Fast acquisition sagittal T1 magnetic resonance imaging (FAST1-MRI): a new imaging approach for the diagnosis of growth hormone deficiency

Whole exome sequencing in patients with ectopic posterior pituitary

Context

Ectopic posterior pituitary (EPP), a condition in which the posterior pituitary gland is displaced due to defective neuronal migration, is frequently associated with hypopituitarism. Genetic variants play a role, but many cases remain unexplained.

Objective

A large EPP cohort was studied to explore the importance of genetic variants and how they correlate with clinical findings.

Methods

Whole exome sequencing was performed on a discovery sample of 27 cases to identify rare variants. The variants that met the criteria for rarity and biological relevance, or that were previously associated with EPP (ROBO1 and HESX1), were then resequenced in the 27 cases plus a replication sample of 51 cases.

Results

We identified 16 different variants in 12 genes in 15 of the 78 cases (19.2%). Complete anterior pituitary deficiency was twice as common in cases with variants of interest compared to cases without variants (9/15; 60% vs. 19/63; 30.1%, respectively; Z test; p=0.06). Breech presentation was more frequent in the variant positive group (5/15 vs. 1/63; Z test; p= 0.003). Four cases had variants in ROBO1 and one in HESX1, genes previously associated with EPP. The ROBO1 p.S18* variant has not been reported previously; ROBO1 p.Q1227H has not been associated with EPP previously.

Conclusions

EPP cases with variants of interest identified in this study were more likely to present with severe clinical disease. Several variants were identified in genes not previously associated with EPP. Our findings confirm that EPP is a multigenic disorder. Future studies are needed to identify additional genes.

Extra-pituitary midline structural abnormalities associated with ectopic posterior pituitary detected on a new rapid MRI protocol (FAST1.2)

Objective

Test if the MRI FAST1.2 protocol can detect extra-pituitary midline structural brain abnormalities in patients with ectopic posterior pituitary (EPP), and highlighting their radiological-laboratory correlations.

Subjects and methods

Cross-sectional study of patients with EPP and control group. All individuals were submitted to FAST1.2, which combines the FAST1 protocol developed by our group with 3D T2DRIVE imaging.

Results

We evaluated 36 individuals with EPP and 78 as control group. Pituitary stalk (PS) was identified in 7/36 patients in EPP group by FAST1, and in 24/36 patients in FAST1.2 (p < 0.001). FAST1 failed to detect PS in one individual in the control group, while the FAST1.2 defined the PS in all individuals. In EPP group, eleven had interhypothalamic adhesion (IHA), three septo-optic dysplasia, and one cerebellar malformation. We didn't observe higher frequency of panhypopituitarism or developmental delay in patients with IHA. In control group, three had pars intermedia cysts, one hydrocephalus, and one hypothalamic hamartoma.

Conclusion

FAST1.2 allows confident recognition of midline structural abnormalities, including the pituitary stalk and IHA, thereby making MRI acquisition faster and with no need for contrast administration. IHA could be associated with defects in neuronal migration, as occur in patients with EPP, with no clinical significance.

Prevalence of brain MRI findings in children with nonacquired growth hormone deficiency: a systematic review and meta-analysis

PURPOSE

To verify and integrate the prevalence and phenotype of abnormalities in the sellar region in patients with growth hormone deficiency (GHD) using MRI data.

METHODS

We searched PubMed and EMBASE up to December 14, 2020. The inclusion criteria were as follows: (1) pediatric patients diagnosed with nonacquired GHD and (2) detailed data sufficient to assess the proportion of sellar and parasellar abnormalities on brain MRI scans. Finally, thirty-two studies with 39,060 children (mean or median age, 3.4-14.1 years) were included. The number and type of MRI findings from all included studies were pooled by two authors. The heterogeneity across studies was evaluated with the Q test or the inconsistency index (I²) statistic. Subgroup analyses were performed according to the type of GHD (isolated GHD [IGHD] vs. multiple pituitary hormone deficiency [MPHD]), MRI magnet, geographical region, and cutoff serum growth hormone (GH) level.

RESULTS

The pooled proportion of sellar and parasellar abnormalities was 58.0% (95% CI, 47.1-68.6%; I², 98.2%). The MPHD group showed a higher proportion of sellar and parasellar abnormalities and pituitary stalk interruption syndrome than the IGHD group (91.4% vs. 40.1%, P<0.001; 65.3% vs. 20.1%, P<0.001). The patients in studies with low peak GH levels on stimulation tests were more associated with severe MR abnormalities (cutoff GH ≤ 5 μg/l vs. cutoff GH = 10 μg/l; 72.8 % vs. 38.0%; P<0.001).

CONCLUSION

The types and incidence of MRI abnormalities of the sellar region differ significantly between the IGHD and MPHD groups.

High Frequency of Normal Response during GH Stimulation Tests in Patients with Ectopic Posterior Pituitary Gland: A Source of False-Negative Diagnosis of Pituitary Insufficiency

AIMS

To report false-negative normal growth hormone (GH) peak response in patients with ectopic posterior pituitary gland (EPP) identified with a simplified magnetic resonance imaging (FAST1-MRI).

METHODS

We analyzed 75 EPP patients with short stature and reduced growth velocity. Sagittal-T1 imaging (thickness: 2 mm and gap: 0.2 mm) without gadolinium administration was used. A GH peak of ≥5 ng/ml after clonidine or insulin stimulation was considered normal.

RESULTS

Normal GH response was observed in 15 of 75 (20%) patients [mean (SDS) peak = 8.2 (4.1) ng/ml]. Age at diagnosis [6.5 (3.0) years vs. 7.8 (4.1) years], gender (10 males/5 females vs. 44 males/16 females), pubertal stage (14 prepubertal/1 pubertal vs. 51 prepubertal/7 pubertal), and target height [-0.4 (0.6) vs. -0.4 (0.9)] were recorded. The perinatal history did not differ between responsive and nonresponsive patients. There was a trend to more frequent multiple hormone deficiency in nonresponsive when compared with responsive patients [3/15 (20%) and 31/60 (51.7%), respectively (p = 0.055)]. Height at diagnosis was lower in nonresponsive patients (p = 0.042). No significant difference in the IGF1 levels (p = 0.598) was observed between the groups.

CONCLUSION

Normal GH values after stimulation tests do not exclude EPP-associated GH deficiency. A simplified fast acquisition sagittal-T1 MRI protocol investigation included at the initial diagnostic approach is able to prevent misdiagnosis of GH deficiency in patients with short stature.

Pituitary Stalk Interruption Syndrome: The Role of MRI and Review of the Literature

Magnetic resonance imaging (MRI) in patients with congenital growth hormone deficiency (GHD) has revealed several morphological abnormalities of the hypothalamo-pituitary region which include hypoplasia of the anterior pituitary lobe, the absence or marked thinning of the pituitary stalk and ectopia of the posterior pituitary lobe (EPP). This triad of abnormalities is called pituitary stalk interruption syndrome (PSIS). Our study reports the imaging findings of 23 patients with idiopathic GHD and short stature who were examined by MRI. The majority of the patients had abnormal MR studies with findings indicating the presence of the pituitary stalk syndrome. The high correlation between the clinical profile and the MR findings in cases of pituitary dysfunction (most often GHD), defines the significant role of MRI as additional tool for the diagnosis of pituitary hormone deficiency.