Precise tumor size measurement under constant pressure by novel real-time micro-electro-mechanical-system hood for...

Tumor size determination is subject to the measurement method used by endoscopists and is especially dependent on the air quantity. As the intraluminal pressure must be measured objectively to obtain an accurate tumor size measurement, insufflation can affect the results. Thus, we examined the utility of a micro-electro-mechanical-system (MEMS) pressure sensor hood.

Twenty consecutive air insufflation/deflation tests were performed in vivo using a dog's stomach. Correlations between the actual pressure measured and the signal strength of the MEMS hood were measured. We marked 2 points 20 mm on the antrum and another 3 points, with insufflation corresponding to the maximum stable distance of two markings. We performed five insufflation/deflation tests to obtain the relationship between pressure and distances to accurately measure the distance under constant pressure.

In the air insufflation/deflation test performed 20 consecutive times, the MEMS hood signal strength (V) and the pressure measurement sensor values (mmHg) showed good correlation. There was good correlation between intraluminal pressures of 2.5-40 mmHg and the two marking distances on the antrum (correlation coefficient 0.952) (P < 0.05). However, once the intraluminal pressure reached a certain level (40 mmHg), expansion of the two marking distances ceased. The same measurements were conducted on the greater curvatures of the lower body and middle body and on the lesser curvature of the lower body.

Correct tumor size measurements using a MEMS hood enable a more accurate diagnosis, which can be used to develop suitable treatment strategies.