3-D Velocity Estimation for Two Planes in vivo

3-D velocity vectors can provide additional flow information applicable for diagnosing cardiovascular diseases e.g. by estimating the out-of-plane velocity component. A 3-D version of the Transverse Oscillation (TO) method has previously been used to obtain this information in a carotid flow phantom with constant flow. This paper presents the first in vivo measurements of the 3-D velocity vector, which were obtained over 3 cardiac cycles in the common carotid artery of a 32-year-old healthy male volunteer. Data were acquired using a Vermon 3.5 MHz 32x32 element 2-D phased array transducer and stored on the experimental scanner SARUS. The full 3-D velocity profile can be created and examined at peak-systole and end-diastole without ECG gating in two planes. Maximum out-of-plane velocities for the three peak-systoles and end-diastoles were 68.5 5.1 cm/s and 26.3 3.3 cm/s, respectively. In the longitudinal plane, average maximum peak velocity in flow direction was 65.2 14.0 cm/s at peak-systole and 33.6 4.3 cm/s at end-diastole. A commercial BK Medical ProFocus UltraView scanner using a spectral estimator gave 79.3 cm/s and 14.6 cm/s for the same volunteer. This demonstrates that real-time 3-D vector velocity imaging without ECG gating yields quantitative in vivo estimations on flow direction and magnitud

Tracing postrepresentational visions of the city: representing the unrepresentable Skateworlds of Tyneside

In any visualisation of the city more is left unseen than made visible. Contemporary visualisations of the city are increasingly influenced by quantification, and thus anything which cannot be quantified is hidden. In contrast, we explore the use of ‘lo-fi’, doodled, participatory maps made by skateboarders in Tyneside, England, as a means to represent their cityscape. Drawing on established work an skateboarding and recent developments in cartography, we argue that skateboarders understand the city from a postrepresentational perspective. Such a framing presents a series of challenges to map their worlds which we explore through a processual account of our mapmaking practice. In this process we chart how skateboarders’ mappings became part of a more significant interplay of performance, identity, visualisation, and exhibition. The paper makes contributions to the emerging field of postrepresentational cartography and argues that its processual focus provides useful tools to understand how visions of the city are produced