Validation of 3D reconstructions of a mimicked femoral artery with an ultrasound imaging robotic system

Abstract

The degree of stenosis is the most important criterion to assess peripheral arterial disease manifested by atherosclerosis mainly in lower limb arteries. Ultrasound (U.S.) imaging offers low-cost, safe, and convenient options to evaluate this disease, but most U.S. freehand approaches cannot optimally locate stenoses and map lower limb arterial geometries. A 3D-U.S. imaging robotic system that can control and standardize image acquisition by scanning typically encountered diseased arterial lower limb segments is presented and validated with phantoms. A Z-phantom calibration procedure was used to characterize spatial transformation of the U.S. probe image plane for different clinical image acquisition settings. Moreover, the accuracy of the calibration transform to reconstruct a lower-limb-mimicking vessel geometry was evaluated with a vascular phantom. A 3D calibration precision of 0.47 +/- 0.27 mm was achieved. Reconstruction errors were less than 1.74 +/- 0.08 mm in all 3D vessel representations and the cross-sectional areas of each image section were close to those of gold standard phantom measures. The best reconstruction accuracy (smallest error) was 0.40 +/- 0.03 mm. Altogether, these results demonstrate the potential of the robotic scanner to adequately represent lower limb vessels for the clinical evaluation of stenoses.