Benefits and pitfalls of iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) imaging in clinical application of the cervical spine MR

Aim: To evaluate efficacy of T2-weighted (T2W) iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL)-fast spin echo (FSE) imaging of the cervical spine.

Materials and methods: The cervical spine of 100 symptomatic patients was imaged using routine magnetic resonance imaging (MRI) versus IDEAL-FSE imaging. The signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), and image quality were analysed. To compare the diagnostic efficiency of degenerative spondylopathy, evaluations of spondylolisthesis, retrolisthesis, disc herniation, myelopathy, disc degeneration, and bone marrow oedema were also performed.

Results: IDEAL-FSE showed significantly higher SNRs and CNRs (all p<0.001) than fat-suppressed (FS) T2W-FSE. Sixteen of 100 patients had cervical spine instrumentation; in those patients, IDEAL-FSE provided significantly better uniformity of fat suppression (p<0.001) and fewer metallic artefacts (p<0.001). For patients without instrumentation, FS T2W-FSE showed significantly better overall image quality (p<0.001) and homogeneity of the cerebrospinal fluid (CSF; p<0.001) with fewer motion artefacts (p<0.001). IDEAL-FSE, however, provided significantly better uniformity of fat suppression (p<0.001). There were no significant differences in the diagnoses of spondylolisthesis, retrolisthesis, disc herniation, or myelopathy between IDEAL and FS T2W images. The only significant differences between the IDEAL and FS T2W images were noted when diagnosing degenerative disc disease at the C2-3 and C5-6 disc levels (p=0.019, p=0.002, respectively) and bone marrow oedema at C3 vertebral body (p=0.029).

Conclusion: T2W IDEAL-FSE imaging should only be considered as an additional sequence to conventional FS T2W images in patients with poor fat suppression or severe metallic artefacts.