肺部单发结节在~(18)氟脱氧葡萄糖-正电子发射体层显像检查后外科决策

目的探讨肺部单发结节(SPN)患者在18氟脱氧葡萄糖-正电子发射体层显像(FDG-PET)检查后的外科决策。方法 1998年10月—2006年4月对375例直径1.0～3.0 cm的SPN患者行FDG-PET检查,采用目测法结合半定量分析判读。结果 FDG-PET定性诊断的敏感度、特异度、准确率分别为73.7%(188/255)、71.7%(86/120)、73.1%(274/375);FDG-PET无法区别良性显影病变与腺癌;对于肺外病灶FDG-PET也存在假阳性。结论 PET检查阳性的SPN,除非抗感染或抗结核治疗有效,否则都应当通过手术切除等途径确诊;对PET检查阴性的SPN患者,或手术切除,或定期随访。     

Interpolating scan and oblique-angle tomograms in myocardial PET using nitrogen-13 ammonia

The effect of low sensitivity areas or gaps between adjacent slices of the multislice positron emission tomography on detection of myocardial perfusion abnormality with 13NH3 was evaluated segmentally in 36 patients with coronary artery disease at rest or during exercise. The detectability of the defects in RCA or LAD region was 80% in single-position scans in stress studies. The false-negative defects were located mainly in the inferior wall, apicoinferior wall, or high anterior wall. When the patients were moved half the slice interval to perform the interpolating scan, and the two sets of images were interlaced with each other, the detectability increased to 88%. The interpolating scan also allowed reconstruction of long-axis and short-axis tomograms in high quality, which further improved the detectability of perfusion defects (100% for RCA or LAD and 75% for LCX lesion) and helped in understanding the anatomic relationships to the coronary artery territories.     

Novel fluorine-18 PET radiotracers based on flumazenil for GABAA imaging in the brain

IntroductionTwo 7-fluoroimidazobenzodiazepines (AH114726 and GEH120348), analogs of flumazenil, were labeled with fluorine-18 and evaluated as alternative radioligands for in vivo imaging of the GABA_A/benzodiazepine receptor by comparing them to [¹¹C]flumazenil in rhesus monkey.MethodsRadiotracers were prepared from the corresponding nitro-precursors in an automated synthesis module, and primate imaging studies were conducted on a Concorde MicroPET P4 scanner. The brain was imaged for 60 (12 × 5 min frames) or 90 min (18 × 5 min frames), and data was reconstructed using the 3D MAP algorithm. Specificity of [¹⁸F]AH114726 and [¹⁸F]GEH120348 was confirmed by displacement studies using unlabeled flumazenil.Results[¹⁸F]GEH120348 and [¹⁸F]AH114726 were obtained in 13–24% yields (end of synthesis) with high chemical (> 95%) and radiochemical (> 99%) purities, and high specific activities (2061 ± 985 Ci/mmol). The in vivo pharmacokinetics of [¹⁸F]AH114726 and [¹⁸F]GEH120348 were determined in a non-human primate and directly compared with [¹¹C]flumazenil. Both fluorine-18 radioligands showed time-dependent regional brain distributions that correlated with the distribution of [¹¹C]flumazenil and the known concentrations of GABA_A/benzodiazepine receptors in the monkey brain. [¹⁸F]AH114726 exhibited maximal brain uptake and tissue time-radioactivity curves that were most similar to [¹¹C]flumazenil. In contrast, [¹⁸F]GEH120348 showed higher initial brain uptake but very different pharmacokinetics with continued accumulation of radioactivity into the cortical regions of high GABA/benzodiazepine receptor concentrations and very little clearance from the regions of low receptor densities. Rapid washout of both radiotracers occurred upon treatment with unlabeled flumazenil.ConclusionThe ease of the radiochemical synthesis, together with in vivo brain pharmacokinetics most similar to [¹¹C]flumazenil, support that [¹⁸F]AH114726 is a suitable option for imaging the GABA_A receptor.     

