Enhanced Gastric Emptying Scintigraphy to Assess Fundic Accommodation Using Intragastric Meal Distribution and Antral Contractility

Determination of fundic accommodation in gastric emptying scintigraphy. Evaluation of its clinical usefulness

AIM

Gastric emptying scintigraphy is used to assess patients with symptoms of dyspepsia or gastroparesis. An alteration of fundus accommodation may explain these symptoms. The aim of this study was to determine the accommodation in gastric emptying scintigraphy studies performed in our institution.

MATERIAL AND METHODS

50 patients (43 children) referred for gastric emptying assessment were evaluated. After fasting for 8 h, and following international guidelines, egg labeling was performed with 37 mBq of [99mTc]Tc-DTPA and administration of standardized food. Areas of interest were defined in the stomach at different times, and the corresponding retention percentages were calculated. Considering the image at time zero, gastric accommodation was qualitatively and quantitatively assessed, calculating the ratio between proximal stomach counts and total counts.

RESULTS

Of the 50 patients studied, 32 had normal emptying, 10 had slowed emptying and 8 had accelerated emptying. Within the group of patients with normal emptying, 8 had altered accommodation (25%) and another 8 in the group with abnormal emptying (44%). Applying the ROC curve analysis to quantitative values, the most appropriate cut-off value was 0.785 with p < 0.001, sensitivity 82.4% and specificity 100%.

CONCLUSION

Gastric emptying scintigraphy in addition to determining motility, made it possible to assess both qualitatively and quantitatively the distribution of the radiotracer in the stomach and thus, indirectly, the accommodation in the fundus. It provided added diagnostic information in a simple manner, without protocol changes and allowing more specific treatments to be assessed.

Randomized, crossover trial: comparing the effects of standardized egg-white meal and Vital® on global gastric emptying parameters and intragastric meal distribution in healthy Asian participants

BACKGROUND AND AIM

Measurements of gastric emptying and accommodation for alternative test-meal protocol during gastric emptying scintigraphy (GES), such as high-calorie nutrient drinks, are not fully established. We aimed to compare the effects of standardized egg-white meal (EWM) versus high-calorie nutrient drink (Vital®; Abbott Laboratories) on global GES parameters and intragastric meal distribution at immediate scan (IMD0h).

METHODS

Of 84 screened participants, 60 asymptomatic healthy Asian population (38 females; 24.0 ± 1.5 years; 23.8 ± 2.6 kg/m2) were recruited in this 2 × 2 (AB/BA) crossover trial. Participants were randomized to a 4-h GES with 99mTc-radiolabeled EWM (~255.8 kcal), followed by a 200 mL Vital® (300 kcal), or vice versa, separated by a 2-week washout period. Global meal retention (GMR), power-exponential model emptying parameters (half-emptying [T1/2], lag phases [Tlag2%, Tlag5%, Tlag10%]), and IMD0h were determined and compared.

RESULTS

GMRs for both test meals were within the international standard references for solid GES. Compared to EWM, Vital® exhibited significantly lower GMRs (faster emptying) from 0.5 to 3 h (all P < 0.001) but comparable at 4 h (P = 0.153). Similar observations were found for the model-based T1/2 and the different Tlag thresholds (all P < 0.001). Furthermore, IMD0h was found to be lower with Vital®, indicating lower gastric accommodation (faster antral filling) immediately post-ingestion (P < 0.001). Both test meals showed significant moderate-to-strong positive associations at the late-phase GE (GMR 2-4 h, T1/2) (all P < 0.05).

CONCLUSIONS

Overall, Vital® is an acceptable alternative test meal to the EWM for GES; however, exercise caution when interpreting early-phase GE. The normative values for global GES parameters and IMD0h are also established.

Extensive scintigraphic gastric motor function testing with concurrent symptom recording predicts prospectively measured daily dyspeptic symptoms

BACKGROUND

Absent "organic" disease, dyspeptic symptoms may arise from abnormal gastric sensation, accommodation, motility or emptying (GE). Extensive gastric sensorimotor evaluation is rarely undertaken because testing is prolonged, invasive, poorly tolerated or unavailable.

AIMS

To investigate whether gastric antral motor function, evaluated with scintigraphy, predicts GE. To explore whether motor testing with symptom recording predicts day-to-day symptoms in patients with dyspepsia.

