Table 1 Perineural involvement response assessment criteria

Complete Response (CR)

No abnormality in nerve at follow up. Previous thickening and enhancement resolved.

Partial Response (PR)

Perineural thickening and/or enhancement diminished but abnormality still remains at follow up compared with baseline scan.

Stable Disease (SD)

Perineural thickening and enhancement is stable compared with baseline scan.

Progressive Disease (PD)

Perineural thickening has increased with or without enhancement compared with baseline scan. Or new sites of disease are identified along the nerve course.