Evaluation of anterior pituitary gland volume in childhood using three-dimensional MRI

Pitfalls of diagnosing pituitary hypoplasia in the patients with short stature

PURPOSE

Height age (HA) and bone age (BA) delay is well known in the patients with short stature. Therefore assessing pituitary hypoplasia based on chronological age (CA) might cause overdiagnosis of pituitary hypoplasia. We aimed to investigate the diagnostic and prognostic value of the PH and PV based on CA, HA, or BA in the patients with GHD.

METHODS

Fifty-seven patients with severe and 40 patients with partial GHD and 39 patients with ISS assigned to the study. For defining the most accurate diagnosis of pituitary hypoplasia, PH and PV were evaluated based on CA, BA and HA. The relationship of each method with clinical features was examined.

RESULTS

The mean PV was significantly larger in patients with ISS compared to the GH-deficient patients. PV was more correlated with clinical features including height SDS, stimulated GH concentration, IGF-1 and IGFBP-3 SDS, height velocity before and after rGH therapy. We found BA-based PV could discriminate GHD from ISS (Sensitivity: 17%, specificity: 98%, positive predictive value: 94%, negative predictive value: 39%), compared to the other methods based on PH or PV respect to CA and HA. 3% of patients with ISS, 17% of patients with GHD had pituitary hypoplasia based on PV-BA.

CONCLUSION

PV based on BA, has the most accurate diagnostic value for defining pituitary hypoplasia. But it should be kept in mind that there might be still misdiagnosed patients by this method. PV is also a significant predictor for the rGH response.

Auxological, Clinical, and MRI Abnormalities in Pediatric Patients With Isolated Growth Hormone Deficiency

OBJECTIVE

 This study aimed to assess the auxological, clinical, and MRI features of pediatric patients with isolated growth hormone deficiency (GHD) by analyzing the demographic and clinical characteristics of the study cohort.

METHODS

A cohort of 115 pediatric patients diagnosed with isolated GHD was included. The patients were evaluated at a tertiary center in Jeddah, Saudi Arabia. Collected data included demographic information and auxological evaluations, such as height standard deviation (SD), height centile, weight SD, weight centile, and bone age SD. Neuroradiological assessments, particularly magnetic resonance imaging (MRI) of the hypothalamic-pituitary region, were collected to identify any structural abnormalities contributing to GHD.

RESULTS

A total of 67 (SD 58.3) were males. The mean age was 9.55 years (SD 3.45). The mean bone age was 7.37 years (SD 3.24), indicating delayed bone development. Height measurements reflected a significant growth impairment, with a mean height SD of -2.45 (SD 1.12). Out of the 115 pediatric patients in the study cohort, 84 (73%) underwent neuroradiological assessments using brain MRI. Among these, 12% were found to have MRI abnormalities. The prevalence of MRI abnormality in the subgroup with severe growth hormone deficiency was higher, reaching 21%. The peak growth hormone (GH) in the growth hormone stimulation test was 6.38 ng/mL (SD 3.24). There was a significant difference in the peak GH levels between the subgroup of patients with normal MRI findings (mean 6.02 ng/mL, SD 2.47) and those with abnormal MRI findings (mean 3.2 ng/mL, SD 2.8) (p=0.01).

CONCLUSION

Children with isolated GHD exhibited significant growth impairment and clinical characteristics consistent with the disorder. Neuroradiological abnormalities are common among patients with severe growth hormone deficiency; therefore, radiological assessment including MRI of the pituitary gland is recommended in patients with severe isolated growth hormone deficiency.

Pituitary gland volumes in children with normal endocrine function

BACKGROUND

Magnetic resonance imaging (MRI) is often the first modality of choice in the detection of pituitary pathologies due to its excellent contrast resolution and high spatial resolution. However, evaluating the size of the pituitary gland is somewhat difficult since the gland morphology varies widely among individuals.

OBJECTIVE

The aim of this study was to provide normal reference values for pituitary volumes in the pediatric population using three-dimensional (3-D) MRI data. We also aimed to compare the volumetric data measured through 3-D images with the mathematical volumes obtained by the ellipsoid formula from 2-D images, considering the demographic subgroups of age and sex.

MATERIALS AND METHODS

This study was performed retrospectively using PACS-archived brain MRIs obtained in the Pediatric Radiology Unit. Eight hundred children under the age of 18 who underwent brain MRI between January 2014 and May 2018 for headaches, seizures or trauma and who had no brain anomaly or endocrine pathology were recruited. Pituitary volumes were separately calculated from those brain MRIs by means of ellipsoid formula and volumetry. The mean, standard deviation, maximum and minimum and median values were achieved for each 1-year age group in both sexes. Normal reference ranges containing 5th -10th -25th -50th -75th -90th -95th percentiles of volumetric pituitary values were tabulated.

RESULTS

Pituitary gland volumes in both sexes were found to increase gradually with age. The average 3-D volume values were greater in girls than boys except for the age groups 1-2 years and 8-9 years. Pituitary volumes showed a growth spurt during early puberty, which was more prominent in girls. Moreover, a strong positive correlation was noted between the 2-D calculated and 3-D measured volumes in both sexes.

CONCLUSION

Normative data obtained through this study can be used for clinical diagnostic purposes as well as a reference for future research. The 2-D calculated volumes be used where it is not possible to obtain 3-D volumetric values.

