正电子发射计算机断层显像／核磁共振：分子影像学技术新进展

背景：正电子发射计算机断层显像（PET）从分子水平反映细胞代谢和功能变化,MRI有更高的软组织对比度和空间分辨率,且无电磁辐射。近年来,随着多模式成像技术飞速发展,作为刚刚应用于临床的多模式分子成像技术,PET／MRI融合显像可提供分子、形态与功能信息,有关研究已成为分子影像领域的关注焦点。目的：就目前PET／MRI研制存在的问题和进展情况做一综述,并展望其潜在的临床和科研价值。方法：由第一作者应用计算机检索CNKI数据库、Springerlink数据库、Pubmed数据库相关文献。检索时间范围：2000年1月至2012年6月。英文检索词：“PET／MRI”和“multimodality imaging or imag efusion”,中文检索词：“分子影像学”和“图像融合”。选择内容与PET／MRI多模式成像相关的文章,同一领域文献则选择近期发表或发表在权威杂志文章,共纳入53篇文献。结果与结论：已有的研究成果表明,PET／MRI较传统显像手段和其他成功的多模式成像技术,如PET／CT和SPECT／CT有更多、更新的应用优势,并已积累临床前和初步临床应用的经验,PET／MRI具有广阔的发展空间,有望将分子影像技术的发展带入一个新的时代,为临床诊断掀开新的篇章。     

CT、MRI及与PET融合显像评价宫颈癌分期及淋巴结转移中的应用进展

传统影像学检查方法(CT、MRI)在宫颈癌分期及淋巴结转移的诊断方面应用较为广泛,对制定治疗方案、改善预后和降低死亡率有重要的作用。近年来,随着分子影像技术的发展,多模态分子影像技术(PET/CT及PET/MR)被逐渐应用于宫颈癌的诊断并指导治疗。本文对CT、MRI及与PET融合显像技术在宫颈癌分期及淋巴结转移评价中的临床应用进行综述。     

肺鳞癌与腺癌PET/MRI影像学比较

目的 分析肺鳞癌与腺癌PET/MRI影像学特点,以提高对肺鳞癌与腺癌的鉴别诊断能力。方法 收集行PET/MRI扫描的肺鳞癌或腺癌患者84例,其中肺鳞癌35例,腺癌49例,比较两组肺癌患者临床资料、PET/MRI影像及病灶代谢参数。结果 肺腺癌与肺鳞癌组年龄、性别、位置、MRI信号、形态、分叶、毛刺、胸膜凹陷征、淋巴结及全身转移、胸腔积液比较差异均无统计学意义(P>0.05),而肿瘤最大截面面积、支气管截断征、阻塞性改变及PET代谢参数差异有统计学意义(P<0.05)。结论 PET/MRI影像对肺鳞癌和腺癌术前病理分型具有一定的价值。     

多模态影像技术在肿瘤诊治中的应用进展

影像学检查是肿瘤检查的重要方法,但传统的检查方法已难以满足临床需要。随着正电子发射计算机断层扫描(PET)/CT、单光子发射计算机断层扫描(SPECT)/CT在临床上的广泛应用及PET/MRI的研制成功,实现了解剖显像与代谢显像结合,大大提高了肿瘤的诊断效能。因此,多模态影像技术得到越来越多的关注。     

基于中国人群建设PET神经影像数据库

<正>医学影像学技术的发展推动了神经影像学临床及科研进步，但获取数据难度及成本均较高。建设神经影像数据库可避免重复采集数据所致成本增加和周期延长，支持在不同背景和目的下深入挖掘数据，提高其利用率。目前国内外已有多个神经影像学数据库，但多针对MRI,核医学PET神经影像学数据库发展相对滞后，尤其缺少基于我国人群的PET神经影像学资料。本研究基于复旦大学附属华山医院资料尝试建立基于我国人群的PET神经影像学数据库，     

