PET／CT的新进展及临床应用

PET/CT将PET功能代谢信息与CT解剖结构信息结合在一起,可以同时反映病灶的病理生理变化及形态结构变化,明显提高了诊断的准确性。PET/CT的探头晶体、图像融合技术、用户平台等方面的发展极大地促进了其临床推广应用,是目前分子影像的最主要设备。     

Current developments in SPECT/CT systems using 99mTc-radiopharmaceuticals

The 3 foundations of nuclear medicine are radiation conscious personnel, specific radiopharmaceuticals and equipment. The trend in molecular radiopharmacy is to develop new radiopharmaceuticals targeting peptides and receptors. 99mTc-radiopharmaceuticals give important clinical and molecular information especially in endocrinology, oncology and cardiology. The basic equipment has relied on crystal scintillation detector gamma cameras and the obtained images represent organ function provided by the specific radiopharmaceutical. Gamma cameras for single emission computed tomography (SPECT) can be added to an X-ray computed tomography (CT) equipment to form a hybrid (SPECT/ CT). The system is coupled to computer algorithms and special software to acquire and process the separate studies and fuse the two images to give a 3-D image of organ function plus anatomy. The new semiconductor or solid state detectors are a big improvement in commercial hybrid scintillation cameras and micro-SPECT/CT. Fused images obtained with SPECT/CT have been very useful in almost all medical areas and play an important role in preclinical research. The aim of this work is to present the current status and future trends of SPECT/CT systems in the clinical practice of nuclear medicine using technetium-99m radiopharmaceuticals. The development of molecular, functional and genetic imaging tools aided by new technology and SPECT/CT image fusion will enhance accurate diagnoses, and understanding of molecular mechanisms of disease and their respective response to radiopharmaceutical therapy.     

小动物SPECT/CT的应用进展

在分子影像学发展的过程中核医学分子成像扮演着至关重要的角色。大型仪器如PET、SPECT的广泛应用为核医学的兴盛带来了新的契机,并以新的成像概念进入到了可实时动态观察在体生物学行为的时代。依据不同成像模态的优势,核医学将CT作为贴合补充,使PET/CT、SPECT/CT应运而生。SPECT/CT融合了SPECT的功能显像和CT的解剖显像,为多种临床疾病的诊断和治疗提供了综合全面的影像依据。小动物SPECT/CT作为基础医学分子影像的重要研究平台,不仅为基础分子研究带来了广阔的发展前景,同时也对临床医学的发展起着重要推动作用。     

双探头SPECT/CT系统符合成像的功能与解剖影像同机融合

双探头SPECT符合显像系统,既能进行常规单光子显像,又能进行~(18)F-FDG代谢显像,大大地推动了~(18)-FDG显像的临床常规应用。SPECT/CT系统的问世,CT不仅能提供高质量的衰减校正图像,保证了FDG显像校正数据的可靠性,而且能与FDG影像进行同机图像融合,克服了异源图像融合的费时、匹配不准的缺点,提高了FDG显像定位诊断的准确性。本文简单介绍图像融合的方法,SPECT/CT的结构及图像融合的产生、临床初步应用及存在技术的不足。     

我国PET/CT的发展和配置管理

目的:PET/CT是正电子发射断层(PET)和X线CT同机融合的新型医学影像设备,它把解剖与功能影像有机的融为一体。我国1995年配置医用回旋加速器和PET,2002年配置和应用PET/CT,已有20多年历史。论文将研究我国PET/CT的应用现状,配置管理和发展方向。方法:通过调查和访问了解我国PET/CT的配置和使用情况,与卫生行政部门共同制定我国PET/CT的配置规划和管理办法。结果:我国目前共有PET/CT150台,医用回旋加速器90台。结论:我国PET/CT的发展是与国民经济的发展相适应的。     

PET/MRI显像技术与其他分子影像技术的比较

目的：比较双模态PET/MRI显像技术与其他分子影像技术的优势和劣势。方法：随着分子医学及影像医学的飞速发展,将二者结合的分子影像技术促进了医学科学的发展。单模态及多模态分子影像技术主要包括了PET/MRI、光学成像、PET/CT、SPECT/CT、SPECT/MRI及超声分子成像。本文比较了以上各种分子影像技术在临床前及临床医学中的应用。结果：双模态PET/MRI优势主要集中在肿瘤学、心脏病学、神经科学中的研究,为研究者及临床医生提供更多的分子信息。结论：多模态分子医学影像设备的发展势必推动整个医学科学的发展,PET/MRI将解开更多的未解之谜。     

