Image quality evaluation of decubitus lumbar spine MRI using a flexible coil and PROPELLER sequence: comparison with conventional supine MRI.

Abstract

To evaluate image quality of decubitus lumbar spine MRI using a flexible coil with or without Periodically Rotated Overlapping Parallel Lines with Enhanced Reconstruction (PROPELLER) sequence compared to that of the conventional supine lumbar spine MRI. This study was conducted on patients who underwent decubitus lumbar spine MRI applying a flexible coil at a single center between February 1 and March 11, 2025, and had a Numeric Rating Scale (NRS) pain score ≥ 5, while examining supine MRI. Signal-to-noise ratio (SNR) in T2-weighted fast-spin-echo (FSE) sequence for supine, decubitus, and PROPELLER sequence at decubitus position were measured and compared using the Wilcoxon signed-rank test. Two radiologists independently evaluated the subjective image quality of each spine MRI. A total of 35 patients (mean age, 66 ± 13 years) were included in our study. On T2-weighted sagittal images, cerebrospinal fluid (CSF) SNR was highest in the supine_FSE (589.3, 95% CI: 482.1-695.1) and significantly lower in both decubitus_FSE (431.2, 95% CI: 365.9-479.9) and decubitus_PROPELLER (417.8, 95% CI: 389.2-439.1) (p < 0.001). On T2-weighted axial images, SNR_CSF values of supine_FSE (284.6, 95% CI: 256.4-331.0) and decubitus_PROPELLER (245.0, 95% CI: 215.7-336.1) were both statistically higher than that of decubitus_FSE (176.1, 95% CI: 135.9-209.2) (p < 0.001). In qualitative analysis, there was no statistical difference across supine_FSE, decubitus_FSE, and decubitus_PROPELLER. Image quality of decubitus lumbar spine MRI using a flexible coil was clinically feasible with acceptable image quality. PROPELLER sequence improved SNR_CSF on axial images in decubitus position.