Characterizing intestinal strictures of Crohn's disease in vivo by endoscopic photoacoustic imaging.

Crohn's disease (CD) is one type of inflammatory bowel disease where both inflammation and fibrosis cause the thickening of the bowel wall and development of the strictures. Accurate assessment of the strictures is critical for the management of CD because the fibrotic strictures must be removed surgically. In this study, a prototype capsule-shaped acoustic resolution photoacoustic (PA) endoscope, which can perform mulitwavelength side-view scanning, was developed to characterize the intestinal strictures of CD. The imaging performance of the probe was tested in phantom experiments and a rabbit trinitrobenzene sulfonic acid (TNBS) model with acute (inflammatory only) or chronic (mixed fibrotic and inflammatory) colitis in vivo. The motion artifacts due to intestinal peristalsis and the respiratory motion of the animals were compensated to improve image qualities. Quantitative molecular component images derived from multi-wavelength PA measurements of normal, acute and chronic intestinal strictures demonstrated statistically significant differences among the three groups that were confirmed by histopathology. A longitudinal study demonstrated the capability of the system in monitoring the development of fibrosis. The results suggest that the proposed novel, capsule-shaped acoustic resolution PA endoscope can be used to characterize fibrostenotic disease in vivo.