Effects of laparoscopic sleeve gastrectomy on gastric structure and function documented by Magnetic Resonance Imaging are strongly associated with post-operative weight loss and quality of life: a prospective study

BACKGROUND: This prospective study applied magnetic resonance imaging (MRI) to assess the effect of laparoscopic sleeve gastrectomy (LSG) on gastric structure and function. The impact of these changes on patient outcomes was analyzed. METHOD: Obese patients without gastrointestinal symptoms referred for bariatric surgery were recruited prospectively. Pre-operative assessment included (i) high-resolution manometry and pH-impedance monitoring and (ii) magnetic resonance imaging (MRI) measurement of gastric capacity, accommodation, and emptying with the 400 ml liquid Nottingham test meal (NTM). Studies were repeated 6-7 months after LSG. Weight loss and changes in the Gastrointestinal Quality of Life Index (GIQLI) assessed patient outcomes. RESULTS: From 35 patients screened, 23 (66%) completed the study (17 females, age 36 ± 10 years, BMI 42 ± 5 kg/m2). Mean excess weight loss was 59 ± 18% at follow-up. Total gastric volume (capacity) after the meal was 467 mL (455-585 ml) before and 139 mL (121-185 ml) after LSG (normal reference 534 (419-675) mL), representing a mean 70% reduction (p < 0.0001). Similar findings were present for gastric content volume indicating rapid early-phase gastric emptying (GE) post-LSG. Conversely, late-phase GE was slower post-LSG (2.5 ± 1.0 vs. 1.4 ± 0.6 mL/min; p < 0.0001; (reference 1.5(1.4-4.9) mL/min)). Patients with ≥ 80% reduction in gastric capacity had greater weight loss (p = 0.008), but worse gastrointestinal outcomes (p = 0.023). CONCLUSIONS: MRI studies quantified the marked reduction in gastric capacity after LSG. The reduction in capacity was associated with rapid early- but slow late-phase GE after surgery. These changes were associated with weight loss; however, reductions in gastric capacity ≥ 80% were linked to increased acid reflux and impacted on gastrointestinal quality of life