Comparative Intra- and Inter-observer Reliability of Two Methods for Evaluating Intraoperative Ultrasonography-based Spinal Cord Hyperechogenicity Intensity in Degenerative Cervical Myelopathy

Objective: To acquire a higher-reliability method, and compare the in-observer and inter-observer reliability of two methods in evaluating the hyperechoic intensity of spinal cord ultrasound in degenerative cervical myelopathy (DCM). Materials: and Methods: Totally 28 patients (20 males and 8 females) who had been followed up for 12 months were included. Their mean age at surgery was 61.2±10.8 years and the average symptom duration was 23.36±22.11 months. The gray values of circles 1, 2 and 3 were recorded as G compression , G norml and G sac , respectively. The gray value ratio (GVR) was calculated as follows: GVR-A= G compression /G norml (method A), and GVR-B= G compression /G sac (method B). The in-observer and inter-observer reliabilities of the two methods were compared. It is generally believed a reliability coefficient 0.75 indicate poor and good reliability respectively. The images-based GVR-B using this protocol demonstrates higher inter- and intraobserver reliabilities than GVR-A, and can be used as the basis for prognostic prediction and future studies. Results: : All examination acquisitions were successfully completed. GVR-A averaged 2.043 (0.318–5.56), and GVR-B averaged 0.578(0.06–1.41). GVR-B has better repeatability of gray value measurement, smaller RSD% (0.298 vs. 0.32) and larger inter-group correlation coefficient compared with GVR-A. The mean value (MD) of the GVR difference calculated by GVR-B between the two clinicians was closer to 0. Conclusions: : For DCM patients routinely using ultrasound for real-time cord visualization during spinal cord decompression by French-door laminoplasty, the images-based GVR-B using this protocol demonstrates better inter- and intraobserver reliabilities compared with GVR-A.