Stitching of 3D ultrasound datasets for the determination of large thyroid volumes – phantom study part II: mechanically-swept probes

Ziel/Aim To investigate the feasibility and accuracy of 3D-US extended field of view data acquired with mechanically-swept ultrasound probes using different measurement methods and for the determination of large volume thyroid phantoms.

Methodik/Methods Fifteen differently shpaed thyroid phantoms (regular, nodular, thickened isthmus) and various volumes (50-400 mL) were created. Two mechanically-swept ultrasound probes (convex and linear) were used for separate scanning of left and right lobes. After specific software based modifications, the 3D-US datasets were stitched together to an extended field of view using landmarks. Volumetric analyses were carried out by conventional ellipsoid model and manual tracing methods. The correspondence of measured and reference volumes was calculated using Pearson’s correlation coefficients and limits of agreement according to Bland and Altman.

Ergebnisse/Results The convex probe proved feasible for the acquisition and processing of the three-dimensional ultrasound extended field of view images. Very high levels of agreement (correlation coefficients: 0.9843-0.9992) were observed for all investigated shapes and volumes. The the time consuming manual tracing method showed superior results in comparison to the ellipsoid model. The field of view of the linear probe was restricted to the 50 mL phantoms.

Schlussfolgerungen/Conclusions The investigated mechanically-swept convex probe proofed suitable for three-dimensional ultrasound extended field of view stitching of large volume thyroid phantoms. Accurate volume analyses could be carried out, particularly with the manual tracing method. The linear probe is limited to a maximum of 50 mL.