Gastric Emptying Study

1. Gastric Emptying Study Raj R. Patel, MD Division of nuclear medicine Baylor College of Medicine October 2, 2010

2. About

3. October 2 Mahatma Gandhi ¡Viva La Revolución! Born in 1869 Gonzalez, Texas 1835

4. Today’s Talk • Why does a doctor order the Gastric Emptying Study? • What diseases are most commonly diagnosed? • How to perform the 90-minute Dynamic protocol? • What is the SNM’s new standard 4-hour Static protocol?

5. Why is this study done?

6. Clinical Indications • Unexplained nausea and vomiting • Persistent symptoms after eating in diabetics who must take insulin • Uncontrollable blood glucose in diabetics • Dyspepsia not caused by an ulcer • Severe refluxesophagitis • Assess effect of prokinetic drug

7. Stomach - Anatomy

8. Stomach - Histology

9. Stomach - Physiology • Proximal stomach (fundus) • Muscle relaxes when food is present  Resevoir • Tonic contraction creates constant pressure gradient  Liquid emptying • Greater volume  Higher tonic pressure  Faster contents will leave fundus • Liquid emptying has exponential emptying pattern • Emptying of liquids begin immediately

10. Stomach - Physiology • Distal 2/3rds of stomach (gastric body & antrum) • Grinds remaining food  Makes into chyme  Propels contents to small intestine • Neural pacemaker  Rhythmic contraction • Food become chyme so it can go through pylorus (1-2 mm) • Lag phase before solid emptying • Solids have more of a linear emptying pattern because pyloric opening diameter is fixed

11. Stomach - Physiology

12. Stomach - Physiology • Emptying rate further affected by: • Osmolality • pH • Volume (greater volume  faster emptying) • Caloric content • Makeup of food (protein, fat and carbohydrate) • Time of day • Position • Gender • Medications

13. When it works well

14. Case 1

15. When things go wrong

16. What diseases does this study diagnose?

17. Gastroparesis • Gastric motility disorder that is characterized by delayed emptying in the absence of mechanical obstruction • Symptoms • Refractory nausea (93% of patients) • Vomiting of retained meals • Early satiety and bloating • Upper abdominal discomfort • Note: Rapid emptying may result in similar dyspeptic symptoms

18. Gastroparesis • Epidemiology • 2 population-based studies: 11–18% of diabetics have upper GI dysmotility symptoms (i.e., nausea) • Etiology • 146 gastroparesis patients at UKMC • 36% idiopathic (52 of 146) • Most had acute viral gastroenteritis-like illness, some had GERD • 29% diabetes (42 of 146) • 13% post-gastric surgery (19 of 146)

19. Gastroparesis • Diagnosed by demonstrating delayed emptying in symptomatic patient • First, physician excludes other potential etiologies • Regurgitation caused by reflux disease (GERD) • Cyclic vomiting syndrome • Bulimia • Study needed to establish definite diagnosis of gastroparesis • Lack of histopathologic findings • Gastric Emptrying Scintigraphy is the “Gold Standard” • Other studies: Stable isotope breath test, antroduodenal motility study and EGG

20. Gastroparesis • Treatments • First, correction of hydration and nutrition • Glycemic control if diabetic • Next, prokinetic medications • Metoclopramide (Reglan) • Cisapride • Erythromycin • Finally, surgical intervention • Gastrostomy or Jejunostomy Placement to avoid hospitalizations • Surgical Treatment of Gastroparesis if refractory • Intrapyloric Injection of Botulinum Toxin (new development) • Gastric Electrical Stimulation (new development)

21. Case 2

22. Dumping Syndrome • Rapid gastric emptying • Undigested stomach contents pass too quickly from stomach into small intestine  Jejunum expands too quickly • Causes: gastric surgery, Zollinger-Ellison syndrome, hypoglycemia

23. Dumping Syndrome • Symptoms • Early: Nausea, vomiting, bloating, cramping, diarrhea and fatigue • Late: Weakness, sweating, and dizziness • Diagnosed by upper GI barium study or gastric emptying scintigraphy • Treatment • Lifestyle modification • Medication • Surgery

