62 resultados para nuclear resonance, medical diagnostic, lung


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Temperature changes caused by laser irradiation can promote damage to the surrounding dental tissues. In this study, we evaluated the temperature changes of recently extracted human mandibular incisors during intracanal irradiation with an 810-nm diode laser at different settings. Fifty mandibular incisors were enlarged up to an apical size of ISO No. 40 file. After the final rinse with 17% ethylenediaminetetraacetic acid, 0.2% lauryl sodium sulfate biologic detergent, and sterile water, samples were irradiated with circular movements from apex to crown through five different settings of output power (1.5, 2.0, 2.5, 3.0, and 3.5 W) in continuous mode. The temperature changes were measured on both sides of the apical and middle root thirds using two thermopar devices. A temperature increase of 7 degrees C was considered acceptable as a safe threshold when applying the diode laser. Results: The results showed that only 3.5-W output power increased the outer surface temperature above the critical value. Conclusion: The recommended output power can be stipulated as equal to or less than 3 W to avoid overheating during diode laser irradiation on thin dentin walls. (c) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.JBO.17.1.015006]

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Objective To evaluate and compare the intraobserver and interobserver reliability and agreement for the biparietal diameter (BPD), abdominal circumference (AC), femur length (FL) and estimated fetal weight (EFW) obtained by two-dimensional ultrasound (2D-US) and three-dimensional ultrasound (3D-US). Methods Singleton pregnant women between 24 and 40 weeks were invited to participate in this study. They were examined using 2D-US in a blinded manner, twice by one observer, intercalated by a scan by a second observer, to determine BPD, AC and FL. In each of the three examinations, three 3D-US datasets (head, abdomen and thigh) were acquired for measurements of the same parameters. We determined EFW using Hadlock's formula. Systematic errors between 3D-US and 2D-US were examined using the paired t-test. Reliability and agreement were assessed by intraclass correlation coefficients (ICCs), limits of agreement (LoA), SD of differences and proportion of differences below arbitrary points. Results We evaluated 102 singleton pregnancies. No significant systematic error between 2D-US and 3D-US was observed. The ICC values were higher for 3D-US in both intra- and interobserver evaluations; however, only for FL was there no overlap in the 95% CI. The LoA values were wider for 2D-US, suggesting that random errors were smaller when using 3D-US. Additionally, we observed that the SD values determined from 3D-US differences were smaller than those obtained for 2D-US. Higher proportions of differences were below the arbitrarily defined cut-off points when using 3D-US. Conclusion 3D-US improved the reliability and agreement of fetal measurements and EFW compared with 2D-US.

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Objective To evaluate the intra- and interobserver reliability of assessment of three-dimensional power Doppler (3D-PD) indices from single spherical samples of the placenta. Methods Women with singleton pregnancies at 2440 weeks' gestation were included. Three scans were independently performed by two observers; Observer 1 performed the first and third scan, intercalated by the scan of Observer 2. The observers independently analyzed the 3D-PD datasets that they had previously acquired using four different methods, each using a spherical sample: random sample extending from basal to chorionic plate; random sample with 2 cm3 of volume; directed sample to the region subjectively determined as containing more color Doppler signals extending from basal to chorionic plate; or directed sample with 2 cm3 of volume. The vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were evaluated in each case. The observers were blinded to their own and each other's results. Additional evaluation was performed according to placental location: anterior, posterior and fundal or lateral. Intra- and interobserver reliability was assessed by intraclass correlation coefficients (ICC). Results Ninety-five pregnancies were included in the analysis. All three placental 3D-PD indices showed only weak to moderate reliability (ICC < 0.66 and ICC < 0.48, intra- and interobserver, respectively). The highest values of ICC were observed when using directed spherical samples from basal to chorionic plate. When analyzed by placental location, we found lower ICCs for lateral and fundal placentae compared to anterior and posterior ones. Conclusion Intra- and interobserver reliability of assessment of placental 3D-PD indices from single spherical samples in pregnant women greater than 24 weeks' gestation is poor to moderate, and clinical usefulness of these indices is likely to be limited. Copyright (c) 2012 ISUOG. Published by John Wiley & Sons, Ltd.

