MRI grading system for abnormal high meniscal signal intensity was reported by Lotysch et al. MR grades 1, 2 and 3 have been used:
- grade 1: small focal area of hyperintensity, no extension to the articular surface
grade 2: linear areas of hyperintensity, no extension to the articular surface
- 2a: linear abnormal hyperintensity with no extension to the articular surface
- 2b: abnormal hyperintensity reaches the articular surface on a single image
- 2c: globular wedge-shaped abnormal hyperintensity with no extension to the articular surface
Some Grade 2 abnormal meniscal signals ware found to be associated with a meniscal tear on arthroscopy. Therefore, they were subdivided into 2a, 2b, and 2c. Dillon et al. said that 50% of patients with grade 2c had meniscal tears on arthroscopy.
- grade 3: abnormal hyperintensity extends to at least one articular surface (superior or inferior), and is referred as a definite meniscal tear
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