24. Conventional Protocol 90-minute Dynamic protocol

25. Dynamic protocol

26. Contraindications But first… • Anything by mouth within 4 hours • Opiates (Vicodin, “codeine”) and benzodiazepines (Xanax, Valium) • Antispasmodic agents (dicyclomine, hyoscyamine) • Atropine, progesterone and octreotide • Prokinetic agents like metoclopramide (Reglan), cisapride and erythromycin • Unless the test is done to assess the efficacy of these drugs • Theoretically, any of the above within the last 2 days • Practically, any of the above within the last 4 hours

27. Dynamic protocol • Been the conventional protocol • It is what NMT’s and MD’s learn in training • Mettler and Guiberteau (2006) textbooks and Zeissman article (2004) advocate using 90 minute protocol: better evaluates stomach and esophagus physiology • Differences from SNM’s 4-hour Static protocol • Patient may be imaged upright or supine • Continuous dynamic acquisition until half of gastric activity is gone or 90 minutes • Consensus normal T1/2 is 60 min ± 30 min (30-90 min)

28. Dynamic protocol – Patient preparation • Stop prokinetics, opiates and anticholinergics 2 days prior • Overnight fast • If patient has diabetes • Fasting glucose should be < 275 mg/dl • When meal ingested, administer insulin at ½ usual dose

29. Dynamic protocol – Meal prep & ingestion • 4 oz.(120 gm, approximately 2 large eggs) egg white • Egg Beaters® or generic equivalent • Radiolabeled with 0.5 -1 mCi Tc-99m sulfur colloid • 255 kcal; 72% carbohydrate, 24% protein, 2% fat and 2% fiber • Cooked on a hot skillet or in microwave • 2 slices of white bread (120 kcal) • Strawberry jam (30 g, 74 kcal) • Water (120 ml)

30. Dynamic protocol – Acquiring the Image • Gamma camera • Centered at 140 keV, ±10% window • ANT/POST if dual head camera • LAO if single head camera • LEAP collimator ideal because maximizes counts • LEHR parallel-hole collimator is alternative • Adult or child sits upright or lies supine • Infant lies supine

31. Dynamic protocol – Analyzing the data • Draw ROI around stomach, which includes pylorus • If ANT/POST projection • Program will do Geometric Mean correction (ANT counts X POST counts)1/2and correct for Tc-99m decay (~6 hr half life) • If LAO projection, no correction is done

32. Dynamic protocol – Reporting the info • Data plotted on graph with T (time) represented on x-axis and gastric counts represented on y-axis • Program will draw T1/2 or calculate half-emptying time using exponential fit method

33. Dynamic protocol – What we docs report • The basics • T1/2 • Abnormal findings on images or graph • About the patient • Amount of meal ingested and time it took • Problems like vomiting • If he has diabetes, what was his last fasting blood glucose • Medications that affect gastric emptying

34. Case 3

35. New Standard Protocol 1, 2, 3 and 4-hour Static Protocol (2007 consensus protocol) (a.k.a., Tougas Protocol)

36. Why New Protocol was Adopted • 1995 Thomforde paper says scintigraphic images at 3 or 4 hour are clinically useful • Improves accuracy and specificity of diagnosing gastroparesis • Scintigraphic images up to 90 min after the meal is eaten leads too often to estimated T1/2 based on mathematical extrapolation of data rather than objective measurements

37. Why New Protocol was Adopted • Tougas et al did an international study of 123 normal patients in 2000 looking at how much was retained in gastric emptying studies after 1 mCi of Tc-99m SC in 120 g of egg, 2 toasts and strawberry jam • Conclusion: 4 hour study detects more cases of delayed gastric emptying than 2 hour study • Sensitivity of 2 hr is much lower than at 4 hr (59%) • Houston, we have a problem

38. Why New Protocol was Adopted • Crossovers • 13% of patients with normal emptying at 2 h  delayed emptying at 4 h • 24% of patients with delayed emptying at 2 h  normal emptying at 4 h • No consensus on how to deal with crossovers • May not get to patient at exactly 1, 2, 3 and 4 hours after eating • No control of what patients do in-between

