Noninvasive Diagnosis of Chronic Exertional Compartment Syndrome With Shear Wave Elastography and Subharmonic Aided Pressure Estimation.

Chronic exertional compartment syndrome (CECS) is an underdiagnosed condition that affects young athletes. CECS is caused by increased compartmental pressure in the fascial spaces during exercise. CECS is diagnosed by direct pressure readings (in mmHg), which is a painful and invasive test. Noninvasive shear-wave elastography (SWE) and subharmonic-aided pressure estimation (SHAPE) using contrast-enhanced ultrasound were compared to compartment pressure testing for the diagnosis of CECS. Ten healthy volunteers and five CECS patients enrolled in this prospective, IRB-approved pilot study. Subjects were scanned pre- and post-exercise using a modified LOGIQ E10 scanner (GE HealthCare). For SWE, muscle stiffness was expressed as median shear velocity over 12 measurements. Following intravenous infusion of Definity (3 mL in 50 mL of saline; Lantheus Medical Imaging) SHAPE power was optimized, and three 5-second clips were acquired. SWE and SHAPE pre-to-post differences were calculated offline and compared to CECS pressure testing (the reference). In the healthy volunteers, pre- versus post-exercise SWE showed a median velocity of 1.16 ± 0.17 versus 1.28 ± 0.22 m/s (P = .01). In the CECS patients, the difference was 1.11 ± 0.11 versus 1.41 ± 0.19 m/s (P = .06). However, there were no SWE differences between healthy volunteers and CECS patients (P = .14). For pre- and post-exercise SHAPE, both healthy volunteers and CECS patients demonstrated significant differences (-62.9 ± 2.09 vs -58.7 ± 2.74 dB and -59.0 ± 2.96 vs -50.8 ± 2.22 dB, respectively; P < .002). Healthy volunteers were statistically significantly different from CECS patients (4.2 ± 2.56 vs 8.1 ± 2.12 dB; P = .01). The SHAPE gradient correlated with compartment pressure testing (r = -0.95; P = .01). These preliminary results indicate that SHAPE may become a noninvasive alternative for diagnosing CECS.