犬下肢枪伤后脑功能PET显像研究

目的:探讨枪伤前后犬18FDG-PET脑显像的改变.材料和方法:选取成年健康家犬6只,分别于左下肢枪伤前后行18FDG-PET脑显像.结果:枪伤后狗脑葡萄糖代谢较枪伤前增强,枪伤后全脑放射性记数的均值具有极显著性差异(P＜0.01),最大值差异显著(P＜0.05).结论:枪伤后犬脑葡萄糖代谢明显增加,其机制有待进一步研究.     

放射性示踪剂在脑功能PET显像中的应用

脑PET显像是利用正电子示踪剂检测脑血流量,血容量,局部葡萄糖利用率,氧、氧基酸代谢和血脑屏障的完整性,以及受体的位置、密度和分布等。因此,PET不仅能研究各种脑疾病的过程和特征,评价神经系统疾病治疗效果,而且能研究正常脑功能。     

猫多巴胺转运蛋白PET脑显像研究

目的:制备多巴胺转运蛋白显像剂~(18)F-FP-βCIT[~(18)F-N-(3-氟丙基)-2β-甲酯基-3β-(4’-碘苯基)去甲基托烷],并进行猫PET脑显像。材料和方法:~(18)F-FP-βCIT的制备应用一步法:用K_(222)催化发生亲核氟化反应,得到~(18)F-FP-βCIT。PET显像仪器为Siemens ECAT HR~+ PET仪,3只健康正常猫进行~(18)F-FP-βCIT PET脑动态显像,观察纹状体体区放射性计数随时间的变化,并进行半定量分析。结果:~(18)F-FP-βCIT总放化合成时间为60～90min,时间校正后放化产率为2％～10％,放化纯度平均为96.3％,tR=3.38±0.20min。PET显像示早期(15min内)猫脑皮质及纹状体可见显影,随显像时间延长,脑皮质放射性减退,而纹状体显影更为清晰,30min纹状体/小脑比值达2.59±0.16,60min、90min及120min时此比值分别为2.73±0.23、2.52±0.13、2.08±0.11。结论:~(18)F-FP-βCIT是一种理想的PET多巴胺转运蛋白显像剂,可利用PET进行猫的脑受体方面的研究。     

脑功能显像在药物滥用研究中的应用价值

药物滥用与中枢神经递质系统功能紊乱密切相关，放射性核素脑功能显在研究滥用药物的成瘾与戒断机制中具有重要的价值。脑血流、脑葡萄糖代谢以及神经递质受体和转运体显像为人们提供了更多的中枢神经系统功能也为人们寻找治疗药物滥用的方案奠定了基础。     

符合线路显像与PET显像中SUV的比较研究

目的比较符合线路显像标准摄取值(SUV)与PET显像的SUV。方法用双探头符合显像仪及PET对模型显像，分别采用不同的重建算法重建，测定图像上热灶的SUV。结果对直径小于30mm热灶，相同大小时，PET、得到的SUV高于符合线路显像；无论对PET还是符合线路显像，随热灶大小增加SUV增加；SUV与重建算法有关；选取的感兴趣区(ROI)越大，获得的SUV越小；由PET图像获得的热灶SUV可见，当热灶大于2倍的系统分辨率时，SUCmax接近热灶的真实值(SUVmax)。结论符合线路显像的SUV低于PET显像；病灶大小、重建算法、ROI大小均影响SUV。     

缺血心肌动物模型PET和SPECT显像及组织学对比研究

目的评估^201TI SPECT及^18F-脱氧葡萄糖（FDG）PET显像对模型猪心肌活力的鉴别。方法健康家猪12头，其中10头于冠状动脉左旋支起始处放置Ameriod环，饲养28d形成慢性心肌缺血动物模型（另2头作正常对照），行^201TI SPECT心肌灌注显像和^18F—FDG PET心肌代谢显像并与HE染色病理学改变进行比较。结果81个心肌节段中，^18F—FDG心肌显像示心肌有活力的节段为73个（90．1％），明显高于^201TI心肌显像所示的62个（76．5％），差异有显著性（P〈0．05）。HE染色结果示有心肌活力的节段为74个（91．3％），与^18F—FDG心肌显像所示结果差异无显著性（P〉0．05）。结论^18F—FDGPET心肌显像检测心肌活力的准确性明显高于^201TI SPECT心肌显像。     

