore not representing a true baseline.Formulating reportsWe aim to provide a succinct and structured report answering the clinical question under the following sub-headings:

▪ Clinical notes: The aim of this section is to identify the clinical question that needs to be addressed in the conclusion. Unfortunately, complete clinical information is frequently not provided by the referring physician, and therefore alternative sources of information must be sought including from the patient directly, via a patient questionnaire (see Table 2), electronic records or contacting the referrer.Table 2 Our patient questionnaire that we use routinely to provide additional history that may assist PET interpretationFull size table

▪ Technique: We suggest including the following minimum details to document the method so that others can be reassured that the scan was technically adequate, and to enable similar acquisition parameters for subsequent scans: acquisition field-of-view, model of PET/CT scanner, reconstruction technique (e.g. use of time-of-flight), CT acquisition parameters (e.g. dose, use of contrast), FDG uptake time and blood glucose level.

▪ Comparative studies: Details of prior PET/CT and/or other imaging studies which have been directly compared.

▪ Findings: We divide this heading into primary tumour (T), nodal metastases (N) and distant metastases (D) sub-headings, followed by other findings to describe any incidental findings. For lymphoma we divide the report into nodal and extra-nodal sub-headings. We strongly prefer this to an anatomic report (e.g. head, neck, chest, abdomen/pelvis) as the important findings are documented first, and incidental findings last. The PET findings are presented first but are directly correlated with the associated correlative CT findings rather than performing sequential or separate PET and CT reports. An ideal descriptive report should enable the reader to visualise the findings even without having access to the images themselves. Where appropriate to support qualitative findings, specific measures including standardised uptake values (SUV), metabolic tumour volume and lesion dimensions should be included.

▪ Conclusion: This should provide a concise answer to the clinical question. We include the American Joint Committee on Cancer (AJCC) TNM stage for staging scans where our referral-base utilises this staging schema. For restaging, we summarise findings as a complete metabolic response, partial metabolic response, stable disease or progressive metabolic disease [14]. Where appropriate, especially when results are equivocal, we provide guidance to the referring clinician. To keep the report succinct, we avoid repetition of interpretative findings in Findings and descriptive findings in the Conclusion. Where a single unifying interpretation is not possible, we provide clinical useful differentials rather than an exhaustive list of all possibilities and try to indicate the most efficient means to address ongoing uncertainty, which might include suggesting an appropriate biopsy site or recommending further laboratory or imaging evaluations.

We include key images embedded in the report, consisting of serial MIP image demonstrating changes over time, and selected annotated fused PET/CT and CT images highlighting key abnormalities. Feedback from referrers indicates that integration of key images in reports is highly appreciated [15].Sensitivity versus specificity: what is optimal?For cancer imaging with FDG PET/CT, we generally aim to report with high specificity acknowledging the consequent trade-off in sensitivity [16]. In our experience, high sensitivity reporting may lead to adverse patient outcomes by resulting in false positive findings and the potential to deny the patient curative-intent therapies, whilst also leading to a cycle of further investigations resulting in patient and physician anxiety. This approach is extended to incidental findings which are often clinically irrelevant in the context of patients with advanced malignancy.ConclusionsCorrect and consistent thresholding of the PET window is essential for consistent and accurate interpretation. The PET coronal or cine MIP images provide the key information needed to obtain an overview that can often answer the clinical question. Not all metabolically active abnormalities are malignant and a variety of physiologic and inflammatory patterns must be recognised. Cohesive integration of functional and anatomic information provided by PET and CT, respectively, is essential for correct interpretation. In doing this, one must not merely use the PET to locate CT abnormalities which are then counted and measured. A key paradigm change with FDG PET/CT is its ability to non-invasively measure glycolytic metabolism, a hall-mark of aggressive malignancy. Integrating this “metabolic signature” into interpretation provides important information. Whilst the intensity of FDG uptake often correlates with disease aggressiveness, recognition of aggressive lesions that are not FDG-avid, and intensely FDG-avid but benign pathologies is essential.

