Adding T2-Weighted Images to FAST1 Protocol to Evaluate the Anatomy of the Hypothalamic-Pituitary Region

Ectopic posterior pituitary (EPP) is a malformation of the hypothalamic-pituitary region presented as a spectrum from isolated growth hormone deficiency (GHD) to multiple pituitary hormone deficiencies (MPHDs). Our goal was to establish whether the FAST1.2 protocol, which combines the FAST1 protocol with 3D-T2 DRIVE images, could identify the pituitary stalk (PS) and the regional anatomy more accurately.

A retrospective study of 36 individuals with EPP and hypopituitarism and a control group of 78 individuals with eutopic posterior pituitary was conducted. All individuals were submitted to FAST1.2. The position and size of the pituitary lobes were described, and the presence/absence of the PS was confirmed.

FAST1 identified the PS in 19% of individuals with EPP, while FAST1.2 identified the PS in 67% (p < 0.001). In the FAST1.2 protocol, the PS was visible in all control individuals. All EPP patients with isolated GHD had visible PS in FAST1.2, while only 58.6% of MPHD cases had visible PS. The size of the anterior lobe and the anteroposterior length of the posterior pituitary were smaller in the EPP group versus controls (p < 0.001). We noticed a reduced anterior pituitary lobe in both diameters in MPHD patients (p < 0.05). Six patients acquired new pituitary hormone deficiencies not recognized at the time of MRI; in this group, only 1 patient had a PS not visible in FAST1.2.

The FAST1.2 protocol could prevent the misdiagnosis of idiopathic GHD in patients with short stature and could also be important in the progression to MPHD. The PS could be considered a predictor of hypopituitarism, but its use as an isolated indicator for the progression to MPHD is not recommended. Our results reinforce the use of the size of the anterior lobe as a predictor of hypopituitarism and a possible predictor of the degree of pituitary insufficiency. The FAST1.2 protocol could be used as an alternative to gadolinium administration, as a cheaper and faster method, while eliminating the potential risks associated with the administration of contrast media.