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

To evaluate positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET) as an diagnostic tool to determine tumor viability after anticancer therapy, fourteen patients were examined by FDG-PET after the end of the treatment. The lesions with residual viable tumor cells showed higher uptake of FDG than surrounding normal soft tissue. The lesions, in which tumor viability was lost or very low, showed higher uptake of FDG in four cases and similar uptake to normal soft tissue in three cases. The residual increased uptake of FDG was considered to be caused by remaining tumor cells and/or inflammatory reaction to anticancer treatment. FDG-PET after anticancer treatment should be interpreted by considering the reaction due to the treatment and the partial volume artifact of PET caused by the limited spatial resolution.
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PMID:FDG-PET for the evaluation of tumor viability after anticancer therapy. 807 56

Two types of image similarity measures, the sum of absolute differences (SAD) and the stochastic sign change (SSC), were compared for three-dimensional registration of images from PET. To test the accuracy of both registration methods, 30 FDG brain studies, 40 13N-ammonia cardiac studies and 20 FDG liver tumor studies (where each image set contained 15 image planes, 128 x 128 pixels per plane) were made into worse case conditions by creating image sets of low counts and extreme defects. These images were then registered to the reference images that had been moved in three dimensions into a random set of known translations, rotations and normalization factors (x, y, z, theta, rho, sigma, nf). Neither method required any external fiduciary markers or operator interventions to register a set of images. The optimization of the image similarity (using the SAD or SSC) was performed with the simplex method and registration was completed within 10 min of computation time on a low-end workstation. Overall, the SAD method had an average inplane (x, y) registration error of 0.5 +/- 0.5 mm, a z-axis registration error of 1.1 +/- 1.1 mm, an inplane rotational error of 0.5 +/- 0.4 degrees, an out-of-plane rotational error of 1.1 +/- 1.2 degrees and a normalization factor error of 0.015 +/- 0.016. The SSC method had an average inplane (x, y) registration error of 0.6 +/- 0.5 mm, a z-axis registration error of 1.1 +/- 1.1 mm, an inplane rotational error of 0.7 +/- 0.5 degrees, an out-of-plane rotational error of 1.0 +/- 1.2 degrees and a normalization factor error of 0.014 +/- 0.014. This study demonstrates that either the SAD or SSC method for measuring image similarity, combined with the simplex method for function optimization, are accurate methods for registration of a wide variety of PET images including low count studies and those with marked interval changes in the pattern of count distribution.
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PMID:Automated iterative three-dimensional registration of positron emission tomography images. 822 52

A total of 48 patients with squamous cell carcinomas (SCC) of the head and neck were examined with positron emission tomography (PET) and 18Fluor-deoxyglucose (FDG). In 25 cases the FDG-PET-data were compared with flow cytometric data of the lesions to investigate the value of PET for the noninvasive determination of a tumor's proliferative activity. The quantitative analysis of the radioactivity concentrations revealed two groups of tumors with a different FDG-uptake. A correlation was seen between the proliferative index and the FDG-uptake with an r-value of 0.64 in the lower uptake group and an r-value of 0.81 in the higher uptake group. There was no correlation between any clinicopathological or morphological parameters of the tumors and the FDG-uptake. It is suggested that the different FDG uptake may correspond to differences at the molecular level. The PET-evaluation of therapeutic effects in patients with advanced SCC of the head and neck revealed different posttherapeutic changes of the metabolism in tumors and in lymph node metastases. Tumors were more sensitive to therapy than lymph node metastases. There was a high correlation between the growth rate and the change in FDG uptake with a different regression function for tumors and for lymph nodes. The data demonstrate the usefulness of PET and FDG for the evaluation of early therapeutic effects. Therefore PET can be applied for the treatment planning in patients with malignant tumors of the head and neck.
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PMID:The relevance of positron emission tomography for the diagnosis and treatment of head and neck tumors. 823 Mar 73

Japanese white rabbits transplanted with VX2 liver tumors are considered to be a suitable experimental model for the evaluation of therapeutic modalities. However, there has been no adequate method of assessing the changes of tumor metabolism during treatment. In the present study, 15 rabbits with VX2 liver tumors were examined by PET using 18F-2-fluoro-2-deoxy-D-glucose (18F-FDG). After an intravenous injection of 18F-FDG, serial arterial blood sampling was performed. One hour after tracer injection, small pieces of normal liver tissue and tumor tissue were excised to determine radioactivity. Dynamic PET images were obtained in 11 of the tumor-bearing rabbits, and tumor enzyme activities were determined in six rabbits. Fluorine-18-FDG uptake by the VX2 liver tumors was 3.5 +/- 0.9 times higher than that by the normal liver tissue; so good contrast between tumor and normal liver tissue was achieved on PET scans. The enzyme activity study showed that VX2 tumors had increased levels of hexokinase and pyruvate kinase activity, suggesting an increase of glycolysis. We conclude that transplanted VX2 liver tumors could be appropriately evaluated by 18F-FDG PET.
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PMID:Evaluation of experimental liver tumors using fluorine-18-2-fluoro-2-deoxy-D-glucose PET. 825 99

