An evaluation of gastric alimetry body surface gastric mapping compared to electrogastrography spectral analysis

Background Although Electrogastrography (EGG) is a non-invasive method of evaluating gastric motility, it has limited clinical utility. Gastric Alimetry (GA) is a novel diagnostic test that aims to address the limitations of the EGG through the combination of high-resolution body surface gastric mapping (BGSM) and validated symptom profiling. To measure performance differences in spectral analysis, the current study directly evaluated EGG with BSGM. Methods 178 subjects (110 controls; 68 nausea and vomiting (NVS) and/or type 1 diabetes (T1D)) completed the standard methodologies for GA BSGM and EGG, with identical data collection. Protocolized evaluations were completed between tests, with statistical evaluations for group-level differences, symptom correlations, and patient-level classifications. The BSGM tests gave Gastric Alimetry Rhythm Index TM (GA-RI), Principal Gastric Frequency (PGF), BMI-Adjusted Amplitude, and Fed:Fasted Amplitude Ratio, while EGG tests gave the% time normal frequency, dominant frequency, amplitude, and amplitude ratio as final spectral metrics. A blinded consensus panel reference standard1 and published reference values2 were used for the patient-level classifications. Results Group-level: BSGM showed tighter frequency ranges vs EGG in controls (median 3.04 cpm (IQR 2.90–3.18) vs 2.88 (1.50–3.12); p<0.0001). Both tests were able to detect rhythm instability in NVS (p<0.001) and T1D (p<0.05), but EGG displayed opposing frequency effects in T1D (2.50 vs controls 2.88; p=0.28) to BSGM (3.15 vs 3.04; p=0.0004). Symptom correlations: GA-RI correlated with nausea, pain, bloating, and total symptom burden; PGF deviation with excessive fullness, pain and bloating;% time in normal frequency correlated with bloating (p<0.05). Patient-level: EGG sensitivity was 1.0, specificity 0.38; BSGM sensitivity 1.0, specificity 0.96 (figure 1). Conclusions and Inferences The limited clinical utility of EGG is demonstrated by its ability to detect group-level differences but not the correlations between symptoms or accurate patient-level classification. Therefore, compared to EGG, BSGM showed considerable improvements across each area.