Reproducibility of sonographic measurement of thickness and echogenicity of the plantar fascia

Background. To evaluate the intra- and interrater reliability of ultrasonographic measurements of the thickness and echogenicity of the plantar fascia. Methods. Eleven patients (20 feet), who complained of inferior heel pain, and 26 volunteers (52 feet) were enrolled. Two sonographers independently imaged the plantar fascia in both longitudinal and transverse planes. Volunteers were assessed twice to evaluate intrarater reliability. Quantitative evaluation of the echogenicity of the plantar fascia was performed by measuring the mean gray level of the region of interest using Digital Imaging and Communications in Medicine viewer software. Results. Sonographic evaluation of the thickness of the plantar fascia showed high reliability. Sonographic evaluations of the presence or absence of hypoechoic change in the plantar fascia showed surprisingly low agreement. The reliability of gray-scale evaluations appears to be much better than subjective judgments in the evaluation of echogenicity. Transverse scanning did not show any advantage in sonographic evaluation of the plantar fascia. Conclusions. The reliability of sonographic examination of the thickness of the plantar fascia is high. Mean gray-level analysis of quantitative sonography can be used for the evaluation of echogenicity, which could reduce discrepancies in the interpretation of echogenicity by different sonographers. Longitudinal instead of transverse scanning is recommended for imaging the plantar fascia. (C) 2011 Wiley Periodicals, Inc. J Clin Ultrasound 40: 14-19, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI:10.1002/jcu.20903