Validity and Test-Retest Reliability of a Hand-Held Ultrasound Device in Measuring Kidney Metrics in Healthy Young Adults

Objective: The use of a hand-held ultrasound device provides a portable, cost-effective solution for renal assessments in rural settings, but their accuracy and reliability in measuring kidney metrics remain uncertain. The aim of this study was to evaluate the validity and reliability of the Lumify hand-held ultrasound device (LHUS) in capturing basic kidney metrics in healthy adults. Materials and Methods: Twenty individuals underwent renal sonography measurements, which included length, height, width, cortical thickness, parenchymal echogenicity, and renal resistive index (RRI). These measurements were completed using LHUS and the Epiq Elite ultrasound equipment system. LHUS measurements were repeated for test-retest reliability (TRR). Validity and TRR were assessed using intraclass correlation coefficient (ICC), Bland-Altman plots, coefficient of variation (COV), and mean absolute percent error (MAPE). Results: There was poor agreement (0.414, p = .048) between equipment systems for RRI. All other measures demonstrated moderate to excellent agreement (ICC = 0.75–0.94, p < .001) between systems. The left kidney showed poor agreement for RRI (0.06, p = .45). MAPE for all measurements between devices was <5%, indicating acceptable accuracy. All repeated measurements showed moderate to excellent reliability (ICC = 0.71–0.96, p < .001), with low mean COV for each measurement (0.02–0.08). Conclusion: Based on this study, LHUS appears to be a valid and reliable tool for basic kidney metrics in healthy adults, but caution should be used when obtaining an RRI, especially in the left kidney.