METHODS

GE was determined using a scintigraphic solid-meal protocol (296 kcal, 35% fat). Antral motility was estimated from 10 min of scintigraphic time-activity curves acquired 40 min after meal consumption. An antral motility index (MI) was derived from contraction amplitude and frequency. Intra-gastric distribution of the meal on scintograms at 1 h (IGD1) was determined. Meal-induced symptoms were evaluated by questionnaire. Patients completed the Gastroparesis Cardinal Symptom Index Daily Diary (GCSI-DD) for 14 days.

RESULTS

Twelve healthy participants and 23 prospectively recruited patients completed the study. Nine patients had delayed, and 2 had rapid, GE. In univariate analysis MI explained 42% of GE half-time. In multivariate analysis MI and GE half-time explained 25% of the variance in meal-induced symptoms. While scintigraphic evaluation of gastric motor function with symptom recording explained 80% of the variance in the GCSI-DD, meal-induced symptoms were the only significant predictor. However, among patients with delayed GE, MI, GE half-time, IGD1, and meal-induced symptoms all significantly predicted GCSI-DD.

CONCLUSIONS

Antral motility predicts GE. In exploratory analyses, only meal-induced symptoms predicted daily symptoms among patients with dyspepsia. However, motor function also predicted symptoms in patients with delayed GE.

Fourier Phase Analysis of Dynamic Antral Contraction Scintigraphy: New Software, Reference Values, and Comparisons to Conventional Gastric Emptying

Dynamic antral contraction scintigraphy (DACS) has been used to evaluate for gastric dysmotility by measuring antral contraction frequency and ejection fraction (EF). Fourier phase image analysis has the potential to assess gastric antral contractions for dyssynchrony as has been used for analyzing nuclear cardiology ventriculography (multigated acquisition studies) for cardiac dyssynchrony. The aims of this study were to determine whether Fourier phase analysis helps to characterize antral motility physiology, whether Fourier phase analysis correlates with conventional gastric emptying scintigraphy (GES), and which DACS parameters may aid in diagnosing gastric dysmotility, particularly delayed gastric emptying (GE). Methods: DACS and GES of healthy volunteers (n = 22) were compared with patients (n = 99) with symptoms of gastroparesis. New DACS Fourier phase analysis software was developed. Results: GE was delayed (n = 53) or normal (n = 46) in patients. There was a linear correlation between the time for the stomach to empty 50% of the meal and the percentage total proximal and distal in-phase antral pixels at 30 min (r = 0.37, P = 0.0001) and 60 min (r = 0.26, P = 0.007). In healthy volunteers, the mean proximal-to-distal ratio of in-phase antral pixels increased from 1.67 (30 min) to 2.65 (120 min) (P = 0.035), and EF increased from 23% (30 min) to 32% (120 min) (P = 0.022). Multivariable regressions of percentage total proximal and distal in-phase antral pixels (30 min) and EF (60 min) were the best predictors of abnormal GE (adjusted odds ratio, 3.30 [95% CI, 1.21-9.00] and 2.97 [95% CI, 1.08-8.21], respectively). Conclusion: This study used Fourier phase analysis to analyze DACS in healthy volunteers and patients with symptoms of gastroparesis. In addition to establishing reference values, new physiologic information on antral motility was obtained. In healthy volunteers, there was an increasing proximal-to-distal ratio of in-phase antral pixels and antral EF over time after meal ingestion. The percentage total proximal and distal in-phase antral pixels at both 30 and 60 min correlated well with GE values for the time for the stomach to empty 50% of the meal. For symptomatic patients, the percentage total proximal and distal in-phase antral pixels at 30 min and the EF at 60 min after meal ingestion correlated with delayed GE on conventional GES. Thus, Fourier phase analysis of DACS appears to have potential to further aid in diagnosing gastric dysmotility in GES.

The role of gastric function in control of food intake (and body weight) in relation to obesity, as well as pharmacological and surgical interventions

PURPOSE

The objectives of this review are to summarize the role of gastric motor functions in the development of satiation (defined broadly as postprandial fullness) and satiety (reduced appetite or postponing desire to eat after a meal) and their impact on weight change. The specific topics are the methods of measurement of gastric emptying and accommodation and their impact on food intake, satiation, and satiety. A second focus contrasts bariatric surgery to endoscopic gastroplasty that alter gastric emptying and incretin responses in markedly divergent manners.

