Variations in the anatomical distribution of peripheral vascular disease according to gender.

BACKGROUND: While large epidemiological studies have suggested that the male gender is more frequently afflicted with intermittent claudication, there is little data whether there are gender differences in the distribution of peripheral vascular disease (PVD). The aim of this study was to clarify this issue on the basis of angiographic findings in patients presenting with claudication. PATIENTS AND METHODS: The radiology department computerised database was used to identify all lower limb angiograms performed for investigation of PVD. Patients undergoing incomplete assessment and those with normal angiograms were excluded. Demographic details for each patient were collected together with details of uni- or bilaterality of disease, the number of lesions present and their anatomical distribution according to the major named vessels. Only lesions reported as radiologically significant were included in the analysis. RESULTS: Five hundred consecutive angiograms fitting the defined study criteria were assessed. There were 310 males and 190 females giving a male to female ratio of 1.6:1. The most common distribution for both genders was multiple bilateral lesions. There were no significant differences in the number of stenoses in terms of ratio of bilateral to unilateral (2.39 vs 2.77) or ratio of multiple to single lesions (1.5 vs 1.7) between the female and male groups. Disease was more common in males at all anatomical locations, the most significant differences being for lesions of the common femoral and profunda femoris arteries. CONCLUSIONS: PVD is more commonly diagnosed in males than females. The disease process is more commonly bilateral in both genders and PVD affects more numerous sites in the male claudicant than in the female claudicant. Nevertheless, there does not appear to be any difference in the anatomical distribution of disease between genders.

Rapid measurement of transient velocity evolution using GERVAIS.

Rapid velocity measurements using GERVAIS (Gradient Echo Rapid Velocity and Acceleration Imaging Sequence), an EPI (Echo Planar Imaging) based technique capable of measuring velocity over an observation time of several milliseconds, are performed on a wide-gap Couette Rheo-NMR cell for the first time. A variable delay time between a control signal to initiate a transition in flow and the start of the measurement sequence is incorporated to allow investigation of the transient evolution of the velocity field following a step change in rotation rate. Both the commencement and the cessation of imposed shear stress are investigated for (i) a shear banding micellar solution of CPyCl (cetylpyridiniumchloride)/NaSal (sodium salicylate) in brine and (ii) a low molecular weight PDMS (polydimethylsiloxane) oil. With respect to the micellar solution, an elastic shear wave is seen to propagate across the cell following the commencement of shear stress whilst an oscillatory 'recoil' is observed following the cessation of shear stress; neither of these phenomena were observed for the PDMS oil which exhibited a purely viscous response as expected for an incompressible Newtonian fluid. This technique has potential applications across a wide range of transient rheological investigations, particularly with respect to optically opaque materials.

Rapid surface-to-volume ratio and tortuosity measurement using Difftrain.

Analysis of diffusion measurements as a function of observation time (Delta), to calculate surface-to-volume ratios (S/V) and tortuosities (kappa), is a useful tool in the characterisation of porous media using NMR. However, using conventional pulsed field gradient (PFG) measurements, this requires long total experiment times (typically hours). Here, we show how the rapid diffusion measurement pulse sequence, Difftrain, can be used to provide the required experimental data much more rapidly (typically within minutes) with a consequential reduction in total experiment time of typically over an order of magnitude. Several novel modifications to the Difftrain pulse sequence are also presented to tailor it to this particular application; these include a variable delay between echoes (to ensure optimal echo position with respect to Delta) and a variable tip angle for the refocusing pulse (to ensure optimal use of available signal). Difftrain is applied to measure both S/V and kappa for a model glass bead pack; excellent agreement is found with both a conventional PFG measurement and with a bulk gravimetric measurement of S/V.