Positron emission tomography scanning in lung cancer

Continuing advances in imaging technology have resulted in an improved ability to evaluate thoracic malignancies with PET. Published reports demonstrate that PET provides accurate, noninvasive detection of malignancy that is useful in the characterization of nonspecific radiographic lung lesions, staging of known lung cancer, and identification of recurrent disease. Preliminary studies suggest that PET may also be able to accurately assess therapeutic response. The incorporation of PET into routine clinical practice has advanced rapidly and undoubtedly PET will continue to be an increasingly important part of the clinical assessment of patients with lung malignancy.     

Positron emission tomography/computer tomography in guidance of extrahepatic hepatocellular carcinoma metastasis management

Hepatocellular carcinoma （HCC） is one of the most common primary cancers in the world. Surgery is the gold standard for treatment of patients with HCC. Recurrence and metastasis are the major obstacles to further improve the prognosis of HCC. Most recurrences are intrahepatic. However, 30% of the recurrences are extrahepatic. The role of resection in intrahepatic recurrences is widely accepted. The role of resection in extrahepatic HCC recurrence and metastasis is not well established. 18F fluorodeoxyglucose （18F-FDG） positron emission tomography/computer tomography （PET/CT） is useful in detecting distant metastasis from a variety of malignancies and shows superior accuracy to conventional imaging modalities in identification of intrahepatic and extrahepatic metastasis. We present one patient with one new isolated omental lymph node metastasis, who had a history of huge HCC resected six years ago. The metastatic focus was identified with 18 F-FDG PET/CT and resected. The follow-up revealed good prognosis with a long-term survival potential after resection of the omental lymphatic metastasis.     

Positron emission tomography scanning in the assessment of patients with lymphoma

BACKGROUND: The detection of lymphoma by computed tomography (CT) scanning is known to be improved by positron emission tomography (PET) and/or gallium scanning, although the direct comparative accuracy of these imaging modalities remains a subject of ongoing review. AIMS: The aim of the present study was to compare PET scanning with conventional imaging (CT and/or gallium scanning) in patients with lymphoma. METHODS: A retrospective study of 38 patients (25 men; 13 women; median age 39.5 years; range 18.0-81.0 years) who had had PET scans (24 scans at initial staging and 46 scans at restaging, including suspected disease relapse) was carried out. Thirty-one concurrent gallium scans had been performed. Disease was validated with clinical follow up or biopsy. RESULTS: The sensitivities of PET and CT at initial staging were 96 and 71%, respectively. PET identified additional sites of disease compared with CT in 29% of patients. Of the 15 patients who had had all three imaging modalities, the sensitivities of PET, CT and gallium were 93, 67 and 87%, respectively. At treatment completion, the positive predictive values of PET, CT and gallium scans for relapse given a residual mass were 100, 33 and 0%, respectively (P = 0.006 for PET and CT comparison). The negative predictive values of PET, CT and gallium were 76, 0 and 70%, respectively (P-value not significant). In suspected disease relapse, PET results changed management in 50% of patients. CONCLUSION: Compared with CT and gallium scans, PET has superior accuracy in staging and restaging, and its greatest value lies in its positive predictive value for relapse in patients with residual masses.     

Positron emission tomography

Positron emission tomography (PET) is currently the most sophisticated scintigraphic imaging technique developed for in-vivo quantification of cardiac physiology and biochemistry. The state-of-the-art PET technology allows delineation of regional tracer activity with high spatial and temporal resolution. A large number of radiopharmaceuticals have been developed to study myocardial perfusion enabling accurate diagnosis and localization of coronary artery disease (CAD) and energy metabolism. More recently, newer tracers such as radiolabeled catecholamine analogues allow the pre- and postsynaptic evaluation of cardiac autonomic innervation. Metabolic imaging with PET represents currently the gold standard for tissue viability assessment with well-validated diagnostic and prognostic information. F-18 deoxyglucose has been also used in combination with SPECT or coincidence imaging providing comparable clinical information but without need for the expensive and rarely available imaging technology of PET. The assessment of coronary flow reserve is the most sensitive scintigraphic method to i) detect vascular abnormalities before their hemodynamic significance, ii) diagnose and define the extent of CAD, and iii) to monitor the effects of (non)pharmacological intervention on regional and global cardiac flow. C-11 hydroxyephedrine (HED) allows imaging of sympathetic neuronal function. the course of cardiac reinnervation after cardiac transplantation was demonstrated with C-11 HED PET, and preliminary evidence suggests that this technique might provide prognostic information on sympathetic neuronal status in congestive heart failure, too. The functional and prognostic relevance of PET imaging together with the increased availability of lower cost instrumentation imaging will define its future role in the diagnosis, assessment of extent, prognosis and in the therapeutic decision making of cardiac disease.     