Quantitative evaluation of regional pulmonary ventilation using PET and nitrogen-13 gas

A new quantitative method, "Simultaneous Exponential Equation method" (SEE), has been developed for the analysis of pulmonary ventilation studies using 13N-labeled nitrogen gas and positron emission computed tomography. This method uses Kety's model assuming insolubility of nitrogen gas in blood or tissues. Activity in poorly ventilated regions does not reach the equilibrium in the so-called equilibrium scan (EQ) performed following 3 or 4 min of washin. Therefore EQ images do not represent lung volume images nor do they provide the initial value of washout phase. Our method corrects for these transient phenomena observed during EQ scan and yields idealistic equilibrium state images (lung volume images) as well as more accurate regional ventilatory time constants than a modified Stewart-Hamilton (A/H) method and tomograms of high resolution.     

18F-FDG PET/CT显像正常腹部消化器官的标准摄取值分析

目的分析^18F-脱氧葡萄糖（FDG）PET/CT显像正常腹部消化器官标准摄取值（SUV）的变化范围.方法60例要求行PET/CT检查的健康人,按体重7.77 MBq/kg静脉注射^18F-FDG,PET采集为三维模式,每个床位3 min.对腹部肝、胆囊、脾、胰腺、胃、盲肠、结肠和直肠进行半定量分析,各器官的SUV由横断面测量,准确定位时参考同机CT.结果正常腹部消化器官^18F-FDG摄取有较大差异,其中摄取较高者SUV平均值（SUVavg）依次为直肠、肝、乙状结肠、回盲部和脾、升结肠,SUV最大值（SUVmax）依次为直肠、乙状结肠、肝、回盲部、升结肠、脾.结论PET/CT显像能较好地识别腹部消化器官;熟悉正常腹部消化器官^18F-FDG摄取的差异,对判读图像十分重要.     

The limited role of myocardial fluorine-18 fluorodeoxyglucose imaging in candidates for cardiac transplantation: a planar imaging study

This study compares the incidence and extent of hibernating myocardium (defined by myocardial perfusion/metabolism mismatch) in 28 cardiac transplant candidates with ischaemic cardiomyopathy and in 16 other patients with coronary artery disease (CAD) undergoing viability assessment. It then reviews the impact of myocardial perfusion metabolism imaging on management decisions in the transplant candidates at 6 months after scintigraphy. Each patient underwent a planar myocardial thallium-201 and fluorine-18 fluorodeoxyglucose scan on a modified gamma camera. Perfusion/metabolism mismatch was sized semi-quantitatively and each patient was assigned a global mismatch score. Transplant candidates had a lower left ventricular ejection fraction (LVEF) (P<0.0002) and extent of hibernating myocardium (lower global mismatch score: P = 0.005) than other CAD patients but the difference in respect of mismatch frequency (8/28 vs 9/16 patients) did not reach statistical significance. Transplant candidates with LVEF <20% had a lower global mismatch score (P<0.02) than those with an LVEF ≥20%. Interestingly, two of three other CAD patients with LVEF <20% had a moderate mismatch. Follow-up studies revealed the lack of impact of metabolic imaging as none of the three transplant candidates who eventually underwent revascularisation had hibernating myocardium and transplantation was offered to one of only two candidates with more than one minor mismatch. Thus metabolic imaging in potential transplant candidates may be of limited value because of the very low extent of hibernating myocardium, particularly if LVEF is below 20% and where clinical decisions are often based on many other factors. Received 7 June and in revised form 11 October 1997     

