Signal, contrast, and resolution in optimized PD- and T2-weighted turbo SE images of the knee.

Abstract

Signal and contrast behavior, delineation of anatomical details, and flow artifacts were compared in dual echo SE and turbo SE (TSE) sequences. Results were correlated with theoretical aspects of the TSE technique. A TSE sequence (TR = 3,500 ms, TEeff = 19, 93 ms, ETL = 3) and a conventional SE sequence (TR = 2,500 ms, TE = 20, 70 ms) were applied to 64 patients with knee injuries. Signal intensities of anatomical structures were measured in regions of interest. Contrast and edge sharpness of menisci and posterior cruciate ligament were evaluated by three independent observers. The TSE sequence yielded similar signal and contrast behavior compared with SE. Visual evaluation revealed nearly equivalent contrast and edge sharpness of menisci and posterior cruciate ligament in proton-density (PD)-weighted TSE images. Contrast and edge sharpness of menisci were significantly lower in T2-weighted TSE images. Reduced flow artifacts were found in PD- and especially in T2-weighted TSE images. Differences between both techniques are interpreted, taking into account influence of TEeff, ETL, k-space trajectory, magnetization transfer effects, and J-coupling. The TSE sequence yielded good image quality in PD-weighted, but slightly inferior quality in T2-weighted, images, reducing the time of acquisition by 50%.