Maria Schmook MD, Presenter: Nothing to Disclose

Peter Brugger, Abstract Co-Author: Nothing to Disclose

Michael Weber, Abstract Co-Author: Nothing to Disclose

Daniela Prayer, Abstract Co-Author: Nothing to Disclose

While the pituitary gland can be demonstrated with in vitro magnetic resonance imaging (MRI) from gestational week (gw) 11 onwards, in vivo data about the time of morphological proof of the pituitary gland are not yet available. The purpose of this retrospective study was to evaluate the detectability of the pituitary gland and infundibulum with in vivo fetal MRI.

MRI studies of 150 fetuses from gw 16 to 40 (average ± std 28±6) were assessed. Indications for MRI were suspected central nervous system (CNS) or extra CNS pathologies. MRI was performed on a 1.5 T magnet using a cardiac coil. T1-weighted GRE (FOV 265-325mm, matrix 166/256, slice thickness 5mm, flip angle 80°, TR/TE: ∞/4.6ms) and T2-weighted SSFSE sequences (FOV 200-300 mm, matrix 169/256, slice thickness 3-4mm, flip angle 90°, TR/TE ∞/100-140ms) were used to screen for the pituitary gland and infundibulum. For statistical analysis crosstabs and Chi-Square tests as well as logistic regressions using gw (5 groups à 4 gestational weeks), examination plane, region (head sequence/whole body sequence) and slice thickness as predictors were assessed.

The pituitary gland could be detected in 78.7% of cases, with a significant increase of detectability between group gw 16-20 and 21-24 (20% versus 75.7%, p<0.001). It appeared hyperintense on T1-weighted (w) images and iso- to hypointense on T2w images. The maximum pituitary diameter was 3 to 8mm, increasing with gw (Pearson correlation: .628). The infundibulum could be depicted on T2w images in 88.7% of cases as a hypointense thread, with a better delineation after week 20 ( 60% (gw 16-20) versus 91.1% (gw 21-25); p=0.016). Gw was the only predictor for pituitary detectability.

The pituitary gland and infundibulum are readily detected on prenatal MRI from gw 21 onwards. Its presence should be evaluated especially in cerebral midline malformations which may be associated with pituitary pathologies.

As the presence of the pituitary gland is of vital importance for survival the proof of its existence by fetal MRI may have an influence on further management in case of a fetal cerebral malformation.

Schmook, M, Brugger, P, Weber, M, Prayer, D, Detectability and Imaging Features of the Pituitary Gland in Fetal MRI.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5009137.html