Abstract
OBJECTIVES: To compare field-of-view optimized and constrained undistorted single-shot (FOCUS), multiplexed sensitivity-encoding (MUSE) and FOCUS-MUSE diffusion-weighted images (DWIs) in orbital imaging quality and staging performance for the patients with thyroid-associated ophthalmopathy (TAO). MATERIALS AND METHODS: 67 TAOs underwent FOCUS, MUSE and FOCUS-MUSE DWIs. Qualitative (artifacts and geometric distortion, overall image quality, sharpness of boundaries) and quantitative parameters (geometric distortion ratio (GDR), signal-to-noise ratio (SNR), apparent diffusion coefficient (ADC) value, normalized ADC (nADC) value) were assessed. Additionally, nADC values of the extraocular muscles (EOMs) and mean nADC values were compared between active and inactive TAOs. Diagnostic performance was also evaluated. RESULTS: FOCUS-MUSE DWI exhibited significantly fewer artifacts and geometric distortion, superior overall image quality, enhanced sharpness of boundaries, higher SNR and lower GDR than MUSE and FOCUS DWIs (all p < 0.05). FOCUS-MUSE DWI showed significantly lower ADC values than MUSE (all p < 0.05) and FOCUS DWIs (all p < 0.05, except for that of superior EOM). The nADC values showed no significance among the three DWIs (all p > 0.05), except for that of the superior EOM. Furthermore, active TAOs showed higher nADC values than inactive TAOs in three DWIs (all p < 0.05). The mean nADC value of FOCUS-MUSE DWI (AUC, 0.890; sensitivity, 84.8%; specificity, 77.3%) performed better than that of MUSE (AUC, 0.713; sensitivity, 54.3%; specificity, 80.7%; p < 0.001) and FOCUS DWIs (AUC, 0.730; sensitivity, 47.8%; specificity, 90.9%; p < 0.001) in diagnosing active TAOs. CONCLUSIONS: FOCUS-MUSE DWI provides superior image quality and staging performance in assessing TAO than MUSE and FOCUS DWIs. We recommend its use for evaluating TAO patients in clinical practice. CRITICAL RELEVANCE STATEMENT: Field-of-view optimized and constrained undistorted single-shot multiplexed sensitivity-encoding DWI shows superior image quality and staging performance for thyroid-associated ophthalmopathy than other echo-planar imaging-based modified sequences. KEY POINTS: The superiority among different echo-planar imaging-based modified DWIs in thyroid-associated ophthalmopathy remains unclear. Field-of-view optimized and constrained undistorted single-shot multiplexed sensitivity-encoding (FOCUS-MUSE) DWI outperforms MUSE and FOCUS DWIs in imaging quality. Normalized apparent diffusion coefficient values derived from FOCUS-MUSE DWI improve staging performance of thyroid-associated ophthalmopathy.