1,720,998 research outputs found
Usefulness of stress cardiac single-photon emission computed tomographic imaging late after percutaneous coronary intervention for assessing cardiac events and time to such events
No full textThis study assessed the predictors and temporal characteristics of cardiac risk in patients undergoing stress single-photon emission computed tomography (SPECT) after percutaneous coronary intervention (PCI). Stress SPECT was performed in 346 patients 12 to 18 months after PCI. Cardiac death and myocardial infarction were considered events. Cox proportional hazards analysis was used to identify predictors of events and parametric survival analysis to predict time to events. During follow-up (31 +/- 10 months), 17 events occurred (4.9% cumulative event rate). Prescan likelihood of ischemia and ischemia at SPECT were independent predictors of events (p or =2% risk of events were >48 months in those with low prescan likelihood of ischemia and >20 months in those with intermediate to high prescan likelihood. Ischemia at SPECT was associated with higher probability of failure accelerating over time. In conclusion, clinical variables and stress SPECT performed 12 to 18 months after PCI are useful to characterize risk of cardiac events and its temporal variation. Parametric survival models seem useful to estimate predicted time to risk and levels of risk at specific intervals after PCI
Structural and clinical changes in previously treated type 1 macular neovascularization in non-responder AMD eyes switched to brolucizumab
No full textPurpose: To examine structural and clinical changes in previously treated type 1 macular neovascularization (MNV) in non-responder age-related macular degeneration (nAMD) eyes switched to brolucizumab. Subretinal hyper-reflective material (SHRM), intraretinal (IRF) and subretinal fluid (SRF) presence, fibrovascular-pigment epithelium detachment (PED) height and central macular thickness (CMT) variation were analyzed using optical coherence tomography (OCT). Methods: In this prospective study all patients underwent a complete ophthalmological evaluation including structural OCT at baseline (T0), one month (T1), three (T2), four (T3) and six months after switching to brolucizumab treatment (T4). Non-responder criterion was the persistence of IRF and SRF. Moreover, CMT and BCVA had shown worsening or no improvement before switching to brolucizumab. Clinical function and structural activity biomarkers were measured at each visit and changes were analyzed. P value <0.05 was considered statistically significant. Results: Twenty eyes of twenty patients were enrolled. All the structural variables examined during the follow-up showed significant reductions. Decreases in IRF, SRF and PED were already significant at T1 (p < 0.05). SHRM was significantly reduced at T2 (p < 0.05). Structural biomarkers were absent at T3. At T4, all biomarkers remained stable while SHRM was no longer detectable in 18 patients. Changes in visual acuity from baseline to T4 were not significant. Conclusion: This short-term experience highlights that brolucizumab might be considered an effective treatment option in nAMD with type 1 MNV, as it can promote a reduction of structural activity biomarkers
Evaluation of LiF:Mg,Ti (TLD-100) for intraoperative electron radiation therapy quality assurance
No full textBackground:
Purpose of the present work was to investigate thermoluminescent dosimeters (TLDs) response to intraoperative electron radiation therapy (IOERT) beams. In an IOERT treatment, a large single radiation dose is delivered with a high dose-per-pulse electron beam (2-12 cGy/pulse) during surgery. To verify and to record the delivered dose, in vivo dosimetry is a mandatory procedure for quality assurance. The TLDs feature many advantages such as a small detector size and close tissue equivalence that make them attractive for IOERT as in vivo dosimeters.
Methods:
LiF:Mg,Ti dosimeters (TLD-100) were irradiated with different IOERT electron beam energies (5, 7 and 9 MeV) and with a 6 MV conventional photon beam. For each energy, the TLDs were irradiated in the dose range of 0-10 Gy in step of 2Gy. Regression analysis was performed to establish the response variation of thermoluminescent signals with dose and energy.
Results:
The TLD-100 dose-response curves were obtained. In the dose range of 0-10 Gy, the calibration curve was confirmed to be linear for the conventional photon beam. In the same dose region, the quadratic model performs better than the linear model when high dose-per-pulse electron beams were used (F test; p<0.05).
Conclusions:
This study demonstrates that the TLD dose response, for doses ≤10Gy, has a parabolic behavior in high dose-per-pulse electron beams. TLD-100 can be useful detectors for IOERT patient dosimetry if a proper calibration is provided
Non linear response of TLD-100 irradiated by an Intra Operative Radiation Therapy accelerator
No full textImaging characterization of benign and malignant pheochromocytoma or paraganglioma: comparison between MIBG uptake and MR signal intensity ratio
No full textObjective We compared metaiodobenzylguanidine (MIBG) uptake and magnetic resonance (MR) signal intensity ratio in differentiating benign and malignant disease in patients with pheochromocytoma or paraganglioma. Methods Eighteen patients (9 men, mean age 37 ± 8 years) with pheochromocytoma or paraganglioma underwent MR imaging and iodine-131 MIBG scintigraphy. MR signal intensity ratio was measured on T1 and T2-weighted images using region of interest analysis and intensity ratio of MIBG uptake was calculated for each tumor lesion on 48 h images. Results A total of 28 tumor lesions was analyzed of which 12 were benign and 16 malignant. MIBG uptake intensity ratio was significantly higher in malignant lesions compared to benign (5.2 ± 2.4 and 2.9 ± 1.4, respectively, p<0.01). On the contrary, no significant difference in tumor size and MR signal intensity ratio between malignant and benign tumor lesions was observed. Conclusions In patients with pheochromocytoma or paraganglioma, iodine-131 MIBG uptake is able to differentiate between benign and malignant disease, while MR imaging is not useful for this purpose. The higher MIBG uptake observed in malignant lesions could reflect major tumor storage of catecholamines compared to benign lesions. {\textcopyright} The Japanese Society of Nuclear Medicine 2012
Uno score non invasivo può predire la presenza di varici gastroesofagee nei pazienti con epatopatia cronica virale.
No full textI soggetti con epatopatia cronica virale ed uno score (basato su rapporto AST/ALT 50 anni, assegnando un punto per ogni predittore) ≤ 1 non necessiterebbero di eseguire una EGDS, poiché la probabilità che essi abbiano varici grandi è nulla. Poiché nella nostra casistica circa il 50% dei pazienti presentava tale score, la metà circa delle EGDS avrebbe potuto essere evitata. L'utilizzo di questo score potrebbe evitare in una rilevante percentuale dei casi un'indagine spesso associata a disagio per il paziente e nello stesso tempo permettere un risparmio sulla spesa sanitaria
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
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