This study aims to investigate whether T2-weighted or high-resolution CUBE MR scans are more reliable in identifying the myodural bridge. The bridge-specific and scan-specific inter-rater reliability of identifying the myodural bridge on these scans will be compared.
Volunteers older than 18 and with no symptoms of chronic headache or history of cervical trauma were scanned via MRI in the Radiology department of UZ Brussel. The scans were a sagittal T2-weighted MR scan from the standard sequence parameters of UZ Brussel for cervical spine and a high-resolution T2-weighted CUBE scan which was developed in a previous study. The scans were analyzed on a 5-point scale by 5 raters with different expertise and background. The raters were trained by the radiology resident in cooperation with the anatomical experts. The primary outcomes are (1) the inter-rater reliability of the two scan methods for the recognition of the myodural bridges, (2) the inter-rater reliability for each myodural bridge, (3) the inter-rater reliability for combined bridges, all three calculated with the Krippendorff’s alpha for ordinal scales.
A total of 33 participants were included in this study. They underwent both T2-weighted and CUBE MR scans. The scan-specific inter-rater reliability resulted in poor agreement for T2 scans (a = 0,559) and for CUBE scans (a = 0,479). The difference between these alpha’s is 0,080. The distribution of differences was summarized with a mean of 0,0180 (CI [-0,133; 0,292]). A low inter-rater agreement was observed for all myodural bridges on both scans. Bridges difficult to differentiate from another were combined. Although the inter-rater reliability remained low, the combined Krippendorff’s alpha at each level was higher.
There is no significant difference between the two scan types used in this study. The low bridge-specific inter-rater reliability indicates a poor agreement among raters on a 5-point scale. Further research is needed regarding the identification of myodural bridges on MR imaging, considering anatomical variations among individuals, the low prevalence of the bridges, and the difference in backgrounds of the raters.
The myodural bridge's attachment to the dura mater could transmit abnormal mechanical forces or tension from the suboccipital muscles to the spinal dura mater, potentially leading to headache symptoms. As seen in this study, not only the RCPMi but also the RCPMa and OCI are connected to the cervical dura mater via a myodural bridge. The analogy can be made for these muscles. The attachments of the hypertrophied RCPMi, RCPMa, and OCI muscles may transmit excess tension on the dura, causing headache.
Magnetic resonance imaging (MRI)
Headache
