Gastric evacuation scintigraphy

A practical guide for referring physicians

gastic-emptyingPrinciple and method

Gastric emptying scintigraphy (gastric emptying study) is a standard functional radionuclide examination for assessing gastric motility and emptying rate. It involves the oral administration of a test meal (standardised solid or liquid food) mixed with a 99mTc-labelled radiopharmaceutical (most commonly 99mTc-DTPA).

Dynamic scintigraphy is used to record the decrease in radioactivity in the stomach over time, which allows for an objective calculation of the evacuation half-life (T½) and comparison with normal values. The examination provides physiological information about the function of the stomach under real digestive conditions.

Main clinical indications

  • Gastroparesis
    • diabetic (the most common cause of gastric evacuation disorders),
    • post-infectious, post-surgical, idiopathic.
  • Upper dyspeptic symptoms of unclear aetiology
    • feeling of fullness, nausea, vomiting, abdominal pain, flatulence.
  • Assessment of gastric motility in neurological diseases
    • Parkinson's disease, systemic sclerosis, amyloidosis.
  • Postoperative conditions
    • after gastric resection, vagotomy, bariatric surgery (especially for the assessment of dumping syndrome).
  • Research and experimental indications
    • evaluation of the effect of drugs affecting motility (prokinetics, opioid analgesics, anticholinergics).

Interpretation 

  • Normal findings: with standard solid food (e.g. egg omelette with 99mTc), physiological emptying of 50% of the content occurs within 90 ± 15 minutes, with complete evacuation within 3–4 hours.
  • Pathological delay: retention >60% after 2 hours or >10% after 4 hours.
  • Accelerated evacuation: typically in dumping syndrome or after surgery.

The advantage over other methods (X-ray passage, breath tests, ultrasound, MRI) is its quantitative nature and more physiological conditions.

Practical information for the referring physician

  • Patient preparation:
    • fasting for at least 6 hours,
    • discontinuation of medications affecting motility (if clinically possible) at least 48 hours before the examination.
  • Test meal:
    • standardised solid food (I would write what we actually give) or liquid phase (99mTc-DTPA in water).
  • Examination duration:
    • dynamic imaging usually 60–120 minutes, sometimes up to 4 hours depending on the protocol.
  • Radiation exposure:
    • low, <1 mSv.
  • Contraindications:
    • pregnancy, inability to cooperate (e.g. vomiting, inability to eat the test meal).

Summary for practice

Gastric evacuation scintigraphy is:

  • the gold standard for assessing gastric motility,
  • key in the diagnosis of gastroparesis (especially diabetic),
  • also suitable for assessing dumping syndrome and motility disorders after surgery,
  • a quantitative method with low radiation exposure and a good cost/benefit ratio.

Correct indication and a standardised protocol ensure high informative value and an irreplaceable place for this method in clinical practice.