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Meditation is a mental training, which involves attention and the ability to maintain focus on a particular object. In this study we have applied a specific attentional task to simply measure the performance of the participants with different levels of meditation experience, rather than evaluating meditation practice per se or task performance during meditation. Our objective was to evaluate the performance of regular meditators and non-meditators during an fMRI adapted Stroop Word-Colour Task (SWCT), which requires attention and impulse control, using a block design paradigm. We selected 20 right-handed regular meditators and 19 non-meditators matched for age, years of education and gender. Participants had to choose the colour (red, blue or green) of single words presented visually in three conditions: congruent, neutral and incongruent. Non-meditators showed greater activity than meditators in the right medial frontal, middle temporal, precentral and postcentral gyri and the lentiform nucleus during the incongruent conditions. No regions were more activated in meditators relative to non-meditators in the same comparison. Non-meditators showed an increased pattern of brain activation relative to regular meditators under the same behavioural performance level. This suggests that meditation training improves efficiency, possibly via improved sustained attention and impulse control. (C) 2011 Elsevier Inc. All rights reserved.

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Objective Genetic sonography following first-trimester combined screening appears to increase substantially detection rates for Down syndrome but it relies on the unproved assumption of independence between these tests. In this study we aimed to investigate the relationship between first-trimester nuchal translucency (NT) and a series of second-trimester soft markers and structural defects in unaffected pregnancies. Methods NT measurement in the first trimester was followed by second-trimester scan (18 to 23 + 6 weeks) including examination for three categorical markers (intracardiac echogenic foci, hyperechogenic bowel and structural defects) and measurement of nasal bone length, nuchal-fold thickness, femur length, humerus length, renal pelvis diameter and prenasal thickness. All continuous variables were expressed in multiples of the median (MoM) for gestation and correlation coefficients between log-transformed NT and second-trimester variables were calculated. In addition, frequencies of soft markers and structural defects in cases with increased NT were compared to those with normal NT, using MoM cut-offs. Results In a dataset of 1970 cases, NT was significantly correlated (P < 0.05) with all second-trimester continuous variables, the correlation being strongest for nuchal-fold thickness (r = 0.10). There was a higher frequency of cases with second-trimester nuchal-fold thickness above the 97.5th centile (10.7 vs. 2.2%) and hyperechogenic bowel (2.4 vs. 0.1%) in cases with increased NT. Conclusions Straightforward reassessment of risk using likelihood ratios derived from the second-trimester genetic sonogram might lead to inaccurate estimates. Multivariate models using continuous second-trimester variables might be preferable in sequential screening strategies. Copyright. 2012 ISUOG. Published by John Wiley & Sons, Ltd.

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Several dosimetric methods have been proposed for estimating red marrow absorbed dose (RMAD) when radionuclide therapy is planned for differentiated thyroid cancer, although to date, there is no consensus as to whether dose calculation should be based on blood-activity concentration or not. Our purpose was to compare RMADs derived from methods that require collecting patients' blood samples versus those involving OLINDA/EXM software, thereby precluding this invasive procedure. This is a retrospective study that included 34 patients under treatment for metastatic thyroid disease. A deviation of 10 between RMADs was found, when comparing the doses from the most usual invasive dosimetric methods and those from OLINDA/EXM. No statistical difference between the methods was discovered, whereby the need for invasive procedures when calculating the dose is questioned. The use of OLINDA/EXM in clinical routine could possibly diminish data collection, thus giving rise to a simultaneous reduction in time and clinical costs, besides avoiding any kind of discomfort on the part of the patients involved.

