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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A comparative multiple-tracer study was performed to assess the tracer feasibility of monitoring tumor radiotherapy. Metabolic tracers for glucose, amino acid, nucleic acid metabolism: F-18-FDG, C-14-Met, H-3-Thd, and F-18-FdUrd and conventional Ga-67 were compared in the same AH109A radiotherapy model using a new quadruple-tracer technique. F-18-FDG showed a large uptake change and a steady response to radiotherapy which is similar to Ga-67. F-18-FdUrd showed a rapid decrease, but the range of change in uptake was narrow. H-3-Thd and C-14-Met showed a rapid response to irradiation and a high sensitivity for monitoring radiotherapy, suggesting that if labeled with C-11, they may be feasible for PET study.
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PMID:Tumor radiotherapy monitoring with radioscintigraphy tracers: a comparative study with multiple-tracer technique. 130 32

The potential of seven tracers for the metabolic imaging of tumors by positron emission tomography was studied using five experimental tumor models. The tracers examined were 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG), 2-deoxy-2-[18F]fluoro-D-galactose (2-[18F]FdGal) and 2-deoxy-2-[18F]fluoro-L-fucose (2-[18F]FdFuc) for investigating energy metabolism. L-[methyl-11C]Methionine ([11C]Met) and 6-[18F]fluoro-L-fucose (6-[18F]FFuc) were used for assessing protein and glycoprotein synthesis, while [3H]thymidine ([3H]Thd) and 2-deoxy-5'-[18F]fluorouridine ([18F]FdUrd) were used to investigate nucleic acid metabolism. The highest mean uptake by the five different tumors was found for [3H]Thd, followed in order by [18F]FDG, [11C]Met, 2-[18F]FdGal, [18F]FdUrd, 2-[18F]FdFuc and 6-[18F]FFuc. The tumor-to-tissue uptake ratios indicated that the nucleosides, [11C]Met and 6-[18F]FFuc were better tracers in the brain region. All the tracers except for the fucose analogs were suitable for the thoracic region, while [11C]Thd and [18F]FDG were superior in the abdominal region. In comparison with the primary tumor model of Lewis lung carcinoma (3LL), [3H]Thd uptake in the artificial metastatic 3LL model showed the maximum enhancement, followed by [18F]FDG, [11C]Met and the other tracers. The [18F]FDG uptake correlated with the [3H]Thd uptake. [18F]FdUrd, 6-[18F]FFuc and 2-[18F]FdGal could be used for distinguishing different types of tumors. The combined use of these radiotracers can possibly allow the assessment of tumor metabolism, and this indicates the viability of tumors.
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PMID:Tumor diagnosis by PET: potential of seven tracers examined in five experimental tumors including an artificial metastasis model. 138 72

While 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is a useful tumor imaging agent, its intratumoral distribution has not been described well at the cellular level. In order to demonstrate cellular localization of [18F]FDG and 2-deoxy-D-[3H]glucose (3H-DG) uptake by the tumor in vivo, C3H/He mice transplanted subcutaneously with FM3A tumors were studied 1 hr after intravenous injection of [18F]FDG or 3H-DG using micro- and macro-autoradiography. Fluorine-18-FDG and 3H-DG showed the same distribution pattern in the tumor with both autoradiographic methods. The newly formed granulation tissue around the tumor and macrophages, which were massively infiltrating the marginal areas surrounding necrotic area of the tumor showed a higher uptake of [18F]FDG than the viable tumor cells. A maximum of 29% of the glucose utilization was derived from nontumor tissue in this tumor. The comparison of double-tracer autoradiographic distribution patterns of [18F]FDG and [6-3H]-thymidine showed the differences and the similarities between glucose utilization and the DNA synthesis. Whole proliferating tissue metabolizes [18F] FDG but not vice versa. High accumulation of [18F]FDG in the tumor is believed to represent high metabolic activity of the viable tumor cells. Our results showed that one should consider not only the tumor cells proper but also the non-neoplastic cellular elements, which appear in association with growth or necrosis of the tumor cells, for precise analysis of [18F]FDG uptake in tumor-bearing subjects, especially after anti-neoplastic treatment.
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PMID:Intratumoral distribution of fluorine-18-fluorodeoxyglucose in vivo: high accumulation in macrophages and granulation tissues studied by microautoradiography. 143 58

