MR volumetry for monitoring intramuscular bromocriptine treatment in macroprolactinomas

To assess volumetric changes of pituitary prolactinomas, we applied a threshold-based segmentation algorithm in two patients during intramuscular bromocriptine treatment.

Tumor volumes were calculated from contiguous slices of a 3D GE sequence and from conventional SE images.

After a single 50 mg i.m. bromocriptine administration, the prolactinoma volumes decreased by 25 and 35% within 7 and 11 days, respectively. Volume calculations from 3D GE images were more accurate than calculations from 3 mm 2D SE images, especially for smaller tumors. A decrease of prolactinoma size was paralleled by a decrease of serum prolactin levels and correlated with an improvement of visual field and endocrine function in both patients. The end of the bromocriptine effect was indicated by a reincreasing tumor volume, which was observed after 30 days in the first patients and after 43 days in the second patient.

Our results suggest that MR volumetry represents a useful tool to monitor changes of prolactinoma volume during bromocriptine treatment and may improve the clinical management of these patients.