High-resolution Fourier-encoded Sub-millisecond Echo Time Musculoskeletal Imaging at 3 Tesla and 7 Tesla

Purpose: The feasibility of imaging musculoskeletal fibrous tissue components, such as menisci, ligaments, and tendons, with a conventional spoiled gradient echo technique is explored in vivo at 3 T and 7 T.

Methods: To this end, the echo time (TE1 ) of a conventional Fourier-encoded multicontrast three-dimensional SGPR sequence is minimized by using nonselective excitation pulses, highly asymmetric readouts, and a variable TE1 along the phase and slice encoding direction. In addition, a fully sampled second echo image (with TE2 >> TE1 ) can be used to highlight components with short transverse relaxation times in a difference image with positive contrast.

Results: Fourier-encoded spoiled gradient echo sequences are able to provide sub-millisecond TE1 of about 800 μs for typical in-plane resolutions of about 0.5 x 0.5 mm(2) . As a result, high-resolution positive contrast images of fibrous tissues can be generated within clinically feasible scan-time of about 2-7 minutes.

Conclusion: After optimization, Fourier-encoded spoiled gradient echo provides a highly robust and flexible imaging technique for high-resolution positive contrast imaging of fibrous tissue that can readily be used in the clinical routine.