骨骼系统PET/CT显像和核医学平面显像对比研究

目的:探讨单光子发射计算机断层(SPECT)骨显像和PET/CT骨显像结果的差异及可能的原因。方法:对2例病例均先后行SPECT骨显像和PET/CT骨显像,并对图像进行对比分析。结果:骨骼对18F-fluoride(PET/CT骨显像剂)和99mTc-MDP(SPECT骨显像剂)的摄取机理类似,均可以反映局部血流量及骨代谢更新的活跃程度,由于18F-fluoride与骨的亲和力强于99mTc-MDP,因此PET/CT图像具有比SPECT更高的系统分辨率和系统灵敏度。结论:PET/CT骨显像灵敏度和分辨率均高于SPECT,但由于其检查费用较高及自身受18F的短半衰期限制,因而其在临床应用受到一定的限制。     

基于多模态分子影像技术的SPECT/CT在临床中的应用进展

核医学分子成像是分子影像技术的一种,它可以将分子医学基础研究取得的成果利用分子影像技术的临床前期研究直接应用到临床中去。随着分子影像技术的发展,将多种模式医学影像成像技术结合的SPECT/CT技术有了一定程度的发展。SPECT/CT是由高端SPECT和多排螺旋CT结合成一体化的设备,不仅提供SPECT的功能影像,而且提供CT的解剖显像,提高了传统定位、定性的准确性。SPECT/CT的诊断效能远远大于单独的SPECT或单独的CT,也大于单独SPECT与单独CT联合诊断的效能。SPECT/CT在多种疾病诊断和治疗方面发挥了重要的作用,越来越受到临床和影像学科的重视。     

~(18)F-FDG PET/CT扫描早期诊断重症急性胰腺炎继发感染的探讨

目的探讨氟脱氧葡萄糖正电子发射断层扫描/计算机断层扫描(~(18 )F-FDG PET/CT)在早期诊断重症急性胰腺炎(SAP)继发感染的评估价值。方法分别构建两种细菌(ATCC 25922和ATCC 25923)的SAP SD大鼠感染组模型,并以生理盐水构建对照组模型。分别在建模后0、1、3h检测动物全血细胞计数和血清淀粉酶,建模后3h行~(18)F-FDG PET/CT显像,并进行生物学分布、HE染色和Gram染色等验证PET显像结果。结果~(18 )F-FDG PET/CT显像提示,两种细菌感染组大鼠模型均显示胰腺部位的放射性浓聚灶;大肠埃希菌组、金黄色葡萄球菌组和生理盐水组靶(胰腺)/非靶(肌肉)比值(SUV)分别为4.22±0.61、4.32±1.21、2.26±0.35,两种细菌感染组模型动物SUV值无统计学差异(P0.05),大肠埃希菌感染组模型与对照组模型比较有统计学差异(P0.01)。生物学分布结果与PET显像结果一致。结论~(18)F-FDG PET/CT可以作为早期诊断SAP继发感染的检测方法。     

Operational radiation safety for PET-CT, SPECT-CT, and cyclotron facilities

Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) are well- established and indispensable imaging modalities in modern medicine. State-of-the-art computed tomography (CT) scanners have now been integrated into multi-modality PET-CT and SPECT-CT devices, and these devices, particularly PET-CT scanners, are dramatically impacting clinical practice. 18F-fluorodeoxyglucose (FDG), by far the most widely used radiopharmaceutical for clinical PET imaging in general and oncologic PET imaging in particular, is highly accurate in detecting (approximately 90%) and staging many types of tumors, monitoring therapy response, and differentiating benign from malignant lesions. Several factors, including the relatively high administered activities [e.g., 370-740 MBq (10-20 mCi) of FDG], the high patient throughput (up to 30 patients per d), and in particular, the uniquely high energies (for a diagnostic setting) of the 511-keV positron-negatron annihilation photons, make shielding requirements, workflow, and other radiation protection issues important considerations in the design of a PET or PET-CT facility. The Report of Task Group 108 of the American Association of Physicists in Medicine (AAPM) provides a comprehensive summary of shielding design and related considerations, along with illustrative calculations. Whether in the form of a PET-CT or a SPECT-CT device, the introduction of CT scanners into a nuclear medicine setting has created new and complex radiation protection issues concerning the radiation burden and attendant risks accrued by patients undergoing such multi-modality procedures (especially in those instances in which higher-dose, diagnostic-quality CT studies are done as part of the PET-CT or SPECT-CT exam). In addition, because PET is dependent on the availability of short-lived 18F (Tp = 110 min) primarily in the form of FDG, and other short-lived positron emitters such as 11C (20 min), 13N (10 min), and 15O (2 min), cyclotrons for production of medically applied radionuclides and associated radiochemistry facilities are now widespread (well over 100 worldwide) and present their own radiation safety issues. In addition to the radioactive product, sources of exposure include neutrons and radioactive activation products in the various cyclotron components and surrounding shielding. Nonetheless, published studies have shown that the radiation doses to personnel working in cyclotron and associated radiochemistry facilities, as well as in PET or PET-CT and SPECT or SPECT-CT facilities, can be maintained below, and generally well below, the pertinent regulatory limits. This presentation will review the basic radiation safety aspects, including shielding and workflow, of these increasingly important and increasingly numerous facilities. The radiation burden accrued by the patients undergoing PET-CT or SPECT-CT exams will be considered as well.     

