Search results for "Ultra"

Verification of a commercial implementation of the Macro-Monte-Carlo electron dose calculation algorithm using the virtual accelerator approach.

2009

Abstract In this work, the accuracy of the implementation of the Macro Monte Carlo electron dose calculation algorithm into the radiation therapy treatment planning system Eclipse is evaluated. This implementation – called eMC – uses a particle source based on the Rotterdam Initial Phase-Space model. A three-dimensional comparison of eMC calculated dose to dose distributions resulting from full treatment head simulations with the Monte Carlo code package EGSnrc is performed using the ‘virtual accelerator’ approach. Calculated dose distributions are compared for a homogeneous tissue equivalent phantom and a water phantom with air and bone inhomogeneities. The performance of the eMC algorithm…

Spontaneous plaque rupture visualized by intravascular ultrasound.

1994

An intravascular ultrasound examination was performed in order to evaluate an angiographically complicated lesion. Intravascular ultrasound was able to demonstrate spontaneous plaque rupture in a patient with recent acute subendocardial infarction. The inconclusive angiographic appearance was clarified by the intravascular examination and led us to conclude that the myocardial infarction was due to plaque rupture with subsequent thrombotic occlusion, which had spontaneously resolved by the time of the study.

Myocardial infarction with non-obstructive coronary arteries (MINOCA): Intracoronary imaging-based diagnosis and management.

2021

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is defined by clinical evidence of myocardial infarction (MI) with normal or near-normal coronary arteries on angiography. This condition is present in about 5% to 25% of patients presenting with acute coronary syndromes. MINOCA is a working diagnosis. Current guidelines and consensus recommend identification of underlying causes of MINOCA in order to optimize treatment, improve prognosis, and promote prevention of recurrent myocardial infarction. An accurate evaluation of patient history, symptoms and use of invasive and non-invasive imaging should lead to identification of epicardial or microvascular causes of MINOCA an…

Tissue characteristics in non-culprit lesions during the acute coronary event and at ten months follow-up

2013

Introduction: It is not well established how the medication recommended in the guidelines will affect plaque compositional changes in non-culprit segments after STEMI. We hypothesized that the proportion of necrotic tissue in the non-culprit lesion in the culprit artery would decrease ten months after STEMI. Methods: In 63 consecutive STEMI patients the non-culprit segment in the culprit artery was analyzed with iMap intravascular ultrasound (IVUS) at the time of the index procedure and 10 months later. The non-culprit segment was identified as being 20mm proximal to the most stenotic culprit segment. All patients were recommended to receive the drug therapy outlined in the STEMI guidelines…

Transcranial magnetic resonance-guided focused ultrasound thalamotomy as a safe treatment option in multiple sclerosis patients with essential tremor

2020

Transcranial magnetic resonance-guided focused ultrasound is a recently introduced incisionless treating option for essential tremor and tremor-dominant idiopathic Parkinson disease. There is preliminary evidence that it may result in a promising effective treatment option for other movement disorders too. Here, we report on two patients with multiple sclerosis with medication refractory debilitating essential tremor comorbidity who successfully underwent unilateral Vim tcMRgFUS thalamotomy for tremor control. Patients' clinical condition and expanded disability status scale scores showed no changes during the 1-year follow-up period with no evidence of multiple sclerosis activity or progre…

2001

Little is known about somatosensory evoked potentials (SEPs) from muscle stimulation compared to that from skin stimulation. The current study examined this issue in the full SEP spectrum (0 - 440 ms). The aims of the study were to (1) establish the dynamics of early to late latency SEPs from intramuscular stimulation in contrast to surface stimulation, (2) compare the effect of non-painful and painful stimuli on SEP latencies and amplitudes of the two methods, and (3) investigate to which extent these results can be shared between the median nerve innervated thenar site and ulnar nerve innervated hypothenar site. Stimuli were delivered (2 Hz) at a non-painful and a painful intensity above …

Effects of Age and Sex on Optic Nerve Sheath Diameter in Healthy Volunteers and Patients With Traumatic Brain Injury.

2020

The measurement of optic nerve sheath diameter (ONSD) has been reported as a non-invasive marker for intracranial pressure (ICP). Nevertheless, it is uncertain whether possible ONSD differences occur with age and sex in healthy and brain-injured populations. The aim of this study was to investigate the effects of sex and age on ONSD in healthy volunteers and patients with traumatic brain injury. We prospectively included 122 healthy adult volunteers (Galliera Hospital, Genova, Italy), and compared age/sex dependence of ONSD to 95 adult patients (Addenbrooke's Hospital, Cambridge, UK) with severe traumatic brain injury (TBI) requiring intubation and invasive ICP monitoring. The two groups we…

Endo-neuro-sonography: anatomic aspects of the ventricles.

1997

To evaluate the usefulness of transendoscopic sonography, we have studied the use of a new sonographic probe of 6 F diameter in 11 fresh specimens. We achieved a precise imaging of well known anatomic structures and, moreover, obtained an additional dimension in endoscopy, since the sonographic probe adds a transverse scan to the endoscopic view, like a mini-CT at the tip of the probe. In this way, we also examined the guiding characteristics of this imaging technique, both in real time and on-line. Our results promise further interesting aspects of this technique in minimally invasive neurosurgery and suggest that further development and clinical experience seem to be justified.

Inclusión de la inyección percutánea de etanol como primera línea de tratamiento de los quistes tiroideos sintomáticos

2021

Abstract Background Our aim was to evaluate the efficacy and security of ultrasound-guided percutaneous ethanol injection therapy (US-PEIT) for the treatment of recurrent symptomatic thyroid cysts in two high-resolution consultations of thyroid nodule in the Valencian Community. Patients and methods The study comprised thirty-three consecutive patients (51 ± 12 years, 76% women) with symptomatic benign thyroid cysts relapsed after drainage and benign cytology prior to treatment. Through ultrasound, maximum cyst diameter and volume were determined, and the content of the cyst was drained. We then instilled between 2 and 4 ml of ethanol (according to initial volume). We followed up with ultra…

Importance of calibration for diameter and area determination by intravascular ultrasound

1996

Intravascular ultrasound (IVUS) permits quantitative assessment of the lumen diameter and area of coronary arteries. The experimental study was performed to evaluate the accuracy of diameter and area measurements.Lumen quantitation (lumen diameter D and cross-sectional area A) in lucite tubes (lumen diameter 2.5 to 5.7 mm, Plexiglas) was performed using a mechanical IVUS system (HP console, 3.5 F catheter, Boston Scientific, 30 MHz). The influence of fluid type (blood, water and saline solution), fluid temperature (20 degrees C/37 degrees C), catheter to catheter variation, gain setting and ultrasound frequency (12, 20 and 30 MHz) was determined. In blood at 20 degrees C there was a constan…