正常前列腺18F-FDG PET/CT代谢显像增龄变化的研究

目的 探讨18F-氟脱氧葡萄糖（FDG） PET/CT显像中正常前列腺标准化摄取值（SUV）、CT值、PET/CT横断位最大层面测量的前列腺左右径（简称最大横径）和患者年龄之间的关系。 方法 回顾性分析2018年6月至2019年2月在安徽医科大学第二附属医院行18F-FDG PET/CT显像的非前列腺癌男性患者181例,年龄19~94(60.6±14.5)岁。将患者按年龄段分为4组:19~39岁16例、40~59岁57例、60~79岁94例、80~99岁14例。采用勾画感兴趣区（ROI）的方法测量各组患者前列腺18F-FDG最大标准化摄取值(SUV_max)、平均标准化摄取值（SUV_mean）和平均CT值（CT_mean）,并在前列腺横断位最大层面测量前列腺最大横径。采用Pearson相关性分析、散点图和线性回归趋势线分析前列腺最大横径、SUV_max、SUV_mean、CT_mean和年龄之间的相关性,采用单因素方差分析及LSD-t检验对各组患者相关参数的均值进行多重比较。 结果 181例患者的前列腺最大横径为3.4~6.5（4.66±0.59） cm,SUV_max为1.0~4.2（2.44±0.49）,SUV_mean为0.7~3.4（1.97±0.44）,CT_mean为25~46（34.48±3.72） HU。前列腺最大横径与患者年龄呈正相关(r=0.465,P<0.001);前列腺SUV_max、SUV_mean与患者年龄、前列腺最大横径无相关性(r=0.047、0.071、0.040、0.035,均P>0.05);前列腺CT_mean随患者年龄的增长而增加,两者呈极弱相关性或无相关（r=0.126,P=0.091）。不同年龄段的各组患者的前列腺最大横径分别为（4.04±0.27）、（4.52±0.53）、（4.77±0.54）、（5.24±0.65）cm;SUV_max分别为（2.48±0.65）、（2.38±0.50）、（2.46±0.47）和（2.48±0.42）;SUV_mean分别为（2.03±0.51）、（1.90±0.44）、（2.00±0.42）和（2.05±0.41）;CT_mean分别为（33.25±3.59）、（34.19±3.76）、（34.76±3.80）、（35.29±2.97） HU。不同年龄段的各组患者前列腺最大横径之间的差异有统计学意义（F=16.278,P<0.001）,而SUV_max、SUV_mean和CT_mean之间的差异均无统计学意义。 结论 前列腺最大横径随着患者年龄的增长而增加,但患者年龄不会显著影响前列腺的糖代谢和CT密度。     

Simultaneous in vitro and in vivo validation of nitrogen-13-ammonia for the assessment of regional myocardial blood flow

Measurement of myocardial blood flow by 13NH3 relies heavily on the assessment of both the input function and the variable tissue extraction fraction. In six open-chest dogs, myocardial and arterial 13NH3 activity was measured both by in vitro sampling and by in vivo positron emission tomography (PET). Regional myocardial blood flow was forced to vary in the range 0.2-5 ml/min/g and actual values were assessed by in vitro counting of 153Gd microspheres. The ammonia input function was processed by: (a) total curve integration; (b) curve integration for 2 min; (c) integral of a fitted curve (gamma variate in vivo and exponential of the downslope in vitro). Method C brought to regional flow values which best approximated microspheres data. The in vitro correlation allows for correcting in vivo values for the flow-dependent extraction fraction. The method can be easily applied for regional myocardial blood flow measurements with PET in human studies.     

Evaluation of liver tumors using fluorine-18-fluorodeoxyglucose PET: characterization of tumor and assessment of effect of treatment.

To evaluate glucose metabolism in patients with tumors involving the liver, 35 patients with liver lesions had PET using 18F-2-fluoro-2-deoxy-D-glucose (FDG). FDG (148 MBq) was injected and radioactivity of the tumor was scanned dynamically by PET. The rate constants (k1, k2, k3, k4) of FDG in a metabolic model were calculated. The results were compared to hexokinase activity in the excised tumor specimens. k3 was found to reflect tumor hexokinase activity. When k3 was used as an index (cut-off value: 0.025), it was possible to distinguish benign and malignant tumors. k4 was significantly higher in hepatocellular carcinoma. By using k3 and k4 as indices, one could assess the degree of differentiation of hepatocellular carcinoma. After treatment, k3 decreased according to the effectiveness of therapy and thus may be a useful index for quantitatively assessing tumor viability.     