39. Why New Protocol was Adopted • Quoting 2009 paper on management of severe gastroparesis in Clinical Gastroenterology and Hepatology: “Before formulating a management plan for patients with suspected gastroparesis, it is crucial to establish the diagnosis of delayed gastric emptying. The current gold standard is the gastric emptying scintigraphy test. The American Neuro-gastroenterology and Motility society as well as the Society of Nuclear Medicine recommend a 4-hour gastric emptying assessment using radiolabeled low-fat (2%), egg-beater meal with anterior and posterior imaging of the stomach every hour with the patient standing, walking, or sitting between images…

40. Why New Protocol was Adopted “Retention of more than 10% at the end of 4 hours is the diagnostic criteria for gastroparesis, with more than 60% retention at the end of 2 hours providing additional support. We invariably see patients referred to us labeled as delayed gastric emptying based on the 90-minute gastric emptying study performed with varying meal compositions who are in turn shown to have a normal 4-hour gastric emptying scintigraphy test using the standardized meal described earlier. We therefore endorse and re-emphasize that performing a 4-hour standardized gastric emptying study is the current standard of care to make the diagnosis of gastroparesis…”

41. Why New Protocol was Adopted • Study in 2000 by Tougas et al established new normals • At 60 min, 10-14% gastric contents should be emptied (95th or 90th percentile or 2 SD and 1.65 SD) • At 120 min, 40-50% gastric contents should be emptied • In 2007, SNM and American Neurogastroenterology and Motility Society came together and advocated these normals in their 2007 Consensus Protocol • At 60 min (1 h): 37-90% • i.e., 10% of stomach contents should be gone by 1 hour • At 120 min (2 h): 30-60% • At 240 min (4 h): 0-10% • i.e., 90% of stomach contents should be gone by 4 hours

42. Consensus 2007 Protocol

43. 4-h Static protocol – Patient preparation • Stop prokinetics, opiates and anticholinergics 2 days prior • Overnight fast • If patient has diabetes • Fasting glucose should be < 275 mg/dl • When meal ingested, administer insulin at ½ usual dose

44. 4-h Static protocol – Meal prep & ingestion • 4 oz.(120 gm, approximately 2 large eggs) egg white • Egg Beaters® or generic equivalent • Radiolabeled with 0.5 -1 mCi Tc-99m sulfur colloid • 255 kcal; 72% carbohydrate, 24% protein, 2% fat and 2% fiber • Cooked on a hot skillet or in microwave • 2 slices of white bread (120 kcal) • Strawberry jam (30 g, 74 kcal) • Water (120 ml)

45. 4-h Static protocol – Acquiring the Image • Gamma camera • Centered at 140 keV, 20% window • ANT/POST projection with dual head camera – No LAO • LEAP collimator ideal because maximizes counts • LEHR parallel-hole collimator is alternative • Adult or child sits upright or lies supine • Infant lies supine

46. 4-h Static protocol – Analyzing the data • Draw ROI around stomach, which includes pylorus, in each data set (ANT and POST datasets at 1, 2, 3 and 4 hours) • Program will do Geometric Mean correction (ANT counts X POST counts)1/2and correct for Tc-99m decay (~6 hr half life)

47. 4-h Static protocol – Reporting the info • Data plotted on graph with T (time) represented on x-axis and gastric counts represented on y-axis • Program may state %age of stomach contents (i.e., counts) emptied at 1, 2, 3 and 4 hours Contents retained: 1 hour: < 90% 2 hours: < 60% 3 hours: < 30% 4 hours: < 10%

48. 4-h Static protocol – What we docs report • The basics • Gastric contents emptied at 1, 2, 3 and 4 hours • Abnormal findings • About the patient • Amount of meal ingested and time it took • Problems like vomiting • If he has diabetes, what was his last fasting blood glucose • Medications that affect gastric emptying

49. Hybrid Protocol Comibining dynamic and 4-hour static

50. Hybrid Protocol • Stop prokinetics, opiates and anticholinergics • Overnight fast • If patient has diabetes • Fasting glucose should be < 275 mg/dl • When meal ingested, administer insulin at ½ usual dose • 4 oz.(120 gm) of Egg Beaters® egg white • Radiolabeled with 0.5 -1 mCi Tc-99m SC • Cooked on a hot skillet or in microwave • Water (120 ml)