PET在全麻机制研究中的应用

正电子发射计算机断层扫描(PET)是一种功能性影像诊断新技术，能够在体反映机体内的物质代谢、局部血流量、受体密度等理化特性的变化。近年来PET技术已开始应用于全麻机制的研究，并在全麻药物的中枢区域定位、相关受体的功能分析等方面显示出独特的应用价值。     

PET在全麻机制研究的应用

脑显像技术的不断发展,为麻醉机制的研究提供了更多的手段.正电子发射断层显像(positron emission tomography,PET)是一种可用于无创性脑功能研究的新技术,可以直观地反映神经元活性的变化,并在活体状况下揭示麻醉药发挥作用的中枢定位及途径.现就近年来PET在全麻机制研究中的应用作一综述.     

PET和PET／CT检查在前列腺癌中的应用

PET和PET／CT作为一项对生理和代谢过程进行显像的技术,已经渐渐地应用于前列腺癌的研究,现将其在前列腺癌中的应用做一综述。     

18F-FDG PET/CT显像在肾癌中的临床应用价值

目的:评价18F-脱氧葡萄糖(18F-fluorodeoxyglucose,18F-FDG)正电子发射计算机断层扫描(PET)/CT显像对肾癌诊断和治疗方案选择的临床应用价值.方法:回顾性分析56例临床诊断为肾癌患者的全身18F-FDG PET/CT和CT平扫加增强扫描的影像学资料.比较两者对肾癌的诊断价值.结果:56例患者中,经手术病理检查实为肾癌者47例.其余9例因18F-FDG PET/CT显像发现有转移病灶者放弃手术.18F-FDG;PET/CT 榆古敏感度为80.4%;CT平扫加增强扫描的敏感度为92.9%.9例转移病例中,3例为腹膜后淋巴结转移,3例两肺多发转移,2例骨转移并肝转移,1例伴有下腔静脉和肾静脉癌栓形成,而CT平扫加增强扫描仅发现1例肾静脉和下腔静脉痛栓形成.结论:18F-FDG PET/CT显像对诊断原发性肾癌的敏感性不如CT,但对淋巴结转移及远处转移的诊断优于CT,对肾癌的分期、治疗方案的选择及预后的判断有重要意义.     

新型PET－CT探针在胃癌应用中的现状与进展

胃癌是我国常见的恶性肿瘤,具有发病率高、生存率低等特点,其10年存活率约15%,因此需要及时准确的诊断和治疗。在近几十年中,正电子发射断层扫描(PET)使用¹⁸F－氟脱氧葡萄糖(¹⁸F－FDG)作为示踪剂已被证明可在多种恶性肿瘤的诊断和评估中提供关于肿瘤代谢的信息。然而,由于胃粘膜的物理摄取和自主运动等原因,某些类型的胃恶性肿瘤会影响胃癌的¹⁸F－FDG检测能力。因此,寻找更具有肿瘤特异性的PET－CT显像剂以弥补¹⁸F－FDG的不足是目前核医学研究的重点。本文就其在胃癌示踪中的应用现状及前景做一综述。     

MRI与PET/CT在前列腺穿刺活检中的应用

前列腺穿刺活检是目前临床前列腺癌（prostate cancer, PCa术前诊断的金标准,主要采取的方式是超声引导下PCa系统穿刺。但系统穿刺会出现低估病灶Gleason评分、漏诊较小的或多灶性肿瘤病灶等情况,最终导致误诊。随着影像技术的不断发展,以MRI与PET/CT精确引导的PCa靶向穿刺已逐渐进入临床应用,为PCa的定位、诊断和术前分期等带来了前所未有的进步。因此,本文结合当前临床MRI与PET/CT介导的不同靶向定位方式,对其在PCa靶向穿刺活检中的应用进展进行综述。     

异丙酚在剖宫产全麻中的应用

异丙酚２．０～２．５ｍｇ．ｋｇ＾－１用于剖宫产全麻诱导，完全可以替代等效量的硫喷妥钠，对新生儿没有明显的抑制作用，而且可以有效地减轻产妇的应激反应，但在用异丙酚静脉维麻醉时，易对新生儿产生抑制作用，故剖宫产全麻的维持，仍以吸入麻醉药为宜。     

核磁共振、正电子发射扫描在感染性脊柱炎诊断中的应用价值研究

目的 探讨核磁共振(MRI)、18氟-氟代脱氧葡萄糖(18F-FDG)正电子发射断层扫描成像/计算机断层扫描成像(PET/CT)在感染性脊柱炎诊断中的应用价值.方法 回顾2001年1月～2019年12月期间在河北北方学院附属第一医院进行感染性脊柱炎筛查的100例患者的临床资料.所有受试者经组织病理学和细菌学检查,有明确...     

