Volume measurement using the Polhemus FastSCAN 3D laser scanning: a novel application for burns clinical research

The Polhemus FastSCAN system offers a noncontact method of quantifying limb edema volume by combining laser scanning with 3D spatial orientation. The aim of this study was to investigate the reliability, validity and clinical utility of this assessment technique in the burn environment. Pilot Studies: Completed in order to develop a standardised scanning procedure. Intertester Reliability: Two testers each scanned 30 uninjured upper limbs. Intratester Reliability: One tester conducted repeated scans for burn survivors (n = 6).

The scan volumes were compared with water displacement measures for all volunteers (n = 36). Intertester reliability was moderate for whole arm scans (R = .59; 95% confidence intervals [CI] = 0.28-0.78) and excellent with hand truncated (R = .95; 95% CI = 0.90-0.98; minimum detectable difference = 242.1 cm3). Intratester reliability was inconclusive (R = .72; 95% CI = -0.07-0.96) but qualitative assessment confirmed poorer quality scans. The FastSCAN system overstated the arm volume by 49.3 cm3 on average, but 95% limits of agreement when compared with water displacement demonstrated the limitations as a clinical or research tool in the burn environment. The Polhemus FastSCAN system provides a noncontact method of limb volume measurement. The reliability was good only with the hand removed from calculations. The accuracy of the system compared poorly with water displacement measures in the burn clinical environment. Using the currently available software and method, the change detectable by this technique was too large for monitoring the efficacy of acute burn edema interventions.