Limiting foetal doses during a four-vessel angiogram and endovascular stent-assisted berry aneurysm repair: A case report

A 36-year-old female patient, 20 weeks pregnant, was diagnosed with a left internal carotid artery aneurysm. Fluoroscopically guided repair was justified. A four-vessel cerebral angiogram was performed, and a left paraclinoid aneurysm was demonstrated. The patient subsequently underwent endovascular stent-assisted berry aneurysm repair. As the patient was pregnant, the procedure was preceded by consideration of the required radiation protection. The foetal dose was estimated as negligible. Active management of foetal exposures may improve radiation protection during pregnancy

The impact of optic nerve movement on optic nerve magnetic resonance diffusion parameters

Background: Optic nerve diffusion imaging is a useful investigational tool of optic nerve microstructure, but is limited by eye-movement-induced optic nerve movement and artifacts from surrounding cerebrospinal fluid, fat, bone and air. Attempts at improving patient cooperation, thus voluntarily limiting eye movement during a standard diffusion imagingsequence, are usually futile. The aim of this study was to establish the impact of optic nerve movement on clinical diffusion parameters of the optic nerve. Method: Twenty-nine healthy volunteers with intact vision and intact conjugate gaze were recruited and subjected to magnetic resonance diffusion-weighted imaging (DWI) and diffusion-tensor imaging (DTI) of the optic nerves. Twenty right eyes had nerve tracking done using single-shot echo-planar imaging at 20 time points over 3 minutes. Optic nerve movement measurements were correlated with diffusion parameters of apparent diffusion coefficient (ADC), mean diffusivity (MD), fractional anisotropy (FA) and anisotropic index(AI) using Spearman’s rank correlation. Results: No significant correlations were noted between optic nerve movement parameters and ADC in the axial plane and MD of the optic nerve. Low to moderate negative correlations were noted between optic nerve movement parameters and AI and FA and positive correlation with ADC in the radial plane. Conclusion: Optic nerve movement documented during the timespan of standard diffusion sequences (DWI and DTI) has a negative effect on the anisotropic diffusion parameters of the optic nerve. With greater eye movement, optic nerve diffusion appears less anisotropic owing to greater radial diffusion

Proximity effects on nuclear spin-spin coupling constants. 1. 1J(CH) couplings in the vicinity of an atom bearing lone pairs

Proximity effects on 1J(CH) couplings are studied from a theoretical point of view in the following systems: CH4/FH (A) and H2O/HCN (B) which form dimers by hydrogen-bond interactions. 1J(CH) couplings for different intermolecular distances are calculated for the C - H bond facing the atom bearing lone pairs. While in the former system, this coupling is increased owing to the proximity to the F atom; in the latter this coupling is decreased owing to the proximity to the O atom. These opposite trends are accompanied by slight shortening and lengthening, respectively, of the corresponding C - H bond lengths. As part of this work, measurements of 1J(CH) couplings in 9-(1,3-dioxolan-2-yl)-1,2,3,4-tetrafluorotriptycene (I) and 1-formyl-2-hydroxy-8-fluoronaphthalene (II) and 1J(NH) in o-fluorobenzamide (III), showing proximity effects as those described above are carried out. These results suggest that 1J(XH) couplings are adequate probes to distinguish two different types of X-H⋯Y hydrogen bonds. © 1994 American Chemical Society.Fil:Vizioli, C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:De Ruiz Azúa, M.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Giribet, C.G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Contreras, R.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina