Figure 1. Coronal Gd-enhanced T₁-weighted MR images. Left: Image obtained in a 40-year-old man who presented with headaches, deterioration of vision, and loss of libido due to a macroadenoma with cavernous sinus extension. The patient's initial serum prolactin level was 3652 ng/ml, which confirmed the diagnosis of a macroprolactinoma. The patient was treated with bromocriptine, which was eventually changed to cabergoline because the man experienced intolerable side effects. Center and Right: Images obtained at 2 (center) and 6 (right) months after initiation of dopamine agonist therapy, demonstrating significant shrinking of the tumor with normalization of serum prolactin levels (5.5 ng/ml at 2 months and 2.6 ng/ml at 6 months).

Figure 2. Graph showing changes in the serum prolactin level during dopamine agonist therapy received by the patient shown in Fig. 1. Note that the hormone levels decreased significantly within 1 week and normalized within 1 to 2 months after initiation of therapy.

Figure 3. Coronal T₂-weighted (left) and axial Gd-enhanced T₁-weighted (right) images obtained in a patient who presented with severe headache and right ophthalmoplegia caused by nonhemorrhagic pituitary apoplexy in a macroprolactinoma. The patient's symptoms resolved after bromocriptine therapy. There is also thickening of the sphenoid sinus mucosa (left), which is usually present in cases of pituitary apoplexy.

Figure 4. Coronal T₁-weighted MR images obtained before (left) and after (right) Gd administration in a 25-year-old woman who presented with amenorrhea and galactorrhea caused by a microprolactinoma. The patient's initial serum prolactin level was 47.7 ng/ml. She underwent a complete transsphenoidal resection of the tumor. The morning fasting serum prolactin level obtained on postoperative Day 1 was 1 ng/ml, which was suggestive of a biochemical cure.