“…Example case of PDD endoscopy of gastric tumor with Si2-P2 ® system is reported in the literature (15). Example cases of PDD using Si2 P2 ® system are presented in Figure 1.…”
Background: Recent improvement of the endoscopic system such as image enhancement has led to the better accuracy of the diagnosis of the gastric cancer. However, the objective and efficient detection method of the gastric cancer is still needed because the detection efficiency could sometimes be low due to the fact that the image enhancement diagnosis needs magnification for its full utilization. The photodynamic diagnosis (PDD) with oral intake of 5-aminolevulinic acid (5-ALA) has been widely used for the detection of the cancerous region for bladder cancer and glioblastoma. The application of the 5-ALA based PDD (5-ALA PDD) to the diagnosis of gastric cancer is recently reported. The efficiency of the detection is reported to be good, however, the objectivity of the method can be impaired by the photobleaching effect with fast decreasing of the intensity of the fluorescence under light exposure. In this article, we investigated the fluorescence spectrum of the gastric tumor and non-tumor mucosa of 5-ALA PDD and revealed the property of the photobleaching effect.Methods: Example cases of PDD endoscopy of gastric tumor were investigated for cases of endoscopic submucosal dissection (ESD). Newly developed spectrometer using a spectrometer with a liquid crystal tunable filter was used for investigating the fluorescence spectrum of 5-ALA PDD. The assumed tumor region and non-tumor region in gastric mucosa were biopsied and the fluorescence spectrum was measured using the spectrometer consecutively several times, to estimate the photobleaching effect.
Results:The fluorescence spectrum has a primary peak at 630 nm, with a broad peak ranging from 660 to 700 nm. The 630 nm peak diminished quickly upon ultraviolet light exposure, whereas the broad peak from 660 to 700 nm diminished slowly. The sum of the altitudes at 660-700 nm, normalized to the altitude at 600 nm, was not as affected by the photobleaching effect as the 630 nm peak was, and can thus be used for 5-ALA-based PDD.
Conclusions:The 5-ALA PDD using the average fluorescence altitude of 660-700 nm instead of the peak altitude at 630 nm, is shown to be more effective in distinguishing between tumorous and non-tumorous tissues, because of the lower photobleaching effect at this specific spectral range. The finding is expected to greatly improve the objective diagnosis of gastrointestinal cancers by 5-ALA-based photodynamic diagnostic endoscopy.
“…Example case of PDD endoscopy of gastric tumor with Si2-P2 ® system is reported in the literature (15). Example cases of PDD using Si2 P2 ® system are presented in Figure 1.…”
Background: Recent improvement of the endoscopic system such as image enhancement has led to the better accuracy of the diagnosis of the gastric cancer. However, the objective and efficient detection method of the gastric cancer is still needed because the detection efficiency could sometimes be low due to the fact that the image enhancement diagnosis needs magnification for its full utilization. The photodynamic diagnosis (PDD) with oral intake of 5-aminolevulinic acid (5-ALA) has been widely used for the detection of the cancerous region for bladder cancer and glioblastoma. The application of the 5-ALA based PDD (5-ALA PDD) to the diagnosis of gastric cancer is recently reported. The efficiency of the detection is reported to be good, however, the objectivity of the method can be impaired by the photobleaching effect with fast decreasing of the intensity of the fluorescence under light exposure. In this article, we investigated the fluorescence spectrum of the gastric tumor and non-tumor mucosa of 5-ALA PDD and revealed the property of the photobleaching effect.Methods: Example cases of PDD endoscopy of gastric tumor were investigated for cases of endoscopic submucosal dissection (ESD). Newly developed spectrometer using a spectrometer with a liquid crystal tunable filter was used for investigating the fluorescence spectrum of 5-ALA PDD. The assumed tumor region and non-tumor region in gastric mucosa were biopsied and the fluorescence spectrum was measured using the spectrometer consecutively several times, to estimate the photobleaching effect.
Results:The fluorescence spectrum has a primary peak at 630 nm, with a broad peak ranging from 660 to 700 nm. The 630 nm peak diminished quickly upon ultraviolet light exposure, whereas the broad peak from 660 to 700 nm diminished slowly. The sum of the altitudes at 660-700 nm, normalized to the altitude at 600 nm, was not as affected by the photobleaching effect as the 630 nm peak was, and can thus be used for 5-ALA-based PDD.
