Contrast-enhanced ultrasound for quantification of skeletal muscle perfusion

The purpose was to develop a clinically feasible contrast-enhanced ultrasound (CEUS) method to quantify skeletal muscle perfusion.

For high mechanical index CEUS, power Doppler ultrasonography (7MHz) after intravenous bolus injection of 10 mL Levovist® (SH U 508A; Schering, Berlin) was used. The perfusion parameters local blood volume, blood flow, and blood flow velocity were quantified by analysing replenishment kinetics.

In studies on volunteers, the validity of the CEUS method was demonstrated. Perfusion measured by CEUS and venous occlusion plethysmography correlated significantly (r=0.8; P<.001). Also, CEUS blood volume correlated significantly with several histologic capillarization parameters and aerobic capacity as parameter of endurance performance (r=0.6; P<.01) with highest values observed in the best-trained volunteers.

The clinical value of the CEUS method was assessed in patients suspected of having myositis, where it is important to rule out early a possible dermatomyositis or polymyositis, because early treatment prevents disabling and irreversible muscle weakness. In patients with typical histological features of myositis, CEUS demonstrated a significantly increased muscle perfusion, which returned to normal after successful medical treatment. Sensitivity and specificity of 73% and 91% were comparable to those achievable with MRI, where oedema-like changes indicate myositis. In adjunct to MRI, CEUS increased specificity in diagnosis of myositis, since oedema-like changes are not disease-specific. Indeed, in all examined patients with oedema-like changes at MRI but normal perfusion at CEUS, myositis was histologically excluded.