Introduction: Selective transsphenoidal microadenomectomy (TSS) is the first-line treatment of paediatric Cushings disease (CD). Corticotroph adenomas in children are often small and difficult to visualize. We aimed to assess the utility of pituitary MRI and bilateral inferior petrosal sinus sampling (BIPSS) in confirming the diagnosis of CD and the localisation of the adenoma. We also report our early experience of STEALTH MRI (volumetric T1 weighted, contrast-enhanced scan).
Methods: Fifty one paediatric CD patients have been managed by our centre since 1982. In 40 children (21 M) mean age 12.9 years (5.617.8), we had data for BIPSS, pituitary MRI and TSS findings (nine did not have BIPSS, two had surgery elsewhere). An inferior petrosal sinus to peripheral (IPS/P) plasma ACTH ratio before CRH >2.0, or peak IPS/P ratio after CRH >3.0 were considered diagnostic for central ACTH secretion. An inter-petrosal sinus gradient (IPSG) after CRH of >1.4 was considered positive for ACTH lateralisation. 39 had pituitary MRI and one patient had a CT scan. Four patients (4F, aged 11.216.0 year) had pre-operative STEALTH MRI recently introduced for surgical planning.
Results: BIPSS correctly identified central ACTH production in 37/40 (93%) and the adenoma position in 27/40 (68%) cases. Conventional MRI scanning identified a pituitary lesion in 18/40 (45%) cases and there was concordance of the position of the adenoma with operative findings during TSS in only 15/40 (38%) children. Following TSS, 31/40 (78%) children were in remission (0900 serum cortisol <50 nmol/l). BIPSS and MRI demonstrated the correct adenoma position in 22/31 (71%) and 10/31 (32%) remission patients, respectively. four patients had additional STEALTH MRI scans (3/4 had inconclusive conventional MRI/BIPSS findings). In all four patients, STEALTH MRI correctly identified the position of the adenoma and all are in post-operative remission.
Discussion: BIPSS is safe and well tolerated in children when performed by an experienced radiologist. BIPSS achieves a high diagnosis rate of central ACTH production in paediatric CD although evidence of adenoma position is less accurate. Microadenoma visualisation rate with conventional MRI scanning is low, however stealth MRI may emerge as a new improved technique for pituitary imaging in paediatric CD.
22 - 24 Nov 2017
British Society for Paediatric Endocrinology and Diabetes