Added value of multiparametric MRI combining dynamic contrast-enhanced and diffusion-weighted imaging for determining thyroid-associated ophthalmopathy activity.

Abstract

To evaluate the performance of model-based dynamic contrast-enhanced (DCE)-MRI and diffusion-weighted imaging (DWI) in determining the disease activity of thyroid-associated ophthalmopathy (TAO), and to establish their additional value to fat-suppressed T2-weighted imaging (FS-T2WI) for staging TAO. Seventy-two patients with TAO (48 active, 96 eyes; 24 inactive, 48 eyes) were prospectively enrolled. DCE-MRI, DWI and FS-T2WI were scanned for pre-treatment evaluation. Simplified histogram parameters (min, mean, max) of DCE-MRI-derived K^trans, K_ep and V_e, apparent diffusion coefficient (ADC) and signal intensity ratio (SIR) on FS-T2WI of extraocular muscles were calculated for each orbit and compared between active and inactive groups. Multivariate analyses were used to identify independent indicators for disease activity. Receiver operating characteristic (ROC) curves analyses and DeLong tests were performed to evaluate and compare the performances of the identified significant imaging parameters and their combinations. Active TAO patients showed significantly higher mean and maximum V_e, higher minimum, mean and maximum ADC, higher minimum, mean and maximum SIR than inactive patients (p < 0.05). Mean SIR (odds ratio (OR) = 3.449, p = 0.002), mean ADC (OR = 1.008, p < 0.001), and mean V_e (OR = 14.138, p = 0.022) were found to be independent predictors of active TAO. Combination of mean V_e, mean ADC and mean SIR outperformed mean SIR alone in staging TAO (area under ROC curves, 0.839 vs 0.769, p = 0.016). DCE-MRI and DWI could determine the disease activity of TAO and provide additional value to FS-T2WI in staging TAO. Question Fat-suppressed T2-weighted imaging was the most commonly used imaging technique for determining the disease activity of thyroid-associated ophthalmopathy; however, its performance needs to be improved. Findings Dynamic contrast-enhanced magnetic resonance imaging and diffusion-weighted imaging could provide added value to fat-suppressed T2-weighted imaging for determining the clinical activity of thyroid-associated ophthalmopathy. Clinical relevance Dynamic contrast-enhanced magnetic resonance imaging and diffusion-weighted imaging can provide information about tissue permeability and water molecule diffusion of extraocular muscles in patients with thyroid-associated ophthalmopathy (TAO), and therefore provide additional value to fat-suppressed T2-weighted imaging in staging TAO.