Effectiveness of GRAPPA-Assisted Head Immobilization in Enhancing Diagnostic Confidence and Interobserver Agreement in Routine Adult Brain MRI: A Prospective Paired Study

Abstract

Background: Motion artifacts in brain MRI may reduce image interpretability and diagnostic confidence. Motion-reduction strategies should be evaluated using blinded radiologist assessment and interobserver agreement. Objective: To assess the effect of simple head immobilization combined with Generalized Autocalibrating Partially Parallel Acquisitions (GRAPPA) acceleration on motion artifact assessment, diagnostic confidence, and interobserver agreement in brain MRI. Methods: This prospective study included 38 adults who underwent standard and intervention diffusion-weighted imaging (DWI) and axial T2-weighted imaging during a single session. The intervention combined foam padding, forehead fixation, and GRAPPA acceleration. Two blinded radiologists assessed motion artifacts and diagnostic confidence. Results: The intervention significantly enhanced both sequences' image quality and diagnostic confidence as rated by the radiologists. In DWI, no-artifact ratings for Radiologist 1 increased from 0.0% to 55.3% and for Radiologist 2 from 5.3% to 60.5%, while very high diagnostic confidence increased from 10.5% to 63.2% and from 7.9% to 71.1% (p=0.0001). In axial T2-weighted imaging, no-artifact ratings increased from 2.6% to 63.2% and from 7.9% to 60.5%, while very high diagnostic confidence increased from 7.9% to 60.5% and from 26.3% to 73.7% (p=0.0001). These results indicate that the reduction in motion led to a clinically significant improvement in the consistency of image interpretation. Cohen's kappa for diagnostic confidence was almost perfect and remained stable in DWI (0.941 to 0.944) and increased in axial T2-weighted imaging (0.469 to 0.964). Conclusions: GRAPPA-assisted head immobilization improved image quality and diagnostic confidence in routine adult brain MRI, supporting strong diagnostic confidence and acceptable interobserver agreement.