BACKGROUND

The hormone, GLP-1, retards gastric emptying and increases gastric accommodation through vagally-mediated effects. Indeed, these effects provide the basis for the association of altered gastric emptying in the appetite and weight loss responses to pharmacological interventions particularly by those acting on receptors of incretin agonists such as liraglutide and the dual agonists, tirzepatide and cotadutide, all of which retard gastric emptying. In fact, retardation of gastric emptying and gastrointestinal adverse effects have been shown to contribute in part to the weight loss in response to this class of pharmacological agents.

SUMMARY

The motor functions of the stomach are relevant to postprandial fullness and to interventions aimed at weight loss in people with obesity.

Abnormal gastrointestinal motility is a major factor in explaining symptoms and a potential therapeutic target in patients with disorders of gut-brain interaction

The objective of this article is to review the evidence of abnormal gastrointestinal (GI) tract motor functions in the context of disorders of gut-brain interaction (DGBI). These include abnormalities of oesophageal motility, gastric emptying, gastric accommodation, colonic transit, colonic motility, colonic volume and rectal evacuation. For each section regarding GI motor dysfunction, the article describes the preferred methods and the documented motor dysfunctions in DGBI based on those methods. The predominantly non-invasive measurements of gut motility as well as therapeutic interventions directed to abnormalities of motility suggest that such measurements are to be considered in patients with DGBI not responding to first-line approaches to behavioural or empirical dietary or pharmacological treatment.

Three-dimensional semiquantitative analysis of gastric emptying SPECT

OBJECTIVE

We used dynamic single-photon emission computed tomography (D-SPECT) to overcome the interference of the planar dynamic imaging due to the overlap of internal organs, thus more accurate physiological function can be obtained.

METHODS

3D printed gastric phantom was used to simulate gastric emptying (GE). First, the planar dynamic liquid GE procedure was used and served as the reference value; second, D-SPECT followed by repeated liquid GE procedures with three gamma cameras were used. The emptying flow rate of the gastric phantom simulated three flow rates of liquid, semisolid and solid. Third, we simulated the intestinal activity that interfered with the residual value obtained by 2D dynamic imaging, which was compared with D-SPECT. Then, we brought the 3D VOI data into the postprocessing program to obtain the residual activity curve and residual percentage.

RESULTS

The residual amount obtained in the phantom at 60th minutes in the first stage is 14.57%; the residual amount of liquid emptying are Siemens: 3.33%, GE: 15.06%, PHILIPS: 1.12%; residual amount for semisolid are Siemens: 47.36%, GE: 54.25%, PHILIPS: 51.57%; residual amount for solids are Siemens: 63.98%, GE: 66.88%, PHILIPS: 63.76%. All values are within the normal range. Then, we simulated the intestinal activity that interfered with the residual value obtained by 2D dynamic imaging: 75-90 min: 10.42, 19.48, 19.51 and 11.02%; however, the residual values obtained with 3D SPECT VOI data: 75-90 min: 1.42, 1.41, 1.35 and 1.02%. These results show that the emptying data errors caused by intestinal overlap can be effectively corrected (P = 0.017).

CONCLUSION

D-SPECT imaging can overcome the interference in the semiquantitative data of residual GE caused in 2D mode.

Gastric accommodation: Physiology, diagnostic modalities, clinical relevance, and therapies

BACKGROUND

Gastric accommodation is an essential gastric motor function which occurs following ingestion of a meal. Impaired gastric fundic accommodation (IFA) is associated with dyspeptic symptoms. Gastric accommodation is mediated by the vagal pathway with several important physiologic factors such as duodenal nutrient feedback playing a significant role. IFA has been described as a pathophysiologic factor in several gastrointestinal disorders including functional dyspepsia, diabetic gastropathy, post-Nissen fundoplication, postsurgical gastrectomy, and rumination syndrome. Modalities for gastric accommodation assessment include gastric barostat, intragastric meal distribution via scintigraphy, drinking tests (eg, water load), SPECT, MRI, 2D and 3D ultrasound, and intragastric high-resolution manometry. Several treatment options including sumatriptan, buspirone, tandospirone, ondansetron, and acotiamide may improve symptoms by increasing post-meal gastric volume.

PURPOSE

Our aim is to provide an overview of the physiology, diagnostic modalities, and therapies for IFA. A literature search was conducted on PubMed, Google Scholar, and other sources to identify relevant studies available until December 2020. Gastric accommodation is an important gastric motor function which if impaired, is associated with several upper gastrointestinal disorders. There are an increasing number of gastric accommodation testing modalities; however, each has facets which warrant consideration. Evidence regarding potentially effective therapies for IFA is growing.

