P072 Quantitative phase imaging for the characterisation of Crohn's disease-derived intestinal strictures. (25th January 2019) - Bokemeyer, A
Abstract: Background: Intestinal strictures are a frequent complication of Crohn's disease (CD). The differentiation of inflammatory from the fibrotic components of CD strictures is crucial for the right choice of therapy. However, currently available imaging modalities have limited capability to determine the degree of fibrosis. Digital holographic microscopy (DHM) enables stain-free quantitative phase contrast imaging and provides determination of the refractive index (RI), which is directly related to tissue density. Therefore, this study evaluates quantitative phase imaging (QPI) with digital holographic microscopy (DHM) for the assessment of fibrosis within CD strictures. Methods: In total, 26 surgical resection specimens were obtained from non-stenotic and stenotic tissue areas of 13 CD patients with symptomatic intestinal strictures. Clinical characteristics were extracted from medical records. Cryostat sections from stenotic and non-stenotic bowel segments for each patient were evaluated separately by conventional H&E staining and were simultaneously analysed by DHM. RI measurements were performed in the epithelium (e), the submucosa (sm) and the muscularis propria (mp). Results: The included patients had a moderately increased disease activity (CD activity index [CDAI]: 202 ± 25.9, white blood cell count: 10.8 ± 1.0 × 10 9 /l, C-reactive protein: 4.6 ± 1.5 mg/dl). Employing DHM, 360 digital holograms were generated in 26 surgical specimens and ultimately 3600 measurements within defined ROIs were performed. The average RI of stenotic compared with non-stenotic tissue samples was significantly higher in all layers of the intestinal wall (e: 1.355 vs. 1.354, p = 0.013; sm: 1.364 vs. 1.359, p < 0.001 and mp: 1.357 vs. 1.355, p < 0.001). Conclusions: QPI using DHM reliably assesses density differences in the intestinal wall and is capable to distinguish non-stenotic from stenotic tissue. Thereby, QPI could help to quantitatively characterise CD strictures in the future.