Simple photoplethysmography pulse encoding technique for communicating the detection of peripheral arterial disease-a proof of concept study.

OBJECTIVE: To assess the feasibility of novel photoplethysmography (PPG) Pulse Sounder/Pulse Visualizer communication techniques for alerting the presence (or absence) of peripheral arterial disease (PAD). APPROACH: Proof of concept evaluation using our previously published multi-site PPG pulse data set (110 participants included; age > 40 years; 44% PAD by ankle brachial pressure index (ABPI)). Two main pulse encoding rules using the risetime as an example feature to mark each heartbeat in a 6 s analysis study window: if risetime at both great toes ⩽time threshold ('no PAD' state) then heartbeat marked with a single 5 kHz audio tone; if risetime from either great toe > threshold ('PAD') then heartbeat marked with a distinct train of 5 kHz audio tones. A simple spectrogram visual plot was also produced for each participant's audio signals. ROC curve analysis first determined an appropriate risetime threshold using the simple-to-evaluate PAD Visualizer and then re-tested at this level with PAD Sounder and classification performance summarized. MAIN RESULTS: The pulse encoding rules used were easy to learn. Visualizer best communication performance at risetime 0.27 s gave specificity 80.6%, sensitivity 95.8%, accuracy 87.3%, negative predictive value 96.2%, and Kappa statistic of 0.75. Classification performance for blinded assessment with audio PAD Sounder was identical. SIGNIFICANCE: Substantial agreements demonstrated between Sounder/Visualizer disease techniques and the ABPI PAD reference. These simple-to-use PAD communications methods when embedded into an appropriate device platform could offer significant benefits in PAD diagnosis for a range of clinical settings, including primary care where low-cost, portable and easy-to-use diagnostics can be desirable.

Evaluating the repeatability and set-up sensitivity of a large field of view distortion phantom and software for magnetic resonance-only radiotherapy.

BACKGROUND AND PURPOSE: Magnetic Resonance (MR)-only radiotherapy requires geometrically accurate MR images over the full scanner Field of View (FoV). This study aimed to investigate the repeatability of distortion measurements made using a commercial large FoV phantom and analysis software and the sensitivity of these measurements to small set-up errors. MATERIALS AND METHODS: Geometric distortion was measured using a commercial phantom and software with 2D and 3D acquisition sequences on three different MR scanners. Two sets of repeatability measurements were made: three scans acquired without moving the phantom between scans (single set-up) and five scans acquired with the phantom re-set up in between each scan (repeated set-up). The set-up sensitivity was assessed by scanning the phantom with an intentional 1 mm lateral offset and independently an intentional 1° rotation. RESULTS: The mean standard deviation of distortion for all phantom markers for the repeated set-up scans was < 0.4 mm for all scanners and sequences. For the 1 mm lateral offset scan 90 % of the markers agreed within two standard deviations of the mean of the repeated set-up scan (median of all scanners and sequences, range 78%-93%). For the 1° rotation scan, 80% of markers agreed within two standard deviations of the mean (range 69%-93%). CONCLUSIONS: Geometric distortion measurements using a commercial phantom and associated software appear repeatable, although with some sensitivity to set-up errors. This suggests the phantom and software are appropriate for commissioning a MR-only radiotherapy workflow.

Novel photoplethysmography cardiovascular assessments in patients with Raynaud's phenomenon and systemic sclerosis: a pilot study.

OBJECTIVE: Multisite photoplethysmography (PPG) cardiovascular assessments can evaluate endothelial, peripheral autonomic and arterial dysfunction. The aim of this pilot study was to investigate the potential clinical utility of the technology in assessing patients with SSc and primary RP (PRP). METHODS: Multisite PPG pulse measurements, a reference ankle brachial pressure index (ABPI) and a full clinical assessment were undertaken for three subject groups: SSc, PRP and controls. Endothelial and autonomic function and arterial disease measures were obtained using pulse wave analysis. RESULTS: Nineteen SSc, 19 PRP and 23 control subjects were assessed and compared. Endothelial function was significantly impaired in SSc (P < 0.02), but with no difference between controls and PRP. Receiver operating characteristic-based classification accuracy was 81% (sensitivity 90%, specificity 74%) for separating SSc from controls and 82% (sensitivity 84%, specificity 79%) for separating SSc from PRP. SSc patients with digital ulcers had significantly lower endothelial function compared with those without ulcers (P < 0.05). Autonomic dysfunction was suggested in both SSc and PRP and was most exaggerated in patients with diffuse SSc. All groups had overall normal ABPI and arterial stiffness timing measures. Bilateral timing differences at the toes, which represents peripheral occlusive arterial disease, did show increased asymmetry in SSc (P < 0.02). CONCLUSION: Multisite PPG pulse technology showed potential diagnostic ability. By using measures of endothelial function, it differentiated SSc from control and PRP subjects with an accuracy of at least 81%. Objective pulse-derived measures of autonomic function and arterial disease in SSc have also been reported in this pilot study.

Healthy cities indicators: analysis of data from cities across Europe

This document provides an analysis of base-line indicators that were endorsed by the WHO Healthy Cities Project. It covers health, demography, health services, environmental and socioeconomical status indicators. This is the first systematic effort to collect and analyse such a wide range of data from cities across Europe. The analysis gives important insights in the way indicators are understood by different countries, the extent of the availability of data, the reliability and validity of the information provided and the appropriateness of the indicators for international comparisions. This document lays the foundation of trying to build a set of indicators that could provide a comprehensive picture of health, not just information on births and deaths.(AU)