终身学习是医生的必经之路——写在《继续教育》栏目开办之前

当代基础医学和临床医学发展之快,使医学发生着日新月异的变化,新方法、新理念层出不穷。在临床医学中,影像医学的发展尤为突出。在影像诊断方面,进展已从形态影像扩展到功能影像,从病例形态影像扩展到分子影像。新的影像技术如CT、MRI和PET/CT等突破了传统X线诊断的限定。当传     

前列腺特异性膜抗原PET/MRI在前列腺癌中的应用现状与前景

前列腺癌(prostate cancer, PCa)是常见的老年男性恶性肿瘤,并是其主要致死原因之一。前列腺特异性膜抗原(prostate specific membrane antigen, PSMA)是一种PCa组织特异性高表达的跨膜蛋白,这使得PSMA成为PCa良好的特异性分子影像靶点。目前,PSMA PET/CT在PCa诊断、分期等方面的价值已被广泛认可。随着PET/MRI逐步进入临床,PSMA PET与MRI两种诊断PCa的重要影像学方法的有机结合成为可能。本文就PSMA PET/MRI在PCa中的应用现状与前景进行阐述,以期为临床诊疗提供借鉴。     

PET/MRI衰减校正技术研究进展

PET/MRI是近年兴起的新型多模式成像设备。PET图像需要利用衰减图进行衰减校正,从而得到真实的放射性药物浓度的分布信息。PET/MRI利用MRI数据得到衰减图对PET进行校正,其获取衰减图的方法是PET/MRI系统的关键技术。PET/MRI衰减校正的方法主要有分割法、地图集法和发射数据重建法。本文介绍这3种方法的原理、校正效果及优缺点,并对PET/MRI衰减校正技术的发展方向进行展望。     

PET和PET/CT在头颈部恶性肿瘤中的临床应用价值

正电子发射断层成像(Positron emission tomography,PET)能较早揭示生物机体异常功能、代谢变化,由于它的灵敏度高、特异性好,在临床肿瘤诊断中起着重要作用.但其影像解剖结构不如CT和MRI清晰,将PET与CT进行同机图像融合的PET,CT则弥补了这个不足,并将各自的优势相结合,代表了核医学显像的未来.     

MRI联合PET诊断原发性骨淋巴瘤

目的 观察原发性骨淋巴瘤的MRI及PET影像特征,探讨MRI联合PET的诊断价值.方法 收集经病理证实的原发性骨淋巴瘤16例,回顾性分析其MRI和PET表现.结果 单骨侵犯15例(股骨5例,椎体3例,髂骨3例,胫骨2例,桡骨1例,上颌骨1例);多骨侵犯1例(胸骨上段及右侧第7肋骨各一病灶).MRI表现:①16例均见髓腔内局部片状或弥漫性不均匀异常信号,T1WI呈等或稍低或混杂信号,T2WI呈稍高信号,不均匀或均匀强化;②均见明显软组织肿块,15例范围超过骨病变,1例与骨病变相当;T1WI多呈均匀等或稍低信号,T2WI呈均匀或不均匀稍高信号,轻度或中度均匀强化或不均匀强化;3例椎体者为单一椎体压缩性骨折伴局部呈硬膜外和(或)椎旁软组织,软组织范围超过病变椎体.PET:术前PET检查13例,均提示病变局部糖代谢增高,局部放射性浓聚,全身其他部位无异常代谢;3例椎体者均为术后PET检查,术后2个月术区局部复发1例.结论 MRI上原发性骨淋巴瘤骨质破坏小而软组织肿块大,T2WI信号相对较低,具有一定特征性;PET对骨原发性淋巴瘤无特异性,但对确定病变性质、鉴别原发与继发、以及术后随访具有优势.MRI与PET相结合为检查原发性骨淋巴瘤的适当方法.     

