Gastric accommodation and ultrasonography

Dear Sirs, In an interesting review, De Schepper et al. 1 give an overview of current methods to assess gastric accommodation. We will argue that ultrasonography, in this review and in general, is underrated as a tool to investigate gastric accommodation and motility. The authors perform a comparison between different imaging methods. However, they do not take into account spatial and temporal image resolution andwe know that these factors strongly influence the accuracy in volume calculation. Compared with ultrasonography, bothMRI and in particular SPECT imaging, have poor spatial and temporal resolution. Furthermore, the stress-factor of the imaging methods should be considered in this context because dyspeptic patients, in general, and vagal reflexes in particular, are very sensitive to psychological stress. Everyone who has been inside a narrow MR scanner knows how frightening this can be. As pointed out by De Schepper the barostat recording is a quite invasive technique and therefore stressful to the patients. Simply because functional disorders are so strongly associated with psychological factors, the examination should be performed in a quiet and relaxing atmosphere with a minimum of distress. Ultrasonography satisfies these criteria as it is non-invasive and does not by itself induce abnormal physiology in stressresponsive individuals. Two-dimensional ultrasonography has been successfully used to study gastric accommodation in healthy humans and in patients with functional dyspepsia. Another advantage with 2D ultrasonography is its clinical applicability; it can easily be performed bedside and repeated numerous times in the same subject. Regarding 3D ultrasound, we have utilized two different systems for acquisition of 3D ultrasound images: a mechanical and a magneto-based system. Both systems have been validated in vitro and in vivo with very good results. In their introduction, De Schepper et al. state that no single test currently available is capable of measuring all parameters of gastric motility simultaneously (gastric emptying, gastric accommodation, antral motility) . However, many authors have demonstrated that ultrasonography can be used to study not only gastric accommodation, but also gastric emptying, gastric configuration, intragastric distribution, antral motility and distensibility, transpyloric flow, and strain of the gastric wall – many of these even simultaneously. We believe that ultrasonography has a strong potential as a non-invasive clinicalmethod, in particular, in patients with functional dyspepsia where it records relevant parameters to assess impairment of gastric motility and accommodation.