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Objective To evaluate whether the presence of polycystic ovary syndrome (PCOS) alters multiple ultrasonographic and laboratory markers of metabolic and cardiovascular disease risk in obese women without any other health condition that could interfere with combined oral contraceptive (COC) eligibility criteria. Methods This was a case- control study evaluating 90 obese women ( body mass index ( BMI) = 30.0 kg/m2 and < 40 kg/m2) aged between 18 and 40 years without any other health condition that could interfere with COC eligibility criteria, of whom 45 had PCOS and 45 were age- matched controls. BMI, waist and hip circumference, arterial blood pressure, fasting insulin and glucose, quantitative insulin sensitivity check index ( QUICKI), highdensity lipoprotein cholesterol, low- density lipoprotein cholesterol, total cholesterol, triglycerides, testosterone, sex hormone- binding globulin, free androgen index ( FAI), carotid stiffness index, intima media thickness, flowmediated dilatation ( FMD) of the brachial artery and non- alcoholic fatty liver disease ( NAFLD) were assessed. Results In women with PCOS, we observed a higher frequency of NAFLD ( 73.3 vs. 46.7%, P < 0.01) and higher FAI ( 10.4 vs. 6.8%, P < 0.01). We also observed a trend towards increased insulin levels ( 10.06 +/- 6.66 vs. 7.45 +/- 5.88 mu IU/mL, P = 0.05), decreased QUICKI ( 0.36 +/- 0.06 vs. 0.39 +/- 0.07, P = 0.05) and decreased FMD ( 7.00 +/- 3.87 vs. 8.41 +/- 3.79%, P = 0.08). No other significant difference was observed. Conclusions NAFLD is frequent in obese women without any other health condition that could interfere with COC eligibility criteria, especially in those with PCOS. This should be considered when choosing the best contraceptive option. Copyright (C) 2012 ISUOG. Published by John Wiley & Sons, Ltd.

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To report the radiological abnormalities of osteoarticular involvement in paracoccidioidomycosis (PCM). After institutional board approval, the medical records and conventional radiology findings of 19 patients with osseous PCM were retrospectively reviewed. Number, distribution, and lesion characteristics were evaluated in consensus by two experienced musculoskeletal radiologists. The mean age of patients was 16.1 years (range 4-49 years), 11 male and eight female. MSK involvement was the only or the primary presentation of the disease in eight of 19 patients (42.1%). In total, 51 focal bone lesions were detected, being 41 in long bones. In long bones lesions, 19 of 41 (46.4%) were metaphyseal, 12 of 41 (29.3%) meta-epiphyseal, and 12 of 41 (29.3%) diaphyseal. The most common presentation was a geographic osteolytic bone lesion (62.7%), without marginal sclerosis (82.4%) and without periosteal reaction (90.2%). Articular involvement was present in six of 19 patients (31.6%), being two cases of primary arthritis. All encountered bone lesions were osteolytic. Metaphyseal or meta-epiphyseal osteomyelitis of a long bone was the most prevalent osteoarticular manifestation of paracoccidioidomycosis. PCM osteoarticular involvement could be solitary or multifocal, occurs almost exclusively in the acute/subacute clinical form, and it is more common in children and in juvenile patients. Axial skeleton involvement, arthritis, or a disseminated osseous pattern of infection may occasionally occur in this fungal disease.

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Modifications in low-density lipoprotein (LDL) have emerged as a major pathogenic factor of atherosclerosis, which is the main cause of morbidity and mortality in the western world. Measurements of the heat diffusivity of human LDL solutions in their native and in vitro oxidized states are presented by using the Z-Scan (ZS) technique. Other complementary techniques were used to obtain the physical parameters necessary to interpret the optical results, e. g., pycnometry, refractometry, calorimetry, and spectrophotometry, and to understand the oxidation phase of LDL particles. To determine the sample's thermal diffusivity using the thermal lens model, an iterative one-parameter fitting method is proposed which takes into account several characteristic ZS time-dependent and the position-dependent transmittance measurements. Results show that the thermal diffusivity increases as a function of the LDL oxidation degree, which can be explained by the increase of the hydroperoxides production due to the oxidation process. The oxidation products go from one LDL to another, disseminating the oxidation process and caring the heat across the sample. This phenomenon leads to a quick thermal homogenization of the sample, avoiding the formation of the thermal lens in highly oxidized LDL solutions. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.JBO.17.10.105003]