cAMP信使系统和全麻机制

3‘,5‘-环腺苷酸（cAMP)信使系统是细胞内重要的信息传递通路，在外界因素调节细胞功能的过程中起着快速跨膜传递和放大信号的作用。在中枢神经系统的信息传递中，兴奋性氨基酸受体，γ-氨基丁酸（GABA）受体和电压依赖性钠通道与麻醉关系十分密切。cAMP可通过PKA转导信息，从而影响突触的兴奋传递。cAMP通过PKA使钠通道磷酸化，减弱兴奋传递，也可使兴奋性氨基酸受体磷酸化并增强其介导的兴奋性传递；cAMP对GABA受体影响的报道不一致。cAMP在全麻药作用机制中起重要的第二信使作用，但是否为一个重要靶位，尚有待于进一步的研究。     

PET在泌尿生殖系统肿瘤诊断中的应用

1998年 4月至 2 0 0 0年 12月 ,我们采用18FDG葡萄糖代谢正电子发射计算机断层显像 (PET)诊断泌尿系肿瘤 17例 ,现报告如下。材料与方法　本组 17例。男 12例 ,女 5例。年龄 33～ 5 9岁。其中肾上腺癌 2例、肾癌 3例、脐尿管癌 1例、膀胱癌 2例、肾盂癌 1例、前列腺上皮内瘤1例、前列腺肉瘤 1例 ,血尿 6例。PET设备为GE公司产品 ,回旋加速器为CTI公司产品。FDG注射前禁食 4～ 6h。空腹血糖确定在正常范围内 ,必要时可使用胰岛素。成人18FDG剂量范围 10～ 15mCi(370～ 5 5 0MBq) ,一般取病灶对侧上肢静脉或下肢静脉作为注射点 ,常…     

Positron Emission Tomography Study of Regional Cerebral Metabolism during General Anesthesia with Xenon in Humans

Background: The precise mechanism by which the gaseous anesthetic xenon exerts its effects in the human brain remains unknown. Xenon has only negligible effects on inhibitory [gamma]-aminobutyric acid receptors, one of the putative molecular targets for most general anesthetics. Instead, xenon has been suggested to induce anesthesia by inhibiting excitatory glutamatergic signaling. Therefore, the authors hypothesized that xenon, similar to ketamine and nitrous oxide, increases global and regional cerebral metabolism in humans.

Methods: The regional cerebral metabolic rate of glucose (rcMRGlu) was sequentially assessed in two groups of six volunteers each, using 18F-fluorodeoxyglucose as tracer. In the xenon group, rcMRGlu was determined at baseline and during general anesthesia induced with propofol and maintained with 1 minimum alveolar concentration xenon. In the control group, rcMRGlu was measured using the identical study protocol but without administration of xenon. rcMRGlu was assessed after the plasma concentration of propofol had decreased to subanesthetic levels (< 1.0 [mu]g/ml). rcMRGlu was quantified in 10 cerebral volumes of interest. In addition, voxel-wise changes in rcMRGlu were analyzed using statistical parametric mapping.

Results: Xenon reduced whole-brain metabolic rate of glucose by 26 +/- 7% (from 43 +/- 5 [mu]mol [middle dot] 100 g-1 [middle dot] min-1 to 31 +/- 3 [mu]mol [middle dot] 100 g-1 [middle dot] min-1; P < 0.005) and significantly decreased rcMRGlu in all volumes of interest compared with the control group receiving propofol only. Voxel-based analysis revealed metabolic depression within the orbitofrontal, frontomesial, temporomesial, occipital, dorsolateral frontal, and lateral temporal cortices and thalami. No increases in rcMRGlu were detected during xenon anesthesia.     

Positron Emission Tomography in Lung Cancer

Reports on positron emission tomography have become more common in the oncology literature. After a short introduction to positron emission tomography, this review will look at the data relating to the use of this technology in the diagnosis, the staging, and the posttreatment evaluation of patients with lung cancer and will discuss its potential role in these evaluations.     

Positron Emission Tomography in Clinical Islet Transplantation

The fate of islets in clinical transplantation is unclear. To elude on this positron emission tomography combined with computed tomography (PET/CT) was performed for 60 min during islet transplantation in five patients receiving six transplants. A fraction of the islets (23%) were labeled with 18F‐fluorodeoxyglucose ([¹⁸F]FDG) and carefully mixed with unlabeled islets just prior to intraportal transplantation. The peak radioactivity concentration in the liver was found at 19 min after start of islet infusion and corresponded to only 75% of what was expected, indicating that islets are lost during the transplantation procedure. No accumulation of radioactivity was found in the lungs. A nonphysiological peak of C‐peptide was found in plasma during and immediately after transplantation in all subjects. Distribution in the liver was heterogeneous with wide variations in location and concentration. Islets found in areas with concentrations of >400 IEQ/cc liver tissue varied between 1% and 32% of the graft in different subjects. No side effects attributed to the PET/CT procedure were found. Clinical outcome in all patients was comparable to that previously observed indicating that the [¹⁸F]FDG labeling procedure did not harm the islets. The technique has potential to be used to assess approaches to enhance islet survival and engraftment in clinical transplantation.     

