196,056 research outputs found
Tumour hypoxia imaging with [F-18]FAZA PET in head and neck cancer patients: a pilot study
No full textPurpose Hypoxia is an important negative prognostic factor for radiation treatment of head and neck cancer. This study was performed to evaluate the feasibility of use of F-18-labelled fluoroazomycin arabinoside ([F-18]FAZA) for clinical PET imaging of tumour hypoxia. Methods Eleven patients (age 59.6 +/- 9 years) with untreated advanced head and neck cancer were included. After injection of approximately 300 MBq of [F-18]FAZA, a dynamic sequence up to 60 min was acquired on an ECAT HR+ PET scanner. In addition, approximately 2 and 4 h p.i., static whole-body PET (n=5) or PET/CT (n=6) imaging was performed. PET data were reconstructed iteratively (OSEM) and fused with CT images (either an external CT or the CT of integrated PET/CT). Standardised uptake values (SUVs) and tumour-to-muscle (T/M) ratios were calculated in tumour and normal tissues. Also, the tumour volume displaying a T/M ratio > 1.5 was determined. Results Within the first 60 min of the dynamic sequence, the T/M ratio generally decreased, while generally increasing at later time points. At 2 h p.i., the tumour SUVmax and SUVmean were found to be 2.3 +/- 0.5 (range 1.5-3.4) and 1.4 +/- 0.3 (range 1.0-2.1), respectively. The mean T/M ratio at 2 h p.i. was 2.0 +/- 0.3 (range 1.6-2.4). The tumour volume displaying a T/M ratio above 1.5 was highly variable. At 2 h p.i., [F-18]FAZA organ distribution was determined as follows: kidney > gallbladder > liver > tumour > muscle > bone > brain > lung. Conclusion [F-18]FAZA PET imaging appears feasible in head and neck cancer patients, and the achieved image quality is adequate for clinical purposes. Based on our initial results, [F-18]FAZA warrants further evaluation as a hypoxia PET tracer for imaging of cancer
Performance of beta- and high-energy gamma probes for the detection of cancer tissue in experimental surgical resection beds
No full textWhile high-energy gamma and beta probes have gained considerable attention due to their ability to detect cancerous lesions using (18)F-FDG in humans intraoperatively, it is unknown whether the sensitivity of such probes would allow the detection of remaining tumor tissue in the resection bed after removal of macroscopically evident disease. 9L tumors (13 primaries, 17 lymph node metastases) were generated at the upper thigh of Fisher 344 rats. After approximately 2 weeks, microPET was performed to verify increased (18)F-FDG tumor uptake. Tumors were surgically exposed and probe readings of tumor and background tissues were performed in triplicate. To evaluate the ability to detect tiny tumor lesions, 12 tumor fragments (range 0.001-0.032 g) were placed into the resection bed and measured to obtain a tumor-to-muscle ratio (TMR). Lesions were classified as positive if count rates were above 2.5 SD of muscle background. All tumor and muscle tissues were weighed and counted to obtain the "true" tumor-to-muscle background ratio (TMR(counter)) for reference. The presence or absence of tumor tissue was verified by histology. In the presence of background gamma radiation, the beta probe detected all tumor lesions with TMR greater than 2.5 SD of muscle background (TMR range 1.24-3.9 for all 41 lesions). Despite suitable shielding, lesion identification by the gamma probe was clearly limited by the presence of background radioactivity. As a result, only 11/13 primary tumors, 6/17 lymph nodes and 1/11 tumor fragments were identified above 2.5 SD of muscle background (TMR range 0.64-3.59 for all lesions). Under experimental conditions, the beta probe was capable to detect minute amounts of tumor tissue at the surface of resection beds. While clinical application of the current beta probe design may depend on the particular intraoperative circumstances including time requirements for surface scanning of resection beds, the data indicate clinical potential for novel designs of hand-held beta probes
Positron emission tomography for radiation treatment planning
