Lingual thyroid gland: sonographic appearance

Thyroid dysgenesis is often manifested by a lingual or sublingual location of the thyroid gland. If radionuclide studies are not readily available or are contraindicated, ultrasound (US) may be used to locate the gland. The US appearance of a lingual thyroid gland and the role of US in the evaluation of suspected thyroid dysgenesis are described.     

Neurotransmitter regulation of neuronal outgrowth, plasticity and survival

Molecules used for communication in mature nervous systems also play important roles in development, maintenance and plasticity of individual neurons. This paper reviews the evidence that neurotransmitters, in addition to their mediation of trans-synaptic information coding, can induce a spectrum of effects on neuronal cytoarchitecture, ranging from neurite sprouting to dendritic pruning and even cell death. Such profound alterations may well constitute a part of the normal functioning and structuring of the nervous system as well as contribute to severe pathological processes.     

Quality assessment and assurance in diagnostic imaging. Theoretical and practical considerations and a quality audit of the excretory urogram

Concepts necessary to an understanding of the basics of quality assurance audits are presented. Included are specific examples that bridged theory and practice by applying the protocol to a real-life diagnostic imaging situation. This method meets the present requirements of the Joint Commission of the Accrediation of Hospitals.     

The effect of linear contrast flow acceleration on catheter tip recoil in selective arteriography

We investigated the effect of the device known as the linear accelerator flow control (linear-rise) available on some angiographic power injectors used for delivering contrast medium. Its influence on catheter tip recoil during selective arteriography was evaluated in two glass models, which simulated assessment of catheter position in visceral and cerebral arterial branches. Contrast medium was injected over a clinical range with and without the linear flow accelerator in operation. Biplane high speed video recordings simultaneously referenced time in thousandths of seconds and the catheter position. The linear flow accelerator failed to prevent, but did delay, catheter tip recoil in proportion to the prolongation of contrast medium injection time. These laboratory results conformed with the findings of catheter behavior during similar experiments in animals undergoing arteriography.     

A quantitative method for determining angiographic jet energy forces and their dissipation: Theoretic and practical implications

Jets emanating from the exit holes of cardiac catheters during angiographic injections are theoretically capable of producing severe localized cardiovascular trauma. We adopted a fluid mechanical model of an axially symmetric jet to define these energy forces quantitatively, especially as they would occur in the clinical setting. During angiographic injection at all catheter flow rates used clinically, the jet emanating from the exit hole was always turbulent. The physical characteristics of the turbulent jet penetration into the intravascular blood fell upon a universal curve independent of the jet Reynolds number. This curve, never previously described, allows ready calculation of hydraulic energy dissipation for any catheter of known length and lumen size. The diameter of the catheter exit orifice has a greater effect than injection flow rate on decreasing jet penetration. These results provide useful guidelines for reducing trauma during routine angiography.