New Developments in Prokinetic Therapy for Gastric Motility Disorders

Prokinetic agents amplify and coordinate the gastrointestinal muscular contractions to facilitate the transit of intra-luminal content. Following the institution of dietary recommendations, prokinetics are the first medications whose goal is to improve gastric emptying and relieve symptoms of gastroparesis. The recommended use of metoclopramide, the only currently approved medication for gastroparesis in the United States, is for a duration of less than 3 months, due to the risk of reversible or irreversible extrapyramidal tremors. Domperidone, a dopamine D2 receptor antagonist, is available for prescription through the FDA's program for Expanded Access to Investigational Drugs. Macrolides are used off label and are associated with tachyphylaxis and variable duration of efficacy. Aprepitant relieves some symptoms of gastroparesis. There are newer agents in the pipeline targeting diverse gastric (fundic, antral and pyloric) motor functions, including novel serotonergic 5-HT4 agonists, dopaminergic D2/3 antagonists, neurokinin NK1 antagonists, and ghrelin agonist. Novel targets with potential to improve gastric motor functions include the pylorus, macrophage/inflammatory function, oxidative stress, and neurogenesis. In the current review, we discuss the use of pharmacological approaches with potential to enhance motor functions in the management of gastroparesis.

Enhancing Scintigraphy for Evaluation of Gastric, Small Bowel, and Colonic Motility

This article reviews the latest enhancements in standards and technology for performing gastric emptying and associated small bowel and colon transit scintigraphic studies. It discusses how developments in appropriate use criteria, American Medical Association Current Procedural Terminology coding, and advanced commercial software permit clinicians to obtain more comprehensive physiologic studies of gastric, small bowel, and colon gastrointestinal motility disorders. It shows how gastrointestinal scintigraphy has expanded to permit assessments of global and regional (fundic and antral) gastric motility and how it permits a single study (whole-gut transit scintigraphy), including measurement of solid and liquid gastric emptying and small bowel and colon transit.

Effects and mechanisms of acupuncture and electroacupuncture for functional dyspepsia: A systematic review

BACKGROUND

Functional dyspepsia (FD) is a common digestive disease with limited therapeutic options. According to evidence-based clinical practice, acupuncture or electroacupuncture (EA) seems to be a promising therapy for patients with FD. However, there is still a lack of systematic reviews that have analyzed current clinical trials for a better understanding of mechanisms involved in the ameliorating effect of acupuncture and EA on FD.

AIM

To evaluate the results and qualities of existing clinical evidence for researching the underlying mechanisms of acupuncture/EA in treating FD.

METHODS

A systematic search of the literature was performed to identify randomized controlled trials in which research on the mechanism of acupuncture or EA was conducted in FD patients. Databases searched included PubMed, EMBASE, Cochrane Library, and Web of Science. Data extraction and quality assessment were completed by two investigators independently and the results of quality evaluation were exported through Review Manager V5.3.

RESULTS

Eight studies were included in this review with a total of 17 items for detecting techniques for mechanistic research. Positive effects of acupuncture and EA were observed in regulating gastric motility, gastric accommodation, mental status, gastrointestinal hormones, and central and autonomic functions while improving dyspeptic symptoms and quality of life.

CONCLUSION

The key findings of this systematic review support the potential of acupuncture and EA in altering the heterogeneous pathophysiology in patients with FD. However, high-quality studies with well-planned designs are necessary to provide more credible evidence.

Using gastric emptying scintigraphy to evaluate antral contractions and duodenal bolus propagation

