The evaluation of a gastric bile probe

The purpose of this study was to validate a new technique for measuring duodenogastric bile reflux in the human subject. A custom built cadmium telluride gamma detector (Radiation Monitoring Devices, Mass), small enough to be passed into the oesophagus and stomach, was developed and tested for sensitivity to 99Tcm and 75Se radioisotopes. When immersed in radiolabelled water, the detector was capable of measuring gamma radiation in quantities as low as 0.1 microCi (0.0037 MBq) per ml. Two patients (A and B) with endoscopically proven bile reflux, and three normal volunteers (C, D and E) underwent oesophageal manometry to map the position of the lower oesophageal sphincter (LOS). The gamma probe was passed via the nose, to a position in the gastric fundus, 5 cm below the LOS. Each subject was placed supine under a gamma camera (Siemens LFOV 37 ZLC head), centred on the epigastrium. A 4 mCi (148 MBq) dose of radiolabelled 99Tcm-HIDA was administered intravenously, and simultaneous internal/external scanning was performed for between 45 and 90 min. Internal gamma probe data was transferred by a screened cable to a Memolog 600 portable recorder, using a 5 s counting interval, and from the gamma camera to a Nodecrest Micas III computer, using a 15 s counting interval. Gamma camera counts from a region of interest over the fundus of the stomach were then correlated with counts from the internal probe using a linear regression analysis program on the Nodecrest. The internal gamma probe functioned well at body temperature in the acidic gastric environment. Radiolabelled bile refluxed into the stomach during HIDA scanning in three out of the five subjects (one patient and two normal volunteers). There was a strong correlation between internal and external gamma counts (A, r = +0.79; C, r = +0.53; E, r = +0.54; P greater than 0.01). In the other two cases, there was no bile reflux, but still a significant correlation between internal and external gamma counts (B, r = +0.89; D, r = +0.75; P greater than 0.01). The mean correlation coefficient for the series of five cases was +0.70. We conclude firstly that the newly developed internal gamma detector is capable of measuring the reflux of radiolabelled bile into the human stomach and, secondly, that bile reflux may occur in normal subjects as well as those with upper gastrointestinal pathology.