Feasibility of high-resolution pituitary MRI at 7.0 tesla.

OBJECTIVES

Since the pituitary gland measures 3-8 mm, imaging with the highest possible spatial resolution is important for the detection of even smaller lesions such as those seen in Cushing's disease. In the current feasibility study, we tested a multi-sequence MRI protocol to visualize the pituitary gland in high resolution at 7.0 Tesla (7.0 T).

METHODS

Ten healthy volunteers were examined with a 7.0 T pituitary gland protocol. The protocol consisted of a T1-weighted magnetization-prepared inversion recovery (MPIR) turbo spin-echo (TSE) sequence and a T2-weighted TSE sequence. Additionally, this protocol was tested in five patients with clinical and biochemical suspicion of a microadenoma.

RESULTS

The dedicated protocol was successful in visualizing normal pituitary anatomy. At 7.0 T compared to 1.5 T, four times as many slices covered the pituitary gland in sagittal and coronal direction. In three patients, a lesion was diagnosed at 7.0 T, and was confirmed by histopathology to be a microadenoma.

CONCLUSION

Head-to-head comparisons of 7.0 T with 1.5 T and 3.0 T are needed with larger samples of patients and with imaging times feasible for clinical settings. However, the current study suggests that high-resolution 7.0 T MRI of the pituitary gland may provide new perspectives when used as a second-line diagnostic examination in the specific context of Cushing's disease.

KEY POINTS: • 7.0 T MRI enables ultra-high-resolution imaging of the pituitary gland. • 7.0 T MRI is appropriate to visualize normal pituitary gland anatomy. • The pituitary protocol consists of a T 1 -MPIR-TSE and a T 2 -TSE sequence. • In four patients, a suspected ACTH-producing microadenoma was visualized at 7.0 T. • Histopathology confirmed three of four lesions to be ACTH-producing microadenomas.