Synchronization of B-scan diagnostic imaging with transducer position tracking for three-dimensional ultrasonic scanning

Abstract

Diagnostic value of ultrasonic B-mode imaging is dependent on interpretation and competence of physician, because only information about single section of tissues volume is used for evaluation. 3D sonography systems for abdominal diagnostics are available, but such systems are not yet available in transcranial sonography and etc. One of possibilities to improve current diagnostic systems could be supplementing the 3D function, by combining a conventional B-mode system with a probe position tracking system. The aim of this study was to synchronize two sub-systems: the position tracker and the B-mode ultrasound apparatus for freehand three-dimensional ultrasonic scanning and to evaluate supplementary 3D system estimating volume of the reconstructed 3D surface image of a tissue mimicking phantom of known dimensions.

The 3D scanning method was implemented by synchronous sampling of B-scan diagnostic images, linear position scanning with position tracking sensors. To evaluate experimentally our method we have used four units: ultrasound diagnostic B-scan system, three axis positioning system, electromagnetic position tracker and frame grabber. The 3D phantom of defined dimensions was laboratory-made from dental duplicating silicon. B-mode transducer positioning was deterministic, but time intervals between position changes where random simulating free-hand positioning. Synchronization of video sequence record with a position tracing was assured using the second channel of the position tracing system.

3D surface was reconstructed relating B-mode images to the position data. The volume of phantom calculated according to physical measurements of the caliper was assumed as a true value V_true = 47.054 ml. The estimated volume of a 3D model of a phantom was V_model = 46.87 ml. The estimated relative error of the volume was 0.4 %. We concluded that a common B-mode sonography diagnostic system could be extended for 3D functionality with the use of a two channel position tracing system without invasive reengineering, but more experiments should be done for approval.

http://dx.doi.org/10.5755/j01.u.66.4.1028