Gastric Emptying Scintigraphy Before Gastric per Oral Endoscopic Myotomy: Imaging May Inform Treatment

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.

A New Paradigm Shift in Gastroparesis Management

Gastroparesis, once regarded as a rare disease, is difficult to diagnose and challenging to treat; there were many breakthrough advances in the 2010s, shifting the paradigm of the understanding of this complex entity and its management. Similar to diabetes, its increasing prevalence reflects increased accessibility to diagnostic modalities and suggests that gastroparesis was underacknowledged in the past. Major developments in the three main aspects of the disease include the discovery of smooth muscle cells, interstitial cells of Cajal, PDGFRα+ cells syncytium, rather than interstitial cells of Cajal alone, as the main gastric pacemaker unit; the development of validated point-of-care diagnostic modalities such as a wireless motility capsule, the carbon 13-labeled breath test, and impedance planimetry; and the introduction of novel minimally invasive therapeutic options such as newer pharmacologic agents and gastric peroral endoscopic pyloromyotomy. All aspects of these advances will be discussed further in this review.

Gastroparesis with concomitant gastrointestinal dysmotility is not a contraindication for per-oral pyloromyotomy (POP)

INTRODUCTION

Per-oral pyloromyotomy (POP or G-POEM) provides significant short-term improvements in symptoms and objective emptying for patients with medically refractory gastroparesis, but it is unclear if patients with gastroparesis and co-existing dysmotility (small bowel or colonic delay) also benefit. In this study, we used wireless motility capsule (WMC) data to measure outcomes in patients with isolated gastroparesis (GP) and gastroparesis with co-existing dysmotility (GP + Dys) who underwent POP.

METHODS

We retrospectively analyzed patients who had POP and completed WMC data during their evaluation of intestinal dysmotility. WMC data were reviewed to identify patients who demonstrated isolated GP or GP + Dys. Each patient's pre-op and post-op Gastroparesis Cardinal Symptom Index (GCSI) and 4-h solid-phase scintigraphy gastric emptying studies (GES) scores were compared to evaluate improvement.

RESULTS

Of the entire cohort (n = 73), 89% were female with a mean age of 47.0 ± 15.0 years old. Gastroparesis etiologies were divided among idiopathic (54.8%), diabetic (26%), postsurgical (8.2%), autoimmune (5.5%), and multifactorial (5.5%). Forty-one patients (56%) had GP and 32 patients (44%) had GP + Dys. GCSI improved after POP whether the patient had isolated GP (- 12.31, p < 0.001) or GP + Dys (- 9.58, p < 0.001); however, there was no significant difference in total GCSI improvement between the two groups. A subset of patients had postoperative GES available (n = 47). In the isolated GP and GP + Dys cohorts, 15/28 (54%) and 12/19 (63%) patients had normal post-op 4-h GES, respectively, but no statistical difference between the two groups.

CONCLUSION

Patients with medically refractory gastroparesis with and without concomitant gastrointestinal dysmotility show short-term subjective and objective improvement after POP. Concomitant small bowel or colonic dysmotility should not deter physicians from offering POP in carefully selected patients with gastroparesis.