Noninvasive measurement of gastric accommodation by SPECT

Indentation of a pressurized silicon stomach model - A non-invasive study of gastric wall stiffness and pressurized gastric content stiffness

BACKGROUND AND AIMS

Evaluation of gastric wall stiffness and intragastric pressure is essential for detailed assessments of gastric accommodation. However, non-invasive assessments are needed for large scale clinical studies and none of the existing methods takes abdominal wall effect into the calculation. This study aimed to assess gastric wall stiffness and gastric content stiffness as a proxy for intragastric pressure using novel mechanical modeling and non-invasive indentation tests on a silicon stomach model.

METHODS

A silicon stomach model (scaling 1:1 with the human stomach) was indented using a pressure algometer at intragastric pressures from 0 to 0.8 kPa. Wall thicknesses and luminal cross-sectional areas along the stomach were measured with ultrasound images. The gastric wall stiffness was compared between measurements from tensile tests on strips cut from the silicon stomach and estimations from a shell indentation model. The pressurized gastric content stiffness was predicted from a bonded two-layer axisymmetric half-space indentation model.

RESULTS

The gastric wall stiffness estimated from the shell indentation model showed no difference to measurements from the mechanical tests on the cutting strips (p = 0.14). The predicted gastric content stiffness was strongly associated with the intragastric pressure (r > 0.83, p < 0.001).

CONCLUSIONS

The mechanical model developed in this study can simultaneously predict the gastric wall stiffness and the pressurized gastric content stiffness. In future studies, the method can be applied to reveal intragastric pressure conditions non-invasively via the pressurized gastric content stiffness during gastric accommodation and emptying such as with magnetic resonance imaging.

Novel targeted nuclear imaging agent for gastric cancer diagnosis: glucose-regulated protein 78 binding peptide-guided 111In-labeled polymeric micelles

Increased expression of cellular membrane bound glucose-regulated protein 78 (GRP78) is considered to be one of the biomarkers for gastric cancers. Therefore, peptides or molecules with specific recognition to GRP78 can act as a guiding probe to direct conjugated imaging agents to localized cancers. Based on this rationale, GRP78-guided polymeric micelles were designed and manufactured for nuclear imaging detection of tumors. Thiolated GRP78 binding peptide (GRP78BP) was first labeled with maleimide-terminated poly(ethylene glycol)– poly(ɛ-caprolactone) and then mixed with diethylenetriaminepentaacetic acid (DTPA)-linked poly(ethylene glycol)–poly(ɛ-caprolactone) to form DTPA/GRP78BP-conjugated micelles. The coupling efficiency of micelles with radioisotope indium-111 (¹¹¹In) was measured and analyzed by instant thin layer chromatography. The coupling efficiency of DTPA-conjugated micelles and DTPA/GRP78BP-conjugated micelles with ¹¹¹In was 85% and 93%, respectively. For characterization and trace imaging, the radioisotope ¹¹¹In-targeting tumors were detected and imaged in a xenograft murine model using nano single photon emission computed tomography/computed tomography. The results revealed that the radioactive intensity measured in the animals administered with GRP78BP-guided ¹¹¹In-labeled micelles was statistically higher than that in animals administered with ¹¹¹In-labeled micelles, demonstrating that GRP78BP more than doubled the accumulation of micelles to the tumor tissue (P < 0.05). The results indicate that the gastric cancer biomarker GRP78 is a probing target in the application of nuclear imaging for tumor diagnosis. This novel GRP78BP-guided micelle agent may be applied in clinical practice to complement the histological diagnosis.

Fundal dysaccommodation in functional dyspepsia: head-to-head comparison between the barostat and three-dimensional ultrasonographic technique

BACKGROUND

Recently, non-invasive techniques such as 3 dimensional ultrasonography (3DUS) have been developed to assess gastric wall characteristics and to investigate their relationship with upper gastrointestinal sensations. To date, no head-to-head comparison has been carried out between the barostat and the 3DUS technique.

AIM

To compare barostat and 3DUS and to investigate the relationship between gastric volumes and sensations in patients with functional dyspepsia and in healthy subjects.

PATIENTS AND METHODS

Gastric accommodation was studied in 15 patients with functional dyspepsia and in 15 healthy subjects after ingestion of a liquid nutrient (300 kcal) using barostat and 3DUS in random order for 60 min. Proximal gastric relaxation was measured using barostat and gastric volume using 3DUS. Change in gastric volume, acquired by 3DUS, was expressed as total gastric volume/proximal volume ratio (TGV/PV) and compared with changes in barostat volume (fundal accommodation).

RESULTS

Patients with functional dyspepsia showed a smaller change in proximal gastric volume than healthy subjects using barostat (mean (SD) 82 (61) v 205 (79) ml, p<0.01) and 3DUS (118 (41) v 199 (39) ml, p<0.01). Dysaccommodation of the proximal stomach was observed in 7 of 15 (46%) patients using the barostat technique. 10 of 15 (67%) patients were found to have an abnormal change in proximal gastric volume using TGV/PV ratio. At 5 min postprandially, fullness was related to the change in distal gastric volume (r = 0.51, p = 0.006) in the 3DUS study, whereas no relationship was observed in the barostat study.

CONCLUSION

3DUS is a feasible non-invasive technique to measure gastric volumes and shows a distinct overlap with barostat data in healthy subjects and patients with functional dyspepsia. Fullness relates to distal gastric volumes when assessed by non-invasive 3DUS.

Functional dyspepsia, upper gastrointestinal symptoms, and transit in children

OBJECTIVE

To assess the prevalence of abnormal gastric emptying and small bowel transit in children with functional dyspepsia at a tertiary care center, and the relationship between abnormal gastric and small bowel transit and symptoms in pediatric patients with functional gastrointestinal disorders.

STUDY DESIGN

Patients were selected by a cross-sectional chart review based on the following inclusion criteria: (1) completion of scintigraphic study of the gastric emptying of solids at 2 hours (GE2), 4 hours (GE4), and small bowel transit at 6 hours (SBT) using a standardized egg meal labeled with 99mTechnetium sulfur colloid, and (2) gastrointestinal (GI) complaints without mucosal or organic disease. Logistic regression analysis was used to assess the association between the presence of upper GI symptoms, and each parameter of gastric and small bowel transit.

RESULTS

Children with upper GI symptoms (n=96) were identified. Among 57 children with functional dyspepsia, 40% had slow SBT. Fast GE at 4 hours, and slow SBT were independently associated with bloating. Children with fast SBT were less likely to report abdominal pain.

CONCLUSION

Incorporating assessments of gastric and small bowel transit may be useful in the evaluation of pediatric patients with upper GI symptoms and functional dyspepsia.