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

Objectives and Design: 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. Patients and Methods: Fifty-one patients aged 25-80 years (mean, 55.6 +/- 12.3 years) were included. Post-operative MRIs were performed 3-12 months (mean, 5.2 +/- 1.7 months) after surgery, 6 months later and then, every 12-18 months for at least 2 years. The mean post-operative follow-up was 67.7 +/- 31.8 months (range, 24-144 months). Results: In 17 patients (33%, group 1) 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 11), 7-66 months (mean, 27.3 +/- 17.3 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 (258 +/- 165 vs 163 +/- 165 mm(3), P = 0.05). Conclusions: 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.