Contrast enhanced ultrasound (CEUS) in the assessment of foot perfusion: a feasibility study in a normal population

Purpose: To prospectively assess the technical feasibility and reliability of contrast enhanced ultrasound (CEUS) for measurements of foot perfusion in healthy participants.

Methods: Stage 1 assessed feasibility (N=6) on measurements obtained in the flexor digitorum brevis muscle (FDBM). Stage 2 (N=10) assessed the reliability of time to peak intensity (TTP) on the FDBM and the extensor hallucis brevis muscle (EHBM). Feasibility was determined by comparing the peak baseline intensity with the peak intensity after contrast administration. Relative reliability was assessed using intra-class correlation coefficient (ICC) and absolute reliability using coefficient of variation (CV).

Results: Peak intensity in stage 1 was higher with contrast than at baseline in all participants, and higher in 94% of overall cases in the FDBM. Peak intensity in the EHBM was higher after contrast than at baseline in 80% of cases. Only 83% and 40% of the time intensity curves obtained in the FDBM and EHBM respectively were eligible for TTP analysis, leaving a total of 8 and 3 comparable data sets. Relative and absolute reliability was poor in both the FDBM (ICC: 0.45, 95% confidence interval -0.35 to 0.86, CV: 27%, range 2-47%) and EHBM (ICC: -0.65, 95% confidence interval -2.38 to 0.96, CV: 46%, range 14-68%). Overlapping arterioles adjacent to the EHBM severely limited analysis.

Conclusions: CEUS is feasible for measurements in the FDBM although repeated measurements of TTP had poor reliability. Measurements on the EHBM displayed higher peak intensities in almost all cases, however reliability was poor and technical limitations likely inhibit utility.