1,009 research outputs found

    Phonon Confinement Effect in III-V Nanowires

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    The protympanum, protiniculum and subtensor recess: an endoscopic morphological anatomy study

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    Objectives: An anatomical study was performed to describe the endoscopic anatomy and variations of the protympanum, including classification of the protiniculum and subtensor recess. Methods: A retrospective review was conducted of video recordings of cadaveric dissections and surgical procedures, which included visualisation of the protympanum, across 4 tertiary university referral centres over a 16-month period. A total of 97 ears were used in the analysis. Results: A quadrangular conformation of the protympanum was seen in 60 per cent of ears and a triangular conformation in 40 per cent. The protiniculum was type A (ridge) in 58 per cent, type B (bridge) in 23 per cent and type C (absent) in 19 per cent. The subtensor recess was type A (absent) in 30 per cent, type B (shallow) in 48 per cent and type C (deep) in 22 per cent. Conclusion: The protympanum is an area that has been ignored for many years because of difficulties in visualising it with an operating microscope. However, modern endoscopic equipment has changed this, providing detailed anatomical knowledge fundamental to ensuring the safety of endoscopic surgical procedures in the region

    Role of endoscopy in lateral skull base approaches to the petrous apex

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    Objective: The aim of this article is to study the role and advantages of combined microscopic/endoscopic procedures or exclusive endoscopic approaches in the treatment of petrous apex pathologies. Methods: The study was designed as a retrospective case series analysis. We included patients affected by pathologies of the petrous apex, who underwent microscopic/endoscopic-assisted or exclusive endoscopic procedures. Patient and pathology characteristics and surgical data (focusing on the involvement of the internal carotid artery (ICA) and facial nerve by the disease) were collected. Residual disease, detected through the endoscopic check, and the feasibility of endoscopic residual tumor removal were also evaluated. Finally, facial nerve and hearing functions were assessed pre- and postoperatively. Results: The records of 75 patients undergoing lateral skull base surgery for petrous apex lesions, from May 2009 to March 2019, were collected. In 17 out of 75 patients, an exclusive endoscopic procedure was possible. The remaining 58 patients underwent a combined microscopic/endoscopic approach. In 15 cases, residual disease was found and removed endoscopically at the end of the microscopic procedure; in eight cases, the residual disease was medial and/or inferior to the horizontal segment of the ICA, while in two cases, it was located in the fundus of the internal auditory canal. In five cases, it involved the labyrinthine segment of the facial nerve. Conclusion: Petrous apex surgery remains a traditional microscopic-based surgery, but the recent advent of endoscopic surgery has permitted an improvement in radicality minimizing the manipulation of neurovascular structures

    18F-FDGPET/CT: diabetes and hyperglycaemia

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    BACKGROUND: Some patients who undergo 18F-FDG PET/CT for neoplastic or benign disease are also affected by diabetes or hyperglycaemia. We propose different preparation procedures in patients (pts) with hyperglycaemia (acute, temporary or chronic) or diabetes (type 1 or 2) at the time of the 18F-FDG injection, in order to improve the diagnostic scheduling of 18F-FDG PET/CT. MATERIAL AND METHODS: We evaluated a sample of 13,063 pts, examined in two different PET/CT centres, one with a stationary scanner (94.4%) and the other with a mobile device (5.6%). High blood sugar was present in 1,698 patients (13%) at the time of the 18F-FDG injection (hyperglycaemia was defined as fasting blood glucose > 11.1 mmol/l). We considered all 18F-FDG PET/CT tests performed over a period of 4 years (2006-2009). In the first 2 years (6,236 tests), scheduling was done directly by the administrative secretary. In the next two years, 6,827 pts underwent a preliminary visit to assess the test indications, medical history, and therapy as well as pre-test preparation. We evaluated different preparation protocols for hyperglycaemic or diabetic pts, especially those recommended in the guidelines of the European Association of Nuclear Medicine (EANM) and Society of Nuclear Medicine (SNM). RESULTS: In the four-year period, 713/13,063 patients (5.45%) were rescheduled; of these, 78.8% were rescheduled in the two years before the implementation of our preparation protocols and 21.2% in the next two years. Before the implementation of our preparation protocols, 562 patients (9%) presented occasional, acute or chronic hyperglycaemia (56.7%), or diabetes (43.3%), requiring postponement of the test to a later date. The test was not performed in 17 of 6,236 pts (0.27%) because of blood glucose levels above 11.1 mmol/l for several days, while in 16/6236 pts (0.26%) the 18F-FDG injection was performed despite high blood glucose levels, in view of the clinical urgency. After the implementation of the preparation protocols, 2.2% of pts were rescheduled because of occasional, acute or chronic hyperglycaemia (79%), or diabetes (21%); 0.1% of pts did not undergo the test because of chronic high blood glucose levels. Although the administration of insulin is recommended in the EANM and SNM guidelines, in our new preparation procedures experience it was not necessary, because we reduced the numbers of hyperglycaemic pts thanks to screening at the preliminary visit and a subsequent good preparation of the patient before scheduling. CONCLUSIONS: The application of our preparation protocols improves the on-time performance and diagnostic accuracy, and increases patients' compliance. Copyright © 2013 Via Medica

