[Increased T1 signal of the residual normal anterior pituitary gland following medical treatment of pituitary prolactinoma].

PURPOSE: To illustrate that residual normal pituitary gland may show hyperintense signal on T1-weighted image after medical treatment of pituitary prolactinoma.

MATERIAL: and methods. Three patients treated with bromocriptine for a prolactinoma and showing hyperintense signal of the residual normal pituitary tissue on T1-weighted images were studied. In all patients, measurements of the anterior pituitary gland signal (APGS) and the temporal lobe white matter signal (TLWMS) were obtained by a "region of interest" (ROI) on coronal T1-weighted images. The APGS/TLWMS ratios were calculated and compared to those of a control group of 30 normal subjects.

RESULTS

In the three patients, the measurements obtained by ROI confirmed the visual impression of high signal of the residual normal pituitary tissue. Ratios were ranging from 1.15 to 1.21, while they were ranging, in the control group from 0.92 to 1.09.

CONCLUSION

In patients with prolactin-secreting adenoma seen after medical treatment, high signal of the residual normal pituitary tissue can be observed, probably due to cellular hyperactivity as it can be noticed during some physiological states. This pattern has to be differentiated from other pituitary abnormalities demonstrating T1 hyperintensity such as hemorrhagic changes of a prolactinoma.