Rapid Diagnosis of Cauda Equina Syndrome: A Prospective Study Comparing Photon-counting CT With MRI.

Abstract

Purpose: Early diagnosis of cauda equina syndrome is essential to prevent irreversible neurological damage, but MRI can be unavailable or contraindicated. This study aimed to evaluate whether photon-counting CT (PCCT) can be a reliable alternative to reference standard MRI for diagnosing cauda equina syndrome.

Methods: In this prospective study, participants with different conditions, including degenerative spinal canal stenosis, disk herniation, vertebral compression fracture, and intraspinal extradural tumor underwent PCCT and MRI between November 2022 and March 2024 at a university hospital. Three radiologists independently evaluated images for compression of cauda equina and/or spinal cord, level and cause of compression, and spinal cord visibility. Intrarater sensitivity and specificity in diagnosing compression of cauda equina and/or spinal cord on PCCT versus MRI were calculated. Pearson correlation between PCCT and MRI was assessed for dural sac areas at all lumbar disk levels. Point-biserial correlation was calculated for body mass index (BMI) versus spinal cord visibility.

Results: A total of 14 participants [mean age 76±6 y (SD); 8 women] were examined. PCCT demonstrated 100% sensitivity and 60% to 83% specificity for diagnosing compression of cauda equina and/or spinal cord across 3 raters, compared with MRI. Axial area measurements showed an almost perfect correlation between modalities (r >0.9), with PCCT slightly underestimating areas in 70% of measurements. PCCT visualized the spinal cord in all participants, but in 19% of the assessments it was barely visible. No correlation was found between BMI and spinal cord visibility (P >.05).

Conclusions: Photon-counting CT demonstrated its usefulness as a rapid alternative in selected patients with suspected cauda equina syndrome (excluding spinal hematomas and spondylodiscitis), when MRI is unavailable or contraindicated. There were strong correlations in spinal canal stenosis measurements with MRI, showing its potential as an alternative to MRI in nonacute conditions of the lumbar spine, such as degenerative disk disease.