Positron emission tomography

Positron emission tomography and tracers of blood flow and of metabolism offer a most unique capability: The noninvasive study of regional myocardial metabolism and its derangements as a result of regional or global myocardial disease. Research with PET not only has confirmed the existence of metabolic fluxes and reactions as established previously through highly invasive or even destructive investigational techniques but has provided new insights into pathophysiologic processes, especially in ischemic and post-ischemic myocardium. From these investigations in both animal experiments and in humans, observations have emerged which indicate a place for PET in clinical cardiology. PET is likely to contribute to detection of disease, to characterizing its extent and severity as well as to decide upon the most appropriate therapeutic strategy and assessing its results. It is recognized that many of these observations with clinical implications await confirmation through larger clinical trials, follow-up studies as well as independent confirmation. Besides exploring ischemic heart disease, PET is equally suitable for examining substrate fluxes and interactions in other disorders as for example in intrinsic myocardial disease like primary and secondary cardiomyopathies. While derangements of metabolism in these disorders may be an expression of the consequences of the disease process or its underlying mechanisms itself, findings on PET will allow formulation of new hypotheses on disease mechanisms that conversely can then be tested. In addition to F-18 2-deoxyglucose and C-11 palmitate, the number of tracers for substrate metabolism is likely to increase. An example is C-11 acetate currently intensely investigated as a tool for measuring overall myocardial oxidative metabolism. Others as for example C-11 labeled short chain fatty acids are on the horizon. The study of cardiac receptors is similarly possible. Thus, a set of tools will soon be available for dissection of entire metabolic pathways and for determination of rate limiting steps in health and disease and to more clearly define specific defects in biochemical reaction steps that critically contribute to or even ae the specific cause of disease.     

Positron emission tomography for preoperative staging of colorectal carcinoma

PURPOSE: Positron emission tomography (PET) is an imaging technique based onin vivo cellular metabolism. Increased glucose metabolism in neoplastic cells is detected by using fluorine-18 deoxyglucose. In an ongoing pilot study to determine the usefulness of this technique, PET is compared with computerized tomography (CT) for the preoperative staging of colorectal carcinoma. METHODS: Sixteen patients were evaluated with both PET and CT of the abdomen and pelvis. Results were compared with operative and histopathologic findings. Fifteen malignant lesions were found in 16 patients by histology. PET had a positive predictive value of 93 percent and a negative predictive value of 50 percent. By comparison CT had a positive predictive value of 100 percent and a negative predictive value of 27 percent. CONCLUSIONS: These preliminary results indicate that PET has increased sensitivity for staging colorectal carcinoma, whereas CT has higher specificity. The predictive value of a positive PET compares favorably with CT. Furthermore, the predictive accuracy for detection of colorectal carcinoma is 83 percent for PET and 56 percent for CT.Poster presentation at the meeting of The American Society of Colon and Rectal Surgeons, San Francisco, California, June 7 to 12, 1992.Presented in part in the Nebraska Medical Journal, February 1993.     

Positron emission tomography in the lung

Positron emission tomography using the ECAT II scanner to image and measure regional lung function is outlined. The combined use of transmission and emission imaging provides quantitative information about regional lung structure (density, extravascular density, and vascular volume) and function (ventilation, perfusion, ventilation-perfusion ratios, glucose metabolic rate). Clinical applications in asthma, chronic obstructive lung disease, pulmonary vascular disease, interstitial lung disease, and squamous cell carcinoma are presented. Future prospects for PET are discussed.     

Positron emission tomography/computed tomography with 18F-fluorocholine improve tumor staging and treatment allocation in patients with hepatocellular carcinoma

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Positron emission tomography of the heart

Positron emission computed tomography (PET) has introduced a new dimension into cardiology by its ability of imaging in-vivo cardiac metabolism non-invasively. Following administration of labelled substrates PET provides display of digitized heart tomograms, which reflect tracer concentration quantitatively. Thus, regional myocardial metabolism and perfusion can be measured using appropriate tracers such as C-11 palmitate, F-18 deoxyglucose, N-13 or C-11 amino acids, N-13 ammonia and Rb-82. Accordingly, the documentation of marked metabolic derangements during ischemia and infarction by initial clinical PET studies have been very promising diagnostically. It has been shown that normal, resting ischemic and acutely ischemic and infarcted tissue can be differentiated reliably. In cardiomyopathies, disturbed energy substrate utilization not known until then was found by means of PET. Unfortunately, PET will be available only in larger centers in the near future because of its high cost.     

