Aim: This study was undertaken to investigate the extent of variation in meals, radiopharmaceuticals and methodology used for gastric emptying studies in the UK.
Materials and methods: Overall, 178 nuclear medicine departments across the UK were contacted by telephone and the gastric emptying protocol was requested. In all, 128 (72%) performed routine gastric emptying studies; 83 protocols were received.
Results: Liquid meal gastric emptying: 15 departments performed liquid gastric emptying either as a dual isotope technique (27%) or as a separate test using Tc-diethylenetriamine pentacetic acid (53%) or Tc-colloid (20%). The radiopharmaceutical was administered in a variety of liquid mediums including water, orange juice/squash or milk. Although dynamic acquisition was most often used for liquid gastric emptying (60%), significant number of departments used static images (40%). Solid meal gastric emptying: Tc was the radioisotope most predominantly used for solid meals (98%). Tc-colloid was the most commonly used radiopharmaceutical (38%), followed by macroaggregated albumin (25%) and diethylenetriamine pentacetic acid (23%). Egg-based meals are most popular (59%) followed by porridge (27%) that was also used as an alternative to egg in some departments. Alternative meals (cooked meals, ready meals, All-Bran, Weetabix, etc.) were used in 22% of the surveyed departments. Patient preparation and positioning: There was a wide range in patient preparation and methodology used. Patients fasted between 2 and 12 h for the test. Overall, 55% departments acquire images with patient sitting or standing. Although 45% of the departments acquired images supine, most allowed patients to stand or walk in between the images, and only 22% performed the entire test with patient supine. Acquisition parameters: 58% of departments used intermittent static images with intervals ranging from 5 to 15 min, followed by hourly static images of up to 4 h. Twenty-five per cent of departments used dynamic acquisition images. Seventeen per cent of departments used a combination with early dynamic study followed by static images. Normal ranges: There was a wide variation in the normal ranges used for reporting. Most departments used 50% emptying time to assess gastric function. The maximum normal range values for solid gastric emptying ranged from 60 to 120 min, with four departments relying on the percentage of activity remaining at 4 h (normal<10%). Liquid gastric emptying also had a wide range of values for the normal range. The most commonly used range for liquid gastric emptying was 40-60 min.
Conclusion: There is a wide variation in radiopharmaceuticals, meals and the methodology used for gastric emptying studies. Solid meal gastric emptying is performed universally by all the departments, while relatively few performed liquid meal gastric emptying. Our survey shows that egg-based meals are most prevalent, followed by a porridge meal. Intermittent static imaging is also the most popular method of imaging. In view of this audit, it would be prudent to establish a protocol for solid meal gastric emptying on the basis of the most commonly used meals and methods that may then be universally acceptable. We propose to undertake a study to establish normal ranges for these meals (egg meal and porridge), using the most accepted imaging methodology in an attempt to establish a standardized normal range and acquisition method for solid gastric emptying studies in the UK.