谷氨酸与谷氨酰胺类似物PET显像剂研究进展

谷氨酰胺是血浆中浓度最高的氨基酸,肿瘤细胞的生长与增殖依赖于谷氨酰胺及其中间代谢产物（如谷氨酸、乳酸、脯氨酸、氨等）,肿瘤细胞的生长速度与细胞内谷氨酰胺和谷氨酸的浓度密切相关,谷氨酰胺与谷氨酸在肿瘤代谢中起着重要作用。肿瘤细胞摄取谷氨酸与谷氨酰胺类似物PET显像剂的机制主要涉及氨基酸转运与蛋白质合成。谷氨酸与谷氨酰胺类似物PET显像剂在肝细胞癌、脑肿瘤、胶质瘤以及其他多种肿瘤的鉴别诊断中具有优势,可以弥补18F-氟脱氧葡萄糖 PET显像的一些不足。笔者主要对谷氨酸与谷氨酰胺类似物PET显像剂的研究进展进行综述。     

靶向表皮生长因子受体小分子类PET显像剂研究进展

表皮生长因子受体（EGFR）在多种癌症的发生发展中起着重要作用,目前已有多种EGFR靶向药物被美国食品与药品管理局批准用于临床,但因个体敏感程度不同,总体疗效偏低。研究表明EGFR高表达或突变患者对靶向药物敏感,因此明确EGFR表达水平和突变状态对临床用药有重要指导意义。PET成像技术能实现分子水平无创显像,并能通过SUV进行半定量研究,使得在体内无创明确EGFR表达、突变情况,指导靶向药物的精准治疗成为可能。笔者综述了靶向EGFR的小分子类PET显像剂,以期为新的探针研发及其临床应用提供一定帮助。     

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。     

PET/CT在头颈部肿大淋巴结定性中的临床价值

目的：探讨PET/CT检查定性诊断头颈部肿大淋巴结的应用价值。材料和方法：于2006-06～2008-10对38例头颈部淋巴结肿大的患者行全身18氟-脱氧葡萄糖（FDG）PET/CT检查,测取相应淋巴结的平均标准摄取值（SUVmean）和颈部正常组织的SUV（SUVneck）。所有恶性淋巴结全部得到病理确诊。结果：30例恶性肿瘤患者中,35个肿大淋巴结的SUVmean高于相应的颈部正常组织SUVneck;5例7个良性肿大淋巴结未见显影,3例4个良性肿大淋巴结显影。PET对头颈部淋巴结肿大定性诊断准确率高于颈部超声与CT、MRI检查（P〈0.001）。结论：对于头颈部淋巴结肿大的患者,PET/CT检查是一种有效的定性诊断途径。     

PET分子探针在类风湿关节炎中的研究进展

类风湿关节炎（RA）是一种病因未明的、以滑膜炎为主要特征的慢性自身免疫性疾病,多累及手、足部小关节,呈对称性、侵袭性关节炎改变,最终导致关节畸形甚至功能丧失。不同于传统的影像学检查方法,PET提供了一种在细胞水平上的显像方法,是一种潜在的、高度灵敏的滑膜炎评估方法。笔者就PET分子探针在RA中的临床应用及研究进展进行综述,旨在为RA的诊断提供思路。     

11C标记的心脏交感神经受体显像剂的研究进展

自主神经系统在调节心血管功能方面起着至关重要的作用,完整的神经支配是心血管功能正常发挥的基础。许多心脏疾病在出现临床症状之前已经出现了神经系统的改变,放射性核素标记的神经递质类似物PET显像可对此进行评估,其可以灵敏地反映心脏自主神经功能的完整性、神经元的分泌功能及活性,以便对心脏疾病进行早期诊断和及时干预。近年来11C标记的心脏交感神经受体显像剂发展迅速,笔者综述了其中几种显像剂的研究新进展。     

