Positron Emission Tomography Molecular Imaging of Dopaminergic System in Drug Addiction

Dopamine (DA) is involved in drug reinforcement, but its role in drug addiction remains unclear. Positron emission tomography (PET) is the first technology used for the direct measurement of components of the dopaminergic system in the living human brain. In this article, we reviewed the major findings of PET imaging studies on the involvement of DA in drug addiction, especially in heroin addiction. Furthermore, we summarized PET radiotracers that have been used to study the role of DA in drug addiction. To investigate presynaptic function in drug addiction, PET tracers have been developed to measure DA synthesis and transport. For the investigation of postsynaptic function, several radioligands targeting dopamine one (D1) receptor and dopamine two (D2) receptor are extensively used in PET imaging studies. Moreover, we also summarized the PET imaging findings of heroin addiction studies, including heroin‐induced DA increases and the reinforcement, role of DA in the long‐term effects of heroin abuse, DA and vulnerability to heroin abuse and the treatment implications. PET imaging studies have corroborated the role of DA in drug addiction and increase our understanding the mechanism of drug addiction. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.     

结直肠癌18氟-氟代脱氧葡萄糖正电子发射断层显像

18氟 -氟代脱氧葡萄糖 (1 8F- FDG)正电子发射断层 (PET)显像已广泛用于诊断肿瘤。结直肠癌细胞葡萄糖代谢活性增高 ,摄取 1 8F- FDG增多 ,1 8F- FDG PET显像技术可对肿瘤进行定位、定性诊断、分期、判断预后、术后或放化疗后随访以及评价疗效。本文综述了 1 8F- FDG PET显像的原理、方法、临床应用和存在的问题。     

Prognostic Value of 18F-Fluorodeoxyglucose Positron Emission Tomography in Patients with Resectable Pancreatic Cancer

Purpose

We evaluated the prognostic value of ¹⁸F-2-fluoro-2-deoxyglucose positron emission tomography (FDG PET) in patients with resectable pancreatic cancer.

Materials and Methods

We retrospectively reviewed the medical records of pancreatic cancer patients who underwent curative resection, which included 64 consecutive patients who had preoperative FDG PET scans. For statistical analysis, the maximal standardized uptake value (SUVmax) of primary pancreatic cancer was measured. Survival time was estimated by the Kaplan-Meier method, and Cox''s proportional hazard model was used to determine whether SUVmax added new predictive information concerning survival together with known prognostic factors. p<0.05 indicated statistical significance.

Results

Overall survival (OS) and disease-free survival (DFS) were respectively 42.9 months (27.6-58.2; 95% CI) and 14.9 months (10.1-19.7; 95% CI). When subjects were divided into two groups according to SUVmax with a cutoff value of 3.5, the high SUVmax group (n=32; SUVmax >3.5) showed significantly shorter OS and DFS than the low SUVmax group. Multivariate analysis of OS and DFS showed that both high SUVmax and poor tumor differentiation were independent poor prognostic factors.

Conclusion

Our study showed that degree of FDG uptake was an independent prognostic factor in pancreatic cancer patients who underwent curative resection.     

Application of Silicon Photomultipliers to Positron Emission Tomography

Historically, positron emission tomography (PET) systems have been based on scintillation crystals coupled to photomultipliers tubes (PMTs). However, the limited quantum efficiency, bulkiness, and relatively high cost per unit surface area of PMTs, along with the growth of new applications for PET, offers opportunities for other photodetectors. Among these, small-animal scanners, hybrid PET/MRI systems, and incorporation of time-of-flight information are of particular interest and require low-cost, compact, fast, and magnetic field compatible photodetectors. With high quantum efficiency and compact structure, avalanche photodiodes (APDs) overcome several of the drawbacks of PMTs, but this is offset by degraded signal-to-noise and timing properties. Silicon photomultipliers (SiPMs) offer an alternative solution, combining many of the advantages of PMTs and APDs. They have high gain, excellent timing properties and are insensitive to magnetic fields. At the present time, SiPM technology is rapidly developing and therefore an investigation into optimal design and operating conditions is underway together with detailed characterization of SiPM-based PET detectors. Published data are extremely promising and show good energy and timing resolution, as well as the ability to decode small scintillator arrays. SiPMs clearly have the potential to be the photodetector of choice for some, or even perhaps most, PET systems.     

