PET/CT多模态显像技术特点及临床应用进展

正电子发射型计算机断层显像（positron emission tomography,PET/CT）融合了PET功能显像与CT解剖显像的优点。PET功能显像可反应组织器官及病灶的生理代谢情况,但图像质量较差,分辨率不能满足临床的需要。CT解剖显像可起到定位病灶的作用,解决了单独PET显像的缺点,二者融合可以在分子水平上实现疾病的临床诊断、分期判断及疗效检测。目前,随着PET/CT的广泛应用,其在肿瘤疾病、心血管系统疾病及神经系统疾病中的应用价值得到了越来越多的关注,有望将分子影像学的发展推向一个新的高度。     

新型显像技术PET／CT优势与存在的问题

目的分析新型显像技术PET／CT存在的优势与的问题。方法PET／CT与MRI、SPECT进行对比。结果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。结论PET／CT能够独立完成多排螺旋CT的临床显像,大大提高临床使用价值。但是,PET／CT定量分析精度受PET／CT设备本身、PET／CT图像采集方式和图象处理方式等诸多因素影响和限制。     

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。     

核医学影像设备的发展与临床应用

γ相机和SPECT只能进行常规单光子显像，PET和双探头SPECT符合显像系统既能进行单光子显像，又能进行正电子符合显像，PET／CT系统的出现不仅提供高质量的衰减校正图像，保证了正电子显像校正数据的可靠性，而且能进行同机图像融合，提高了影像定位诊断的准确性。本文简要介绍了核医学影像设备发展历程，PET和PET／CT的原理以及在临床的应用。     

PET/CT图像融合技术及其临床应用

图像融合技术是一种全新的影像学技术，它将解剖显像与功能显像两者有机的结合起来，实现了从单一的形态学诊断进入到功能与形态相结合的多角度的综合影像诊断。本文简介了PET/CT这一图像融合设备的融合技术及其在临床方面的应用。     

GE DiscoverySTPET／CT图像融合故障的分析与排除

X线-正电子发射计算机断层扫描仪（positronemission tomography／computedtomography,PET／CT）是将PET的功能代谢显像与CT的解剖结构显像2种不同的影像技术相融合,实现PET、CT图像的同机融合。     

PET／CT在体部γ刀定位中应用体会

目的：阐述PCT／CT在体部γ刀定位中的应用。方法：2007—05-2008—05，利用PET／CT设备对120例患者进行体部γ刀定位及图像融合。结果：用PET／CT扫描可在不用碘造影剂增强情况下进行肿瘤有效显像．较单纯CT定位获得更丰富和准确的图像信息，有助于指导靶区（GTV）勾画。结论：PET／CT在γ刀治疗定位中明显提高了GTV的定位精度，增加了碘过敏患者的治疗机会。     

国产18F-FDG合成器低产率分析

PET/CT显像技术作为最先进的分子及功能显像技术,已经被临床所认可并得到极大地推广使用。PET/CT显像技术是一种药物依赖性的显像技术,目前虽然开发出了许多新的正电子示踪剂．但18F-FDG仍然是临床使用最多、应用最广的示踪剂。随着受检者的增加,正电子药物全自动化学合成器的产能与药物的日需要量之间的矛盾日益明显．回旋加速器所提供18F-已近饱和量,其受损的风险和维护费用大大提高。     

功能影像设备PET-CT

PET—CT是功能医学影像设备,其成像理论和技术复杂,在临床实际应用过程中,对PET—CT设备和技术的认识尚存在着争论,本文就PET—CT设备相关的技术理论、未来软硬件发展的趋势进行探讨。以期对PET—CT的全面认识和评价。     

冠状动脉CT血管造影与18F-FDGPET心肌显像在冠心病诊断中的价值

目的:探讨18F-脱氧葡萄糖(18F-FDG)PET心肌显像与冠状动脉CT血管造影(CTA)相结合提高冠心病临床诊断水平,规范化应用冠心病诊断处理技术。方法:使用正电子核素药物18F-FDG对35例确诊为冠心病患者进行心肌代谢显像和冠状动脉CTA检查,对所有患者行18F-FDG PET心肌显像与冠状动脉CTA相结合检查结果与确诊病例结果进行比较。结果:18F-FDG PET心肌显像与冠状动脉CTA相结合诊断冠心病的灵敏度、特异度分别为100%和96%。结论:将18F-FDG PET数据与冠状动脉CTA数据进行精确融合,得到的精确融合图像,既可提供反映冠状动脉解剖的指标,又可提供反映心肌病理生理及代谢的指标,各项指标之间可互相印证和补充。     