Conclusions:The 5-ALA PDD using the average fluorescence altitude of 660-700 nm instead of the peak altitude at 630 nm, is shown to be more effective in distinguishing between tumorous and non-tumorous tissues, because of the lower photobleaching effect at this specific spectral range. The finding is expected to greatly improve the objective diagnosis of gastrointestinal cancers by 5-ALA-based photodynamic diagnostic endoscopy.
“…However, the first endoscopic identification of gastric tumors is usually performed by white-light endoscopy, because magnification is needed for full utilization of the NBI method in the identification of gastric tumors. Photodynamic diagnosis (PDD) endoscopy after oral intake of 5-aminolevulinic acid (5-ALA) has proven useful for detecting gastric tumors [ 4 , 5 , 6 ]. A recent study found additional lesions that were identified as tumors in 13 cases with the use of PDD endoscopy [ 7 ].…”
Positive diagnoses of gastric tumors from photodynamic diagnosis (PDD) images after the administration of 5-aminolevulinic acid are subjectively identified by expert endoscopists. Objective methods of tumor identification are needed to reduce potential misidentifications. We developed two methods to identify gastric tumors from PDD images. Method one was applied to segmented regions in the PDD endoscopic image to determine the region in LAB color space to be attributed to tumors using a multi-layer neural network. Method two aimed to diagnose tumors and determine regions in the PDD endoscopic image attributed to tumors using the convoluted neural network method. The efficiencies of diagnosing tumors were 77.8% (7/9) and 93.3% (14/15) for method one and method two, respectively. The efficiencies of determining tumor region defined as the ratio of the area were 35.7% (0.0–78.0) and 48.5% (3.0–89.1) for method one and method two, respectively. False-positive rates defined as the ratio of the area were 0.3% (0.0–2.0) and 3.8% (0.0–17.4) for method one and method two, respectively. Objective methods of determining tumor region in 5-aminolevulinic acid-based endoscopic PDD were developed by identifying regions in LAB color space attributed to tumors or by applying a method of convoluted neural network.
“…We reported diagnostic yield of laser-based photodynamic diagnosis (PDD) for gastric neoplasms, but the dark images and weak fluorescence contrast remained unsatisfactory. [2][3][4] PDD is based on 5-aminolevulinic acid (5-ALA) being metabolized into protoporphyrin IX, which accumulates in tumor cells; when exciting around 410-nm light, tumor cells emit red fluorescence at 635 nm. We have trialed a new prototype light-emitting diode (LED)-based PDD system that can provide monochromatic excitation light.…”
Gastric cancer incidence remains high in Japan owing to a progressing elderly society, even with the reduction of the Helicobacter pylori infection rate. 1 Early gastric cancer (EGC) after eradication of H. pylori infection often resembles gastritis, making EGC detection and demarcation difficult. It is desirable to develop an alternative diagnostic method enabling objective evaluation, irrespective of the examinee's expertise. We reported diagnostic yield of laser-based photodynamic diagnosis (PDD) for gastric neoplasms, but the dark images and weak fluorescence contrast remained unsatisfactory. [2][3][4] PDD is based on 5-aminolevulinic acid (5-ALA) being metabolized into protoporphyrin IX, which accumulates in tumor cells; when exciting around 410-nm light, tumor cells emit red fluorescence at 635 nm. We have trialed a new prototype light-emitting diode (LED)-based PDD system that can provide monochromatic excitation light. We present the feasibility of LED-based PDD for detecting and demarcating EGC. Following approval of a certified review board (#20C003), a 63-year-old female patient with EGC after successful eradication of H. pylori underwent LED-based PDD using an EG-760Z endoscope, EPX-7000-P with modification of VP-7000 Processor, and BL-7000 Light Source in ELUXEO 7000 (Fujifilm Co., Tokyo, Japan); the system enables general application without the cut-off filter of blue-violet LED light. Three hours after taking 5-ALA (20 mg/kg) orally, an EGC lesion was identified with distinct red fluorescence accompanied by nontumor bluish purple background mucosa (Fig. 1a,b). Compared to the laser-based PDD image of a different case (Fig. 1c), it was brighter and had improved contrast. On the same day, the EGC lesion was successively resected by endoscopic submucosal dissection and the pathological diagnosis was tubular adenocarcinoma with slight invasion into the submucosa (Fig. 1d). Furthermore, the substantial red fluorescence enabled clear demarcation of the horizontal extent that was almost consistent and confirmatory after gross and histopathological evaluations (Fig. 2). No adverse events were observed in relation to LEDbased PDD.
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