Vastly undersampled isotropic projection steady-state free precession imaging of the knee: diagnostic performance compared with conventional MR.

To compare a vastly undersampled isotropic projection steady-state free precession (VIPR-SSFP) sequence and routine magnetic resonance (MR) imaging for evaluating the cartilage, ligaments, menisci, and osseous structures of the knee in symptomatic patients. All subjects signed written informed consent prior to participation in this prospective, HIPAA-compliant, institutional review board-approved study. VIPR-SSFP was added to the routine 1.5-T MR imaging performed on 95 symptomatic patients (52 men, 43 women; average age, 41.6 years) who subsequently underwent arthroscopic knee surgery. All MR examinations were independently reviewed twice by two musculoskeletal radiologists to detect cartilage lesions, anterior and posterior cruciate ligament tears, meniscal tears, and bone marrow edema lesions, first by using routine MR and second by using VIPR-SSFP. By using arthroscopy as the reference standard, the sensitivity and specificity of both MR protocols were calculated. The z test was used to compare sensitivity and specificity values. VIPR-SSFP had significantly higher specificity (P < .01) for helping detect cartilage lesions (92.2% for VIPR-SSFP and 88.4% for routine MR), while routine MR had significantly higher sensitivity (P = .02) and accuracy (P = .05) for helping detect lateral meniscal tears (73.2% sensitivity and 88.4% accuracy for VIPR-SSFP and 87.5% specificity and 93.2% accuracy for routine MR). There was no significant difference (P = .14 to >.99) between VIPR-SSFP and routine MR in the remaining sensitivity and specificity values. VIPR-SSFP helped detect 69.3% of bone marrow edema lesions identified at routine MR. VIPR-SSFP can provide important clinical information regarding the cartilage, ligaments, menisci, and osseous structures of the knee, but is less sensitive than conventional MR imaging at helping detect lateral meniscal tears and bone marrow edema lesions.