Use of a novel portable three-dimensional imaging system to measure limb volume and circumference in patients with filarial lymphedema

The World Health Organization's Global Program to Eliminate Lymphatic Filariasis (LF) has reduced LF transmission worldwide, but millions remain affected by filarial lymphedema. Tools for clinically monitoring lymphedema in developing nations are limited. We tested a novel, portable, infrared three-dimensional imaging system (3DIS) against water displacement (WD) and tape measurement of limb circumference (TMLC) among patients with filarial leg lymphedema in Galle, Sri Lanka. Outcomes were accuracy and reproducibility of imaging system measurements. In parallel, we also tested the reproducibility of skin thickness ultrasound (STU) measurements.Weexamined 52 patients (104 limbs) with lymphedema of stages 0-6 (N = 28, 19, 20, 21, 2, 4, and 10, respectively). 3DIS measurements correlated nearly perfectly with WD (r2 = 0.9945) and TMLC values (r2 > 0.9801). The median time required to acquire imaging system measurements for both legs was 2.1 minutes, compared with 17, 7, and 29 minutes, respectively, forWD, TMLC, and STU. Median interexaminer coefficients of variation (CVs) for volume measurements were 1.1% (interquartile range [IQR] 0.5-2.1%) for WD and 1.7% (IQR 1.2-2.4%) for the 3DIS. CVs for circumference measurements were 1.4% (IQR 0.8-2.4%) by TMLC and 1.3% (0.8-1.9%) by 3DIS. Median interexaminer CV for STU was 13.7% (IQR 8.5-21.3%). The portable imaging system noninvasively provided accurate and reproducible limb volume and circumference measurements in approximately 2 minutes per patient. This portable technology has the potential to greatly improve assessment and monitoring of lymphedema in the clinic and in the field.