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DOI: 10.1055/s-0029-1224030
Functional lumen imaging probe (FLIP) to study the three-dimensional profile of the human sphincter of Oddi (SO)
Introduction: Currently endoscopic perfusion manometry (ESOM) is the gold standard method to evaluate SO motility. However, in biomechanical terms the ability of the SO to seal, distend or release is related to a numerous factors including three-dimensional muscle tone, passive viscoelasticity (ie. resistance), and propulsive peristalsis evoked by perception of bolus transport, which are could not be assessed by ESOM. Our aims were to develop a new method for functional imaging of the SO and to assess the in vivo distensibility of SO with FLIP in a pilot study.
Methods: The FLIP was designed to assess three-dimensional SO geometric profile, SO stiffness and peristalsis. FLIP was constructed as to measure 8 cross-sectional areas (CSA) at 1mm intervals inside a saline filled bag with a maximum of 8mm in diameter. After calibration, the FLIP was stationed in the SO, and during controlled distension the actual time related changes of the three-dimensional geometric profile of the SO was generated by the computer using impedance planimetry. Capillary channels inside the bag were perfused and bag pressure was continuously monitored.
Results: The feasibility and safety of the FLIP method to study SO function assessed in 5 consecutive patients with suspected SOD. The FLIP measurement was successful in all patients without complications. Prophylactic pancreas stents were applied in all patients. Balloon distension was gradually increased from 0 to 70 cmsH20 during 10 minutes. Phasic peristaltic activity of the SO could be visualized at perfusion pressures less than the SO basal pressure (10–15 cmsH20). At higher balloon distension pressures (20–40 cmsH20) different three dimensional distensibility and variable stiffness profile of the SO could be visualized with the FLIP technique.
Conclusions: The FLIP technique is feasible and useful to study patients with SO dysfunction. In addition to parfusion ESOM, FLIP may offer new data to understand SO function, and also may offer better guidance to endoscopic therapy. (Supported by grant EU DIAMARK WP3–2008)