Joint Program in Nuclear Medicine

Gastric Emptying Scintigraphy

Alexander Matthies, MD 
Kevin J. Donohoe, MD

January 6, 1998

Presentation

A 26 year old female with IDDM presented with nausea and the sensation of abdominal fullness. Abdominal ultrasound and upper GI series with contrast were unremarkable. The patient was started on metoclopramide without improvement in her symptoms.

Imaging Findings

Gastric emptying scintigraphy revealed a markedly prolonged lag phase with subsequent rapid emptying (anterior dynamic images and posterior dynamic images; anterior images and posterior images as a montage). Gastric activity is calculated from the geometric mean of the counts over the stomach on anterior and posterior images (anterior, posterior, and geometric mean curves). Although the lag phase was markedly prolonged, the gastric half-emptying, 54 minutes, was near normal.

Discussion

Abnormalities in gastric emptying have been documented in a wide variety of clinical conditions. Patients usually present with non-specific symptoms such as intermittent or constant nausea, vomiting, bloating, post-prandial abdominal pain. Initial work-up usually includes plain X-rays, abdominal ultrasound, upper GI series with contrast and/or upper GI endoscopy. These studies are used to rule out mechanical causes like tumors or other anatomic pathologies. If these modalities fail to explain the patient's symptoms, motility disorders should be considered.

Gastric emptying scintigraphy was introduced in 1966 by Griffith et al. (1) and was further developed during the following decade. Despite the advances in radiology, endoscopy, and manometry in recent years, scintigraphy remains the gold standard for evaluation of gastric emptying due to its physiologic approach, ease of use, and quantitative results.

The association between symptoms and proven anatomic gastro-intestinal abnormalities is not consistent and often results in a confusing clinical picture (2). In this setting gastric emptying scintigraphy can demonstrate or exclude actual functional pathology as well as document success or failure of treatment.

Technique:

Gastric emptying scintigraphy requires the patient to fast for at least 12 hours. For baseline studies it is desirable that the patient is on no medication, that can influence the gastric motility. Frequently, however, stopping such medication may not be possible.

A variety of test meals have been used, including eggs, oat meal and beef stew etc., most often labeled with Tc-99m sulfur colloid. It is important to use a standardized meal since emptying depends on a several factors, including particle size, viscosity, and protein/fat/caloric content.

Dual isotope imaging has also been applied, using the same solid meal components together with In-111 labeled water (3). However only a very few patients have isolated liquid emptying abnormalities and the solid test meal has a higher sensitivity for the detection of delayed emptying than a liquid only emptying study.

Imaging is best performed with a dual headed camera system, which allows simultaneous anterior and posterior acquisition. Simultaneous acquisition allows documentation of movement of the meal moves from the more posterior located fundus to the anterior located antrum. Calculation of the anterior-posterior geometric mean is the preferred way to display emptying data. Using dynamic acquisition with 1 frame/minutes (instead of multiple static views every 5-15 minutes) provides information about the movement of the meal within the stomach. As documented by the described case, dynamic acquisition can reveal abnormal motility even if the half-emptying time is normal or near normal.

Causes:

Conditions that lead to abnormal gastric emptying are:
  1. Neurogenic
    1. Postsurgical (esp. vagotomy with/without partial/subtotal gastrectomy, etc.)
    2. Diabetes
    3. Medication/Drugs
    4. Infection (Trypanozoma cruzi, VZV, EBV)
    5. Neurologic disorders (Stroke, Multiple sclerosis)
  2. Myogenic
    1. Scleroderma/Polymyositis/SLE
    2. Progressive muscular dystrophy
    3. Amyloidosis
  3. Other etiologies
    1. Zollinger Ellison Syndrome
    2. Gastritis/Peptic ulcer disease
    3. Anorexia nervosa
    4. Endocrine disorders (Hypothyroidism, CRF)
    5. Abdominal Radiation
  4. Idiopathic

Incidence:

The exact incidence of abnormal gastric motility is not known. It is common in diabetic patients. Keshavarzian et al. (4) found delayed gastric emptying in 27% of patients with IDDM for more than 5 years. Diabetic patients pose a particular problem for clinicians, as a delay in gastric emptying has a severe impact on blood sugar control with hypo- or hyperglycemic episodes as consequence.

Therapy:

For these and other patients with delayed gastric emptying the therapeutic options have increased in recent years. In addition to metoclopramide and erythromycin, cisapride and - to a lesser extent - domperidone have been shown to be effective in a significant number of patients.

References

1) Griffith GH, Owen GH, Kirkman S, et al.: Measurement of Rate of Gastric Emptying Using Chromium-51. Lancet 1966; 1:1244-1245

2) Lin H., Hasler W. (p.1318-1346) in: Textbook of Gastroenterology 2nd edition, Lippincott, 1995

3) Urbain J.-L., Vekemans M.-C., Malmud L. (p 733-747) in: Diagnostic Nuclear Medicine, 3rd edition, Williams and Wilkins, 1996

4) Keshavarzian A et al.: Gastric Emptying in Patients with Insulin- Requiring Diabetes Mellitus Am. J Gastro 1987, 82: 29-35

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J. Anthony Parker, MD PhD, Tony_Parker@bidmc.harvard.edu