Of the 87 cases of syrinx, there were 23 mass lesions, 11 Chiari malformations, three spinal cord contusions, and 50 idiopathic syringes. Using T2-weighted imaging alone, readers detected no findings suspicious for a syrinx-associated mass in 55 cases and detected findings suspicious for a mass in 32 of 87 cases. Reader sensitivity for an underlying mass lesion was 100%; specificity, 86%; positive predictive value, 72%; and negative predictive value, 100%. Interreader agreement was excellent (κ = 0.88)