Evaluation of Ultrafast Wave-CAIPI 3D FLAIR in the Visualization and Volumetric Estimation of Cerebral White Matter Lesions

BACKGROUND AND PURPOSE To evaluate an ultrafast 3D-FLAIR sequence using Wave-CAIPI encoding (Wave-FLAIR) compared to standard 3D-FLAIR in the visualization and volumetric estimation of cerebral white matter lesions in a clinical setting. MATERIALS AND METHODS 42 consecutive patients underwent 3T brain MRI including standard 3D-FLAIR (acceleration factor R=2, scan time TA=7:15 minutes) and resolution-matched ultrafast Wave-FLAIR sequences (R=6, TA=2:45 minutes for the 20-ch coil; R=9, TA=1:50 minutes for the 32-ch coil) as part of clinical evaluation for demyelinating disease. Automated segmentation of cerebral white matter lesions was performed using the Lesion Segmentation Tool in SPM. Student’s t-test, intra-class correlation coefficient (ICC), relative lesion volume difference (LVD) and Dice similarity coefficients (DSC) were used to compare volumetric measurements between sequences. Two blinded neuroradiologists evaluated the visualization of white matter lesions, artifact and overall diagnostic quality using a predefined 5-point scale. RESULTS Standard and Wave-FLAIR sequences showed excellent agreement of lesion volumes with an ICC of 0.99 and DSC of 0.97±0.05 (range 0.84 to 0.99). Wave-FLAIR was non-inferior to standard-FLAIR for visualization of lesions and motion. The diagnostic quality for Wave-FLAIR was slightly greater than standard-FLAIR for infratentorial lesions (p<0.001), and there was less pulsation artifact on Wave-FLAIR compared to standard FLAIR (p<0.001). CONCLUSIONS Ultrafast Wave-FLAIR provides superior visualization of infratentorial lesions while preserving overall diagnostic quality and yields comparable white matter lesion volumes to those estimated using standard-FLAIR. The availability of ultrafast Wave-FLAIR may facilitate the greater use of 3D-FLAIR sequences in the evaluation of patients with suspected demyelinating disease.