Search results for "frequency [modulation]"
showing 10 items of 569 documents
Comparison of short-term heart rate variability indexes evaluated through electrocardiographic and continuous blood pressure monitoring
2019
Heart rate variability (HRV) analysis represents an important tool for the characterization of complex cardiovascular control. HRV indexes are usually calculated from electrocardiographic (ECG) recordings after measuring the time duration between consecutive R peaks, and this is considered the gold standard. An alternative method consists of assessing the pulse rate variability (PRV) from signals acquired through photoplethysmography, a technique also employed for the continuous noninvasive monitoring of blood pressure. In this work, we carry out a thorough analysis and comparison of short-term variability indexes computed from HRV time series obtained from the ECG and from PRV time series …
Acute inactivation of the medial forebrain bundle imposes oscillations in the SNr: a challenge for the 6-OHDA model?
2010
It has been recently shown that the substantia nigra pars reticulata (SNr) of 6-hydroxydopamine (6-OHDA)-lesioned rats, under urethane anaesthesia, manifests a prominent low frequency oscillation (LFO) of around 1Hz, synchronized with cortical slow wave activity (SWA). Nevertheless, it is poorly understood whether these electrophysiological alterations are correlated only with severe dopamine depletion or may also play a relevant pathogenetic role in the early stages of the dopamine denervation. Hence, here we recorded SNr single units and electrocorticogram (ECoG) in two models of dopamine denervation: (i) acute dopamine denervated rats, obtained by injection of tetrodotoxin (TTX), (ii) ch…
3D versus 2D contrast-enhanced sonography in the evaluation of therapeutic response of hepatocellular carcinoma after locoregional therapies: prelimi…
2014
Objective: To investigate diagnostic performance of 3D contrast-enhanced ultrasound (CEUS) compared with 2D CEUS in the assessment of therapeutic response of hepatocellular carcinoma (HCC) treated with locoregional therapies (LRT). Materials and methods: Twenty-three consecutive patients (13 men and 10 women; mean age 65.5 years) with 23 HCCs (size range 1.2–7.2 cm; mean size 2.9 ± 1.4 cm) treated by means of radiofrequency ablation (RFA n = 9), transarterial chemoembolization (TACE n = 8), combined RFA and TACE (n = 3), percutaneous alcoholization (n = 2), and wedge resection (n = 1) underwent 2D and 3D CEUS 1 month (30 ± 2 days) after treatment. Magnetic resonance (n = 17) and computed to…
Hepatocellular cancer response to radiofrequency tumor ablation: contrast-enhanced ultrasound
2007
Radiofrequency ablation (RFA) is increasingly being used as percutaneous treatment of choice for patients with early stage hepatocellular carcinoma (HCC). An accurate assessment of the RFA therapeutic response is of crucial importance, considering that a complete tumor ablation significantly increases patient survival, whereas residual unablated tumor calls for additional treatment. Imaging modalities play a pivotal role in accomplishing this task, but ultrasound (US) is not considered a reliable modality for the evaluation of the real extent of necrosis, even when color/power Doppler techniques are used. Recently, newer microbubble-based US contrast agents used in combination with grey-sca…
Percutaneous Radiofrequency Ablation for Hepatocellular Carcinoma Before Liver Transplantation: A Prospective Study with Histopathologic Comparison
2006
OBJECTIVE. The aims of this study were to determine the feasibility and efficacy of percutaneous radiofrequency ablation in patients with hepatocellular carcinoma waiting for liver transplantation and to compare the radiologic and pathologic findings. SUBJECTS AND METHODS. Twenty-six patients with 35 hepatocellular carcinomas were addressed for transplantation. Complications of the procedures were recorded. Primary and secondary technique effectiveness and causes of exclusion from the waiting list were assessed. After transplantation, tumor recurrence was evaluated for at least 1 year in all patients. Radiologic-pathologic comparison of the explant was performed. RESULTS. Percutaneous radio…
Incidence of new foci of hepatocellular carcinoma after radiofrequency ablation: role of multidetector CT
2012
Purpose. The authors sought to assess the incidence of new foci of hepatocellular carcinoma (HCC) using multidetector computed tomography (MDCT) in patients treated with radiofrequency ablation (RFA). Materials and methods. Two readers retrospectively reviewed by consensus the follow-up MDCT studies of 125 patients (88 men and 37 women; mean age 68 years) with 141 HCCs (size 1–5.2 cm; mean 2.2 cm) treated with RFA. MDCT follow-up was performed at 1 and 3 months and every 6–12 months thereafter. Reviewers assessed: (1) the presence of new HCC foci in the same liver segment or in a different segment; (2) complete or incomplete tumor ablation; (3) tumour progression. Results. A total of 113 ne…
Conventional radiofrequency treatment in five patients with trigeminal neuralgia
2010
Introduction: In trigeminal neuralgia, when drug treatment proves ineffective, other management options must be considered. In this context, conventional radiofrequency of Gasser’s ganglion is a safe and effective alternative. Material and Methods: We describe 5 patients with long-evolving trigeminal neuralgia subjected to conventional radiofrequency according to the Sweet technique, with a follow-up of two years. Results: Pain relief was complete after two months in all cases. One patient suffered an unexpected episode of nausea, vomiting and foul odor sensation that subsided after three days of rest and drug treatment. Three patients described non-painful hypoesthesia in the region of the…
Minor hepatic resection for hepatocellular carcinoma in cirrhotic patients: Kelly clamp crushing resection versus heat coagulative necrosis with bipo…
2011
Hemorrhage and postoperative liver insufficiency are frequent and serious complications of hepatic resection in cirrhotic patients. The aim of this study was to assess retrospectively whether the surgical techniques using Kelly clamp crushing resection or heat coagulative necrosis with a bipolar radiofrequency device can reduce the incidence of the above complications and an eventual recurrence of neoplasia on the liver slice. We retrospectively reviewed the results of 35 patients who had undergone resection for monofocal hepatocellular carcinoma at our center. Thirteen patients (Group A) had undergone liver resection with Kelly clamp crushing resection, 22 patients (Group B) had had liver…
Acoustics of snoring and automatic snore sound detection in children
2017
Objective Acoustic analyses of snoring sounds have been used to objectively assess snoring and applied in various clinical problems for adult patients. Such studies require highly automatized tools to analyze the sound recordings of the whole night's sleep, in order to extract clinically relevant snore- related statistics. The existing techniques and software used for adults are not efficiently applicable to snoring sounds in children, basically because of different acoustic signal properties. In this paper, we present a broad range of acoustic characteristics of snoring sounds in children (N = 38) in comparison to adult (N = 30) patients. Approach Acoustic characteristics of the signals we…
Image-Guided Thermal Ablation as an Alternative to Surgery for Papillary Thyroid Microcarcinoma: Preliminary Results of an Italian Experience
2021
PurposeTo report the results of our preliminary experience in treating patients with papillary thyroid microcarcinoma (PTMC) with image-guided thermal ablation, in particular estimating the feasibility, safety and short-term efficacyMaterials and MethodsFrom 2018 patients with cytologically proven PTMC < 10 mm were discussed in a multidisciplinary team and evaluated for feasibility of image-guided thermal ablation. In case of technical feasibility, the three possible alternatives (i.e., image-guided thermal ablation, surgery, and active surveillance) were discussed with patients. Patients who agreed to be treated with image guided thermal ablation underwent radiofrequency (RFA) or la…