AbbreviationsFDG:

18F-fluorodeoxyglucose

MIP:

Maximum intensity projection

SUV:

Standardised uptake value

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Author informationAuthors and AffiliationsCentre for Molecular Imaging, Dept of Cancer Imaging, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne, 3000, AustraliaMichael S. Hofman & Rodney J. HicksSir Peter MacCallum Department of Oncology and Department of Medicine, University of Melbourne, Melbourne, AustraliaMichael S. Hofman & Rodney J. HicksAuthorsMichael S. HofmanView author publicationsYou can also search for this author in

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氟代脱氧葡萄糖 - A+医学百科

氟代脱氧葡萄糖

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氟代脱氧葡萄糖是2-脱氧葡萄糖的氟代衍生物。其完整的化学名称为2-氟-2-脱氧-D-葡萄糖，通常简称为F-FDG或FDG。FDG最常用于正电子发射断层扫描（PET）类的医学成像设备：FDG分子之中的氟选用的是属于正电子发射型放射性同位素的氟-18（fluorine-18，F-18，F，氟），从而成为F-FDG（氟-[F]脱氧葡糖）。在向病人（患者，病患）体内注射FDG之后，PET扫描仪可以构建出反映FDG体内分布情况的图像。接着，核医学医师或放射医师对这些图像加以评估，从而作出关于各种医学健康状况的诊断。　　

1 历史

2 作用机理与代谢命运

3 临床应用

4 生产与配送手段

历史

二十世纪70年代，美国布鲁克海文国家实验室（Brookhaven National Laboratory）的Tatsuo Ido首先完成了F-FDG的合成。1976年8月，宾夕法尼亚大学的Abass Alavi首次将这种化合物施用于两名正常的人类志愿者。其采用普通核素扫描仪（非PET扫描仪）所获得的脑部图像，表明了FDG在脑部的浓聚（参见下文所示的历史参考文献）。　　

作用机理与代谢命运

作为一种葡萄糖类似物，FDG将为葡萄糖高利用率细胞（high-glucose-using cells）所摄取，如脑、肾脏以及癌细胞。在此类细胞内，磷酸化过程将会阻止葡萄糖以原有的完整形式从细胞之中释放出来。葡萄糖之中的2位氧乃是后续糖酵解所必需的；因而，FDG与2-脱氧-D-葡萄糖相同，在细胞内无法继续代谢；这样，在放射性衰变之前，所形成的FDG-6-磷酸将不会发生糖酵解。结果，F-FDG 的分布情况就会很好地反映体内细胞对葡萄糖的摄取和磷酸化的分布情况。

在FDG发生衰变之前，FDG的代谢分解或利用会因为其分子之中'位上的氟而受到抑制。不过，FDG发生放射性衰变之后，其中的氟将转变为O；而且，在从环境当中获取一个H之后，FDG的衰变产物就变成了葡萄糖-6-磷酸，而其2'位上的标记则变为无害的非放射性“重氧”（heavy oxygen，oxygen-18）；这样，该衰变产物通常就可以按照普通葡萄糖的方式进行代谢。　　

临床应用

正常葡萄糖分子的化学结构式

在PET成像方面，F-FDG可用于评估心脏、肺脏以及脑部的葡萄糖代谢状况。同时，F-FDG还在肿瘤学方面用于肿瘤成像。在被细胞摄取之后，F-FDG将由己糖激酶（在快速生长型恶性肿瘤之中，线粒体型己糖激酶显著升高）),加以磷酸化，并为代谢活跃的组织所滞留，如大多数类型的恶性肿瘤。因此，FDG-PET可用于癌症的诊断、分期（staging）和治疗监测（treatment monitoring），尤其是对于霍奇金氏病（Hodgkin's disease，淋巴肉芽肿病，何杰金病）、非霍奇金氏淋巴瘤（non-Hodgkin's lymphoma，非何杰金氏淋巴瘤）、结直肠癌（colorectal cancer）、乳腺癌、黑色素瘤以及肺癌。另外，FDG-PET还已经用于阿耳茨海默氏病（Alzheimer's disease，早老性痴呆）的诊断。