肿瘤短链脂肪酸代谢PET显像剂研究进展

18F-FDG PET显像在临床上发挥着越来越重要的作用,但其在某些肿瘤的应用中存在一定的弊端,易产生假阳性和假阴性。脂肪酸代谢PET显像在脂类代谢显像中占有非常重要的地位,在一定程度上可弥补糖代谢的不足,能提高对肿瘤诊断的灵敏度和准确率。笔者就目前应用于临床前和临床研究中的肿瘤短链脂肪酸代谢PET显像剂进行综述。     

多巴胺转运体PET显像剂11C-Altropane的研究进展

帕金森病（PD）是一种慢性进行性神经系统变性疾病,患者黑质纹状体多巴胺能神经元的变性脱失会伴随有突触前膜多巴胺转运蛋白（DAT）数量及功能的明显下降。DAT显像剂11C-Altropane可与DAT特异性结合,且比同类药物吸收快、具有更高的亲和力,能直接、灵敏地反映突触前多巴胺能神经元的变化,是PD早期诊断的最佳手段。笔者介绍了PD诊断的现状、PET显像剂的原理及发展过程、11C-Altropane的合成及其作为PET显像剂在临床研究中的应用。     

P-糖蛋白抑制剂在PET显像中的应用研究

目的 探讨11C-GF120918作为PET显像探针对人体P-糖蛋白(P-gp)和乳腺癌耐药蛋白(BCRP)功能的检测及其意义。 方法 化学合成11C-GF120918;给小鼠注射11C-GF120918, 使用自动伽玛粒子计数管测定不同时间、不同剂量、小鼠各组织器官中11C-GF120918的放射性强度; 并使用高效液相色谱监测30 min后小鼠脑部和血液中11C-GF120918代谢情况; P-gp基因敲除组、BCRP基因敲除组、P-gp/BCRP基因敲除组和野生型对照组小鼠分别注射11C-GF120918, 进行PET显像, 实时监测小鼠大脑中的11C-GF120918放射强度变化。 结果 11C-GF120918在小鼠各个组织器官中均有广泛分布, 相对于正常小鼠差异有统计学意义(χ2=8.14, P＜0.05);且11C-GF120918代谢稳定, 注射后30 min, 在大脑和血液中仍有(99.3±0.5)%和(83.2±3.5)%未被代谢, 具有较好的生物化学稳定性和辐射稳定性。P-gp/BCRP基因敲除组小鼠大脑中11C-GF120918放射性强度是野生型对照组的9倍(χ2=7.69, P＜0.05), 而BCRP基因敲除组小鼠大脑中放射性强度是野生型对照组的3倍(χ2=8.24, P＜0.05), 差异有统计学意义。且11C-GF120918标记效果比较稳定。 结论 使用11C-GF120918作为PET显像探针可以用来评价P-gp和BCRP的耐药功能。     

胶质瘤显像剂的研究与应用进展

核医学显像在胶质瘤的诊断、分级及预后等方面有重要的临床价值,随着核医学的发展,用于胶质瘤的显像剂也越来越多样化,目前研究应用较多的SPECT显像剂有201Tl、99Tcm-MIBI、123I-碘代甲基酪氨酸以及新型受体类显像剂131I-蝎氯毒素等,PET显像剂主要有葡萄糖代谢显像剂、氨基酸代谢显像剂、胆碱代谢显像剂、核...     

创伤性脑损伤PET显像研究进展

创伤性脑损伤(TBI)是由外伤引起的脑组织损害,有着较高的发生率及病死率.传统医学影像学技术难以做出诊断.PET作为一种定量测定脑糖代谢及脑血流量变化的显像技术,可以比较精确地显示TBI所致的脑功能变化.目前,18F-FDG PET显像通过评价脑内葡萄糖代谢及脑血流量变化对TBI做出诊断.笔者对TBI18F-FDG PET显像及脑血流灌注显像进行综述.     

