The structure enhancement function has two modalities, an A mode and a B mode. Independent settings can also be made for white-light imaging (WLI) and NBI. Because blood vessel diameters increase as the level is raised with the A mode, I use the B mode. Using the user-selectable functions on the video processor, I preset the structure enhancement function to B mode levels 4, 6, and 8. In actual procedures, I begin with level 4 or 6 non-magnifying examination and then switch over to magnified examination at level 8 (Fig. 2.3).

I use the upper gastrointestinal NBI color mode 1, with the B mode levels 4, 6, and 8 structure enhancement function settings. As I only use NBI in conjunction with magnifying endoscopy, in practice I only use level 8 structure enhancement with NBI.

At the same time, I preset the IHb color enhancement function at levels 0, 2, or 4, changing between them using the video processor switch. In practice, I rarely use the IHb color enhancement function and usually leave it at level 0. I would like to emphasize that IHb color enhancement function is particularly useful in magnified examinations with WLI in the case of lesions with a high microvascular density.

I allocate the user-selectable switches on the control section as follows: (1) freeze, (2) switching between the three preset levels of structure enhancement, (3) switching between WLI and NBI, and (4) shutter.

To obtain steady ME images of the gastric mucosa at the maximal magnifying ratio, a soft black rubber hood (MB 162/MAJ-1989 for use with the GIF-Q240Z, MB 46/MAJ-1990 with the GIF-H260Z; both Olympus) should be attached to the endoscope tip (Fig. 2.4). The depth of the hood is the same as the observation depth for the endoscope at the maximal magnifying ratio, so placing the hood perpendicularly right up against the mucosal surface enables us to readily obtain images at maximum magnification and in focus. In other words, we can steadily observe down to the capillary level at the maximal magnifying ratio (7.9 μm [1] with the GIF-Q240Z). Without a hood, it is impossible to quickly and easily obtain properly focused images, no matter how high the resolution of the magnifying endoscope, in the stomach with its broad lumen, as well as interference from respiratory movements and aortic pulsations. On other words, as long as we do use a hood, we can easily obtain magnified images of the required resolution.

Although I used a transparent plastic hood when I commenced zoom gastroscopy, in 2000 I changed over to a soft black hood designed for use with ME. The reasons I prefer a soft black hood to a clear plastic hood are as follows: (1) as the rubber is softer than plastic, it is less likely to damage the lesion or surrounding mucosa, thereby avoiding hemorrhage; (2) the depth of the hood is such that it only enters the very small part of field of vision even during non-magnifying examinations, so there is no need for it to be transparent; and (3) during non-magnifying examinations, reflections from within the plastic hood are more likely to interfere with observations, and less reflection occurs from a black surface. I perform all endoscopies, screening as well as detailed examinations, with a soft black hood in place. If a lesion is detected during a non-magnifying screening examination, this can be followed immediately by a magnified examination at the maximal magnifying ratio.

Before each procedure, I check that the endoscope’s optical magnification function is working normally and that the hood is attached in the correct position. In practice, I use a 1 cm² piece of graph paper attached to the instrument trolley with adhesive tape. After mounting the hood on the endoscope tip, I place the end of the hood perpendicularly onto the graph paper and press down on the zoom lever on the control section to provide maximum magnification. If the width of the field of view as shown on the monitor screen agrees with the graph paper gradations at 3.2 mm, we have confirmed that the optical zoom function is working normally, and the hood is mounted correctly (Fig. 2.5).

We prepare a solution mixing Pronase^® (Roche Applied Science) 20,000 U, sodium bicarbonate (NaHCO₂) 1 g, and Baros^® antifoaming agent (20 mg/mL polydimethylsiloxane, Horii Pharmaceutical Ind., Ltd) 10 mL in 100 mL of water and ask the patient to drink this solution 30 min before their procedure. Pronase, however, is not available for use in all countries. An alternative mixture comprises 100 mL of water mixed with 2 mL of acetylcysteine (200 mg/mL Parvolex, Celltech, UK; or Mucomyst, Bristol-Myers Squibb, USA) and 0.5 mL (40 mg/mL) activated dimethicone (Infacol, Forest Laboratories, UK).

The indications for sedation prior to a screening endoscopy procedure are the same as for non-magnifying gastroscopy. I only employ sedation when the patient wishes it or we have prior warning of a strong gag reflex. Sedation should be used prior to detailed examinations. I administer an intramuscular antispasmodic injection such as Buscopan^® or Glucagon^® before commencing the procedure.

Insertion of the endoscope is the same as for conventional gastroscopy. After examining the middle and lower pharynx, larynx, and esophagus, the scope is introduced into the stomach. As described below, I aspirate as much of the gastric juices as possible in advance so they do not get in the way when the air is removed and the scope applied to the gastric mucosa. If a lesion is detected, I rinse the lesion and surrounding mucosa with Gascon^® (polydimethylsiloxane, Kissei Pharmaceuticals Co., Ltd) solution and conduct a non-magnified examination.