Evaluation of the Ossification of the Cervical Posterior Longitudinal Ligament Utilizing X-Ray, CT and MR Imaging

Abstract

Background: Cervical ossification of posterior longitudinal ligament (OPLL) is a common 
disease among the elderly population of East Asian countries. Cervical OPLL is often misdiagnosed in lateral radiography or magnetic resonance imaging (MRI). The present study 
analyzes the diagnostic accuracy of cervical OPLL in lateral radiography and MRI compared 
to computed tomography (CT).
Methods and Materials: A total of 60 Japanese patients who were clinically diagnosed with 
cervical OPLL by CT imagining were considered in this study. Firstly, a lateral radiograph 
was checked identifying a high-density structure along the posterior aspect of vertebral bodies as OPLL. Secondly, a T2 weighted MRI sagittal image was obtained which delineated a 
thick low-signal posterior longitudinal ligament as OPLL. Thirdly, a cervical CT investigated 
vertebral bodies in which OPLL was present. Subsequently, lateral radiographs and MRIs were 
compared to the CT scans. The diagnostic accuracy in lateral radiograph and MRI were evaluated and causes of misdiagnosis were postulated.
Results: Diagnostic accuracy utilizing lateral radiograph and MRI were 20% (12/60) and 25% 
(15/60), respectively. Only 5 out of the 60 cases displayed evidence of OPLL in all three modalities. Regarding each vertebral level, accuracy using lateral radiograph and MRI of each 
C2-C7 was C2 (88.8% and 100%), C3 (88.8% and 100%), C4 (79.5% and 97.9%), C5 (95.5% 
and 110.6%), C6 (42.5% and 70.2%) and C7 (23.8% and 66.6%).
Conclusions: Diagnosing cervical OPLL using lateral radiograph is prone to underestimation; 
whereas, diagnosis via MRI is prone to overestimation. If severe spondylosis, facet joints, 
and pedicle shadows occur, they can hinder the detection of OPLL in the lateral radiograph. 
Regarding the MRI-based diagnosis, it would be difficult to distinguish ossifications from ligament hypertrophy. However, the use of X-ray and MRI present an accurate diagnostic tool for 
cervical OPLL at the levels of C2, C3, C4 and C5.