Two-dimensional ultrasonic computed tomography of growth bone

Philippe Lasaygues (1) , Emilie Franceschini (2) , Régine Guillermin (1) , Jean-Pierre Lefebvre (1) , Nadège Salaud (3) , Philippe Petit (4)

1 LMA - Laboratoire de Mécanique et d'Acoustique [Marseille]
2 LBUM - Laboratory of Biorheology and Medical Ultrasonics
3 ESIL - Ecole Supérieure d'Ingénieurs de Luminy
4 Radiologie et imagerie médicale

Ultrasonography is the main first-line imaging technique used to diagnose various pediatric pathologies. Pediatric radiologists are very keen on ultrasonography since it is a non-invasive, non-irradiant, painless, inexpensive imaging modality, which is also practicable on bedside. In bone diseases, this technique has also proved to be a very effective tool to assess congenital (i.e., hip dysphasia), infectious (i.e., sub-periostal abscess), inflammatory (i.e., chronic arthritis), and even traumatic (i.e., ankle sprain) processes. However, with standard devices, this exam is not suitable for diagnosis or monitoring bone tumors, classically explored by other more effective techniques, which presented various disadvantages (cost, irradiation, sedation, accessibility). Many authors have dealt with the ultrasonic imaging of bones. Their main aim has usually been to assess the thickness of the diaphysis and to calculate the speed of sound of a wave crossing the structure. Our group has been focusing on the cross-sectional radial imaging process, using ultrasonic computed tomography. Known to be a potentially valuable method of imaging objects with a similar acoustical impedance, difficulties arise when it is proposed to obtain quantitative tomograms of more highly contrasted media (hard bone tissues). Finding solutions here involves either using non-linear schemes and/or performing extensive studies on the limitation of the initial approximation. In this paper, we recall the limits of the ultrasonic computed tomography when dealing with highly contrasted scatterers, using a high-order tomographic method. The performances and limitations are evaluated in the basis of simulated and experimental data, obtained using an ultrasonic scanner, to one geometrical-mimicking phantom and to a real children fibula. Sample thicknesses and speed-of-sound varied as a function of radial position and the experimental procedure fulfilled the criteria of the diffraction tomography. Results are promising and suggest that the geometrical and acoustical characteristics of the bones, which are known to be one of the main factors contributing to the growth bone disease, can be determined using this ultrasonic computed tomography.

Domaines: Acoustique [physics.class-ph]; Acoustique [physics.class-ph]

Philippe Lasaygues, Emilie Franceschini, Régine Guillermin, Jean-Pierre Lefebvre, Nadège Salaud, et al.. Two-dimensional ultrasonic computed tomography of growth bone. IEEE International ultrasonics symposium, 2007, United States. pp.1816-1819. ⟨hal-00440749⟩