Objective: To examine some typical histological findings in Crohn's disease using high-frequency ultrasound and to define the echo properties of these findings.
Material and methods: Bowel resection specimens from 14 patients operated on for Crohn's disease were examined with a 10 MHz linear array ultrasound transducer in a saline reservoir. Needles were placed in the specimen corresponding to the ultrasound plane. After formalin fixation, histological sections were taken according to these markings. Fifty-eight ultrasonographic images with 123 regions of interest were compared with corresponding histology.
Results: A thickened muscularis mucosae (>0.3 mm) was found in 48 of 69 regions of interest on histology. Submucosa with slight to moderate fibrosis was imaged as an echo-rich layer with sporadic, echo-poor elements (36/56), while severe fibrosis was seen as an echo-rich layer with diffuse, echo-poor elements (40/55). Muscularis propria with slight to moderate fibrosis was seen as an echo-poor layer with sporadic, echo-rich elements (49/66) while severe fibrosis was seen as an echo-poor layer with diffuse, echo-rich elements (17/22). Crohn's rosary was seen as echo-poor extensions of the 4th echo layer (31/50).
Conclusions: Typical histological findings in Crohn's disease such as a thickened muscularis mucosae and Crohn's rosary can be imaged with high-frequency ultrasound in vitro. Fibrosis in the submucosa and muscularis propria is associated with decreasing and increasing echogenicity, respectively.