    The dose makes the poison: A case report of acquired methemoglobinemia

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    Background: Methemoglobinemia (MET) should be suspected in cases where cyanosis is not associated with signs and symptoms of lung and/or heart disease, or in a cyanotic child exhibiting discrepancies in the partial pressure of oxygen in the arterial blood, the blood oxygen saturation, and the clinical assessment. Case presentation: A 10-month-old girl was taken to the Pediatric Emergency Department for the acute, sudden development of significant peroral cyanosis associated with gray pigmentation of the skin. The problem was evidenced approximately one hour after she ingested a homemade puree of mixed vegetables, mainly composed of potatoes and chards that had been prepared three days before and had been kept in the refrigerator since then. Physical examination revealed that the child was very pale, conscious, and without respiratory distress. Oxygen saturation of hemoglobin in the arterial blood (SpO2) was 94%. Respiratory, cardiovascular, and abdominal evaluations did not reveal any signs of disease. A venous blood sample showed chocolate-colored blood with a pH of 7.404, a partial pressure of CO2 (pCO2) of 40.6 mmHg, a partial pressure of oxygen (pO2) of 21.3 mmHg, a bicarbonate level of 24 mmol/L, and an oxygen saturation (SO2%) of 47.7%. CO-oximetry carried out simultaneously identified a methemoglobin level of 22%. MET was suspected, and oxygen via nasal cannula at a rate of 4 L/min was given with only a slight increase in oxygen saturation (96%). Slow intravenous injection of methylene blue 1 mg/kg over a period of 5 minutes was initiated. The peripheral oxygen saturation (SpO2) gradually improved to 100% over the next 20 minutes. Forty minutes later, venous blood gas analysis showed a methemoglobin level of 0.9% with a complete resolution of cyanosis; supplemental oxygen via nasal cannula was therefore discontinued. During the next 36 hours, the patient remained hemodynamically stable with good oxygenation on room air. Conclusions: This case report shows that recognition of acquired MET in a child with sudden cyanosis onset requires a high index of suspicion. In daily activities, there is a need to pay particular attention when homemade vegetable soups for child alimentation are prepared. The consumption of vegetable soups must occur immediately after preparation. Storage in a refrigerator must last no more than 24 hours and if longer storage is needed, vegetable soups should be frozen

    Imaging in breast cancer follow-up: preliminary investigation on clinical practice adherence to the guidelines

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    PURPOSE: The aim of this study was to assess compliance with guidelines recommendations in the follow-up of patients with breast cancer. In this setting of patients we analyzed the appropriateness of the imaging exams recommended by different specialists in the management of follow-up. MATERIALS AND METHODS: From January 2019 to December 2019 we analyzed the clinical data and the results of the imaging exams of 146 asymptomatic patients followed for follow-up in different regional radiotherapy centers. A logistic regression analysis was performed taking into account the advanced pathological stage, the absence of surgical staging of the lymph nodes, the dubious results from previous basic imaging tests, correlating them to the excessive use of advanced imaging. The association was expressed in terms of odds ratio (OR) together with their 95% confidence intervals (CI). RESULTS: For 96% of patients, a frequent prescription of at least one basic imaging exam (complete abdomen ETG and chest X-ray 2p) was observed in contrast to the guidelines. A finding of a large number of bone scans suggested their use as routine surveillance A positive correlation with advanced imaging (OR <1) was seen in patients with borderline basic imaging. CONCLUSIONS: Follow-up with intensive imaging is poorly effective both for the early diagnosis of relapses and for any remote localizations

    Low energy polarization sensitivity of the Gas Pixel Detector

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    An X-ray photoelectric polarimeter based on the Gas Pixel Detector has been proposed to be included in many upcoming space missions to fill the gap of about 30 years from the first (and to date only) positive measurement of polarized X-ray emission from an astrophysical source. The estimated sensitivity of the current prototype peaks at an energy of about 3 keV, but the lack of readily available polarized sources in this energy range has prevented the measurement of detector polarimetric performances. In this paper we present the measurement of the Gas Pixel Detector polarimetric sensitivity at energies of a few keV and the new, light, compact and transportable polarized source that was devised and built to this aim. Polarized photons are produced, from unpolarized radiation generated with an X-ray tube, by means of Bragg diffraction at nearly 45 degrees. The employment of mosaic graphite and flat aluminum crystals allow the production of nearly completely polarized photons at 2.6, 3.7 and 5.2 keV from the diffraction of unpolarized continuum or line emission. The measured modulation factor of the Gas Pixel Detector at these energies is in good agreement with the estimates derived from a Monte Carlo software, which was up to now employed for driving the development of the instrument and for estimating its low energy sensitivity. In this paper we present the excellent polarimetric performance of the Gas Pixel Detector at energies where the peak sensitivity is expected. These measurements not only support our previous claims of high sensitivity but confirm the feasibility of astrophysical X-ray photoelectric polarimetry.Comment: 15 pages, 12 figures. Accepted for publication in NIM
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