The potential of positron emission tomography (PET) to distinguish benign from malignant ovarian tissue was evaluated by comparing the results of F-18 fluoro-2-D-deoxyglucose (F-18-FDG) PET scans with computed tomography and surgical findings. If sufficiently sensitive, this method might play a role in localizing metabolically active tumor sites for diagnosis, staging, and follow-up of ovarian cancer. Fifty-one patients had imaging studies prior to laparotomy for suspected ovarian cancer. PET scans were done with an ECAT 931-08-12 or ECAT EXACT (Model 921, Siemens/CTI, Knoxville, TN) after iv injection of 185-370 MBq of F-18-FDG. (ECAT is a trade name for "emission computerized axial tomograph.") Data were acquired in dynamic scanning mode and time activity curves (TACs) were evaluated in multiple regions of interest identified by visual interpretation of the PET scans. Scan interpretation, standardized uptake values, and TAC profiles were related to surgical and histological findings. The results of this pilot study show good correlation between PET and histological findings. The positive predictive value of PET for ovarian cancer was 86% and, perhaps more important, the negative predictive value was 76%. This early work indicates that PET may be useful in the management of patients with ovarian neoplasms by identifying occult foci of metabolically active tumor that do not appear on morphological studies.
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PMID:Assessment of primary and metastatic ovarian cancer by positron emission tomography (PET) using 2-[18F]deoxyglucose (2-[18F]FDG). 827 94

The distribution of specific radiolabeled biological compounds in tumor tissues can be imaged by positron emission tomography (PET). The substance used is fluorodeoxyglucose, labeled with the positron emitter fluorine-18. This substance is partly trapped in tumor cells with increased glucose metabolism. This noninvasive imaging technique allows to assess quantitatively and in three dimensions the extent of metastatic disease in ENT cancer. The case presented illustrates the important value we foresee for this new imaging modality in the presurgical staging of cervical metastatic disease of ENT tumors. Sensitivity and specificity of the PET-FDG imaging technique for the loco-regional staging of ENT cancer are, according to preliminary results of an ongoing, prospective clinical study, very high.
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PMID:[Positron emission tomography (PET) in the preoperative evaluation of cervical lymph node metastasis of ORL cancer]. 829 Aug 39

Positron emission tomography is an imaging technique that produces images reflective of tissue biochemistry rather than anatomy. Utilizing different isotopes, many biochemical processes can be studied repetitively and non-invasively in cancers in vivo. Malignant tissue is characterized by an accelerated rate of glycolysis. This biochemical characteristic of malignancy can be exploited by PET imaging with the radiopharmaceutical FDG. PET with FDG has been successful in imaging primary and metastatic cancer of the breast, colon, lung, head and neck, as well as sarcomas and lymphomas. PET FDG imaging has potential as a screening, diagnostic and staging tool in cancer. Recently, whole body PET techniques have been developed which permit imaging of the entire body during a single scanning session. PET also has tremendous potential as a cancer research tool to study serial estimates of tumor glycolysis, DNA turnover, oxygen metabolism, protein synthesis, and blood.
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PMID:Use of positron emission tomography in oncology. 834 60

Over the past 20 years morphologic imaging of various tumors and tissues experienced substantial progress by the introduction of ultrasonography, CT scanning and MRI. None of these techniques provide information on functional aspects. Positron-emission tomography (PET) now allows to measure local perfusion, oxygen extraction and glucose utilisation in different tissues. These 3 parameters do not necessarily develop in parallel and can potentially be differentiated by PET. Thus, they become detectable in brain tumors as well as in vascular and degenerative dementias and, therefore, directly permit therapeutic measures. In brain tumors PET is clinically useful today for grading and therapy control by means of FDG (18fluoro-deoxyglucose) and amino-acids. Postoperatively it allows differentiation of tumor recurrence from scar-tissue, fibrosis and necrosis. In dementias of different etiologies possible fields of application for the PET lie in differentiation between dementias of vascular origin and Alzheimer's disease as well as in control of therapy (FDG).
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PMID:[Clinical indications for PET of the central nervous system: primary brain tumors, vascular and degenerative dementia]. 837 94

Sequential positron emission tomographic scans with [18F]-2-fluorodeoxyglucose (PET-FDG) were performed on 6 patients with glioblastoma multiforme who were treated with adjuvant BCNU. Scans were acquired before and 24 hours after BCNU. All patients had prior brain irradiation. Ratios between the maximal tumor FDG uptake and the contralateral white matter FDG uptake, the glucose uptake ratio, were determined. Percent changes in the glucose uptake ratio between the baseline scan and the 24 hour post-treatment scan were of prognostic significance. Patients with the largest percent changes in FDG uptake had the shortest survival. In contrast, neither the baseline glucose uptake ratio nor the visual tumor grade accurately predicted length of survival.
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PMID:Acute changes in glucose uptake after treatment: the effects of carmustine (BCNU) on human glioblastoma multiforme. 838 54

Positron emission tomography (PET) is a unique technique for imaging functional metabolism of normal and diseased tissue. Accelerated rate of glucose metabolism typical of malignant tumor cells can be detected by using fluorine-18 deoxyglucose. In this pilot study, PET FDG imaging was compared to computerized tomography for the pre-operative staging of colorectal carcinoma. We prospectively evaluated 16 patients by simultaneously performing PET FDG and CT imaging for lesions in the liver, colon and rectum. The results were compared to the operative findings in all patients. Twenty tumor sites (lymph nodes 5, colon and rectum 13, liver 2) were found on histology in 16 patients. On comparison with histology, sensitivity, specificity and predictive accuracy for detection of tumor sites were 90%, 66% and 87% with PET as compared to 60%, 100%, and 65% with CT. These findings represent increased sensitivity and predictive accuracy for staging of colorectal carcinoma with PET FDG imaging as compared to CT scanning.
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PMID:Pre-operative staging of colorectal carcinoma using positron emission tomography. 844 82


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