在旨在查找肿瘤或转移性疾病（metastatic disease）的体部扫描应用当中，通常是将一剂FDG溶液（通常为5至10毫居里，或者说200至400兆贝克勒尔）迅速注射到正在向病人静脉之中滴注生理盐水的管路当中。此前，病人已经持续禁食至少6小时，且血糖水平适当较低（对于某些糖尿病病人来说，这是个问题；当血糖水平高于180 mg/dL = 10 mmol/L时，PET扫描中心通常不会为病人施用该放射性药物；对于此类病人，必须重新安排PET检查）。在给予FDG之后，病人必须等候大约1个小时，以便FDG在体内充分分布，为那些利用葡萄糖的器官和组织所摄取；在此期间，病人必须尽可能减少身体活动，以便尽量减少肌肉对于这种放射性葡萄糖的摄取（当我们所感兴趣的器官位于身体内部之时，这种摄取会造成不必要的伪影（artifacts，人工假象））。接着，就会将病人置于PET扫描仪当中，进行一系列的扫描（一次或多次）；这些扫描可能要花费20分钟直至1个小时的时间（每次PET检查，往往只会对大约体长的四分进行成像）。　　

生产与配送手段

1934年欧内斯特.劳伦斯专利之中的回旋加速器原理图

医用回旋加速器（medical cyclotron）之中用于产生F的高能粒子轰击条件（bombardment conditions）会破坏像脱氧葡萄糖（deoxyglucose，脱氧葡糖）或葡萄糖之类的有机物分子，因此必须首先在回旋加速器之中制备出氟化物形式的放射性F。这可以通过采用氘核（deuterons，重氢核）轰击氖-20来完成；但在通常情况下，F的制备是这样完成的：采用质子轰击富O水（O-enriched water，重氧水），导致O之中发生(p,n)核反应（中子脱出，或者说散裂（spallation）），从而产生出具有放射性核素标记的氢氟酸（hydrofluoric acid，HF）形式的F。接着，将这种不断快速衰变的F （18-氟化物，18-fluoride）收集起来，并立即在“热室（hot cell）（放射性同位素化学制备室）”之中，借助于一系列自动的化学反应（亲核取代反应或亲电取代反应），将其连接到脱氧葡萄糖之上。之后，采取尽可能最快的方式，将经过放射性核素标记的FDG化合物（F的衰变限定其半衰期仅为109.8分钟）迅速运送到使用地点。为了将PET扫描检查项目的地区覆盖范围拓展到那些距离生产这种放射性同位素标记化合物的回旋加速器数百公里之遥的医学分子影像中心，其中可能还会使用飞机空运服务。

最近，用于制备FDG，备有自屏蔽（integral shielding，一体化屏蔽，一体化防护）以及便携式化学工作站（portable chemistry stations）的现场式回旋加速器（on-site cyclotrons），已经伴随PET扫描仪落户到了偏远医院。这种技术在未来具有一定的前景，有望避免因为要将FDG从生产地点运送到使用地点而造成的忙乱.。

出自A+医学百科 “氟代脱氧葡萄糖”条目 http://www.a-hospital.com/w/%E6%B0%9F%E4%BB%A3%E8%84%B1%E6%B0%A7%E8%91%A1%E8%90%84%E7%B3%96 转载请保留此链接

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18F-FDG(氟代脱氧葡萄糖)

生活中的分子

18F-FDG(氟代脱氧葡萄糖)

2015/12/19 生活中的分子 18F, PET, 癌细胞检测, 葡萄糖 Comment: 0 Author: JiaoJiao18,459views　■

构造

葡萄糖2位的羟基被放射性同位素18F取代的18F-FDG(氟代脱氧葡萄糖)。因为自然界存在的氟元素100%都是19F，而18F是人工产物，半衰期是108分、衰变过程中释放出正电子，生成稳定不具放射性的18O（重氧）。利用这一性质，可以将18F-FDG用于PET(Positron Emission Tomography正电子发射断层扫描)，在肿瘤学临床医学影像和癌扩散方面的研究有着大量的应用。

合成方法

因为上述的18F元素在自然间不存在，用正电子轰击18O的水（富氧水，重氧水），原子序号上升，水的一个氢脱离，形成18F的氢氟酸。这个H18F转化为K18F后，与2位羟基三氟磺酸酯化的甘露糖反应，2位立体构型翻转制成了18F-FDG。

