Gastric Emptying Study

• Tc-99m Sulfur colloid is the tracer

  • T1/2 = 6 hours

  • Note that a typical gastric emptying scan goes on for 4 hours, so you need to correct for radiotracer decay in order accurately asssess the radiotracer amount

• Administration

  • Diet provided matters, high carb = faster transit, high fat & protein = slower transit

  • Required diet

    • 1 mCi of Tc99 sulfur colloid

    • 4 oz egg whites only

    • 2 slices of bread

    • 30 g of jam

    • 120 ml water

• Images taken at

  • 1 minute after administration

  • 1 hour

  • 2 hour

  • 4 hour

  • Images taken with the patient standing in anterior and posterior views- and then geometric means can be performed (math shit) to estimate the amount of tracer in the stomach

  • When you use a dual head gamma camera, the anterior and posterior pics are obtained at the same time

  • If only have one camera

    • Take anterior image immediately followed by posterior image

    • Second best option would be to take a left anterior oblique pic

• Diabetics

  • Schedule them early in the morning

  • Instruct them to take 1/2 their normal insulin dose

  • If on oral diabetic med, take it shortly before the meal

  • If fasting glucose > 200, reschedule, hyperglycemia can cause delayed gastric emptying

• Need to stop drugs that influence gastric emptying beforehand

  • Drugs delaying gastric emptying

    • Narcotics including morphine

    • Calcium channel blockers

    • Antacids

    • Anticholinergic meds

  • Drugs that will increase gastric emptying

    • Metoclopramide

    • Domperidone

  • Ondansetron = no significnat effect = ok to use for nausea and shit