The non-invasive measurement of the ability of Pelvic Floor muscles (PFM) to contract voluntarily can be of clinical value in the assessment and treatment of women with urinary or fecal incontinence. Voluntary contraction of the PFM is also used clinically for rehabilitation of patients with lumbo-sacral back pain. Currently available approaches used to measure PFM strength such as digital palpation; EMG, periniometry, and dynamometry while providing important new information are invasive and have limited anatomic specificity or sensitivity. MR imaging, while providing excellent anatomic representation of abdominal structures, has major limitations in identifying the dynamic response of the PFM to stress inducing forces. (Constantinou et al 2002). Traditional radiographic imaging approaches using video urodynamics have to a large extend been replaced by ultrasound, yielding dynamic information on the morphology of the urogenital organs. In particular perineal, introital and trans-vaginal ultrasound has become an imaging platform for the evaluation of the Pelvic Floor (PF) and for treatment planning of many urogynecological conditions. (Tunn & Petri 2004).
By its nature, ultrasound imaging provides a very large amount of dynamic data that cannot be visually assimilated by the observer in its totality particularly during fast occurring events. Such dynamic events contain information relating the integrity of the supporting structures of the bladder neck, the role of the PFM and the compliance of pelvic floor structures. ( Barbic M, et al 2003). Furthermore, because the urogenital structures are anatomically interconnected, ultrasound based dynamic imaging can substantiate urodynamic observations of the effective distribution of pressure transmission to the urethra. (Constantinou et al 1982.)
Current quantitative measures that are yielded from 2D ultrasound tell us about the resting position of these structures, and their displacement at the end of a particular manoeuvre . These measures so far described do not inform us about how the structures reached their final destination. They are unable to inform us about the direction of the overall movement at a given moment in time, their velocity or acceleration throughout the manoeuvre itself. These parameters maybe important, both in the field of measurement and rehabilitation of the PFM.
It is both a clinical and research observation that strength of PFM does not always correlate to continent state (Morin et al 2004). Many measurement tools for PFM function have quantified PFM strength, however other properties of muscle function such as motor recruitment and speed of contraction, maybe important in defining PFM function and dysfunction
Using perineal ultrasound it was noted clinically (Whelan, M 2000), that there appeared to be subtle differences in the direction of displacement of the urogenital structures some women produced when asked to contract their PFM, and the direction of PFM contraction appeared to be a clinical indicator of rehabilitation outcome.
It is postulated that in order for the PFM to be used more successfully to rehabilitate women with incontinence, there needs to be a well timed, specific contraction (one that supports the urethra), resilient enough to withstand changes in intra-abdominal pressure ( Jo nes, RC 2002, 2003). These other pelvic floor muscle parameters have been discussed and used clinically, however they have little research validity as they have been difficult to quantifiably measure. In view of these considerations, other parameters of PFM function needed to be quantitatively defined and measured.
In order to develop more sensitive measures to define normal PFM function we designed a means of capturing and visualizing the sequence of dynamic changes produced by the PFM on the urethra, vagina and rectum using image-processing methods . The approach taken is to use an edge extraction algorithm to outline the coordinates of the symphysis, urethra and rectum interfaces on a frame -by-frame basis for sequences of stress inducing events such a cough, valsalva and voluntarily induced PF contractions. During each event the trajectory of the boundary of each structure was identified to characterize the sequential history of the ensuing movement. The resulting image analysis was focused to reveal the anatomical displacement of the urogenital structures and to enable the evaluation of their biomechanical parameters in terms of displacement, velocity and acceleration. On the basis of these observations, we expect that the urogenital response to PFM contractions can be quantified and the mechanism through which continence is maintained elucidated. Given that ultrasound imaging contains a considerable amount of useful data, which can be obtained with the minimum of invasion to the patient, it is appropriate to find a way that this information be revealed and displayed quantitatively.
Top of Page  |
Next Project  |
