1,720,969 research outputs found
The usefulness of 99mTc-tetrofosmin SPECT in the detection of lung metastases from extrapulmonary primary tumors
No full textPurpose. The appearance of pulmonary metastases in neoplastic patients previously submitted to radical operation of an extrapulmonary primary tumor and with no recurrences and/or secondary distant localizations can markedly worsen disease prognosis if the lesions are in advanced stages and no longer removable by surgical procedures. In this study, we evaluated the usefulness of 99mTc-tetrofosmin scintigraphy, both planar and SPECT, in the detection of pulmonary metastases from previously treated extrapulmonary primary tumors, comparing the results with those obtained with CT. Materials and methods. We studied 73 patients, 33 M and 40 F, aged 24 to 79 yrs, had who undergone previously surgical resection extrapulmonary primary tumors; 31 patients had mammary, 13 gastrointestinal, 13 genitourinary, 13 thyroid and 3 laryngeal carcinomas. In all patients CT ascertained single (42 cases) or multiple (31 cases) pulmonary lesions. 99mTc-tetrofosmin scintigraphy, always performed within a week of CT, was acquired 10 min after 740 MBq i.v. tracer injection, using a rectangular, large field of view, dual head gamma camera, equipped with low energy, parallel-hole and high resolution collimators. Conventional planar acquisition, with the patient in the supine position, was followed by SPECT over 360° with body contouring system, using a zoom factor of 1-1.3. a 64×64 matrix size, a 3° angular step and an acquisition time of 30 sec/frame; image reconstruction was performed with the Back Projection Filtered Method using a Metz filter. In the coronal slices of SPECT images a semiquantitative analysis of the lesion was also made and the tumor-to-background (T/B) ratio was calculated; the calculation of the latter, considered indicative for tumor when >1.4, was performed in the lesion with the highest radiotracer uptake in patients with multiple lung lesions. The results of SPECT qualitative images were compared with those of planar scintigraphy and both of these with the data obtained with CT, and statistical difference was calculated with McNemar's test. The definitive diagnosis was achieved after scintigraphy by the analysis of cytologic or histologic specimens obtained by thoracotomy, percutaneous thoracic needle biopsy or bronchoscopic biopsy, and in some cases by the confirmation of instrumental exams at 6-8 month follow up. Pulmonary metastases were ascertained in 65/73 cases, while benign lesions were present in the remaining 8 patients. Results. CT was true positive in 60/65 (92.3%) patients with metastases and false negative in the remaining five, four with a single lesion and one with two lesions in the same lung. SPECT detected metastases in 62/65 (95.4%) patients, including the five CT false negative cases, while it was false negative in three cases with single lesions, all positive at CT, with a size of 1.0, 1.0, 2.0 cm, respectively. Planar scintigraphy was only positive in 23/65 (35.4%) patients, with a sensitivity value significantly (p6 lesions ≤0.5 cm in size, while it was more sensitive in three other cases; CT and SPECT were concordant in macronodular metastases detection, except in one case in which SPECT depicted more lesions. Planar scintigraphy had 42 false negative results and, when positive, underestimated the number of multiple lesions in respect of both SPECT and CT; it was positive but CT negative in only one case with two lesions. Specificity was higher for both SPECT and planar scan (87.5%) than CT (62.5%) but not significantly; accuracy was higher for SPECT (94.5%) than both planar scan (42%) and CT (89%), but the difference was significant only in respect of planar. The combined use of SPECT and CT achieved 100% sensitivity and accuracy values. The T/B ratio was >1.4 in all SPECT positive cases (range: 1.6-5.3), indicating a suspected tumor, while it was 1.2 in the only benign case which turned out to be false positive at qualitative SPECT imaging. Conclusions. 99mTc-tetrofosmin SPECT seems to be a reliable diagnostic tool in the detection of pulmonary metastases from extrapulmonary primary tumors, in particular in the cases in which CT is indeterminate or false positive, and therefore contributes to a more correct patient classification. Moreover, SPECT image semiquantitative analysis can give additional information for a differential diagnosis between malignant and benign lesions as well as offering a more accurate selection of the lesions to be subjected to biopsy in patients with multiple metastases. However, only the combined use of CT and 99mTc-tetrofosmin SPECT can achieve the highest sensitivity and accuracy values and obtain the correct staging in most patients, thus suggesting that these two procedures must be employed together