图1

图2 注：Kryptofix是商用名，化学专用名称是 [2.2.2]cryptand，三维的笼状结构，相比起二维的冠醚对碱金属钾有高的亲和性和选择性

18F是半衰期仅有108分的试剂，没法长久保存，做PET测试的医院一般都有自动合成装置–现场式回旋加速器。

而在治疗过程中，通常给禁食数小时、血糖值较低的病人静脉注射含18F-FDG的溶液，病人安静等候约1个小时，以便FDG在体内充分分布，为那些利用葡萄糖的器官和组织所摄取，然后通过PET扫描仪检测信号分布。

PET诊断的原理

PET诊断、用PET扫描仪对体内的18F-FDG的分布进行观测检出。由18F衰变放出的正电子很快与周围的电子结合释放出γ射线。PET扫描仪的功能就是检测出γ線产生的位置。18F-FDG是葡萄糖类似物，可以通过葡萄糖载体蛋白运输到细胞内部，被己糖激酶磷酸化，但之后的代谢过程因为毕竟还是和葡萄糖有区别，没法继续发生转化，所以通过磷酸化物的形式滞留在细胞内(参考图3葡萄糖代谢)。

图3 葡萄糖初步代谢过程

大脑、心脏，肿瘤这样非常消耗葡萄糖的部位对18F-FDG的摄取比其他地方多，18F-FDG的磷酸化物的滞留增加非常明显，所以，衰变时产生的γ射线就能被PET扫描仪记录下来，这样一来，就能对癌细胞准确定位。18F-FDG发生放射性衰变之后，其中的氟将转变为无害、非放射性的重氧；而且，在从环境当中获取一个H+之后，FDG的衰变产物就变成了葡萄糖-6-磷酸，衰变产物通常按照普通葡萄糖的方式进行代谢。

图4 PET診断图

参考文献

Asymmetric 18F-fluorination for applications in positron emission tomography. Buckingham, F.; Gouverneur, V. Chem. Sci., 2016, 7, 1645–1652 DOI：10.1039/C5SC04229A

