RESUMEN
A 63-year-old man with multiple previous orthopedic procedures in both lower extremities had presented to us for a third opinion regarding the point-specific pain in his right lateral calf. The initial diagnosis had been venous reflux at two other institutions. However, repeat imaging studies demonstrated an aneurysmal gastrocnemius vein without any other abnormalities, such as venous reflux or thrombosis. The patient had received compression stocking therapy for 6 months but had continued to experience increasing pain at night, especially when lying in bed. The patient was reexamined in the supine position, which showed a prominent bulge in the lateral calf. The bulge disappeared while he was in the upright position. The findings from a bedside ultrasound study confirmed that the gastrocnemius vein bulged out when the muscles were relaxed in the supine position and that the muscles compressed the vein in the standing position, squeezing the aneurysm. Thus, the decision was made to proceed with surgical excision. At 7 months after surgery, the patient remained symptom free.
RESUMEN
A combined magnetization and (57)Fe spin-echo nuclear magnetic resonance (NMR) study has been carried out on mesoporous nanostructured materials consisting of the magnetite (Fe3O4) and maghemite (γ-Fe2O3) phases. Two series of samples were synthesized using a recently developed one-step soft-templating approach with systematic variations in calcination temperature and reaction atmosphere. Nuclear magnetic resonance has been shown to be a valuable tool for distinguishing between the two magnetic iron oxide spinel phases, Fe3O4 and γ-Fe2O3, on the nanoscale as well as monitoring phase transformation resulting from oxidation. For the Fe3O4 and γ-Fe2O3 phases, peaks in the NMR spectra are attributed to Fe in the tetrahedral (A) sites and octahedral (B) sites. The magnetic field dependence of the peaks was observed and confirmed the site assignments. Fe3O4 on a nanoscale readily oxidizes to form γ-Fe2O3 and this was clearly evident in the NMR spectra. As evidenced by transmission electron microscope (TEM) images, the porous mesostructure for the iron oxide materials is formed by a random close-packed aggregation of nanoparticles; correspondingly, superparamagnetic behavior was observed in the magnetic measurements. Although X-ray diffraction (XRD) shows the spinel structure for the Fe3O4 and γ-Fe2O3 phases, unlike NMR, it is difficult to distinguish between the two phases with XRD. Nitrogen sorption isotherms characterize the mesoporous structures of the materials, and yield BET surface area values and limited BJH pore size distribution curves.