A case of anaplastic astrocytoma following radiotherapy for growth hormone secreting pituitary adenoma is presented with a review of the literature. A 43 year old female was admitted with the signs of acromegaly and hypertension. An eosinophilic pituitary adenoma was subtotally removed by transsphenoidal approach, and followed by 60 Gy irradiation using a 2 x 2 cm lateral opposed field. Fourteen years later at the age of 57, she suffered from headache, recent-memory disturbance and uncinate fits. CT scan and MRI disclosed ring-like enhanced mass lesion in the left temporal lobe, corresponding to the previous irradiated field. 18F-FDG PET showed hypermetabolism at the lesion. Left frontotemporal craniotomy was performed, and a reddish gray gelatinous tumor containing necrotic center and cyst was partially removed. Histologically, the tumor consisted of hypercellular astrocytic cells with perivascular pseudorosette. Coagulation necrosis at the center of the tumor, and hyalinosis and fibrosis of the blood vessels in and around the tumor, which might have been caused by the antecedent radiotherapy, were recognized. Postoperative radio- and chemotherapy were given, however, she expired 13 months after the operation. Seven cases, including ours, of malignant glioma following radiotherapy for pituitary adenoma were reported in the literature. A total dose of irradiation varies from 45 to 95 Gy with a mean of 50 Gy. The period of latency before tumor occurrence ranges from 5 to 22 years with a mean of 10 years. The differentiation of radiation-induced gliomas from radionecrosis of the brain is also discussed.
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PMID:[Anaplastic astrocytoma 14 years after radiotherapy for pituitary adenoma]. 157 77

21 patients were followed by positron-emission-tomography (PET) FDG (18Flourdeoxyglucose) uptake, physical examination, CT and CEA levels after combined photon-neutron irradiation for inoperable recurrent rectal carcinoma. In order to evaluate the response to radiotherapy symptomatic relief, CEA levels, decrease of tumor volume measured by CT analysis were correlated with the FDG-uptake. The objective of this study was also to investigate if the level of FDG-uptake prior to radiotherapy or the early decrease after therapy can be used as a prognostic factor. Prior to radiotherapy sacral pain was the predominant symptom. All malignancies showed measurable tumor masses, evaluation of CEA levels and enhanced tracer accumulation of FDG in the PET cross section. The mean FDG-uptake before radiotherapy was 2.3 +/- 1.1 (range 1.1 to 5.0) in 21 patients in contrast to 1.9 +/- 0.7 (range 0.8 bis 4.0) three months after radiotherapy. In six patients FDG concentration values decreased to the range of normal soft tissue, moreover, two of them relapsed after six and 22 months. Elevated FDG-uptake of the sacral bone was noted in PET cross sections in two patients, while there was no evidence of osseous alterations in CT. Normal levels of CEA were achieved in 14 patients and complete or partial pain relief in 20 of 21 patients. A decrease of tumor volume of more than 50% was detected in the follow-up CT scans of three patients but no complete remission was found. The result suggests that enhanced glucose uptake is associated with recurrent rectal cancer. However, enhanced glycolytic activity is related not only to malignant cells but also to all proliferating cells. To distinguish between proliferation, repair, inflammation, and residual viable tumor cells is not possible and may be responsible for an unchanged or elevated FDG-uptake after radiotherapy.
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PMID:Therapy monitoring of presacral recurrences after high-dose irradiation: value of PET, CT, CEA and pain score. 157 69

In this study, we used 18F-FDG PET to differentiate gastroenterological malignancy from benignity. We investigated 122 patients with gastroenterological disease before treatment (with lesions exceeding 2.0 cm in diameter only). 60 min after injection of FDG, although 16 cases out of 17 benign disease did not reveal accumulation higher than normal tissue, 105 cases of malignant tumor except some of hepatocellular carcinoma revealed high accumulation of FDG. FDG uptake was expressed as the Ci/Cp ratio, calculated from radioactivity of the tumor (Ci) and the plasma (Cp). 89 cases out of 90 which show more than 2.0 of Ci/Cp ratio were malignant tumor. On the other hand, 32 cases which show less than 2.0 contained 16 cases of benign disease and 15 of hepatocellular carcinoma. FDG PET is a useful tool for differential diagnosis of malignant tumor from benign disease except some of hepatocellular carcinoma.
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PMID:[Evaluation of gastroenterological disease by using 18F-FDG PET--differential diagnosis of malignancy from benignity]. 164 Jun 53

The uptake of 18F-Deoxyglucose (FDG) was studied in vivo in patients with head and neck tumors with positron emission tomography (PET) in relation to the proliferation rate of these tumors. The quantitative analysis of the radioactivity concentrations revealed two groups, showing a high or a lower FDG uptake pattern. In both groups the FDG uptake and the proliferation rate were correlated with a flat slope of the regression function. It is suggested that these differences in uptake in histologically identical tumor populations may correspond to differences at the molecular level, e.g. differences in the amount of the glucose carrier, perhaps caused by activated oncogenes. Furthermore PET was applied to evaluate therapeutic effects in patients with advanced head and neck cancer. We found that multiple lymph node metastases in the same patient can show a different baseline metabolism and also different changes following therapy. Tumors were more sensitive to therapy than lymph node metastases. The growth rate and the change in FDG uptake were highly correlated with different regression functions for tumors and lymph node metastases. These data demonstrate that PET with FDG can be used to assess early chemotherapeutic effects. The information gained with PET can be included in the treatment planning in patients undergoing systemic chemotherapy.
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PMID:[Positron emission tomography (PET) in the evaluation of tumor proliferation and follow-up of therapy in ear, nose and throat tumors]. 164 87

Forty-four patients with recurrent colorectal carcinoma were examined prior to a combination of conventional photon radiotherapy (40 Gy) and neutron therapy (10 Gy). Twenty-one of these underwent a PET examination after photon therapy and 12 also were studied after the end of combined therapy. CEA plasma levels were measured from blood samples taken immediately before the PET study. A significant decrease in FDG uptake despite good palliative results were observed in only 50% of the patients. This may be explained by inflammatory reactions caused by radiation injury. Inflammation and metabolically active residual tumor tissue cannot be distinguished. It is concluded that an observation interval longer than 6 mo may more effectively detect residual tumor activity. In 14 of 41 examinations, an increased FDG uptake was associated with a normal CEA value, and in only two cases were normal FDG uptake values and increased CEA levels found, suggesting that PET is more sensitive than the measurements of CEA plasma levels for tumor recurrence.
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PMID:PET studies of fluorodeoxyglucose metabolism in patients with recurrent colorectal tumors receiving radiotherapy. 171 97

PET has a promising role in neuroradiology for accurate diagnosis and prognostication of malignant tumors as well as differential diagnosis of radiation necrosis and recurrent tumors. Particularly, PET has proven its ability to accurately differentiate radiation necrosis from recurrent brain tumor. Active tumors have accelerated glycolysis, and a remarkable accumulation of FDG radiotracer in high grade brain tumors is evident on PET images. Tumor metabolism also proportionally increases with increasing pathologic grades of brain tumor, and accelerated tumor metabolism indicates a poor prognosis for the tumor.
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PMID:Application of positron emission tomography to neurological oncology. 185 43

The uptake of 18F-Deoxyglucose (FDG) was studied in vivo in relation to the proliferation rate of human head and neck tumors. Forty-two patients with histologically proven squamous-cell carcinoma of the head and neck and four patients with metastases of head and neck tumors were examined with PET and FDG prior to surgery. In 35 of these patients, a flow cytometric analysis of the DNA content and the proliferation rate was done using one-dimensional flow cytometry rate was done using one-dimensional flow cytometry (DAPI staining). In 17 cases, perfusion studies with 15O-labeled water were performed. Twenty-seven specimens were evaluable by flow cytometry. The analysis of the distribution of the FDG uptake revealed two groups, showing a high and a lower uptake pattern. In both groups the FDG uptake and the proliferation rate were correlated with an r-value of 0.64 and 0.8 respectively. However, the slope of the regression function was flat. No correlation was found between the perfusion and the proliferation rate. It is suggested that these differences in uptake in histologically identical tumor populations may correspond to differences at the molecular level, e.g., differences in the amount of the glucose carrier, perhaps caused by oncogenic transformation.
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PMID:Glucose uptake, perfusion, and cell proliferation in head and neck tumors: relation of positron emission tomography to flow cytometry. 186 78


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