Diagnosis and evaluation of cervical ossification of the posterior longitudinal ligament on Zero-Echo Time Magnetic Resonance Imaging: an illustrative case series

Purpose: Computed tomography (CT) scans are widely used clinically in the diagnosis of ossification of the posterior longitudinal ligament (OPLL). Conventionally acquired magnetic resonance imaging (MRI) is limited by insufficient signal intensity within bone tissue. Osseus conspicuity may be enhanced by applying sequences with "CT-like" bone contrast zero-echo time (ZTE) MRI. This is a case series aimed to understand if ZTE-MRI is sensitive in detecting cervical OPLL and if this modality is suitable for evaluating OPLL morphology.

Methods: A retrospective review was performed to identify adult patients with available cervical ZTE-MRI and CT scans. ZTE-MRI and CT were evaluated for their ability to detect OPLL by 2 attending spine surgeons, 1 spine surgery clinical fellow, and 1 senior orthopedic resident. The phenotype of OPLL was then described and compared between the two modalities.

Results: A total of 50 patients were reviewed. All clinicians detected 4 cases of OPLL on CT, and the same cases were independently found on ZTE-MRI. The modalities were then compared to assess the phenotype of OPLL.

Conclusion: ZTE-MRI may have the potential to obviate the need for concurrent CT scans in diagnosing OPLL. When OPLL was suspected on MRI, ZTE-MRI could confirm the OPLL diagnosis. With conventional MRI sequences that include additional post-processed ZTE-MRI, clinicians can also assess OPLL morphology and the resulting spinal cord change to make a complete diagnosis and identify patients at higher risk for progression or complications. ZTE-MRI avoids CT-related radiation, can improve diagnosis, and decrease health costs.