Positron Emission Tomography Study of Regional Cerebral Metabolism in Humans during Isoflurane Anesthesia

Background: Although the anesthetic effects of the intravenous anesthetic agent propofol have been studied in the living human brain using brain imaging technology, the nature of the anesthetic state evident in the human brain during inhalational anesthesia remains unknown. To examine this issue, the authors studied the effects of isoflurane anesthesia on human cerebral glucose metabolism using positron emission tomography (PET).

Methods: Five volunteers each underwent two PET scans; one scan assessed awake-baseline metabolism and the other scan assessed metabolism during isoflurane anesthesia titrated to the point of unresponsiveness (means +/- SD; expired = 0.5 +/- 0.1%). Scans were obtained with a GE2048 scanner (4.5-mm resolution-FWHM) using the18 fluorodeoxyglucose technique.

Results: Awake whole-brain glucose metabolism averaged 6.9 +/- 1.5 mg [center dot] 100 g sup -1 [center dot] min sup -1 (means +/- SD). Isoflurane reduced whole-brain metabolism 46 +/- 11% to 3.6 +/- 0.3 mg [center dot] 100 g sup -1 [center dot] min sup -1 (P less or equal to 0.005). Regional metabolism decreased fairly uniformly throughout the brain, and no evidence of any regional metabolic increases were found in any brain region for any participant. A region-of-interest analysis showed that the pattern of regional metabolism evident during isoflurane anesthesia was not significantly different from that seen when participants were awake.     

Functional Anatomy of Reaching and Visuomotor Learning: A Positron Emission Tomography Study

The purpose of this study was to identify the functional corticalfields involved in reaching for targets in extrapersonal space,and to identify the specific fields representing visual targetinformation in long-term memory. Ten healthy subjects were askedto learn the positions of seven circular targets that were repeatedlyprojected on a screen. The regional cerebral blood flow wasmeasured with positron emission tomography during a rest state,at an early learning stage, at a later learning stage, and finallyat 30 min after the course of learning had been completed. MeanrCBF change images for each task minus rest were calculatedand fields of significant rCBF changes were identified. In all three task states, cortical fields were consistentlyactivated in the left motor and premotor areas, the posteriorpart of the superior parietal lobule, and the right angulargyrus. When learning of the target positions had been achieved,additional fields appeared bilaterally in the posterior partof the superior parietal lobule, the right superior occipitalgyrus, the left motor and premotor areas, the medial aspectof the superior frontal gyrus, the postcentral gyrus, the superiorpart of the cuneus, the inferior part of the angular gyrus,and the anterior part of the insula. The results indicate thatthere are at least two different types of functional fieldsin the posterior part of the superior parietal lobule; one isactive during reaching for the targets when guided by internalrepresentations of target positions; the other likely representsthe storage sites of visual target information that is addressedin long-term memory.     

Use of Positron Emission Tomography in Surgery Follow-Up of Esophageal Cancer

Introduction  Although the prognosis of patients with esophageal cancer has been improved by extended dissection, the incidence of recurrence still remains high. In esophageal cancer, positron emission tomography (PET) using ¹⁸F-fluorodeoxyglucose (FDG) already demonstrated to be useful for initial staging and monitoring response to therapy. This prospective study compared the ability of FDG-PET and conventional imaging to detect early recurrence of esophageal cancer after initial surgery in asymptomatic patients. Materials and Methods  Between October 2003 and September 2006, 41 patients with esophageal cancer were included in a prospective study after initial radical esophagectomy. FDG-PET, thoracoabdominal computed tomography (CT), abdominal ultrasonography, and endoscopy were performed every 6 months after initial treatment. Results and Discussion  Twenty-three patients had recurrent disease (56%), mostly within the first 6 months after surgery (70%). Despite two false-positive scans due to postoperative changes, FDG-PET was more accurate than CT (91% vs. 81%, p = 0.02) for the detection of recurrence with a sensitivity of 100% (vs. 65%), a specificity of 85% (vs. 91%), and a negative predictive value of 100% on a patient-by-patient-based analysis. For the detection of locoregional recurrence, FDG-PET was more accurate than CT (96.2% vs. 88.9%). FDG-PET was also more accurate than CT for the detection of distant metastases (92.5% vs. 84.9%), especially when involving either bones (100%) or liver (98.1%). A lower sensitivity of FDG-PET (57%) for the early detection of small lung metastases did not affect patient management (accuracy = 92.5%). Conclusion  FDG-PET appears to be very useful for the systematic follow-up of asymptomatic patients after esophagectomy with an initial scan performed 6 months after surgery. Presented at the Forty-sixth Annual Meeting of The European Society of Nuclear Medicine, Athens, Greece, September 30–October 4, 2006 (oral presentation).