Inter-observer and Intra-observer Variability in Volume Measurements of the Lower Extremity Using Perometer

Abstract

Background: The swelling of the extremities seen in lymphedema can be measured with many different volumetric devices; however, many methods lack important characteristics including reproducibility and independence from the subjectivity and skill of the operator. The aim of this study was to validate the use of the Perometer Ò as a possible standard for volumetric measurement methods based on the inter-observer and intraobserver variability when using a standard method of Perometry Ò. Methods and Results: Volumetric measurements were performed on 10 healthy test subjects by 5 individuals (the observers) who had been instructed in the measurement techniques to be used. The inter-observer variability was assessed by having the five observers measure all the test subjects both in the morning and in the early afternoon. The intra-observer variability was examined by having each observer measure all the 10 test subjects 4 times in a row in the aforementioned time frames. A data set was created using the measurements, allowing for the assessment of other parameters including variation of volume between the right and left leg and daily variation in swelling. Statistical measurements were performed using the Statistical Package for the Social Sciences (SPSS), from which it was determined that there was no statistically significant inter-observer (p-value 0.997) and intra-observer variation (p-value 0.995) based on a significance level of >5%. Furthermore, it was observed that a statistically significant difference in volume occurred in the leg volume during the day. Conclusion: It was concluded that the use of the Perometer provides consistent measurements of volume independent of the observer and therefore appears to provide a candidate standard for volumetric measurements.

New Device to Measure Cross-Sectional Areas and Segmental Volumes of Objects and Limbs

“…Current techniques to determine volumes locally are water displacement, girth, and caliper measurements, MRI imaging, X-ray tomography, ultrasound, and three dimensional imaging. 21,[31][32][33][34] The distance between girth measurements on a limb determines the length of the segment that is used in the calculation of geometric volume. This segment length has not been standardized, 18 and varies from 1 cm, 6 3 cm, 27,35-37 4 cm, 6,20,25,28,[38][39][40][41][42][43] 5 cm 44 to 10 cm and more and in between.…”

“…14,18,[44][45][46][47][48][49] The Perometer measures a change in volume every 2.54-4.7 mm. 8,21,28,42,50,51 In contrast, the slice thickness using the PAM is 1.1 mm or less measuring an arm. This enables extreme local volume determination.…”

Establishing regions of interest of the lower leg and ankle for perioperative volumetric assessment with a portable 3D scanner in orthopedic and trauma surgery – a pilot study

“…To cover the average size of the human tibial metaphysis, the ROI ankle was chosen at a location 5 cm proximal from the medial malleolus [ 30 ]. There exists a dearth of information concerning the volume variability between contralateral limbs in healthy subjects such as may be caused by leg dominance [ 31 ]. This study demonstrates no significant differences in the overall volume and the respective ROI between right and left leg in our study participants (Fig.…”