Background: Palpation of tumors during thoracoscopic surgery remains difficult, and identification of deep-seated tumors may be impossible. This preclinical study investigated the usefulness of a novel indocyanine green (ICG) fluorescence spectroscopy system for tumor localization.Methods: ICG was diluted to 5.0×10 −2 mg/mL in fetal bovine serum (FBS) and mixed with silicone resin to prepare pseudo-tumors. Sponges of different densities and a porcine lung were placed on top of the pseudo-tumors, which were examined using a novel fluorescence spectroscopy system and a near-infrared (NIR) camera. Spectra were measured for different sponge and lung thicknesses, and the lung spectra were measured during both inflation and deflation.Results: The fluorescence spectroscopy system was able to identify tumors at depths ≥15 mm, while the NIR system was not. The spectroscopy system also detected tumors at greater depths when the density of the intervening material was lower. Depending on the density and thickness of the intervening material, the system could detect spectra as deep as 40 mm for sponges and 30 mm for lungs.Conclusions: This new fluorescence spectroscopy system can be used to identify lung tumors up to a depth of 30 mm in experiments using pseudo-tumors and a porcine lung, which may aid in tumor identification during thoracoscopic surgery.

The clearance system in the brain is not completely understood. The aim of this study was to prove the presence of the "glymphatic system" in the human brain using magnetic resonance spectroscopy (MRS). Spectral data of the brain white matter were obtained from healthy volunteers and patients with hydrocephalic dementia and used to measure intracerebral metabolites, including macromolecules (MMs) and lipids. Data were transferred from the MRS scanners to a workstation, and metabolites were quantified with the spectrogram-based eddy current method and water scaling. MM levels were significantly higher in patients with a slow gait and executive dysfunction due to normal pressure hydrocephalus (NPH) than in asymptomatic volunteers (p <0.01). In contrast, the N-acetyl aspartate (NAA) level was significantly lower in patients with executive dysfunction than in asymptomatic volunteers (p <0.01). There were no statistically significant differences in metabolites, including alanine, aspartate, creatine, γ-amino butyric acid, D-glucose, glutamine, glutamate, glycerophosphorylcholine, phosphorylcholine, lactate, myoinositol, N-acetyl-aspartyl-glutamate, scyllo-inositol, taurine, creatine methylene, and guanine, in the centrum semiovale between patients with NPH and asymptomatic volunteers. We quantitatively evaluated cerebral metabolites, particularly in the centrum semiovale, with MRS. In the brain of patients with a slow gait and executive dysfunction due to NPH, MRS revealed significantly higher MM levels and lower NAA levels compared to healthy volunteers. Therefore, it may be concluded that the patients have a dysfunctional glymphatic system in the brain.

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This patient has survived over the long term after undergoing three resections of lung metastases from resected pancreatic ductal adenocarcinoma.

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