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This study was designed in an attempt to identify the risk factors that could be significantly associated with angio graphic recurrences after selective endovascular treatment of aneurysms with inert platinum coils. A retrospective analysis of all patients with selective endovascular coil occlusion of intracranial aneurysms was prospectively collected from 1999 to 2003. There were 455 aneurysms treated with inert platinum coils and followed by digital subtraction angiography. Angio graphic results were classified according Roy and Raymond's classification. Recurrences were subjectively divided into minor and major. The most significant predictors for angio graphic recurrences were determined by ANOVAs logistic regression, Cochran-Mantel-Haenszel test, Fisher exact probability. Short-term (4.3 +/- 1.4 months) follow-up angiograms were available in 377 aneurysms, middle-term (14.1 +/- 4.0 months) in 327 and long-term (37.4 +/- 11.5 months) in 180. Recurrences were found in 26.8% of treated aneurysms with a mean of 21 +/- 15.7 months of follow-up. Major recurrences needing retreatment were present in 8.8% during a mean period follow-up of 17.9 +/- 12.29 months after the initial endovascular treatment. One patient (0.2%) experienced a bleed during the follow-up period. Recurrences after endovascular treatment of aneurysms with inert platinum coils are frequent, but hemorrhages are unusual. Single aneurysm, ruptured aneurysm, neck greater than 4 mm and time of follow-up were risk factors for recurrence after endovascular treatment. The retreatment of recurrent aneurysm decreases the risk of major recurrences 9.8 times. Long-term angiogram monitoring is necessary for the population with significant recurrence predictors.

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Objectives: Previous evidence supports a direct relationship between the calcium burden (volume) on post-contrast CT with the percent internal carotid artery (ICA) stenosis at the carotid bifurcation. We sought to further investigate this relationship by comparing non-enhanced CT (NECT) and digital subtraction angiography (DSA). Methods: 50 patients (aged 41-82 years) were retrospectively identified who had undergone cervical NECT and DSA. A 64-multidetector array CT (MDCT) scanner was utilised and the images reviewed using preset window widths/levels (30/300) optimised to calcium, with the volumes measured via three-dimensional reconstructive software. Stenosis measurements were performed on DSA and luminal diameter stenoses >40% were considered "significant". Volume thresholds of 0.01, 0.03, 0.06, 0.09 and 0.12 cm(3) were utilised and Pearson's correlation coefficient (r) was calculated to correlate the calcium volume with percent stenosis. Results: Of 100 carotid bifurcations, 88 were available and of these 7 were significantly stenotic. The NECT calcium volume moderately correlated with percent stenosis on DSA r=0.53 (p<0.01). A moderate-strong correlation was found between the square root of calcium volume on NECT with percent stenosis on DSA (r=0.60, p<0.01). Via a receiver operating characteristic curve, 0.06 cm(3) was determined to be the best threshold (sensitivity 100%, specificity 90.1%, negative predictive value 100% and positive predictive value 46.7%) for detecting significant stenoses. Conclusion: This preliminary investigation confirms a correlation between carotid bifurcation calcium volume and percent ICA stenosis and is promising for the optimal threshold for stenosis detection. Future studies could utilise calcium volumes to create a "score" that could predict high grade stenosis.

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Purpose: To evaluate the effectiveness and safety of postoperative low single-dose of beta-irradiation (beta-RT) in pterygium comparing conjunctival autograft (CAG) surgery with CAG plus adjuvant beta-RT in a randomized clinical trial. Methods: This trial was designed as a prospective, randomized, single-center study. Surgery was performed in all cases according to the CAG technique. One hundred and eight pterygia were post-operatively randomized to CAG + beta-RT or CAGalone. In the case of beta-RT, a (90) Sr eye applicator was used to deliver 10 Gy to the sclera surface at a dose rate of between 200 and 250 cGy/min. After treatment, both an ophthalmologist and a radiation oncologist performed the follow-up examinations. The accumulated data were analyzed using a group sequential test. Results: Between February 2008 and September 2008, 116 eyes with primary pterygium were operated on according to the trial protocol. Adjuvant treatment was performed within 24 h post-operatively. Eight patients were lost to follow-up, resulting in 108 patients who could be analyzed. At a mean follow-up of 18 months (range, 8-33), in the 54 eyes randomized to receive CAG + beta-RT, 5 relapses occurred compared with 12 recurrences in the 54 eyes in CAG, for a crude control rate of 90.8 % vs. 78%; p = 0.032, respectively. The treatment complications as hyperemia, total dehiscence of the autograft and dellen were significantly more frequent in the CAG (p < 0.05). The arm of beta-RT resulted in better cosmetic results and improves of symptoms than CAG. Conclusions: A low single-dose of beta-RT of 10 Gy after CAG surgery was a simple, effective, and safe treatment that reduced the risk of primary pterygium recurrence, improved symptoms after surgery, resulting in a better cosmetic effect than only CAG. (C) 2012 Elsevier Inc.

