The FXA-Method combines
state of the art digital image processing, object recognition and orientation algorithms and utilizes vector and matrix math to compute and quantify relative motion within medical images.
How does FXA work?
Behind the scenes of the FXA-Software
The analysis of the x-ray, computer tomographic (CT) or magnetic resonance images (MRI) is essentially carried out in five steps:
1.First, the images (for example in DICOM, JPG or TIF format) are imported into the FXA software and a manual selection of the areas of interest is made.
The selection may be, for example, vertebrae, bony structures or implants.2.The FXA software then processes the images with state of the art filters and procedures known from digital image processing. Hereby unwanted noise is reduced and the image clarity and definition is improved.
3.In the third step, each preselected object is overlaid between the various images and moved, scaled and rotated through a patent pending matching algorithm.
The main advantage of our proprietary algorithm is that the matching works independent of manual landmark placement, contour identification routines or a manual alignment between the images. For this reason, the analysis results of the FXA-method are operator independent and foster a reliable reproducibility. Furthermore, this algorithm is (to a certain level) robust against projection errors due to out-of-plane effects and can inherently compensate for these.4.As a result of the matching process, the FXA software calculates translations, rotations and scaling factors and evaluates the differences amongst the objects of interest. Out of these differences, the relative motion can be calculated and quantified. The centers of rotation (CoR) can be determined utilizing the method described by Franz Reuleaux.
5.In the last step, the analysis results are processed in order to visualize the relative motion using animated images. An analysis report is prepared, which includes a statistical representation of the results, along with an assessment of the image quality and matching accuracy. The results are stored in a database and sent to the physician or CRO (online or by email) requesting the data.
Which computing power is necessary for this?
The filtering process (wavelet filters) and the matching process is very demanding on CPU power. A typical application with three spinal motion segments takes about 15 min on a computer equipped with a Core i7 CPU with 8 CPU cores. The total processing time of a typical analysis case takes up to 2h.
Utilizing a web interface, special hardware and increasing automation of the FXA-software will allow us to speed this process up so that it should take less than 30 minutes in the near future.Copyright © 2012 ACES GmbHto the top


