Optimization of fast field echo resembling a CT using restricted echo-spacing (FRACTURE) in cervical ossification of the posterior longitudinal ligament

OBJECTIVES: Fast field echo resembling a CT using restricted echo-spacing (FRACTURE) provides superior cortical and trabecular bone contrast. However, scan parameters may be suboptimal for imaging ossification of the posterior longitudinal ligament (OPLL) because of low contrast between cerebrospinal fluid and ossified ligaments. This study aimed to optimize FRACTURE parameters for improved visualization of cervical OPLL. MATERIALS AND METHODS: Twenty-four patients with OPLL underwent 3.0-T MRI. Three FRACTURE-based sequences were acquired: (1) FRACTURE (ORG), using fast-field echo with a flip angle (FA) of 15˚; (2) FRACTURE (FA5˚), using fast-field echo with an FA of 5˚; and (3) mFRACTURE, a turbo-field echo with an FA of 5˚. Contrast ratios between OPLL and cerebrospinal fluid, cervical spinal cord, and the intervertebral disc were calculated. Two radiologists independently graded OPLL visualization. RESULTS: Contrast ratios between OPLL and cerebrospinal fluid and between OPLL and the spinal cord were significantly higher with FRACTURE (FA5°) and mFRACTURE than with FRACTURE (ORG) (all p < .05), whereas the contrast ratio between OPLL and the intervertebral disc was significantly higher only with mFRACTURE (p < .05). Image quality scores were significantly higher for mFRACTURE than for FRACTURE (ORG) in both readers (both p < .05) and than for FRACTURE (FA5°) in Reader 2 (p < .05). CONCLUSION: mFRACTURE improves contrast between OPLL and surrounding tissues and may be a useful MRI technique for enhancing visualization of cervical OPLL. ADVANCES IN KNOWLEDGE: A low FA combined with TFE may optimize FRACTURE imaging for cervical OPLL by improving lesion conspicuity.