Abstract

Introduction: High frequency ultrasound (HFUS) can create real-time two-dimensionalimages of internal structures to examine the first few centimetresdepth of sub-dermal soft tissue, thus may have the potential to detect tissuechanges in pressure ulcer prevention. However, there is no evidence on the repeatabilityof HFUS. This study aimed to investigate the inter- and intra-raterrepeatability of HFUS scanning.Methods: In a laboratory based study, 24 healthy subjects (21 females, 3 males;32.0812.25 years; BMI 24.945.57) participated on two occasions, one dayapart. Consenting subjects had points marked (day 1 only) on both heels (lateral,posterior and medial aspects) and seating interface (coccyx, and left and right ischialtuberosities) and scanned by a researcher, then repeated by a second researcher usingaHFUS scanner. Both researchers were blinded to each other’s scanning.HFUSimages were quantitatively and qualitatively analysed blindly by two assessors.Results: Qualitative visual analysis showed almost perfect agreement betweentwo assessors (0.88 kappa co-efficient). Intraclass correlation coefficients (ICCs)conducted on pixel intensity summation quantitative results showed low interandintra-rater repeatability (25% moderate or high ICCs; ICC Z0.6).Conclusions: Although quantitative analysis showed low inter- and intra-raterrepeatability, qualitative analysis showed better agreement. In practice, cliniciansqualitatively read the images, and visual analysis appears to be the goldstandard in HFUS interpretation. Quantitative methods of analysing HFUSimages require further exploration by industry, scientists and clinicians.