GIQuant - Bowel motility analysis
The raw dynamic data
A major barrier for the application of motility analysis with MRI lies in the analysis of these images which until recently has been done subjectively by visually assessing the raw data or with manual annotation of single bowel loops. This is time consuming and unsuitable for clinical practice.
The dynamic series seen above can be acquired on any modern MRI scanner providing an excellent physiological view of the small bowel peristalsing.
This process is essential for mixing our food and moving it along through the gastrointestinal (GI) tract. MRI is safe, well tolerated by patients and non-invasive making it an excellent modality for physiological investigations of the bowel.
The Image registration
GIQuant is a image processing software developed to facilitate the analysis of dynamic image series using image registration. The registration process warps each image in the time-series to a target 'reference' image producing a deformation field for each time point.
These deformation fields can be visualised as a grid with higher changes in deformation apparent in the small bowel compared to the liver. These deformation fields are exceptionally useful for motility analysis to both automatically propagate regions of interest (ROIs) and to produce parametric motility maps.
A parametric map is a form of quantitative representation of some aspect of the raw data which, in this case, is motility in the small bowel.
A parametric motility map shares a 1:1 relationship with the reference image making ROI analysis in any DICOM browser easy with the numerical value of the map representing the magnitude of small bowel motility at that location. We summarise motility by taking the standard deviation of the Jacobian determinant of the deformation field. This metric has been widely published but is quite abstract, for more information on what the SD Jacobian metric is, and how to interpret it, feel free to contact us or see the original publication by Odille et al.