Can MRI be used as a safe and expedient option for calculating Spinal Instability Neoplastic Score (SINS) for patients with metastatic spinal cord compression?


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Patrick Hurley, Christine Azzopardi, Rajesh Botchu, Melvin Grainger, Adrian Gardner

Abstract

Background

Metastatic spinal cord compression (MSCC) is a common presentation of cancer. Spinal lesions in MSCC can be assessed using the Spinal Instability Neoplastic  Score (SINS) to help guide management with surgical stabilisation if appropriate. The score comprises five CT (Computed Tomography) based and one clinical parameter. Patients also undergo an MRI (Magnetic Resonance Imaging) to image the spinal cord and marrow. This study investigates whether MRI scans of the spine can be used to calculate the SINS score.


Method

102 individuals were retrospectively identified as suitable for review. Each patient’s MRI and CT scans were reviewed by two Consultant Musculoskeletal Radiologists independently to calculate the SINS score. To avoid potential bias, the MRI scans were reviewed in the first instance. Bland-Altman analysis was performed to identify the limits of agreement between the SINS scores from the MRI and CT scans for the two observers.


 

Results

The limits of agreement between the SINS score from the MRI and CT scans was 0.11 and 0.12 (95% CI 0.82 to –1.04 and 1.24 to –1.48). The differences between the imaging modalities was explained entirely through the assessment of bone lesion. All other SINS components scored the same for both MRI and CT for both observers. The use of MRI tended to increase the SINS score when compared to that derived from the CT scan. At the cross over point of unstable, indeterminate and stable, the use of MRI always led to a SINS score the same or greater than that from CT.  


Conclusion

This study shows that MRI scans can be used to calculate the SINS score reliably when compared to that scored from a CT scan. The major point of discrepancy between MRI and CT was shown to be in defining bone lesion type. This challenge could potentially be alleviated through knowledge of the primary site of cancer when calculating the score or through the use of other MRI sequences (inverted T1 Volumetric Interpolated Breath-hold Examination (VIBE)) to better assess the bone lesion compared to a CT.

 

Impact statement

This research will allow for faster decision making and efficient utilisation of resources in the field of MSCC.