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The usefulness of 99mTc tetrofosmin scintigraphy in patients with breast cancer recurrences
No full textTo verify the usefulness of 99mTc tetrofosmin scintigraphy in the follow-up of breast cancer patients, we studied 72 surgically treated breast cancer patients with suspected local recurrences (20 cases) or distant metastases (52 cases) at clinical examination and/or at conventional imaging procedures (CIPs). In all patients, a whole-body scan followed by planar and single photon emission tomography (SPET) images of selected sites were acquired 10 min after the intravenous injection of 740 MBq of 99mTc tetrofosmin, using a rectangular dual-head gamma camera equipped with high-resolution parallel-hole collimators. Loco-regional recurrences were diagnosed in 19 patients and distant metastases in 44 cases, while benign lesions were ascertained in nine cases. 99mTc tetrofosmin SPET showed higher sensitivity, specificity and accuracy per patient than did CIP (96.8% vs 85%, 77.7% vs 55.5% and 94.4% vs 81.1%, respectively) with statistical significance for accuracy (P <0.05). The combined use of SPET and CIP achieved 100% sensitivity and 98.6% accuracy. Planar imaging did not give additional information in respect of either SPET or CIP, showing significantly lower sensitivity and accuracy values (47.6% and 52.8%, respectively). Our data seem to suggest that 99mTc tetrofosmin SPET, but not planar, may be useful in the follow-up for the detection of loco-regional and distant recurrences in patients with breast cancer. The technique can play a complementary role to conventional diagnostic imaging procedures in selected patients
The role of 99mTc-tetrofosmin Pinhole-SPECT in breast cancer axillary lymph node staging
No full text99mTc-tetrofosmin SPECT in solitary pulmonary nodule evaluation
No full textA correct differential diagnosis between benign and malignant lesions is mandatory in patients with solitary pulmonary nodule (SPN). The aim of the present study was to investigate whether 99mTc-tetrofosmin SPECT may play a role in SPN evaluation. A consecutive series of 111 patients with an uncalcified </=3 cm (range: 0.8-3 cm) SPN, without definite benign findings and indeterminate at CT, were studied. Within 1 week of CT scan, following 740 MBq of 99mTc-tetrofosmin i.v. injection, all patients underwent chest SPECT using a rectangular dual head gamma camera with HR collimators. The images were analysed both qualitatively and semiquantitatively by calculating tumor/normal tissue ratio (T/N). All nodules were referred to a definitive diagnosis after scintigraphy: 84/111 nodules resulted malignant (primary lung carcinomas in 59 cases and metastases in 25), whereas 27/111 were benign. SPECT was true positive in 77/84 malignant nodules (overall sensitivity: 91.7%), detecting 55/59 carcinomas (93.2%) and 22/25 metastases (88%), whereas it was false negative in 4 carcinomas (3 adenocarcinomas and 1 squamous cell carcinoma, the latter with necrotic areas; range size: 1.5-2.4 cm) and in 3 metastases (range size: 1.0-1.2 cm). SPECT was true negative in 24/27 benign lesions (specificity: 88.9%) and false positive in 2 hamartomas and in 1 aspecific inflammation (range size: 0.8-2 cm), each with a T/N value </=1.4. Accuracy, positive predictive value and negative predictive value were 91, 96.2 and 77.4%, respectively. Mean T/N value was significantly higher in malignant than in benign nodules (2.1+/-0.6 vs. 1.3+/-0.1, P<0.05), whereas no significant differences were observed between primary lung carcinomas and metastases (2.1+/-0.6 vs. 1.9+/-0.6) or in the different histologic types of carcinomas. 99mTc-tetrofosmin SPECT proved a highly sensitive imaging method in both primary and secondary malignant </=3 cm SPNs detection, with a high accuracy value in discriminating malignant from benign lesions, also by adding semiquantitative analysis. A larger clinical application of this non-invasive, simple and widely available procedure is thus suggested in SPN management, especially when FDG-PET is not available
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
- …