头颈部影像学研究进展

随着影像技术和诊断水平的提高,头颈部影像学取得了重大进展。薄层高分辨力成像可很好地显示头颈部小器官,并能满足诊断需求;fMRI、PET/CT、PET/MRI、DWI等可从多方面推动头颈部影像学的发展。本文就近年来头颈部影像学的主要进展进行综述。     

Cardiac PET/MRI

Medical imaging plays an important role in clinical management of patients with cardiac diseases and in preclinical and clinical research. The recent availability of hybrid PET/MRI devices that combine positron emission tomography (PET) with magnetic resonance imaging (MRI) opens up new opportunities. Technical advancements have been necessary to make the two systems with different underlying principles work well together. Growing evidence points to a significant value of this novel modality for imaging of the myocardium and the coronary arteries in order to gain broad insight into the morphological, functional, molecular and cellular aspects of cardiac pathophysiology. PET/MRI can deliver the combined information of stand-alone PET and MRI with improved spatial and temporal co-registration; it can additionally be used to improve PET image quality and quantification accuracy by addressing factors such as motion and partial volume effects, making PET/MRI more than its parts.     

低剂量PET/CT及PET/MRI临床研究进展

PET/CT及PET/MRI为新兴影像学手段,可定量反映生物体功能、提供病变相关影像学信息,应用日益广泛;而其所带来的辐射安全问题亦引起广泛关注。本文就低剂量PET/CT及PET/MRI临床研究进展进行综述。     

一体化TOF-PET/MR的临床应用与挑战

精准化医疗是现代医学发展的趋势,而反映生命过程不同侧面信息的多模态影像学技术是实现精准化医疗的必要条件。PET及MRI的出现推动了多模态影像学的发展,特别是一体化TOF-PET/MR,可克服PET探测器与MRI强磁场相互干扰的技术难题、实现时间和空间上的同步扫描,对于从结构、功能、分子代谢等方面探索疾病的发生、发展及诊断具有重要意义。TOF技术有助于提高PET图像质量,降低假阳性或假阴性。本文就一体化TOF-PET/MR的临床应用及其面临的挑战进行综述。     

一体化PET/MRI用于直肠癌研究进展

MRI是目前可用于直肠癌局部分期的最佳影像学方法之一。一体化PET/MRI可通过同步双模态扫描获得病变的形态、功能及代谢等多方面信息,较PET/CT或单模态MRI、CT评估直肠癌分期、观察新辅助放化疗疗效及监测复发的效能更优。本文对一体化PET/MRI评估直肠癌的现状及进展进行综述。     

An integrated MR/PET system: prospective applications

Radiology is strongly depending on medical imaging technology and consequently directing technological progress. A novel technology can only be established, however, if improved diagnostic accuracy influence on therapeutic management and/or overall reduced cost can be evidenced. It has been demonstrated recently that Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) can technologically be integrated into one single hybrid system. Some scientific arguments on the benefits are obvious, e.g., that simultaneous imaging of morphological and functional information will improve tissue characterization. However, crossfire of questions still remains: What unmet radiological needs are addressed by the novel system? What level of hardware integration is reasonable, or would software-based image co-registration be sufficient? Will MR/PET achieve higher diagnostic accuracy compared to separate imaging? What is the added value compared to other hybrid imaging modalities like PET/CT? And finally, is the system economically reasonable and has the potential to reduce overall costs for therapy planning and monitoring? This article tries to highlight some perspectives of applying an integrated MR/PET system for simultaneous morphologic and functional imaging.     