FDG PET在胰腺癌中的应用

胰腺癌的影像诊断手段较多 ,如CT、MRI、超声等 ,由于特异性及其敏感性的限制 ,难以早期作出诊断 ,延误患者早期的治疗。因此如何早期提高胰腺癌的诊断为早期治疗提供理论上的依据 ,仍是影像医学和临床医学的研究热点。正电子发射计算机断层(PET)是利用正电子放射性药物在体内的分布来反映人体组织的生理生化代谢功能 ,其中FDGPET利用肿瘤组织的葡萄糖代谢增加来鉴别恶性病变与良性病变。本文就PET的显像基本原理及其在胰腺癌诊断和分期中的应用价值作一简要介绍 ,可以看到FDGPET在胰腺肿块的良恶性鉴别的灵敏度和特异性均较高 ,对临床分析有很好的应用价值 ,在胰腺癌的分期 ,尤其是确定有否肝脏转移方面极具价值。并对FDGPET临床应用的优点和局限性做出分析。     

放射性核素标记的胆碱在PET/CT肿瘤显像中的应用

18F-FDG PET/CT可明显提高恶性肿瘤诊断的准确性,指导恶性肿瘤的分期与再分期,对患者治疗方案的选择产生了重要影响。其在全身许多肿瘤中的应用价值已获得认可,但还存在一些不足。随着正电子标记药物的不断研发,放射性核素标记的胆碱逐渐应用于临床。胆碱是细胞膜的重要组成成分,恶性肿瘤的胆碱代谢增高。近年来的研究表明,胆碱PET/CT在胶质瘤、头颈部肿瘤、肺癌、肝细胞肝癌、前列腺癌、膀胱肿瘤等的诊断、分期及复发检测等方面具有很好的应用价值,特别是对颅内病变的观察、高分化肝细胞肝癌的诊断、生物靶区勾画、复发病灶的定位等,在一定程度上弥补了18F-FDG PET/CT的不足。笔者回顾了放射性核素标记的胆碱（11C-胆碱和18F-胆碱）在肿瘤显像中的应用。     

PET recognition of pulmonary metastases on PET/CT imaging: impact of attenuation-corrected and non-attenuation-corrected PET images

Purpose The aims of this study were to assess the performance of FDG PET at PET/CT imaging for the detection of pulmonary metastases and to evaluate differences in lesion detectability on attenuation-corrected (AC) and non-attenuation corrected (NAC) PET images.Methods The institutional PET/CT database was searched for patients with pulmonary metastases of 3–60 mm in diameter. Ninety-two patients with 438 metastases to the lungs were included in the study. The primary tumours were 33 malignant melanomas, 12 carcinomas of unknown primary, 11 colorectal carcinomas, eight differentiated thyroid carcinomas, seven aggressive non-Hodgkins lymphomas, six head and neck cancers, three breast cancers, two prostate cancers and ten others. Lesion detectability was visually compared between PET and CT and between AC and NAC PET images using a five-point scale.Results Of the 438 pulmonary metastases, 174 were detected with FDG PET (39.7%), six of them on NAC images only (not significant). Visual scores were higher on NAC images in 41.4% and equal in 54.6% of lesions. The sensitivity of FDG PET increased significantly from 0.405 for metastases of 5–7 mm in diameter to 0.784 for lesions of 8–10 mm and to 0.935 for lesions measuring 11–29 mm in diameter. No metastases smaller than 5 mm in diameter were seen on PET images.Conclusion FDG PET/CT is useful for the assessment of pulmonary metastases. The frequency of lesion detection is similar for AC and NAC PET images. A reduced sensitivity of FDG PET has to be considered for lesions smaller than 11 mm in diameter.     

HER-2阳性乳腺癌PET及SPECT靶向探针研究进展

HER-2阳性乳腺癌的恶性度高,易复发和转移。正电子发射体层成像（PET）和单光子发射体层成像（SPECT）可特异性提供靶组织的HER-2表达信息,并能对乳腺癌的疗效及预后实时评估,在乳腺癌诊疗过程中发挥了重要作用。随着HER-2靶向分子探针研究不断深入,降低正常器官和组织的非特异性摄取成为研究的重点。对PET及SPECT成像的HER-2分子靶向探针作一介绍,并综述HER-2分子探针的应用现状及进展,客观分析各种靶向探针的优势及不足。     

Exploring new frontiers in molecular imaging: Emergence of Ga PET/CT

Since US Food and Drug Administration approval of 18-fluorodeoxyglucose as a positron tracer, and the development of hybrid positron emission tomography/computed tomography machines, there has been a great increase in clinical application and progress in the field of nuclear molecular imaging. However, not underestimating the value of (18)F, there are known limitations in the use of this cyclotron-produced positron tracer. We hence turn our focus to an emerging positron tracer, (68)Ga, and examine the advantages, current clinical uses and potential future applications of this radioisotope.     

