Alterations in T1-weighted Contrast in 3T MRI
Because relaxation times are longer at 3.0 T than at 1.5 T, there may be decreased soft-tissue contrast and decreased lesion conspicuity on unenhanced T1-weighted images (Fig 2). To compensate, longer repetition times are required to improve soft-tissue contrast when performing high-field-strength abdominal imaging. However, longer repetition times result in a longer imaging time and are often limited by the length of the patient’s breath hold. One solution that has been used for unenhanced T1-weighted imaging at higher field strengths is incorporating an inversion recovery preparatory pulse to accentuate T1 contrast. Use of a magnetization preparation prepulse for gradient-echo imaging is also beneficial (53,54). Parallel imaging techniques also may be used to decrease overall acquisition time at T1-weighted imaging.