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.