State of the Art in Cardiac Hybrid Technology: PET/MR

Simultaneous PET/MRI is an emerging technique combining two powerful imaging modalities in a single device. The wide variety of available tracers for perfusion and metabolic studies and the high sensitivity of positron emission tomography (PET) combined with the high spatial resolution and soft tissue contrast of magnetic resonance imaging (MRI) in depicting cardiac morphology and function as well as MRI’s absence of ionizing radiation makes PET/MRI very attractive to radiologists and clinicians. Nevertheless, PET/MR scientific and clinical promise is to be considered in the context of numerous technical challenges that hinder its use in the clinical setting. For example, in order for a PET system to work correctly within an MR field, major changes are required to the photon detection chain such as the elimination of photomultiplier tubes, etc. Another significant limitation of PET/MRI is the lack of an electron density map (as is the case with PET-CT) that can be readily obtained from MRI (the latter measures proton not electron density) and used to correct PET data for attenuation. Moreover, as with PET-CT, cardiac and respiratory motions cause image degradations that affect image quality and accuracy both in static and dynamic PET imaging. As a result, overcoming these (and other) technical limitations is a very active area of research both in academic institutions as well as industry. In this paper, we review recent literature on cardiac PET/MRI, present the state-of-the-art of this technology, and explore promising preclinical and clinical cardiac applications where PET/MRI could play a substantial role.     

Combined PET/MRI: <Emphasis Type="Italic">Global Warming—</Emphasis>Summary Report of the 6th International Workshop on PET/MRI,March 27–29, 2017, Tübingen,Germany

The 6th annual meeting to address key issues in positron emission tomography (PET)/magnetic resonance imaging (MRI) was held again in Tübingen, Germany, from March 27 to 29, 2017. Over three days of invited plenary lectures, round table discussions and dialogue board deliberations, participants critically assessed the current state of PET/MRI, both clinically and as a research tool, and attempted to chart future directions. The meeting addressed the use of PET/MRI and workflows in oncology, neurosciences, infection, inflammation and chronic pain syndromes, as well as deeper discussions about how best to characterise the tumour microenvironment, optimise the complementary information available from PET and MRI, and how advanced data mining and bioinformatics, as well as information from liquid biomarkers (circulating tumour cells and nucleic acids) and pathology, can be integrated to give a more complete characterisation of disease phenotype. Some issues that have dominated previous meetings, such as the accuracy of MR-based attenuation correction (AC) of the PET scan, were finally put to rest as having been adequately addressed for the majority of clinical situations. Likewise, the ability to standardise PET systems for use in multicentre trials was confirmed, thus removing a perceived barrier to larger clinical imaging trials. The meeting openly questioned whether PET/MRI should, in all cases, be used as a whole-body imaging modality or whether in many circumstances it would best be employed to give an in-depth study of previously identified disease in a single organ or region. The meeting concluded that there is still much work to be done in the integration of data from different fields and in developing a common language for all stakeholders involved. In addition, the participants advocated joint training and education for individuals who engage in routine PET/MRI. It was agreed that PET/MRI can enhance our understanding of normal and disrupted biology, and we are in a position to describe the in vivo nature of disease processes, metabolism, evolution of cancer and the monitoring of response to pharmacological interventions and therapies. As such, PET/MRI is a key to advancing medicine and patient care.     

Application of MR/PET in Oncologic Imaging

The present review aims to depict the possibilities offered by hybrid imaging with magnetic resonance positron emission tomography (MR/PET). Recently, new whole-body MR/PET scanners were introduced allowing for the combination of both modalities outside the brain. This is a challenge for both modalities: For MRI, it is essential to provide anatomical images with high resolution. Additionally, diffusion-weighted imaging (DWI), proton spectroscopy, but also dynamic contrast-enhanced imaging plays an important role. With regard to PET, the technical challenge mainly consists of obtaining an appropriate MR-based attenuation correction for the PET data. Using MR/PET, it is possible to acquire morphological and functional data in one examination. In particular, children and young adults will benefit from this new hybrid technique, especially in oncologic imaging with multiple follow-up examinations. However, it is expected that PET/CT will not be replaced completely by MR/PET because PET/CT is less cost-intensive and more widely available. Moreover, in lung imaging, MRI limitations still have to be accepted. Concerning research, simultaneous MR/PET offers a variety of new possibilities, for example cardiac imaging, functional brain studies or the evaluation of new tracers in correlation with specific MR techniques.