The value of fluorine-18 fluorodeoxyglucose PET in patients with medullary thyroid cancer

The early detection of metastases from medullary thyroid cancer (MTC) is important because the only curative therapy consists in surgical removal of all tumour tissue. There is no single sensitive diagnostic imaging modality for the localization of all metastases in patients with MTC. Therefore, in many cases several imaging modalities (e.g. ultrasonography, magnetic resonance imaging, computerized tomography and scintigraphy using pentavalent technetium-99m dimercaptosuccinic acid, thallium-201 chloride, indium-111 pentetreotide, anti-CEA antibodies or metaiodobenzylguanidine) must be performed consecutively in patients with elevated calcitonin levels until the tumour is localized. In this prospective study, we investigated the value of fluorine-18 fluorodeoxyglucose positron emission tomography ([18F]FDG PET) in the follow-up of patients with MTC. [18F]FDG PET examinations of the neck and the chest were performed in 20 patients with elevated calcitonin levels or sonographic abnormalities in the neck. Positive [18F]FDG findings were validated by histology, computerized tomography or selective venous catheterization. [18F]FDG PET detected tumour in 13/17 patients (nine cases were validated by histology, four by computerized tomography). Five patients showed completely negative PET scans (of these cases, one was true-negative and four false-negative). One patient with [18F]FDG accumulation in pulmonary lesions from silicosis and one patient with a neck lesion that was not subjected to histological validation had to be excluded. Considering all validated localizations, [18F]FDG PET detected 12/14 tumour manifestations in the neck, 6/7 mediastinal metastases, 2/2 pulmonary metastases and 2/2 bone metastases. In two patients with elevated calcitonin levels, no diagnostic modality was able to localize a tumour. The sensitivity of [18F]FDG PET in the follow-up of MTC was 76% (95% confidence interval 53%-94%); this is encouraging. [18F]FDG PET promises to be a valuable diagnostic method, especially for the detection of lymph node metastases, surgical resection of which can result in complete remission.     

The role of positron emission tomography with fluorine-18-deoxyglucose in identifying colorectal cancer metastases to liver

Liver metastasis is a common consequence of colorectal carcinoma. Early and accurate detection of liver metastasis is crucial for a decision about partial hepatectomy, which is considered a standard and potentially curative therapy in such a setting. The presence of extrahepatic metastases will exclude surgical resection as a therapeutic option. Positron emission tomography with fluorine-18-deoxyglucose (FDG-PET) has been successful in detecting and staging a variety of malignancies. The purpose of this study was to assess the utility of FDG-PET in the accurate detection of liver and distal metastases from colorectal cancer. The results of 80 PET and computed tomography (CT) scans were compared with surgical pathology and clinical outcome. FDG-PET detected liver metastases in 28 patients, with a sensitivity of 100%. CT detected metastasis in 20 patients, giving a sensitivity of 71.4%. In addition, in one patient with negative CT findings, PET detected a focus of hypermetabolism in the region adjacent to liver, which was proven to be a second focus of primary colon carcinoma. In six patients with liver metastases, PET correctly detected extrahepatic lesions, while CT only detected hepatic lesions. In conclusion, FDG-PET is an excellent imaging modality for the detection and staging of liver metastases in patients with colorectal carcinomas.     

Amyloid PET imaging in cardiac amyloidosis: a pilot study using 18F-flutemetamol positron emission tomography

Annals of Nuclear Medicine - Cardiac amyloidosis is a rare disease characterized by amyloid heart deposits and is usually a part of systemic amyloidosis, in relation to systemic light chain (AL)...     