阿尔茨海默病的~(18)F-FDDNP脑断层扫描显像

目的探讨标记物18F-FDDNP在脑断层扫描(PET)显像中诊断阿尔茨海默病(AD)的价值。方法分别对7例AD患者(AD组)、6例血管性痴呆(VaD)患者(VaD组)及6例智能正常老年对照者(NC,NC组)进行18F-FDDNP脑PET显像,受试者分别在药物注射后5 min2、5 min和45 min采集图像。结果AD患者3个时段放射性清除情况与其他2组图像有明显的不同。药物注射45 min后脑内放射性清除率较VaD组、NC组明显减低。结论18F-FDDNP脑PET显像是诊断AD的一个有效的影像学指标。     

阿尔茨海默病与血管性痴呆的18F-FDDNP脑PET显像

目的探讨1-{6-[（2-^18F-氟乙基）-甲氨基]-2-萘基}-亚乙基丙二氰（^18F-FDDNP）PET脑显像鉴别诊断阿尔茨海默病（AD）与血管性痴呆（VaD）的价值。方法分别对9例AD、6例VaD及6例智能正常老年对照者（NC）进行^18F-FDDNPPET脑显像，受试者分别在药物注射后5、25、45min采集图像。结果AD患者大脑皮层及皮层下灰质核团3个时间段放射性清除情况与其他2组图像有明显的不同。药物注射5-45min后脑内放射性清除率：AD组（39％～45％），较NC组（55％～64％）明显减低（P〈0．05）。除外基底节区，VaD组（47％～59％）与NC组比较无显著性差异（P〉0．05）。结论^18F-FDDNPPET脑显像在AD诊断及与VaD的鉴别诊断中有重要的临床应用价值。     

Positron emission tomography imaging in the thorax

Positron emission tomography imaging has proven valuable in the evaluation and management of thoracic abnormalities. It is more accurate than CT or MR imaging in characterizing indeterminate focal abnormal pulmonary opacities, staging lung cancer, and assessing the therapeutic response. PET imaging in lung cancer also appears to be cost-effective, particularly with whole-body studies. The metabolic and physiologic abnormalities used in FDG-PET imaging, rather than conventional anatomic or morphologic characteristics, provide an invaluable model for the future of tumor imaging.     

Positron emission tomography for the detection of metastases of differentiated thyroid carcinoma

OBJECTIVE: To show the value of positron emission tomography (PET) with 18-F-fluorodeoxyglucose (18-FDG) for the detection of metastases of differentiated thyroid carcinoma in selected patients. PATIENT HISTORIES: There were four patients, who had undergone total thyroidectomy for papillary (two) or follicular thyroid carcinoma (two). All patients had subsequent treatment with (131)iodine. Three patients had an increasing serum concentration of thyroglobulin, one patient had antibodies against thyroglobulin. A diagnostic (131)iodine scintigraphy was negative in two patients, and uncertain in two patients. Positron emission tomography was performed about 45 min after administration of 10 mCi 18-F-fluorodeoxyglucose. In three patients PET showed uptake in the cervical region, caused by lymph node metastases in two (confirmed by neck dissection) and recurrent tumor on the trachea in one patient (confirmed by surgery). In the fourth patient uptake of 18-FDG was seen in the neck and in both lungs. This led to discontinuation of treatment with (131)iodine because the lung metastases did not accumulate (131)iodine. DISCUSSION: In selected patients with differentiated thyroid carcinoma with an increasing serum concentration of thyroglobulin, PET is an important diagnostic option when scintigraphy with (131)iodine is negative or uncertain. In the four presented case histories, the results of PET led to a therapeutic decision: surgery in three patients and discontinuation of (131)iodine in one patient. The development of guidelines for the use of PET in the diagnosis of recurrent thyroid cancer is discussed.     

Positron emission tomography in esophageal cancer

Positron emission tomography (PET), a functional imaging modality, has provided the transition between the research environment and the clinical environment over the last 10 years. Its primary use is in the field of oncology, where it is being increasingly used in the management of several tumor types including esophageal cancer. ¹⁸F-Fluorodeoxyglucose PET (FDG-PET) scans may also be used to distinguish between benign and malignant tumors, to identify different stages of tumor spread, to assess for tumor recurrence, and monitor the response to therapy of malignant diseases. This review aims to outline the current and future roles of PET scanning in the field of esophageal cancer.