Repeat MRI scans for pituitary microadenomas may be unnecessary: study suggests

Autopsy and imaging studies have shown that around 10% of adults may have pituitary microadenomas, which are small growths in the pituitary gland. These growths are often found incidentally during an MRI scan and are usually less than 10mm in size. Researchers at the Mass General Brigham healthcare system studied 177 patients who had pituitary microadenomas and at least one follow-up MRI scan. Patients with high levels of prolactin hormone were excluded from the study.

At the start of the study, the average size of the microadenomas was 4mm. During a follow-up period of about 5 years, the size of the microadenomas stayed the same in 44% of patients, increased in 28%, decreased in 19%, and increased but later decreased in 9%. Larger microadenomas tended to decrease in size with time, while smaller ones tended to increase in size.

However, the average increase in size for the smaller microadenomas was very small, only 0.1 mm per year. Only three microadenomas grew to be larger than 10mm during the study period. Based on the findings, it appears that frequent follow-up MRIs for patients with incidentally discovered pituitary microadenomas may not be necessary.

The researchers suggest a somewhat arbitrary schedule of repeating MRIs at 1, 4, and 9 years, assuming the initial lesion has not increased in size. However, it is important to note that if patients develop symptoms such as changes in peripheral vision, it is advisable to seek prompt evaluation regardless of the scheduled follow-up.