PET/CT在肿瘤学中的应用进展

PET/CT实现了功能与解剖信息的同机融合,本文介绍PET/CT的优势、在肿瘤诊断与临床分期、疗效监测与预后评价中的应用价值,常见的假阳性与假阴性,并简要介绍PET/CT发展前景。     

18F—FDG PET／CT对乳腺癌分期及疗效监测的价值探讨

目的探讨18F—FDG PET／CT在乳腺癌诊断及术后疗效监测的应用价值。方法对2006年1月～2009年12月笔者所在医院收治的的76例病理类型最终确诊为乳腺癌的病例行”F—FDGPET／CT显像和胸部诊断CT扫描,检查范围包括乳房原发肿瘤、淋巴结及全身器官,并将18F—FDG PET／CT和胸部CT检查的结果进行对比。结果18F—FDG PET／CT检查对乳腺癌诊断的灵敏度为91．3％,特异性为53．1％,准确性为85．3％;而胸部诊断cT的灵敏度检查为62．1％,特异性为29．8％,准确性为55．6％。在对淋巴结转移的诊断上,18F—FDG PET／CT的灵敏度（99．8％）高于胸部诊断CT的灵敏度（53．1％）。而在对肺部转移灶检测上胸部CT的灵敏度（989％）高于18F—FDG PET／CT（42．9％）。结论18F—FDG PET／CT在对乳房原发肿瘤、淋巴结转移和术后诊断复发的发现和判断上显示出明显优势;但胸部CT在发现肺部转移灶的作用不容忽视,其地位不可取代。     

~(18)F-FDG PET/CT显像对鼻咽癌放疗后复发早期诊断的临床价值

目的探讨18F-FDGPET/CT对鼻咽癌(nasopharygeal carcinoma,NPC)放射治疗后复发早期诊断的临床价值。方法20例NPC病人于放疗后12～18个月同期行18F-FDGPET/CT和MRI检查,分别由两位核医学科及放射科主治医生进行独立诊断,将18F-FDGPET/CT与MRI结果进行比较,其中12例经活检病理证实。结果11例MRI检查未见明显肿瘤复发征象,18F-FDG PET/CT显像提示其中5例有局灶性FDG摄取明显增高,诊断为复发,5例经活检未发现复发。7例CT和MRI提示肿瘤复发,18F-FDG PET/CT均显示局部病变有放射性摄取浓聚,该7例18F-FDGPET/CT摄取浓聚的病变处均经活检病理证实为肿瘤复发。另两例MRI提示鼻咽癌颅内侵犯,而18F-FDG PET/CT诊断为放射治疗后脑损伤,后经随访证实,其余经临床随访证实,随访中位时间为13个月。结论与MRI检查相比,18F-FDG PET/CT在鼻咽癌放射治疗后肿瘤复发的早期定性诊断上具有明显的优势。     

正电子发射断层扫描/计算机断层扫描（PET/CT）成像在肿瘤筛查中的应用进展

我国是世界癌症发病最多的国家，筛查可以实现肿瘤早期诊断、改善患者预后、提高生存质量、降低死亡率。正电子发射断层扫描/计算机断层扫描（PET/CT）提供的代谢信息有助于肿瘤筛查初始分期、治疗计划、反应评估，并在较小程度上可用于肿瘤的随访；PET/CT成像在放射治疗中的渐进式整合在肿瘤间和肿瘤内恶性病变的生物异质性中具有其基本原理，需要单独调整辐射剂量以获得癌症患者的有效局部肿瘤控制；PET/CT提供有关肿瘤病变的生物学特征（如代谢、缺氧和增殖）的信息，可以识别放射性耐药区域并利用这些信息来优化治疗计划，PET/CT减少了肿瘤部位解剖学描绘的不确定性和可变性。本文主要就目前常见肿瘤在PET/CT研究中的应用进展进行综述。     