脑梗塞后脑功能激活的SPECT脑血流显像研究

脑梗塞后脑功能激活的ＳＰＥＣＴ脑血流显像研究谢瑞满牛敬忠朱文炳修雁陈可靖陈绍亮本研究主要观察脑梗塞患者经体外反搏治疗的脑功能激活方式后，ＳＰＥＣＴ脑血流显像的变化规律，结合临床脑神经功能缺损评分，并与头颅ＣＴ和ＭＲＩ检查比较，进一步探讨脑梗塞后脑功能...     

脑功能显像在药物滥用研究中的应用价值

药物滥用与中枢神经递质系统功能紊乱密切相关,放射性核素脑功能显像在研究滥用药物的成瘾与戒断机制中具有重要的应用价值。脑血流、脑葡萄糖代谢以及神经递质受体和转运体显像为人们提供了更多的中枢神经系统功能信息,同时也为人们寻找治疗药物滥用的方案奠定了基础。     

PET显像仪的类型及临床应用

近几年来,核医学PET显像发展迅速,在临床应用中发挥着越来越重要的作用。目前,PET显像仪共有三种类型:专用型PET(dedicated PET)、混合型PET(hybrid PET)和组合型PET(combined PET)。PET与CT组合即PET-CT,不仅能反映人体解剖结构改变,更重要的是可以提供体内功能代谢信息,从分子水平揭示疾病发病机理和治疗效应,是临床诊断心脑疾病和肿瘤的重要手段。PET-CT临床应用十分广泛,尤其是在肿瘤、神经系统、心血管系统等病变的临床应用方面具有其独特的功能和作用。     

FDG PET显像的定量及半定量分析

PET显像可动态观察显像剂在体内的分布及变化过程，可了解局部组织、器官的功能代谢情况，借助合适的生理数学模型及软件，可将PET影像的放射性浓度分布图转换为更具生物学意义的参数影像，如葡萄糖代谢率、氧代谢率、DNA或蛋白质的合成速率、受体的数量与亲合力等，使进一步深入研究人体正常及病变组织的功能与代谢成为可能。     

PET/MRI: Multiparametric imaging of brain tumors

A combination of morphological imaging of the brain with microstructural and functional imaging provides a comprehensive overview of the properties of individual tissues. While diffusion weighted imaging provides information about tissue cellularity, spectroscopic imaging allows us to evaluate the integrity of neurons and possible anaerobic glycolysis during tumor hypoxia, in addition to the presence of accelerated synthesis or degradation of cellular membranes; on the other hand, PET metabolic imaging is used to evaluate major metabolic pathways, determining the overall extent of the tumor (¹⁸F-FET, ¹⁸F-FDOPA, ¹⁸F-FCH) or the degree of differentiation (¹⁸F-FDG, ¹⁸F-FLT, ¹⁸F-FDOPA and ¹⁸F-FET). Multi-parameter analysis of tissue characteristics and determination of the phenotype of the tumor tissue is a natural advantage of PET/MRI scanning. The disadvantages are higher cost and limited availability in all centers with neuro-oncology surgery. PET/MRI scanning of brain tumors is one of the most promising indications since the earliest experiments with integrated PET/MRI imaging systems, and along with hybrid imaging of neurodegenerative diseases, represent a new direction in the development of neuroradiology on the path towards comprehensive imaging at the molecular level.     

PET/CT and MR imaging in myeloma

Myeloma is the most common primary bone malignancy. It accounts for 10% of all hematological malignancies and 1% of all cancers. In the United States, there are an estimated 16,000 new cases and over 11,000 deaths yearly due to myeloma. Plasma cell dyscrasias manifest themselves in a variety of forms that range from MGUS (monoclonal gammopathy of undetermined significance) and smoldering myeloma that require no therapy, to the “malignant” form of multiple myeloma. The role of imaging in the management of myeloma includes: an assessment of the extent of intramedullary bone disease, detection of any extramedullary foci, and severity of the disease at presentation; the identification and characterization of complications; subsequent assessment of disease status. This review will focus on the use of PET/CT and MR imaging for myeloma patients at the time of initial diagnosis and for follow-up management, based on current reports in the literature and our practice at the Marlene and Stewart Greenebaum Cancer Center, University of Maryland Medical Center in Baltimore, USA.     