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作者：北京大学人民医院核医学科李原王茜病史及检查目的：患者男性18岁，主因“骨肉瘤术后1年，化疗后发热2个月，发现右手及小腿肿物1个月”就诊。患者1年前于外院行颈椎骨肉瘤切除术，术后行APMI方案化疗4程，同时因发现多发肺内转移瘤行射波刀治疗；2个月前于放、化疗结束后复查胸CT，发现肺内转移灶明显缩小或消失，但患者开始出现发热，体温最高41℃，予抗生素治疗效果不佳，查血常规示白细胞及中性粒细胞减低，C反应蛋白及血沉明显增高，行血培养阴性；1个月前触及双小腿及右手肿物，伴压痛，肿物穿刺活检提示“未见肿瘤成分”，予激素治疗10天未见明确效果；近期入院查MR提示“双侧小腿肌肉内多发类圆形异常信号，双侧胫骨髓腔内大片地图状高信号”（图1）；进一步查G试验阳性，予抗真菌治疗2周后每日发热频次减少，但最高体温为39℃。为进一步明确诊断行FDG PET/CT显像（图2）。图1图2 检查所见：FDG PET/CT全身显像示：肝脏见多发点状FDG浓聚灶（SUVmax分布在3.0～4.5），平扫CT于部分浓聚灶相应区域可见类圆形稍低密度结节影，直径分布在0.4～0.8cm；右手、右前臂、双侧臀小肌、双小腿肌肉及皮下组织内可见多发FDG浓聚灶（SUVmax分布在2.0～7.7），CT于部分肌肉组织内可见类圆形稍高密度结节影，直径分布在0.2～1.6cm；双侧股骨远段、胫骨近段及远段髓腔内可见不规则片状FDG浓聚影（SUVmax：2.5），平扫CT于相应部位髓腔可见斑片状高密度影；左膝关节滑膜增厚伴髌上囊积液，相应区域可见FDG摄取增高（SUVmax：2.2）；脾脏及富含红骨髓区域骨FDG代谢弥漫性轻度增高，CT未见明确异常结构改变。检查意见：1．肌肉组织、肝脏及左膝关节多发FDG代谢增高灶，首先考虑多脏器累及的感染性病变（真菌性可能性大）2．下肢骨髓腔内FDG代谢增高灶考虑骨梗死可能性大3．脾脏及富含红骨髓区域骨FDG代谢活跃，考虑与发热有关最终临床诊断：患者随后行下肢肌肉切开活检，病理检查结果提示脓肿伴周围肉芽组织形成；分子测序及脓液培养提示热带念珠菌感染。临床根据药敏试验结果予抗真菌治疗后患者体温恢复正常，症状明显好转。病例相关知识及解析：血液系统肿瘤、化疗、器官移植、艾滋病等免疫缺陷或免疫抑制的患者常发生机会性感染，导致病死率明显增高，其中侵袭性真菌感染（Invasive fungal infections, IFIs）是这些患者常见的死亡原因[1]。IFIs的致病菌多为曲霉菌和念珠菌[2]，其治疗需基于药物敏感性测定给予足量和全程的抗真菌药物，但IFIs早期诊断困难，有赖于获得确定性细胞学或组织学证据，患者常常因诊断不明确而导致治疗延误[3,4]。在组织病理切片中,真菌感染可表现为（1）中性粒细胞浸润和化脓性炎，常表现为小脓肿形成；（2）肉芽肿形成，其内伴中性粒细胞、单核细胞和淋巴细胞浸润；（3）出血坏死性炎。IFIs可累及肌肉软组织、骨骼、中枢神经系统、肺、心包、胃肠道及泌尿生殖系统等器官组织[2,5]。软组织脏器受累的影像表现多为结节样病灶，在MRI中呈环形高信号包绕中心低信号病灶，提示伴有中心坏死的肉芽肿性病变；骨骼受累时由于骨髓炎多表现为骨髓水肿和骨质破坏，关节可见滑膜增生、关节腔积液及周围软组织水肿；肺内病灶表现多样，当出现新月形空气征时诊断曲霉菌感染具有较高特异性。本例患者为骨肉瘤患者，以发热伴四肢软组织多发结节就诊，首先需与肿瘤转移相鉴别。但患者化疗后原肿瘤病灶明显好转，颈椎术区及肺内无复发征象，病变累及肌肉组织、关节及肝脏，这些均非骨肉瘤常见转移部位，结合患者化疗后处于免疫抑制状态、临床表现发热、G试验阳性以及穿刺活检未见恶性病变征象，故考虑并发感染可能，而病灶表现环形强化及高FDG摄取均可符合肉芽肿性病变（PET病灶中心未见低摄取考虑可能为部分容积效应对小病灶的影响所致）。本例患者的PET/CT检查同时发现下肢骨髓腔内对称性分布的斑片状高FDG摄取，CT无骨质破坏表现，结合MRI影像特征应考虑骨梗死，其发生可能与治疗期间大剂量激素应用有关，相似病例以往曾在规培103号病例中报道。研究显示，FDG PET/CT诊断IFIs的准确性可达90%，可因发现更多病灶改变55%患者的分期及46%患者的治疗方案[6]。总之，对于恶性肿瘤的患者，PET/CT显像不仅可用于肿瘤的诊断、分期、复发检出、疗效监测等方面，对于临床过程中伴发的感染或炎症的检出亦具有重要作用，但实际工作中需结合临床进行诊断。参考文献：1. Colombo AL, de Almeida Junior JN, Slavin MA, et al. Candida and invasive moulddiseases in non-neutropenic critically ill patients and patients with haematological cancer. Lancet Infect Dis. 2017;17(1): e344-e356.2. Ankrah AO, Span LFR, Klein HC, et al. Role of FDG PET/CT in monitoring treatment response in patients with invasive fungal infections. Eur J Nucl Med Mol Imaging. 2019;46(1):174-183.3. Spitzer M, Robbins N, Wright GD. Combinatorial strategies for combating invasive fungal infections. Virulence. 2017;8(2):169-185.4. Zaoutis TE, Argon J, Chu J, et al. The epidemiology and attributable outcomes of candidemia in adults and children hospitalized in the United States: a propensity analysis. Clin Infect Dis. 2005;41(9):1232-1239.5. Orlowski HLP, McWilliams S, Mellnick VM, et al. Imaging Spectrum of Invasive Fungal and Fungal-like Infections. Radiographics. 2017;37(4):1119-1134.6. Leroy-Freschini B, Treglia G, Argemi X, et al. 18F-FDG PET/CT for invasive fungal infection in immunocompromised patients. QJM. 2018;111(9):613-622.

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