18F-FDG与18F-FLT PET/CT延迟显像对肺结节诊断效能的评价

目的 通过对多中心、前瞻性研究中接受了18F-脱氧葡萄糖(FDG)与18F-脱氧胸腺嘧啶核苷(FLT)延迟显像病例的分析,探讨18F-FDG与18F-FLT延迟显像对肺结节诊断的效能.方法 6个PET/CT中心,从2006年1月至2007年6月,按照统一标准,采用同机型、同一扫描条件,开展了肺结节样病变18F-FLT和18F-FDG PET/CT显像的多中心临床研究.在经确诊的55例病例中,25例患者进行了18F-FLT显像和延迟显像,34例患者进行了18F-FDG延迟显像.按常规计算延迟显像时病灶最大标准摄取值(SUVmax)及与早期显像时SUVmax相比的变化率(△SUVmax).对照临床确诊结果分析其诊断效能.采用SPSS11.0软件进行统计学处理.结果 18F-FDG延迟显像患者中,6例肺癌中5例、12例结核中9例、16例炎症或其他良性结节中9例的SUVmax较早期相升高.18F-FLT延迟显像组中,7例肺癌中3例、8例结核中3例和10例其他良性病灶中2例的SUVmax上升.经分组统计分析,不同疾病组间18F-FDG延迟显像SUVmax和△SUVmax差异无统计学意义;18F-FLT延迟显像SUVmax和△SUVmax组间差异也无统计学意义.无论18F-FDG还是18F-FLT,延迟显像的诊断效能均不如早期相.无论早期还是延迟显像,单独18F-FDG或18F-FLT显像的诊断效能均不如二者联合应用.结论 18F-FDG和18F-FLT延迟显像的SUVmax变化规律性不强,不宜单独应用于肺结节的鉴别诊断.     

The relationship between myocardial blood flow and glucose uptake in ischemic canine myocardium determined with fluorine-18-deoxyglucose.

The relationship between myocardial blood flow as a marker of severity of ischemia and exogenous glucose utilization was examined following occlusion of the left anterior descending coronary artery in 10 fasted, anesthetized, open-chest dogs. Fluorine-18-fluorodeoxyglucose (FDG) was injected 10 min after the onset of ischemia and serial blood samples were obtained to measure FDG in plasma. Tracer-labeled microspheres, used to measure myocardial blood flow (MBF), were injected 10 and 40 min postocclusion. After the last microsphere injection, the heart was arrested and removed rapidly. Tissue samples of the left ventricle were obtained, weighed and FDG counts were determined. Two days later, the same samples were assayed for radioactivity from the tracer-labeled microspheres and blood flow was calculated. Thus, FDG uptake and MBF measurements were made in the same tissue samples. When normalized for variations in blood flow, there were no significant differences in FDG uptake between the subendocardial and subepicardial halves of the tissue samples. FDG uptake was relatively high and uniform in normal myocardium, paralleling the pattern of MBF. In ischemic myocardium, however, FDG uptake and MBF did not vary in parallel. In tissue samples with MBF reduced by up to 80% from control levels, relative FDG uptake increased such that absolute FDG uptake remained at normal or near normal levels. In samples with more severe ischemia, FDG uptake decreased precipitously with additional decrements in MBF. We propose that sufficient glycolytic flux may be sustained to maintain cellular viability when perfusion is above the threshold value. Below the threshold, however, irreversible changes may be initiated.     

Normal variants, artefacts and interpretative pitfalls in PET imaging with 18-fluoro-2-deoxyglucose and carbon-11 methionine

Interpretation of studies from all imaging modalities requires a knowledge of the possible pitfalls that may occur due to normal variation, artefacts and processes which may mimic pathology. The applications and use of not only 18-fluoro-2-deoxyglucose but also l-[methyl-¹¹C] methionine positron emission tomography (PET) are widening and it is timely that the currently recognised interpretative pitfalls are reviewed as the number of dedicated PET scanners and coincidence gamma cameras increases.     

PET tomographic imaging of the human heart,pancreas, and liver with nitrogen-13 derived from [13N]-L-glutamate

The first commercial version of the Massachusetts General Hospital (MGH) positron camera was used to image the relative distributions of ¹³N (T _1/2=9.96min) in the human heart, pancreas, and liver after intravenous administration of [¹³N]-l-glutamate. The instrument was operated in two imaging modes. Conventional 2-dimensional (2-D) focal-plane images showed high concentrations of ¹³N in the heart and pancreas, and lower levels in the liver. Five PET tomographic transverse section (3-D) images were made through the heart and three through the pancreas. Our results suggest that further studies designed to gain an improved understanding of the biochemistry of [¹³N]-l-glutamate aided by PET imaging, especially with newer instrumentation, are worthy of further investigation.