Quantitative assessment and ligament traceability of volume isotropic turbo spin echo acquisition (VISTA) ankle magnetic resonance imaging : fat suppression versus without fat suppression

Abstract

Objective: To compare the image quality and ligament traceability in ankle images obtained using Volume Isotropic Turbo Spin Echo Acquisition (VISTA) MRI with and without fat suppression.Materials and Methods: The signal-to-noise ratios (SNRs) in images from a phantom and from the ankle of a volunteer were compared. Ten ankles from 10 non-symptomatic volunteers were imaged for comparisons of contrast ratio (CR) and ligament traceability. All examinations were performed using VISTA sequences with and without fat suppression on a 3T MRI scanner. The SNRs were obtained from images with subjects and without subjects (noise-only). Contrast ratios from images of the 10 ankles were acquired between fluid and tendon (F-T), F-cartilage (C), F-ligament (L), fat (f)-T, f-C and f-L. Two musculoskeletal radiologists independently scored the traceability of 7 ligaments, in sagittal, axial and coronal images respectively, based on a 4-point scale (1 as not traceable through 4 as clearly traceable). The Wilcoxon signed-rank test was used to compare the CR. Fisher''s exact test and Pearson''s chi-squared test were used to compare the ligament traceability.Results: The SNRs did not differ significantly between the two sequences except in bone marrow. VISTA Spectral Attenuated Inversion Recovery (SPAIR) showed the higher CR only in F-T (p=0.04), whereas VISTA showed higher CR in f-T (p=0.005), f-C (p=0.005) and f-L (p=0.005). The calcaneofibular ligament traceability with VISTA was superior to that obtained with VISTA SPAIR (p < 0.05) in all planes.Conclusions: VISTA showed significant superiority to VISTA SPAIR in tracing CFL due to the superior CR between fat and ligament