Hybrid image and blood sampling input function for quantification of small animal dynamic PET data

We describe and validate a hybrid image and blood sampling (HIBS) method to derive the input function for quantification of microPET mice data. The HIBS algorithm derives the peak of the input function from the image, which is corrected for recovery, while the tail is derived from 5 to 6 optimally placed blood sampling points. A Bezier interpolation algorithm is used to link the rightmost image peak data point to the leftmost blood sampling point. To assess the performance of HIBS, 4 mice underwent 60-min microPET imaging sessions following a 0.40–0.50-mCi bolus administration of ¹⁸FDG. In total, 21 blood samples (blood-sampled plasma time–activity curve, bsPTAC) were obtained throughout the imaging session to compare against the proposed HIBS method. MicroPET images were reconstructed using filtered back projection with a zoom of 2.75 on the heart. Volumetric regions of interest (ROIs) were composed by drawing circular ROIs 3 pixels in diameter on 3–4 transverse planes of the left ventricle. Performance was characterized by kinetic simulations in terms of bias in parameter estimates when bsPTAC and HIBS are used as input functions. The peak of the bsPTAC curve was distorted in comparison to the HIBS-derived curve due to temporal limitations and delay in blood sampling, which affected the rates of bidirectional exchange between plasma and tissue. The results highlight limitations in using bsPTAC. The HIBS method, however, yields consistent results, and thus, is a substitute for bsPTAC.     

A comparison of the sensitivity of PET and NMR for in vivo quantitative metabolic imaging

Using positron emission tomography (PET) in combination with compounds labelled with positron-emitting radionuclides like ¹¹C, ¹³N and ¹⁵O, it is possible to study metabolism in vivo in a non-invasive way. Nuclear magnetic resonance (NMR) imaging takes advantage of the spin of protons in water molecules to measure both their number and relaxation times in vivo, but is, in principle, not limited to protons and can also be used for other nuclei with a non-zero spin, e.g. ¹³C and ³¹P. The use of ¹³C opens the possibility of studying the metabolism of a large number of compounds. In order to choose the appropriate methodology for metabolic imaging, i.e. PET or NMR, it is important to know the sensitivity of each modality. The present study outlines the sensitivity of both techniques.     

肝脏孤立性坏死结节的影像和病理对照

目的认识肝脏孤立性坏死结节的影像及病理学表现，提高诊断准确率。方法１６例中１２例经手术病理证实，４例根据ＭＲＩ表现随访半年以上证实。对照病理，分析１６例超声、ＣＴ及ＭＲＩ表现。结果组织病理显示全部为凝固坏死结节，６个病灶含有小片液化坏死，平均直径２．３ｃｍ，外周的薄层纤维包膜中有淋巴细胞、浆细胞、嗜酸性细胞及少数中性白细胞浸润。超声为内部回声欠均匀的低回声结节。ＣＴ表现为边缘清楚、无强化的低密度病灶。在ＭＲＩ的Ｔ１及Ｔ２ＷＩ上分别呈低信号及等低信号，４个病灶内间以点片状更低信号及高信号，增强后病灶内部无强化，４４％（７／１６）有细环状轻度延迟强化的包膜。结论平扫加动态增强ＭＲＩ能良好反映孤立性坏死结节的病理特征，其表现具高度的诊断特异性，明显优于超声和ＣＴ。     

PET kinetic analysis: wavelet denoising of dynamic PET data with application to parametric imaging

Physiological functions (e.g., cerebral blood flow, glucose metabolism, and neuroreceptor binding) can be investigated as parameters estimated by kinetic modeling using dynamic positron emission tomography (PET) images. Imaging of these physiological parameters, called parametric imaging, can locate the regional distribution of functionalities. However, the most serious technical issue affecting parametric imaging is noise in dynamic PET data. This review describes wavelet denoising of dynamic PET images for improving image quality in estimated parametric images. Wavelet denoising provides significantly improved quality directly to dynamic PET images and indirectly to estimated parametric images. The application of wavelet denoising to radio-ligand and kinetic analysis is still in the development stage, but even so, it is thought that wavelet techniques will have a substantial impact on nuclear medicine in the near future.     

