MRI protocol technique in the optimal therapeutic strategy of non-functioning pituitary adenomas

We performed a prospective study using magnetic resonance imaging (MRI) at regular post-operative intervals in non-irradiated patients with non-functioning pituitary adenomas (NFAs) to assess the frequency of tumoral regrowth and recurrences, in order to define the indications of post-operative radiotherapy.

Fifty-one patients aged 25--80 years (mean, 55.6plus minus12.3 years) were included. Post-operative MRIs were performed 3--12 months (mean, 5.2plus minus1.7 months) after surgery, 6 months later and then, every 12--18 months for at least 2 years. The mean post-operative follow-up was 67.7plus minus31.8 months (range, 24--144 months).

In 17 patients (33%, group I) no tumoral residue was observed on post-operative MRIs and no tumoral recurrence was diagnosed. Tumour regrowth was detected in 13 of the 34 patients (38.2%) with post-operative tumoral residue (group II), 7--66 months (mean, 27.3plus minus17.3 months) after surgery. In this group, Kaplan--Meier analysis showed 78.8% recurrence free survival at 2 years and 60.9% at 5 years. Patients with tumoral regrowth had higher mean residual tumoral volume than patients without any tumoral regrowth in the group II (258plus minus165 vs 163plus minus165 mm(3), P=0.05).

We suggest a MRI protocol that includes, a 4- to 6-, 12- and 24-month post-operative MRI for every patient. When no tumoral residue is seen, pituitary radiotherapy is useless. MRI must be repeated 3, 5 and 10 years after surgery to eliminate late recurrence. The observed frequency of tumoral regrowth in patients with tumoral residue does not justify systematic post-operative radiotherapy. It should be performed only when tumoral regrowth is proved by a yearly MRI survey.