Positron Emission Tomography in the Study of Aging and Senile Dementia

¹⁸F-2-deoxy-2-fluoro-D-glucose (¹⁸FDG) is a positron emitting tracer for rate of glucose utilization in brain. When used in conjunction with positron emission tomography (PET), the PET-FDG technique permits in vivo quantitation of regional brain metabolism in man. We have applied this technique to the study of regional brain function in normal aging and senile dementia. Preliminary results for 7 patients with senile dementia of the Alzheimer's type (SDAT) and 3 elderly normal subjects indicated a large, statistically significant (p < 0.01) diminution in rate of glucose utilization in SDAT. Furthermore, the degree of diminution in metabolic activity in SDAT was highly correlated with objective measures of degree of cognitive impairment. These results demonstrate the feasibility and potential utility of the PET-FDG technique for studying regional brain function in normal aging and dementia.     

正电子发射断层成像重建算法评述

正电子发射断层成像（PET）是核医学中最为重要的应用之一，也是科学研究的强有力的工具，本文综述了PET图像重建方法研究现状，并着重介绍了滤波反投影算法和期望最大算法的最新进展。     

Positron Emission Tomography in the Study of Aging and Senile Dementia

¹⁸F-2-deoxy-2-fluoro-D-glucose (¹⁸FDG) is a positron emitting tracer for rate of glucose utilization in brain. When used in conjunction with positron emission tomography (PET), the PET-FDG technique permits in vivo quantitation of regional brain metabolism in man. We have applied this technique to the study of regional brain function in normal aging and senile dementia. Preliminary results for 7 patients with senile dementia of the Alzheimer's type (SDAT) and 3 elderly normal subjects indicated a large, statistically significant (p < 0.01) diminution in rate of glucose utilization in SDAT. Furthermore, the degree of diminution in metabolic activity in SDAT was highly correlated with objective measures of degree of cognitive impairment. These results demonstrate the feasibility and potential utility of the PET-FDG technique for studying regional brain function in normal aging and dementia.     

正电子发射断层图(PET)的原理与展望

1导言正电子发射断层图（positronemissiontomogfaphy,PET）是电子计算机图像处理、核医学、微量放射化学合成、生物物理学的示H踪动力学模型等多学科综合产生的医学成像新技术。目前在理论研究和临床诊断方面,已有广泛的应用l'－'l。PET是用示踪核素标记的化合物注入人...     

Perfluorocarbon Nanoemulsions for Quantitative Molecular Imaging and Targeted Therapeutics

A broad array of nanomaterials is available for use as contrast agents for molecular imaging and drug delivery. Due to the lack of endogenous background signal in vivo and the high NMR sensitivity of the ¹⁹F atom, liquid perfluorocarbon nanoemulsions make ideal agents for cellular and magnetic resonance molecular imaging. The perfluorocarbon core material is surrounded by a lipid monolayer which can be functionalized with a variety of agents including targeting ligands, imaging agents and drugs either individually or in combination. Multiple copies of targeting ligands (∼20–40 monoclonal antibodies or 200–400 small molecule ligands) serve to enhance avidity through multivalent interactions while the composition of the particle’s perfluorocarbon core results in high local concentrations of ¹⁹F. Additionally, lipophilic drugs contained within molecularly targeted nanoemulsions can result in contact facilitated drug delivery to target cells. Ultimately, the dual use of perfluorocarbon nanoparticles for both site targeted drug delivery and molecular imaging may provide both imaging of disease states as well as conclusive evidence that drug delivery is localized to the area of interest. This review will focus on liquid perfluorocarbon nanoparticles as ¹⁹F molecular imaging agents and for targeted drug delivery in cancer and cardiovascular disease.     

