title: Detection and Measurement of Stones With Ultrasound Strain Elastography: A Phantom Study.
abstract: The sonoelastographic appearances of stones in a phantom were evaluated in this study. Ten stones were embedded into a tissue-mimicking meat phantom. The stone axial (vertical) and transverse (horizontal) dimensions measured by an electronic digital caliper, gray-scale ultrasound, and strain elastography (SE) were compared in 5 groups with stones embedded at different depths. In this study, physically measured axial and transverse stone dimensions were 1.17 to 6.86 and 1.30 to 11.15 mm, respectively. Strain elastography showed a characteristic 3-layer pattern associated with stones, comprising a superficial transition region, a hard region, and a deep transition region. As SE data were available in group 5, only data of groups 1 to 4 were analyzed. Compared with physical measurements, measurement mean errors of SE horizontal and SE vertical dimensions ranged from -0.20 to 0.42 mm and from -1.28 to -0.05 mm, respectively, in the 4 groups. Paired t testing demonstrated a significant horizontal dimension measurement error difference between B mode and SE method in group 4 (0.44 vs -0.20 mm, P < 0.05; F = 1.18, P > 0.05), but not in the other groups. Strain elastography horizontal dimension measurement error was not statistically correlated with stone size in the 4 groups. Strain elastography vertical dimension measurement error significantly correlated with stone size only in group 4 (P < 0.05). Preliminary results indicate that stone horizontal and vertical dimensions can be measured using SE in a soft tissue phantom, including when shadowing precludes measurement of vertical dimension on conventional 2-dimensional ultrasound. These results provide substantial motivation to further investigate SE as a modality to image stones in clinical practice.
authors.affiliation: *Department of Ultrasound, Peking University First Hospital, Peking University Health Science Center, Beijing, China; and †Institute for Technology Assessment and ‡Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA.
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Elkan F
authors.initials: EF
authors.lastname: Halpern
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Samir
mesh_terms: D054459:Elasticity Imaging Techniques / Q000379:methods*; D006801:Humans; D019047:Phantoms, Imaging; D012372:ROC Curve; D015203:Reproducibility of Results; D014545:Urinary Calculi / Q000000981:diagnostic imaging*