Search results for "Contrast"

Abdominal and Thoracic Magnetic Resonance Angiography: Challenges, Technical Approaches, and First Clinical Applications

1993

The main goal of magnetic resonance angiography (MRA) is to enrich the huge potential of magnetic resonance imaging (MRI) by additional morphological and functional information about the vasculature. In spin echo sequences fast flowing blood leads to signal extinction, providing high contrast between tissue and vascular structures without the need for contrast media. However, various artifacts are frequently observed which alter the assessment of the vasculature. They are due to alterations of flow (slow velocity or turbulences) or induced by the acquisition technique (Mills et al. 1983; Bradley and Waluch 1985). By using gradient echo sequences, high-quality angiograms can be obtained from…

Qualitative and quantitative evaluation of solitary thyroid nodules with contrast-enhanced ultrasound: initial results

2005

To assess the feasibility of contrast-enhanced ultrasound (CEUS) of the thyroid gland and to evaluate the potential of this method for characterising solitary thyroid nodules.18 patients affected by solitary thyroid nodules (size range: 0.6 to 3.6 cm; mean: 1.8 cm) confirmed by surgery (nine papillary carcinomas, four follicular carcinomas, three hyperplasias, one follicular adenoma and one Plummer’s adenoma) underwent pulse inversion US at low M.I. (0.06 to 0.08) after i.v. injection of a 2.4-mL bolus of SonoVue. Baseline echogenicity and the dynamic enhancement pattern of each nodule, in comparison with adjacent thyroid parenchyma, were assessed. Signal intensity values on grey-scale imag…

Performance of Contrast-Enhanced Ultrasound in Thyroid Nodules: Review of Current State and Future Perspectives

2021

Simple Summary Ultrasound has been used as baseline imaging for thyroid nodules for decades; nevertheless, no single feature is sensitive or specific enough to exclude or confirm thyroid malignancy. Therefore, clinical practice and research still focus on less invasive diagnostic patterns to reduce unnecessary fine-needle aspiration biopsies or surgery. The main advantage of CEUS is the ability to assess the sequence and intensity of vascular perfusion and hemodynamics in the thyroid nodule, thus providing real-time characterization of nodule features, and considered a valuable new approach in the determination of benign vs. malignant nodules. In addition, contrast agents used in CEUS can h…

Optimization and Inversion

2009

Computational evidence that frequency trajectory theory does not oppose but emerges from age-of-acquisition theory.

2012

International audience; According to the age-of-acquisition hypothesis, words acquired early in life are processed faster and more accurately than words acquired later. Connectionist models have begun to explore the influence of the age/order of acquisition of items (and also their frequency of encounter). This study attempts to reconcile two different methodological and theoretical approaches (proposed by Lambon Ralph & Ehsan, 2006 and Zevin & Seidenberg, 2002) to age-limited learning effects. The current simulations extend the findings reported by Zevin and Seidenberg (2002) that have shown that frequency trajectories (FTs) have limited and specific effects on word-reading tasks. Using th…

Stability of irinotecan-loaded drug eluting beads (DC BeadTM) used for transarterial chemoembolization

2009

Purpose. The aim of this study was to determine the loading efficiency, physicochemical stability, and release of irinotecan-loaded DC BeadsTM (bead size 100—300 μm, 300—500 μm) before and after mixing with nonionic contrast medium (Accupaque® 300, Imeron® 300, Ultravist ® 300) during a prolonged period of time (28 days) when stored at room temperature or refrigerated. Methods. DC Beads TM were loaded with 50 mg irinotecan (Campto®) per milliliter beads in a 2 h loading period. Drug loading efficiency and stability were determined by measuring the irinotecan concentration in the excess solution. A free-flowing in vitro elution method for a period of 2 h and phosphate buffered solution (PBS…

Introduction to coronary imaging with 64-slice computed tomography

2005

The aim of this article is to illustrate the main technical improvements in the last generation of 64-row CT scanners and the possible applications in coronary angiography. In particular, we describe the new physical components (X-ray tube-detectors system) and the general scan and reconstruction parameters. We then define the scan protocols for coronary angiography with the new generation of 64-row CT scanners to enable radiologists to perform a CT study on the basis of the diagnostic possibilities.

The development of “junk”. Irregularization strategies of have and say in the Germanic languages

2001

Although it is a wellknown fact that the most frequent verbs are the most irregular ones (if not suppletive), it is rarely asked how they became irregular. This article deals with the irregularization process of two originally regular (weak) verbs, HAVE and SAY in the Germanic languages, e.g. have, but has/’s and had/’d (instead of regular *haves/*haved) or say [sei], but says [sez] and said [sed] in English. Other verbs, such as DO, GO, STAND, BE, COME, and so on, also tend to irregularizations again and again without any apparent reason. In contrast to HAVE and SAY these verbs have always been rather irregular, at least dating from their first written records.

Acanthocyturia detects glomerular bleeding.

1993

Unveiling species assemblage rules in gypsum plant communities

2023

Plant communities are not merely snapshots of species located in the same area. Instead, they are dynamic entities connected through complex biotic interactions. Understanding the interplay of processes that bind species within a community is vital for comprehending species maintenance and may assist us in predicting how communities respond to the perturbations of a changing world. This Ph.D. aims to unveil how abiotic conditions, plant strategies, and biotic interactions shape plant communities growing in stressful environments. Plant species can thrive in stressful environments through contrasted strategies, either showing species-specific adaptive strategies or reliance on facilitative i…