Absorbed fractions for dose calculations of neuroreceptor PET studies

A simple Monte Carlo program was constructed for the purpose of calculating absorbed fractions of relevance to neurologic positron-emission-tomography studies. The caudate, putamen, and cerebellum regions of the brain were mathematically modeled to serve as source regions for the absorbed-fraction calculations for positron-annihilation photons. The target organs were the caudate, putamen, cerebellum, brain, spine portion in the head, skull, and head. Absorbed fractions were also calculated for a uniform ring source which encircled the head phantom.     

~(18)F-FDG PET/CT在食管癌的应用进展

食管癌恶性程度高、预后差,严重威胁了人类健康,18F-FDG PET/CT集功能和解剖信息于一身,这种医学影像技术在食管癌的应用优势日益受到广大医务工作者的关注。本文综述了18F-FDG PET/CT在食管癌的诊断、分期、复发、疗效和预后评估、放射治疗计划制定等方面的研究进展。     

18F-choline PET/CT imaging of RECIST measurable lesions in hormone refractory prostate cancer

Purpose  Apply measurability criteria based on the response evaluation criteria in solid tumors (RECIST) to lesions found on ¹⁸F-choline positron emission tomography (PET)/computerized tomography (CT) in patients with hormone refractory prostate cancer. Methods  Whole-body PET followed by CT or in-line PET/CT using 3.3–4 MBq/kg of ¹⁸F-choline was performed prospectively on 30 patients with prostate cancer, castrate testosterone levels, and rising post-treatment prostate specific antigen (PSA) levels. Lesions demonstrating increased ¹⁸F-choline uptake were classified as measurable or non-measureable based on RECIST. Results  Three patients were known previously to have RECIST measurable lesions, 10 patients had metastatic findings on radionuclide bone scan, and 17 patients had elevated serum PSA level as the only evidence of disease. Lesions demonstrating increased ¹⁸F-choline uptake were found in 28 (93%) patients. Thirty-eight PET/CT lesions from 14 patients were measurable by RECIST. Lymph node maximum standardized uptake value (SUV_max) correlated with lymph node diameter (Pearson r = 0.44, p < 0. 001). RECIST measurable lymph node SUV_max was significantly higher than that of non-measurable nodes (8.1 vs. 3.7, p < 0.0001). Detection of skeletal, prostatic, or RECIST-compatible lesions was more likely with a PSA level greater than 4.0 ng/ml (Fisher exact p = 0.0005). Conclusion  Lesions detected with ¹⁸F-choline PET/CT are frequently measurable by RECIST at baseline. Therefore, it may be feasible to include comparisons to RECIST in evaluations of ¹⁸F-choline as a therapeutic response marker for hormone refractory prostate cancer. The findings and conclusions expressed in this study do not necessarily represent the views of The Queen’s Medical Center.     

FDG–PET imaging findings of a pulmonary sclerosing hemangioma

Pulmonary sclerosing hemangiomas are generally regarded as benign lung lesions arising from type II pneumocytes and bronchial epithelium. In some cases malignant features may be present. There are several case reports describing the radiographic, computed tomography (CT), and magnetic resonance imaging (MRI) characteristics of pulmonary sclerosing hemangiomas. Given the potential for low-grade malignancy 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging may be useful in the diagnostic work up and therapeutic planning in these patients, however the FDG–PET imaging features of pulmonary sclerosing hemangiomas are not well defined. We report a case of histopathologically diagnosed sclerosing hemangioma of the lung which demonstrated intermediate uptake of FDG on the preoperative PET/CT evaluation.