Abstract

Monitoring Leg Lymphedema Over the Course of Therapy Using an Infrared System

Iris M. Lu, MS,1 Michael J. Weiler, PhD,2 Nathan D. Frank, MBA,2 John Jordi, PTA, BS, CLT-LANA, CI,3 and J. Brandon Dixon, PhD1,2,4,5. Lymphatic Research Biology, 2019.

Background: There are many techniques of monitoring leg lymphedema during physical therapy. Taking volumetric measurements with a tape measure is among the most common clinically, and changes in volume are typically used to measure therapy efficacy. This study shows how the Kinect infrared (IR) sensor with custom algorithms can assess leg circumferences and volumes comparable with tape measurements taken by a trained therapist while exploring regional leg changes to determine uniformity of change.

Methods and Results: Leg volumes were measured in 38 lymphedema patients using the tape measure circumference method and the Kinect IR system. Changes in circumferences in various leg regions over the course of therapy were analyzed in 23 patients. The leg circumferences (R2=0.9522) and volumes ( R2=0.9847) strongly correlated between the two methods. The Bland–Altman analysis indicated a circumference percent different bias of 1.6 (6.2%), requiring a minor correction factor between the two methods. Over the course of therapy, patients with a reduction in leg volume, defined as a change >6.5% have greater reduction most distal to the body.

Conclusion: The Kinect IR system explored can be used clinically for leg volume measurements to monitor leg lymphedema patients over the course of their therapy. Implementing analysis of regional leg changes can better inform physical therapy to improve efficacy of treatment.

Main findings

• The Kinect IR system the patient was asked towalk tothe delineated spoton theground (*1.8min front of the sensor). The feet were spaced about shoulder width apart to ensure separation of the legs. When in the correct positioning, the software interface visually indicated this correct positioning by painting the cartooned version of the patient blue. In the background, there were parameters built-in to ensure that the legs were fully separated, although actual separation becomes more difficult to achieve with larger volume legs. When in an incorrect positioning, the cartooned patient in the software. display would be painted red. The patient was scanned from the front, left side, back, and right side in this body positioning for *30 seconds per side. Ten frames per side were used to calculate leg volumes.
• When taking measurements with a tape measure, the patient was positioned on a table, where the trained therapist could take circumference measurements every4cmalongthe leg, starting at the ankle.
• Circumference and volumes trongly correlated whencomparing the tape measure method and the Kinect IR system. In addition, in this study, the therapist collected all the scans after a brief training session during regular patient treatment visit, which indicates that clinical implementation is realistic and logistically possible with minimal training.
• The system is quick and requires less training to operate but the system results in a slightly weaker correlation when the circumferences (>60cm) and volumes (>7000mL) are larger.