Anorectal three-dimensional quantitative ultrasonography – new concept

Introduction: anorectal ultrasonography had a significant advance in the last years. Three-dimensional (3D) ultrasonography might be an important complement to conventional ultrasonography. The systems of 3D image acquisition obtain the images of two elementary dimensions at a established acquisition rate, assuming that the ultrasonography probe is moved at a constant velocity; however, if the movement is made by human hand it is obtained a distorted geometrical 3D image with consequent problems in the morphologic and quantitative 3D analysis.

Aims: to overcome the errors due to human manipulation of the ultrasonography probe during the image acquisition process and create the possibility to quantify different structures and lesions contained in the reconstructed volume.

Material and methods: modular supports for the ultrasonography probes were built allowing easy, fast and correct manipulation in clinical practice. It was conceived a linear dislocation system that assures a constant low velocity probe movement integrated with the existent 3D acquisition and treatment package. It was applied simple reference technique and the Pitágoras theorem in order to allow measurements of linear dimensions and angles to be done. The system was tested in tumour staging, quantification of the response to adjuvant treatment and delineation of abscesses, fistulas and sphincter lacerations.

Results: it was conceived an electromechanical device that assures a constant velocity movement of the ultrasonography probe during the image acquisition phase. Development of a computerized tool that enables measurements to be done in any plane obtained of the 3D image.

Conclusion: we created a complete new system which complements conventional 3D-ultrasonography allowing a correct morphologic and quantitative analysis of structures and lesions of the anorectal area.