Gwansuk Kang

All Publications

• High-resolution photoacoustic/ultrasound imaging of the porcine stomach wall: an ex vivo feasibility study. Biomedical optics express Kim, J., Ahn, J., Kang, G., Hwang, J. H., Kim, C. 2021; 12 (11): 6717-6729

  Abstract

  Photoacoustic (PA) imaging has become invaluable in preclinical and clinical research. Endoscopic PA imaging in particular has been explored as a noninvasive imaging modality to view vasculature and diagnose cancers in the digestive system. However, these feasibility studies are still limited to rodents or rabbits. Here, we develop a fully synchronized simultaneous ultrasound and photoacoustic microscopy system using two spectral bands (i.e., the visible and near-infrared) in both optical- and acoustic-resolution modes. We investigate the feasibility of imaging gastric vasculature in an ex vivo porcine model. The entire gastric wall, including the mucosa, submucosa, muscularis propria, and serosa, was excised from fresh porcine stomachs immediately followed by ultrasound and PA imaging being performed within a few hours of sacrifice. PA images of the mucosal vasculature were obtained at depths of 1.90 mm, which is a clinically significant accomplishment considering that the average thickness of the human mucosa is 1.26 mm. The layer structure of the stomach wall could be clearly distinguished in the overlaid PA and US images. Because gastric cancer starts from the mucosal surface and infiltrates into the submucosa, PA imaging can cover a clinically relevant depth in early gastric cancer diagnosis. We were able to detect mucosal vasculature in the entire mucosal layer, suggesting the potential utility of combined PA/US imaging in gastroenterology.

  View details for DOI 10.1364/BOE.441241

  View details for PubMedID 34858676

  View details for PubMedCentralID PMC8606154

• High-resolution photoacoustic/ultrasound imaging of the porcine stomach wall: an ex vivo feasibility study BIOMEDICAL OPTICS EXPRESS Kim, J., Ahn, J., Kang, G., Ha Hwang, J., Kim, C. 2021; 12 (11): 6717-6729

  View details for DOI 10.1364/BOE.441241

  View details for Web of Science ID 000714969300003

• The reasons why fractional flow reserve and instantaneous wave-free ratio are similar using wave separation analysis. BMC cardiovascular disorders Min, S., Kang, G., Paeng, D., Choi, J. H. 2021; 21 (1): 48

  Abstract

  BACKGROUND AND OBJECTIVES: Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are the two most commonly used coronary indices of physiological stenosis severity based on pressure. To minimize the effect of wedge pressure (Pwedge), FFR is measured during hyperemia conditions, and iFR is calculated as the ratio of distal and aortic pressures (Pd/Pa) in the wave-free period. The goal of this study was to predict Pwedge using the backward wave (Pback) through wave separation analysis (WSA) and to reflect the effect of Pwedge on FFR and iFR to identify the relationship between the two indices.METHODS: An in vitro circulation system was constructed to calculate Pwedge. The measurements were performed in cases with stenosis percentages of 48, 71, and 88% and with hydrostatic pressures of 10 and 30mmHg. Then, the correlation between Pback by WSA and Pwedge was calculated. In vivo coronary flow and pressure were simultaneously measured for 11 vessels in all patients. The FFR and iFR values were reconstructed as the ratios of forward wave at distal and proximal sites during hyperemia and at rest, respectively.RESULTS: Based on the in vitro results, the correlation between Pback and Pwedge was high (r=0.990, p<0.0001). In vivo results showed high correlations between FFR and reconstructed FFR (r=0.992, p<0.001) and between iFR and reconstructed iFR (r=0.930, p<0.001).CONCLUSIONS: Reconstructed FFR and iFR were in good agreement with conventional FFR and iFR. FFR and iFR can be expressed as the variation of trans-stenotic forward pressure, indicating that the two values are inferred from the same formula under different conditions.

  View details for DOI 10.1186/s12872-021-01855-4

  View details for PubMedID 33494709