MUSCULARIS MUCOSAE, FIBROSIS AND NODULAR LYMPHOCYTE AGGREGATES IN CROHN'S DISEASE – NOVEL ULTRASONOGRAPHIC FINDINGS IN VITRO

Purpose: Transabdominal ultrasound (US) is applied in the examination of patients with Crohn's disease (CD). Advances in US technology enables detailed imaging of the gastrointestinal wall like evaluation of normal and abnormal wall layers and intramural structures. The aim of this study was to improve interpretation of US images of bowel wall changes in CD by comparing US images of bowel resection specimens with the corresponding histological sections.

Materials and methods: Bowel resection specimens of 7 patients with CD were examined with a 10 MHZ linear array US transducer in a saline reservoir. Marking needles were placed in the specimen corresponding to the US plane. After formalin fixation, histological sections were taken according to these markings. 78 histological sections were examined with special emphasis on muscularis mucosae(MM) thickness, fibrosis and nodular lymphocyte aggregates.

Results: A thickened MM was seen in 47/78 histological sections and MM could be identified on 31 US images. Significant fibrosis was seen as reduced echogenicity in the normally hyperechoic submucosa layer and as enhanced echogenicity in the normally hypoechoic muscularis propria layer. Nodular lymphocyte aggregates in close relation to the outer border of the proper muscle were seen in 43/78 histological sections. US images indicated hypoechoic areas corresponding to these aggregates on 37/43 images.

Conclusions: High frequency ultrasound could visualise characteristic bowel wall changes in CD like thickened muscularis mucosa, fibrosis and nodular lymphocyte aggregates.