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High intake of saturated fat from meats has been associated with cardiovascular disease, cancer, diabetes, and others diseases. In this paper, we are introducing a simple, high-throughput, and non-destructive low-resolution nuclear magnetic resonance method that has the potential to analyze the intramuscular fat content (IMF) in more than 1,000 beef portions per hour. The results can be used in nutritional fact labels, replacing the currently used average value. The method is based on longitudinal (T(1)) and transverse (T(2)) relaxation time information obtained by a continuous wave-free precession (CWFP) sequence. CWFP yields a higher correlation coefficient (r=0.9) than the conventional Carr-Purcell-Meiboom- Gill (CPMG) method (r=-0.25) for IMF in beef and is just as fast and a simpler pulse sequence than CPMG. The method can also be applied to other meat products.

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The Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence has been used in many applications of magnetic resonance imaging (MRI) and low-resolution NMR (LRNMR) spectroscopy. Recently. CPMG was used in online LRNMR measurements that use long RF pulse trains, causing an increase in probe temperature and, therefore, tuning and matching maladjustments. To minimize this problem, the use of a low-power CPMG sequence based on low refocusing pulse flip angles (LRFA) was studied experimentally and theoretically. This approach has been used in several MRI protocols to reduce incident RF power and meet the specific absorption rate. The results for CPMG with LRFA of 3 pi/4 (CPMG(135)), pi/2 (CPMG(90)) and pi/4 (CPMG(45)) were compared with conventional CPMG with refocusing pi pulses. For a homogeneous field, with linewidth equal to Delta nu = 15 Hz, the refocusing flip angles can be as low as pi/4 to obtain the transverse relaxation time (T(2)) value with errors below 5%. For a less homogeneous magnetic field. Delta nu = 100 Hz, the choice of the LRFA has to take into account the reduction in the intensity of the CPMG signal and the increase in the time constant of the CPMG decay that also becomes dependent on longitudinal relaxation time (T(1)). We have compared the T(2) values measured by conventional CPMG and CPMG(90) for 30 oilseed species, and a good correlation coefficient, r = 0.98, was obtained. Therefore, for oilseeds, the T(2) measurements performed with pi/2 refocusing pulses (CPMG(90)), with the same pulse width of conventional CPMG, use only 25% of the RF power. This reduces the heating problem in the probe and reduces the power deposition in the samples. (C) 2011 Elsevier B.V. All rights reserved.

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Nuclear magnetic resonance (NMR) was successfully employed to test several protocols and ideas in quantum information science. In most of these implementations, the existence of entanglement was ruled out. This fact introduced concerns and questions about the quantum nature of such bench tests. In this paper, we address some issues related to the non-classical aspects of NMR systems. We discuss some experiments where the quantum aspects of this system are supported by quantum correlations of separable states. Such quantumness, beyond the entanglement-separability paradigm, is revealed via a departure between the quantum and the classical versions of information theory. In this scenario, the concept of quantum discord seems to play an important role. We also present an experimental implementation of an analogue of the single-photon Mach-Zehnder interferometer employing two nuclear spins to encode the interferometric paths. This experiment illustrates how non-classical correlations of separable states may be used to simulate quantum dynamics. The results obtained are completely equivalent to the optical scenario, where entanglement (between two field modes) may be present.