Acoustic Radiation Force Impulse Elastography: Tissue Stiffness Measurement in Limb Lymphedema

Purpose To evaluate the feasibility of cutaneous and subcutaneous limb tissue elasticity measurement in participants with limb lymphedema by using acoustic radiation force impulse (ARFI) elastography. Materials and Methods From July 2015 to June 2017, ARFI elastography was performed in 64 participants with lymphedema (seven men and 57 women; age range, 23-85 years) by using a US system. Tissue stiffness quantification with shear-wave velocity (SWV) was obtained in the cutaneous and subcutaneous limb tissues. Lymphoscintigraphy was the reference standard. Results SWV was significantly higher in limbs with lymphatic obstruction than in unaffected limbs (cutaneous tissue: 2.75 m/sec vs 1.74 m/sec, respectively; subcutaneous tissue: 1.90 m/sec vs 1.35 m/sec, respectively; P < .001). SWV was significantly different among limbs without lymphatic drainage obstruction, with partial obstruction, and with total obstruction (cutaneous tissue: 1.74 m/sec vs 2.75 m/sec vs 2.77 m/sec; subcutaneous tissue: 1.35 m/sec vs 1.90 m/sec vs 1.90 m/sec, respectively; P < .001). By using a cut-off value of 2.10 m/sec and 1.43 m/sec for cutaneous and subcutaneous tissue, respectively, sensitivity was 83.1% (59 of 71) and 80.3% (57 of 71), and specificity was 86.0% (49 of 57) and 70.2% (40 of 57) for manifestation of lymphatic obstruction. The corresponding areas under the receiver operating characteristic curve were 0.91 and 0.83, respectively. Conclusion Acoustic radiation force impulse elastography showed that cutaneous and subcutaneous tissues are stiffer in lymphedematous limbs than in unaffected limbs. Acoustic radiation force impulse elastography is a feasible imaging modality for noninvasive tissue stiffness quantification in limb lymphedema. © RSNA, 2018 Online supplemental material is available for this article.