Author of 1 Presentation
SS 8.5 - Reliability in villous tumours staging between preoperative MRI and histopathological examination (ID 320)
Abstract
Purpose
This study aimed to assess the reliability of rectal villous tumors staging between rectal MRI and histological examination used as the gold standard and to investigate causes for discrepancies.
Material and methods
The rectal 1.5T MR scans of 40 patients followed for a histologically proven rectal villous adenoma were retrospectively included. Two independent experienced radiologists staged each tumor according to the TNM classification and described the occurrence of retraction of the rectal wall or spiculations within the associated mesorectum. A third radiologist collected tumor’s morphological characteristics.
Results
The mean volume of tumors with spiculations and retraction was significantly greater (p<0.05) compared to tumors without these characteristics. Spiculations and retraction of the rectal wall were observed regardless of the definitive histological stage and did not represent a malignancy criterion. A weak inter-observer reliability (Gwet’s AC2: 0.31 [0.04–0.57]) in T-staging was observed between the two readers. Reader 1 showed a high reliability (Gwet’s AC2: 0.90 [0.81–0.99]) in T-staging between histopathological examination and preoperative MRI. In the opposite, reader 2 showed a weak reliability (Gwet’s AC2: 0.31 [0.03–0.58]) in T-staging. He overstaged all tumors (100%) with spiculations (p <0.05).
Conclusion
MRI understaged rectal villous adenoma and was unable to detect degenerative criteria, along with slight interobserver agreement. The typical pejorative signs of rectal tumors, such as retractions and spiculations, occurred in all stages and were responsible for misstaging in most cases, in particular, bulky tumors.