Enhanced-magnification endoscopy may be useful for identifying gastric tumors and determining the extent of horizontal spread, especially in tumors of the depressed type.
Background and Aim: Various techniques using magnifying endoscopy (ME) have been developed to enhance images of early gastric cancer (EGC) demarcations, which are often obscure. We investigated four ME methods to determine which is most effective in enhancing the recognition of EGC demarcations: conventional ME (CME), ME with narrow band imaging (NBI-ME), enhanced-magnification endoscopy with acetic acid (EME), and ME with NBI and acetic acid (NBI-EME). Methods: Thirty-seven successive patients having a total of 40 EGCs participated in the investigation. The endoscope was fixed and magnification images of EGC demarcations in each patient were recorded using four different ME methods (CME, NBI-ME, EME and NBI-EME). Eight experts and eight non-experts scored each of the four images of each lesion for ease of recognition of demarcation (1 to 4, with 4 being easiest). Results: The mean scores of expert and non-expert judges, respectively, for images acquired using each technique were: CME 1.23, 1.24; NBI-ME 2.61, 2.95; EME 2.62, 2.32 and NBI-EME 3.54, 3.50. There were significant differences between the mean scores for the four techniques (P < 0.0001) using one-way repeated-measures anova. In a Bonferroni's multiple comparison, the average scores (expert and non-expert) of images acquired using NBI-EME were significantly higher than those acquired using other methods; images acquired by NBI-ME or EME also scored significantly higher than those by CME. Nonexperts also scored NBI-ME images significantly higher than CME and EME images. Conclusions: Early gastric cancer demarcations were recognized most easily using NBI-EME, and more easily using EME or NBI-ME than CME.
We have developed a noncontact-type centrifugal blood pump with hydrodynamic bearings and a semi-open impeller for mechanical circulatory assist. The impeller is levitated by an original spiral-groove thrust bearing and a herringbone-groove journal bearing, without any additional displacement-sensing module or additional complex control circuits. The pump was improved by optimizing the groove direction of the spiral-groove thrust bearing and the pull-up magnetic force between the rotor magnet and the stator coil against the impeller. To evaluate hemocompatibility, we conducted a levitation performance test and in vitro hemocompatibility tests by means of a mock-up circulation loop. In the hemolysis test, the normalized index of hemolysis was reduced from 0.721 to 0.0335 g/100 L corresponding to an expansion of the bearing gap from 1.1 to 56.1 microm. In the in vitro antithrombogenic test, blood pumps with a wide thrust bearing gap were effective in preventing thrombus formation. Through in vitro evaluation tests, we confirmed that hemocompatibility was improved by balancing the hydrodynamic fluid dynamics and magnetic forces.
Complications due to pump thrombus remain the weak point of mechanical circulatory support (MCS), such as the use of a left ventricular assist device (LVAD) or extracorporeal membrane oxygenation, leading to poor outcomes. Hyperspectral imaging (HSI) is an effective imaging method using a hyperspectral (HS) camera, which comprises a spectrophotometer and a charge-coupled device camera to discriminate thrombus from whole blood. Animal experiments were conducted to analyze dynamic imaging of thrombus inside a prototype of a hydrodynamically levitated centrifugal blood pump using an HSI system. Six pigs were divided into a venous circulation group (n = 3) and an arterial circulation group (n = 3). Inflow and outflow cannulae were inserted into the jugular veins in the venous circulation group. The latter simulated an LVAD application. To create thrombogenic conditions, pump flow was maintained at 1 L/min without anticoagulation. An image of the bottom surface of the pump was captured by the HS camera every 4 nm over the wavelength range of 608-752 nm. Real-time dynamic images of the inside of the pump were displayed on the monitor. Appearance of an area displaying thrombus was detected within 24 h after the start of the circulation in every experiment. This imaging system also succeeded in determining the origins of pump thrombus: from inside the pump in two cases, and from outside in four cases. Two main possible sources of pump thrombus originating outside the pump were identified on autopsy: wedge thrombus around the inflow cannula; and string-like thrombus at the junction between the pump inlet and circuit tube. The results of this study from close observation of the changing appearance of pump thrombus may contribute to improvements in the safety of extracorporeal MCS.
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