18F-FDGPET-CT显像在头颈部肿瘤的临床诊断中的效果研究

目的评价18F-FDGPET-CT对头颈部肿瘤患者的临床诊断价值。方法患者均行18F-FDGPET-CT显像,对图像进行分析。结果 PET/CT的总检出率高于PET和CT,PET/CT的定位准确率高于PET。结论 18F-FDGPET-CT能够有效地鉴别头颈部肿瘤治疗后瘢痕与肿瘤复发、淋巴结及远处脏器转移,可提高对其诊断的敏感性和准确性。     

PET-CT工作原理及应用

目的:PET-CT实现了同机图像融合,是一种功能性医学影像学设备,通过了解其工作原理,掌握设备的日常维护方法,为医学研究和临床诊断提供便利。方法:分别介绍PET与CT两种设备同机组合的不同成像原理以及设备应用时对环境的要求。结果:了解PET-CT的工作原理,掌握一般维护保养项目和方法,使PET-CT融合影像为临床正确确定放疗的计划靶区、检测治疗过程中的疗效提供最佳方案。结论:PET-CT设备的工作状态是否良好与设备的维护保养密不可分。在设备的日常维护过程中要保持设备符合环境要求,工程技术人员必须熟悉设备的各个运行环节,保证设备的正常运转。     

Bewertung der PET-CT

Since 1994, PET – and later PET-CT – have gained significant clinical importance. Since 2002, PET-CT systems (PET + multislice CT) are available. The combination of high sensitivity PET images fused with high resolution CT images has gained widespread clinical acceptance for diagnosis, staging and re-staging as well as prediction of response to chemotherapy in oncology. Besides oncology, there are clear indications in diseases of the heart and the brain. The development of new systems in mainly based on multislice CT (64 slice). Radiopharmacology is advancing quickly, especially in the fields of oncology and neurological disorders. However, the limited reimbursement in Germany hampers this development.     

18F-FDG和18F-FET PET-CT检查致受检者辐射剂量研究

目的 估算接受¹⁸F-FDG(¹⁸F-2-deoxy-D-glucose)和¹⁸F-FET(O-2-¹⁸F-fluoroethyl-L-tyrosine)PET-CT全身检查受检者的有效剂量和器官剂量。方法 使用两种PET-CT扫描协议进行全身显像。PET部分的有效剂量和器官剂量利用基于医学内照射剂量(Medical Internal Radiation Dose, MIRD)计算模式的计算程序IDAC 2.1进行计算,CT部分的有效剂量和器官剂量利用VirtualDose软件计算,PET和CT剂量之和为受检者总的有效剂量。结果 在常规PET-CT扫描中,男性受检者受¹⁸F-FDG辐射所致的有效剂量为(4.81 ±1.04) mSv,女性受检者为(6.09 ±0.73) mSv;男性受检者受¹⁸F-FET辐射所致的有效剂量为(2.67 ±0.38) mSv,女性受检者为(3.21 ±0.38) mSv;CT部分男性受检者的有效剂量为(5.63 ±0.32) mSv,女性受检者为(5.51 ±0.29) mSv。¹⁸F-FDG PET-CT检查男性和女性受检者所受总有效剂量分别为(10.44 ±1.09) mSv和(11.60 ±0.79) mSv。¹⁸F-FET PET-CT检查总有效剂量分别为(8.30 ±0.50) mSv和(8.72 ±0.49) mSv。在诊断性CT扫描中,CT扫描致男性受检者的有效剂量为(16.28 ±1.01) mSv,女性受检者为(13.49 ±0.72) mSv;¹⁸F-FDG PET-CT检查男性和女性受检者总有效剂量分别为(21.09 ±1.45) mSv和(19.58 ±1.03) mSv。¹⁸F-FET PET-CT检查总有效剂量分别为(18.95 ±1.08) mSv和(16.70 ±0.81) mSv。结论 不同的PET-CT扫描参数致受检者受到不同大小的辐射剂量,在日常工作中应根据受检者的实际情况,优化PET和CT的采集参数,降低受检者剂量,实践辐射防护最优化。     

