Ultrashort Echo Time MRI of Cortical Bone at 7 Tesla Field Strength: A Feasibility Study

Purpose: To implement and examine the feasibility of a three-dimensional (3D) ultrashort TE (UTE) sequence on a 7 Tesla (T) clinical MR scanner in comparison with 3T MRI at high isotropic resolution. Materials and Methods: Using an in-house built saddle coil at both field strengths we have imaged mid-diaphysial sections of five fresh cadaveric specimens of the distal tibia. An additional in vivo scan was performed at 7 Tesla using a quadrature knee coil. Results: Using the same type of saddle coil at both field strengths, a significant increase in SNR at 7T compared with 3T (factor 1.7) was found. Significantly shorter T2* values were found at the higher field strength (T2* = 552.2 +/- 126 mu s at 7T versus T2* = 1163 +/- 391 mu s at 3T). Conclusion: UHF MRI at 7T has great potential for imaging tissues with short T2.