Our aim was to investigate the feasibility of measuring antral contractions and duodenal bolus propagation (DBP) during dynamic antral contraction scintigraphy (DACS) as an assessment of antro-pyloro-duodenal coordination (APDC). Gastric emptying scintigraphy (GES) with DACS was performed with Tc-99m sulfur colloid (SC) using increasing doses of 74 MBq (2 mCi) for 10 subjects, 185 MBq (5 mCi) for 11, and 370 MBq (10 mCi) for 11. DACS was performed for 10 min after static images at 0, 30, 60, 120, 180, and 240 min in anterior and right anterior oblique (RAO) projections. Best projection and lowest dose of Tc-99m SC were assessed visually. DBP were quantified utilizing duodenal activity peaks from a region of interest in the first portion of the duodenum. DBP was better visualized in the RAO projection than anterior projection and using 185 MBq (5 mCi) and 370 MBq (10 mCi) compared with 74 MBq (2 mCi). DBP showed infrequent and irregular bolus transfers from the antrum to the duodenum. Antral activity peaks at 60 min averaged 2.91 ± 0.66 per minute and duodenum bolus peaks 0.36 ± 0.18 per minute (ratio 0.36/2.91 = 0.12). DBP activity peaks can be measured during GES with DACS but requires a 185-MBq (5 mCi) dose of Tc-99m SC radiolabeled test meal for adequate DBP signal detection and is better imaged in RAO than anterior projection. DBPs over the first 60 min postmeal ingestion are infrequent with only 12% of the antral contractions propagating into the duodenum. This methodology appears promising to assess APDC.NEW & NOTEWORTHY This study shows that duodenal bolus propagations after meal ingestion can be measured during gastric emptying scintigraphy using dynamic scintigraphy. Duodenal bolus propagation over the first 60 min postmeal ingestion are infrequent with only 12% of the antral contractions propagating into the duodenum. This methodology appears promising to assess antropyloroduodenal coordination in patients with unexplained symptoms of upper gastrointestinal dysmotility.

Gastroparesis: a turning point in understanding and treatment

Gastroparesis is defined by delayed gastric emptying (GE) and symptoms of nausea, vomiting, bloating, postprandial fullness, early satiety and abdominal pain. Most common aetiologies include diabetes, postsurgical and postinfectious, but in many cases it is idiopathic. Clinical presentation and natural history vary by the aetiology. There is significant morbidity and healthcare utilisation associated with gastroparesis. Mechanistic studies from diabetic animal models of delayed GE as well as human full-thickness biopsies have significantly advanced our understanding of this disorder. An innate immune dysregulation and injury to the interstitial cells of Cajal and other components of the enteric nervous system through paracrine and oxidative stress mediators is likely central to the pathogenesis of gastroparesis. Scintigraphy and 13C breath testing provide the most validated assessment of GE. The stagnant gastroparesis therapeutic landscape is likely to soon see significant changes. Relatively newer treatment strategies include antiemetics (aprepitant), prokinetics (prucalopride, relamorelin) and fundic relaxants (acotiamide, buspirone). Endoscopic pyloromyotomy appears promising over the short term, especially for symptoms of nausea and vomiting. Further controlled trials and identification of the appropriate subgroup with pyloric dysfunction and assessment of long-term outcomes are essential. This review highlights the clinical presentation, diagnosis, mechanisms and treatment advancements for gastroparesis.

Gastric accommodation measurements by single photon emission computed tomography and two-dimensional scintigraphy in diabetic patients with upper gastrointestinal symptoms

OBJECTIVE

To compare estimates of gastric accommodation (GA) with single photon emission computed tomography (SPECT) to measurements based on intragastric meal distribution immediately post-meal ingestion (IMD⁰ ).

METHODS

We evaluated 108 diabetics with upper gastrointestinal (UGI) symptoms who had undergone gastric emptying of solids (GE) by scintigraphy and GA measurements by SPECT. Immediately after ingestion of a ^99m Tc-labeled egg meal (time 0), we estimated IMD⁰ as radioactive counts or area of the proximal half of the stomach on two-dimensional images. Gastric volume (GV) during fasting and after 300 mL Ensure^® was measured by SPECT to quantify accommodation volume (AV) or postprandial to fasting volume ratio (GVR). From the measured proximal gastric area, we estimated the volume of proximal stomach (4/3 × π × r³ ). We performed regression analyses to assess relationships between IMD⁰ and GA (AV) and GVR.

RESULTS

There was a significant correlation between area and radioactivity counts in the proximal stomach (r = 0.67, P < 0.001); however, there was considerable interpersonal variation [bias 0.20 (95% CI -0.07, 0.47)]. There were no significant correlations between total GV or AV or VR by SPECT and measurements using IMD⁰ : proximal gastric counts, area, and estimated volume as continuous variables of dichotomized patient groups, based on published cutoff values. There were no significant differences in total gastric area or the IMD⁰ parameters (% area or % radioactive counts) between those with and without UGI symptoms except for fullness and satiety.

CONCLUSIONS

Intragastric meal distribution immediately post-meal ingestion is not significantly correlated with GA measurement by SPECT.