Does 18F-FDG PET/CT play a role in the differential diagnosis of parotid masses

AIM: The aim of the present study was to assess the accuracy of an hybrid PET/CT scanner in the evaluation of newly diagnosed parotid masses, comparing the results with those reported in the literature with using PET scanners only. METHODS: The potential role of 18F-FDG PET/CT in distinguishing benign from malignant parotid masses in 14 consecutive patients was investigated. All patients were preoperatively evaluated by means of ultrasound (US), US-guided fine needle aspiration (FNA) cytology, computed tomography (CT) scan, magnetic resonance imaging (MRI) and 18F-FDG PET/CT. For To interpreting FDG PET findings, the right to left parotid (R/L) SUV max ratio was calculated in a group of 54 patients without evidence of parotideal disease (mean+/-SD = 1+/-0.2; range = 0.8-1.2); considering the R/L SUV max ratio, focal or diffuse uptakes <0.8 or >1.2 were considered as potentially pathological. RESULTS: Imaging data were compared with surgical and histopathological findings. At FDG PET/CT, 9 false positive cases were found (8 Warthin's tumours, 1 pleomorphic adenoma), 1 false negative (acinar cell carcinoma), 4 true negative (1 Warthin's tumour, 1 pleomorphic adenoma, 1 lymph epithelial cyst, 1 parotid inflammation) whereas there was no case of true positive. The global accuracy of FGD PET/CT was rather low = at 29%. CONCLUSIONS: In agreement with other preliminary reports in which the FDG PET without CT fusion imaging was used, in our experience 18F-FDG PET/CT did not prove to play a significant role in differential diagnosis (benign vs malignant) of parotid masses. Further studies collecting larger groups of patients are needed to further elucidate this observation.     

肿瘤患者放疗后照射野内椎体骨髓FDG PET/CT影像学表现

目的 探讨肿瘤患者放疗后椎体骨髓FDG PET/CT改变及其临床意义。方法 对32例患者放疗后椎体FDG PET/CT SUV与正常健康人椎体SUV比较分析。结果 与正常人椎体相比,放疗后椎体SUV明显降低,并且界限清晰。结论 肿瘤患者放疗后照射野内椎体FDG PET/CT SUV具有特征性,能够指导临床治疗。     

PET/CT的技术性能及临床应用

目的：介PET／CT的性能特点及临床应用。方法：对PET／CT的技术性能进行了分析，并对其发展趋势进行了展望。结果：PET能从分子水平上反映人体组织的生理、病理、生化、代谢改变；多排螺旋CT则可显示机体精细的解剖结构。结论：PET／CT可实现PET图像和CT图像的同机融合，形成2种技术的优势互补，具有极高的诊断性能和临床应用价值。     

一种小波域上运用变分模型的PET／CT图像融合方法

目的：研究一种新的算法用于PET／CT图像的异机融合。方法：在小波域上运用变分的方法，结合小波和变分的优点，首先对PET和CT图像进行小波分解，然后运用提出的两个假设分别对分解后的近似和细节分量进行融合，最后进行小波逆变换得到融合图像。结果：根据具体的融合算法实例，并与MATLAB的小波融合工具箱的融合结果进行了比较，发现新算法对图像中病变区域的解剖定位更加的准确。结论：实验证明在小波域上运用变分法进行图像的融合可以得到很好的效果，能够更好地满足临床治疗的需要。     

Clinical PET scanning. A "short-lived" orphan.

Positron emission tomography (PET) is a method of nuclear medicine imaging that uses short-lived radiopharmaceuticals to detect and quantify the metabolic abnormalities of disease processes. PET initially was developed in a research environment as a research tool; data from these research studies resulted in the gradual recognition that PET studies would be useful for various routine clinical applications. The diffusion of PET into clinical practice has been slow in comparison with other new imaging methods (e.g., magnetic resonance imaging). This slow diffusion is attributable to several factors, including the complexity and high cost of PET, the uncertain role of the U.S. Food and Drug Administration in regulating the radiopharmaceuticals that are produced and used on-site for PET studies, and the apparent slow pace at which the Health Care Financing Administration and other third-party payers are developing policies for reimbursing for PET.     

FDG PET/CT在胸部肿瘤放疗中的应用

目的总结葡萄糖类似物（FDG）PET/CT在胸部肿瘤放疗中应用的初步经验。方法 2009年8月~2011年12月,42例胸部肿瘤患者在我院接受PET/CT（GE Discovery）定位。图像传至VarianEclipse 8.6治疗计划系统进行图像分析处理及治疗计划设计。分析PET/CT图像融合对认定肿瘤靶区范围及对总体放疗方案和治疗计划的影响。结果 42例患者共确诊肿瘤病灶109个,其中,80.7%病灶在CT和PET图像均明确显示;19.3%病灶通过融合PET图像而确诊。融合图像在明确小的转移性淋巴结方面有显著优势。在肺部病灶大小和范围的显示上PET图像与CT图像常有一定差异,可能与呼吸运动或/和化疗影响肿瘤糖代谢有关。通常FDG PET/CT不能有效鉴别肿瘤与合并的炎症和手术创伤。结论 FDG PET/CT应用显著提高了肿瘤的诊断水准,并对放疗方案和治疗计划产生积极影响,但仍需探求排除假阳性信息的有效方法。