Polymeric Microbubbles for Ultrasonic Molecular Imaging and Targeted Therapeutics

Gas-filled microbubbles ultrasound agent have received wide attention, not only because they can improve ultrasound signals, but also they can be used as drug/gene carriers. Among all types of microbubbles fabricated by different membrane materials and core gases, polymer-shell microbubbles are highly promising. Polymeric microbubbles are more stable than other soft shell microbubbles in vivo. Under destructive ultrasound, polymer-stabilized microbubbles disintegrate and emit a strong non-linear signal, which enables ultrasound imaging with superior sensitivity. Except for ultrasound imaging, polymeric microbubbles could also be applied as drug/gene-delivery system. The thick polymeric shells allow loading a large amount of drugs. Meanwhile, site-specific targeting and controlled drug release in the area of interest can be realized through chemical and physical modification. In this review, we highlight some of the recent examples on polymeric microbubbles and their applications in ultrasound molecular imaging and drug delivery.     

Promising Role of 18-F-Fluoro-D-Deoxyglucose Positron Emission Tomography in Clinical Infectious Diseases

18-F-fluoro-D-deoxyglucose positron emission tomography (FDG PET) has become an established imaging tool in clinical oncology, cardiology and neurology and is now entering the field of clinical infectious diseases. The purpose of this article is to review the currently available, albeit limited, literature on FDG PET in the diagnosis of various infections and fever of unknown origin. Those indications for which FDG PET offers added value over more available techniques like labelled leucocyte scanning, gallium scanning and magnetic resonance imaging are especially highlighted. FDG PET seems to have an incremental value in the assessment of chronic osteomyelitis, especially in the axial skeleton, as well as in the diagnostic workup of fever of unknown origin and HIV complications. Cost-effectiveness studies are needed to define its place in the current diagnostic strategies of these pathologies. Electronic Publication     

18氟-氟代脱氧葡萄糖正电子发射计算机断层扫描在肺部结节诊断中的临床应用

目的 探讨18氟-氟代脱氧葡萄糖（18F-FDG）正电子发射计算机断层扫描（PET/CT）在肺部结节诊断中的应用价值。方法 回顾性分析2016年6月~2017年12月常熟市中医院呼吸科收治的21例肺部结节病例资料,计算PET/CT在该类疾病中的诊断特异度及敏感度,评价PET/CT对肺部结节的诊断价值。结果 PET/CT诊断肺癌的特异度、敏感度分别为50.00%、94.10%;与血清肿瘤标志物检测相比,该检查的敏感度更高,差异具有统计学意义（P＜0.05）。结论 PET/CT相对于血清肿瘤标志物检测在诊断早期肺癌方面,其诊断敏感度更高,对肺部结节的诊断有较高的价值。     

Pilot Study: Evaluation of Dual-Energy Computed Tomography Measurement Strategies for Positron Emission Tomography Correlation in Pancreatic Adenocarcinoma