胶质瘤磁敏感成像表现及与病理对照

目的：探讨磁敏感加权成像（SWI）在胶质瘤分级诊断中的作用。方法：25例经手术病理证实的脑胶质瘤患者术前均行MRI平扫、增强和SWI检查,11例患者行MRS检查。由两位高年资神经放射诊断医师对SWI肿瘤内的低信号进行评分,并与病理学结果对照分析。结果：14例高级别胶质瘤中12例瘤内出现不同程度多发斑片状、索状低信号,病理学证实为瘤内出血及瘤内血管;11例低级别胶质瘤中3例瘤内未出现明显低信号,6例瘤内出现少许斑点、线状低信号,病理证实为瘤内血管,2例瘤内可见少量斑片状低信号,病理证实为瘤内出血。高级别组胶质瘤内低信号评分值高于低级别组（P〈0.05）。结论：不同级别胶质瘤在磁敏感加权成像表现有明显差异,SWI有助于术前对胶质瘤分级进行评估。     

脉络丛肿瘤的影像学征象与病理对照分析

目的：探讨脉络丛肿瘤（CPTs）的CT和 MRI表现特征,提高影像诊断的准确性。方法：回顾性分析28例经病理证实的CPTs患者的影像学资料,其中脉络丛乳头状瘤（CPP）22例,非典型性脉络丛乳头状瘤（ACPP）2例,脉络丛癌（CPC）4例。全部病例均行CT平扫、MRI平扫及增强扫描。结果：28例CPTs患者中男16例,女12例,年龄5个月～66岁,中位年龄30岁。发病部位包括侧脑室（12例）、第四脑室（8例）、桥脑小脑角区（6例）、三脑室（1例）和小脑蚓部（1例）。CPPs CT平扫多表现为较均匀等密度或稍高密度,其中6例伴有钙化;肿瘤实性部分在T1 WI 上呈等或稍低信号, T2 WI上呈等或稍高信号;MRI 增强扫描示肿瘤实性部分及囊壁呈明显强化。CPPs 内可见肿瘤血管,出血和囊变少见;APCCs更易发生囊变,可侵犯周围脑实质,易出现瘤周水肿;CPCs 可见瘤内出血、囊变、脑实质浸润、沿脑脊液播散等改变。结论：脉络丛肿瘤的CT和 MRI表现具有一定的特征性,MRI 能清晰显示肿瘤的形态学改变,为手术方案的制定及预后判断提供可靠的依据。     

Comparison of the prognostic value of SPECT after nitrate administration and metabolic imaging by PET in patients with ischaemic left ventricular dysfunction

Purpose We compared the prognostic value of ^99mTc-tetrofosmin single-photon emission computed tomography (SPECT) after nitrate administration and positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (FDG) in patients with ischaemic left ventricular (LV) dysfunction. Methods Eighty-nine patients with previous myocardial infarction and LV dysfunction (LV ejection fraction 33 ± 10%) underwent ^99mTc-tetrofosmin SPECT under control conditions (baseline) and after sublingual administration of 10 mg of isosorbide dinitrate (nitrate). Within 1 week, all patients underwent PET imaging with ¹⁸F-FDG. Four patients were excluded because of inadequate FDG uptake caused by severe diabetes. Follow-up data were obtained by phone contact with patients and by review of hospital or physicians’ records. Cardiac death, myocardial infarction and late revascularisation for unstable angina were considered as events. Follow-up data were not available in three patients. Follow-up was 96% complete at a mean period of 29 ± 19 months. Results At baseline SPECT, 59 (72%) patients had evidence of viable myocardium, while 23 did not. Of these latter patients, 12 (52%) demonstrated viable myocardium after nitrate and 13 (56%) had preserved metabolic activity. Cardiac events (cardiac death, myocardial infarction and late revascularisation for unstable angina) occurred in 24 (29%) patients. Event-free survival was similar in patients with and patients without viable myocardium at baseline SPECT (p = 0.8). In contrast, event-free survival was lower in patients with viable myocardium at nitrate SPECT and PET compared to those without viable myocardium (both p<0.05). Conclusion In patients with ischaemic LV dysfunction, the prognostic value of SPECT imaging after nitrate is comparable to that of PET metabolic imaging.