Despite this recommendation, scintigraphy is still not well standardized. Low nutrient liquids should Y-27632 nmr not be used to quantify gastric emptying for diagnostic purposes since they do not stimulate small intestinal feedback mechanisms which retard gastric emptying. Contrary to what is generally assumed, there is little, if any, evidence that the use of high nutrient
liquid, or semi-solid, meals is inferior to solids. Moreover, the concurrent measurement of solid and nutrient liquid emptying adds diagnostic value, since, as shown in the original study, the relationship between gastric emptying of solids and nutrient liquids is poor in diabetes.20 If carbohydrate is included in the meal the relationship between glycemic response and the rate of gastric emptying can be evaluated. Another non-invasive method for assessing gastric emptying is the stable isotope breath test. This uses 13C-acetate or 13C-octanoate as a label and, in contrast to scintigraphy, does not involve exposure to ionising radiation. It has good reproducibility and the results have been reported to correlate well with scintigraphy, with a sensitivity and specificity of 86% and 80%, respectively, for the presence of delayed gastric emptying,26 including in a diabetic population. Following ingestion, the labelled meal passes through the stomach
to the small intestine, where the 13C-acetate or 13C-octanoate Megestrol Acetate is absorbed, metabolized into 13CO2 in the liver and exhaled via the breath.13 CO2 in breath samples is analyzed by mass spectrometry. While this technique has MLN0128 manufacturer advantages over scintigraphy, information relating to the validity of breath tests
in patients with markedly delayed gastric emptying is limited. Transabdominal ultrasound is a simple, non-invasive, inexpensive and convenient method to assess gastric distension, antral contractility, transpyloric flow and gastric emptying and is uniquely able to measure the latter three parameters simultaneously.18 However, the necessity for considerable expertise, and technical limitations of obesity and abdominal gas, restrict its widespread use. While 2-dimensional ultrasonography provides an indirect measure of gastric emptying which is determined by changes in antral area over time,27 the more recently applied 3-dimensional ultrasonography has the capacity to provide comprehensive imaging of the stomach, including information about intragastric meal distribution. It has also been validated against scintigraphy to measure gastric emptying in both healthy subjects and patients with diabetic gastroparesis.28–31 Magnetic resonance imaging (MRI) has also been used to measure gastric emptying and motility with excellent reproducibility.18 However, its use is limited to research purposes because of its high cost and limited availability.