We sought to determine whether dual-energy computed tomography (DECT) measurements correlate with positron emission tomography (PET) standardized uptake values (SUVs) in pancreatic adenocarcinoma, and to determine the optimal DECT imaging variables and modeling strategy to produce the highest correlation with maximum SUV (SUV_max). We reviewed 25 patients with unresectable pancreatic adenocarcinoma seen at Mayo Clinic, Scottsdale, Arizona, who had PET–computed tomography (PET/CT) and enhanced DECT performed the same week between March 25, 2010 and December 9, 2011. For each examination, DECT measurements were taken using one of three methods: (1) average values of three tumor regions of interest (ROIs) (method 1); (2) one ROI in the area of highest subjective DECT enhancement (method 2); and (3) one ROI in the area corresponding to PET SUV_max (method 3). There were 133 DECT variables using method 1, and 89 using the other methods. Univariate and multivariate analysis regression models were used to identify important correlations between DECT variables and PET SUV_max. Both R² and adjusted R² were calculated for the multivariate model to compensate for the increased number of predictors. The average SUV_max was 5 (range, 1.8–12.0). Multivariate analysis of DECT imaging variables outperformed univariate analysis (r = 0.91; R² = 0.82; adjusted R² = 0.75 vs r < 0.58; adjusted R² < 0.34). Method 3 had the highest correlation with PET SUV_max (R² = 0.82), followed by method 1 (R² = 0.79) and method 2 (R² = 0.57). DECT thus has clinical potential as a surrogate for, or as a complement to, PET in patients with pancreatic adenocarcinoma.     

采用MRF二次混合多阶先验的PET图像的贝叶斯重建

在正电子发射成像（肿）中，很多方法被用来抑制重建图像中的噪声效果，其中。在所有方法中，贝叶斯重建或者最大化后验估计的方法被证明具有在重建图像质量方面相对于其他方法的优越性。基于贝叶斯重建，本研究提出了一种应用于贝叶斯重建中新的综合了二次一阶先验和二次二阶先验的马尔可夫随机场混合多阶先验。基于不同阶数的二次平滑先验的自身的不同性质，该新先验的设计的目的是实现自适应的发挥这些算子的作用。该混合先验能够保持其先验能量函数凸性，从而保证整体目标贝叶斯后验能量函数的凹性。模拟实验和实验结果的比较证明了对于PET重建，该先验在抑制背景噪声和保持边缘方面均具有很好的表现。     

正电子发射体层显像PET/CT检测妇科恶性肿瘤的临床价值探讨

目的探讨正电子发射体层显像PET/CT检测妇科恶性肿瘤的临床价值。方法选取妇科恶性肿瘤患者114例分为两组,A组58例,行PET/CT检测,B组56例,行MRI检测,对检查结果进行评价和比较。结果 (1)A组的初诊阳性率,治疗后的转移/复发率以及代谢异常率分别为17.24%、44.83%和37.93%,与B组的10.71%、50.00%和21.43%均无明显差异(P0.05)。(2)A组敏感性、特异性、阳性预测值以及阴性预测值分别为88.89%、100%、100%和84.62%,均高于B组的52.94%、72.73%、75.00%和50.00%,组间差异均有意义(P0.05)。结论在妇科恶性肿瘤的诊断中,正电子发射体层显像PET/CT检测不会对患者造成创伤,是一种安全可靠的影像学诊断方法,可以显著提高诊断的准确率,具有良好的临床应用价值。     

一种适用于正电子断层图像去噪研究的简易图像模拟方法

正电子断层成像作为一种先进的成像技术,广泛地应用于临床诊疗和医学研究。正电子断层成像设备昂贵,成像药物具有放射性,所以相关图像处理研究大多以电脑模拟生成的正电子断层图像作为研究对象。目前比较常见的正电子断层图像模拟方法主要是基于蒙地卡罗法,使用GATE或者SimSET来得到模拟图像。这些模拟方法较为复杂,整个模拟过程也需要花费大量的时间。为此提出一种PET图像模拟方法,通过对比模拟图像与真实图像经小波去噪处理后的结果,进而论证模拟方法的有效性。该模拟方法基于Matlab平台,以实际物理模型的数码照片作为蓝本,通过拉登变换并加入强度为5的泊松噪声,最终得到模拟PET图像。在小波去噪的处理中,选择图像的SNR、CR、FWHM等指标进行对比。对比结果表明,经过小波去噪处理后的模拟图像与真实图像在SNR与FWHM两个指标中具有相同的变化趋势,在CR指标中,图像变化率误差小于10%。实验结果证明,该模拟方法是合理有效的。