No full textPurpose: To evaluate the impact of positron emission tomography (PET) on target volume delineation for radiation treatment planning. Material and Methods: The data of the Literature concerning the use of PET in target volume delineation are summarized. The following points are discussed for each tumor entity: biological background for the PET investigation, sensitivity and specificity of PET (with different tracers) in comparison to computed tomography (CT) and magnetic resonance imaging (MRI) and impact of PET on target volume definition. New PET tracers, which could visualize biological pathways, such as hypoxia, proliferation, angiogenesis, apoptosis and gene expression patterns, will also be discussed. Results: The results of clinical studies on the integration of PET in target volume definition for Lung, head-and-neck, genitourinary and brain tumors were analyzed. Fluorodeoxyglucose-(FDG-) PET has a significant impact on GTV (gross tumor volume) and PTV (planning target volume) delineation in Lung cancer and can detect Lymph node involvement and differentiate malignant tissue from atelectasis. In head-and-neck cancer, the value of FDG-PET for radiation treatment planning is still under investigation. For example, FDG-PET could be superior to CT and MRI in the detection of Lymph node metastases and unknown primary cancer and in the differentiation of viable tumor tissue after treatment. Therefore, it might play an important role in GTV definition and sparing of normal tissue. Choline PET and acetate PET are promising tracers in the diagnosis of prostate cancer, but their validity in Local tumor demarcation, Lymph node diagnosis and detection of recurrence has to be defined in future clinical trials. FDG-PET seems to be particularly valuable in Lymph node status definition in cervical cancer. In high-grade gliomas and meningiomas, methionine PET helps to define the GTV and differentiate tumor from normal tissue. For other entities like gastrointestinal cancer, Lymphomas, sarcomas, etc., the data of the literature are yet insufficient. The imaging of hypoxia, cell proliferation, angiogenesis, apoptosis and gene expression Leads to the identification of different areas of a biologically heterogeneous tumor mass that can individually be targeted using intensity modulated radiotherapy (IMRT). In addition, a biological dose distribution can be generated, the so-called dose painting. However, systematic experimental and clinical trials are necessary to validate this hypothesis. Conclusion: Regarding treatment planning in radiotherapy, PET offers advantages in terms of tumor delineation and the description of biological processes. To define the real impact of this investigation in radiation treatment planning, subsequent experimental, clinical and cost-benefit analyses are required
Positron detection for the intraoperative localisation of cancer deposits
No full textPurpose The study investigated the feasibility of a positron-sensitive hand-held detector system for the intraoperative localisation of tumour deposits resulting from intravenous [F-18]FDG administration. Methods A total of 17 patients (12 receiving preoperative [F-18]FDG PET imaging) with various histologically proven malignancies were included. Radioactivity from tumours and surrounding normal tissue was measured on average 3 h after administration of 36-110 MBq [F-18]FDG and the tumour-to-background (T/B) ratio was calculated. In addition, phantom studies were performed to evaluate the spatial resolution and sensitivity of the probe. Results All known targeted tumour sites were identified by the positron probe. T/B ratios were generally high, with a mean T/B ratio of 6.6, allowing easy identification of most tumour sites. In one case of a hepatic metastasis, the T/B ratio of 1.34 was below expectations, since the preoperative [F-18]FDG PET scan was positive. The probe was instrumental in the localisation of three additional tumour lesions (two lymph nodes, one anastomotic ring) that were not immediately apparent at surgery. Phantom studies revealed that [F-18]FDG-containing gel (simulating tumour tissue), having 10 times more [F-18]FDG than surrounding "normal" background gel, was clearly detectable in quantities as low as 15 mg. As measured in two cases, the absorbed radiation doses ranged from 2.5 to 8.6 mu Sv/h for the surgical team to 0.8 mu Sv/h for the aesthetician. Conclusion [F-18]FDG-accumulating tumour tissues can be localised with positron probes intraoperatively with a low radiation burden to the patient and medical personnel. The methodology holds promise for further clinical testing
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
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