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在肺癌诊断与临床分期中的应用

目的：探讨^18F-脱氧葡萄糖正电子发射显像／电子计算机断层扫成像（^18F-FDG PET-CT）在肺癌诊断及其在临床分期方面的价值。方法：75例患者进行了PET-CT检查诊断为肺癌,分析其PET-CT代谢情况与影像学检查结果（薄层增强CT和HIKCT检查结果）进行对照分析。结果：75例患者通过^18F-FDGPET-CT检查,均诊断为肺癌,其中经纤维支气管检查或者穿刺检查有明确病理的49例,经术后病理证实的23例;^18F-FDGPET-CT75例均表现为放射性摄取异常增高,最大SUV值在1．5-18．8之间;30例CT增强扫描病例中,病灶边缘毛糙,明显强化,CT值升高在20-46Hu之间;45例HRCT检查中病灶有明显分叶、毛刺征、血管集束征、胸膜凹陷征及支气管截断现象等。结论：^18F-FDGPET-CT与诊断性CT联合应用,可以对肺癌进行明确诊断与分期。     

国产PET／CT技术进展

本文对PET／CT系统构成及工作原理进行了概述,重点介绍了国产PET／CT技术近年的进展,与国外同类商品化设备性能对照,开展临床对比研究。结果表明：国产PET／CT技术已较为成熟,商品化的产品可以替代国外同类产品．     

PET-CT图像对靶组织(病灶)体积计算方法的研讨

目前PET-CT的应用已从简单定性分析发展到定量分析,靶组织体积对于肿瘤放射计划治疗生物靶区确定、肿瘤放射性核素治疗、组织脏器功能评价、受体亲和力计算和药代动力学研究等均有重要临床意义.靶组织体积的计算受PET图像采集模式,散射校正方法,衰减校正方法,重建技术,图像显示模式,正电子药物等因素影响.目前常采用的靶体积的计算方法有本底阈值法,最大值结合阈值法,本底与最大值结合阈值法等.本文阐述靶组织体积计算方法.     

Display of positron emission tomography with Cadplan

Recent clinical experience at Peter MacCallum Cancer Institute (PMCI) with the use of unregistered Positron Emission Tomography (PET) images for radiotherapy target marking in the lung suggests that co-registered PET images would be invaluable. PMCI has three radiotherapy treatment planning systems but none of them currently is able to display or co-register PET images with Computed Tomography (CT) images. This paper details the approach taken to display co-registered PET images with the CADPLAN treatment planning system. CT Image files are normally transferred to Cadplan by DICOM transfer, but the Cadplan DICOM server will not receive (has no presentation context for) PET images. The fundamental design of the CADPLAN system envisages display of only a single image dataset, which must be a CT scan for planning reasons. The problem of data transfer is crudely solved by File Transfer Protocol (FTP) over the network. Fortunately the multislice format of the PET image files makes individual transfer manageable. A menu based C program running at the same time as Cadplan is invoked to sample the DICOM PET Image and create multiple Cadplan CART image format files that are co-registered with each existing transverse CT slice. With the Cadplan in contour mode, the program allows the co-registered PET images to be swapped in and out of the image section of the CART files promptly, while keeping the contour information. This allows radiotherapy target volumes to be marked using transverse PET emission images, and effectively circumvents the design constraints prohibiting the display of more than one image set. Contours can be over-laid for review on reconstructed sagittal or coronal views of CT or PET images constructed using the standard Cadplan tools. Co-registration is facilitated by identical positioning with the aid of lasers and FDG loaded fiducial markers on the PET scanner and CT couch. A polyurethane cast fixed with EFFILOCK is used to ensure identical patient orientation on the CT and PET couches. Since both imaging modalities are without significant geometric distortion the co-registration is then simply a translation. PET transmission images can be used for co-registration verification. The practical implementation of display of PET images with CADPLAN has enabled us to begin a trial of 10 patients, the results of which will be reported separately.