Two-slice-touch rule (knee MRI)

The two-slice-touch rule is a sign on MRI of the knee used to increase the sensitivity of diagnosing meniscal tears.

This rule states a meniscal tear is present if abnormal findings are present on two or more images - these do not have to be contiguous, e.g. can occur on sagittal and coronal slices but at the same anatomical location. The only exception to this rule applies to a meniscal root tear, for which abnormal signal in only one slice is considered highly specific for an underlying tear. A possible meniscal tear is present if abnormal findings are present on only one slice in other types of meniscal tear.