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.

Associations between early life stress and anterior pituitary gland volume development during late childhood

Early Life Stress (ELS) is thought to influence Hypothalamic-Pituitary-Adrenal-Axis (HPAA) functioning, contributing to an increased risk for psychopathology through dysregulation of biological stress responses. Research exploring relationships between ELS and HPAA functioning has largely focused on its key hormonal output, cortisol. However, findings have been inconsistent, potentially due to cortisol's distinctive diurnal patterns and dynamic nature complicating its accurate measurement. Thus, this study explored the link between ELS and a more stable, structural component of the HPAA, specifically, anterior pituitary gland volume (PGV) in a community sample of children (N = 129, 68 female). PGV was traced from Magnetic Resonance Imaging brain scans across two time-points at ages 8 (baseline) and 10 years (follow-up). ELS exposure was assessed at baseline through parent-report questionnaires and maternal affective behavior observed in mother-child interaction tasks. ELS variables were reduced to a 5-factor structure using exploratory factor analysis - Uninvolved Parenting, Negative Affective Parenting, Neglect, Trauma, and Dysfunctional Discipline. Direct and sex-moderated associations between ELS and PGV were explored using regression and linear mixed models analyses. PGV-mediated associations between ELS and internalizing symptoms were also investigated. Childhood Neglect was significantly associated with greater baseline anterior PGV, that was stable over the follow-up period. This effect was found in the whole sample, and in males, specifically. No mediation effects were found. Results suggest that neglect may play a unique role in HPAA neurodevelopment; however, it is important that future research extends into adolescence to more clearly characterize these neurodevelopmental associations and any subsequent psychopathological outcomes.

A unified framework for simultaneous assessment of accuracy, between-, and within-reader variability of image segmentations

Medical imaging is utilized in a wide range of clinical applications. To enable a detailed quantitative analysis, medical images must often be segmented to label (delineate) structures of interest; for example, a tumor. Frequently, manual segmentation is utilized in clinical practice (e.g., in radiation oncology) to define such structures of interest. However, it can be quite time consuming and subject to substantial between-, and within-reader variability. A more reproducible, less variable, and more time efficient segmentation approach is likely to improve medical treatment. This potential has spurred the development of segmentation algorithms which harness computational power. Segmentation algorithms’ widespread use is limited due to difficulty in quantifying their performance relative to manual segmentation, which itself is subject to variation. This paper presents a statistical model which simultaneously estimates segmentation method accuracy, and between- and within-reader variability. The model is simultaneously fit for multiple segmentation methods within a unified Bayesian framework. The Bayesian model is compared to other methods used in literature via a simulation study, and application to head and neck cancer PET/CT data. The modeling framework is flexible and can be employed in numerous comparison applications. Several alternate applications are discussed in the paper.

Pubertal hormones predict sex-specific trajectories of pituitary gland volume during the transition from childhood to adolescence

Pituitary gland volume (PGV) increases during childhood and adolescence in a sex-specific manner, and previous research suggests that puberty may be associated with PGV development. However, existing research to date has focused on sex hormones associated with gonadarche. Given the role of the pituitary gland in hypothalamic-pituitary-adrenal (HPA) axis function, the present study investigated associations between PGV development and HPA hormones that play a role in the earlier pubertal phase of adrenarche. Participants were a community sample of 249 children and early adolescents who participated in longitudinal brain imaging and pubertal assessments. Each participant provided data at one or two waves 1.5-3 years apart, resulting in 409 datasets that covered the age range 8-13 years. PGV was estimated from T1-weighted Magnetic Resonance Imaging (MRI) scans, and dehydroepiandrosterone (DHEA), its sulfate (DHEA-S) and testosterone were measured from saliva. Estradiol was measured for a subset of females. Parents reported on physical pubertal development. Linear mixed modeling was used to investigate associations between age, pubertal measures and PGV development. DHEA, DHEA-S and testosterone (in addition to physical maturation) explained variance in PGV development over and above age, and in a sex-dependent fashion. In all cases, associations were stronger, or only present in females. Estradiol was associated with PGV in females, but this did not appear to account for adrenarcheal hormone effects. Our findings suggest a key role for the hormones of adrenarche, the first biochemical phase of puberty, in PGV development. Further research is required to understand the sex-specific role of adrenarcheal and gonadarcheal hormones on the PGV across development.

Classical and non-classical causes of GH deficiency in the paediatric age

Growth hormone deficiency (GHD) may result from a failure of hypothalamic GHRH production or release, from congenital disorders of pituitary development, or from central nervous system insults including tumors, surgery, trauma, radiation or infiltration from inflammatory diseases. Idiopathic, isolated GHD is the most common sporadic form of hypopituitarism. GHD may also occur in combination with other pituitary hormone deficiencies, and is often referred to as hypopituitarism, combined pituitary hormone deficiency (CPHD), multiple pituitary hormone deficiency (MPHD) or panhypopituitarism. Children without any identifiable cause of their GHD are commonly labeled as having idiopathic hypopituitarism. MRI imaging is the technique of choice in the diagnosis of children with hypopituitarism. Marked differences in MRI pituitary gland morphology suggest different etiologies of GHD and different prognoses. Pituitary stalk agenesis and ectopic posterior pituitary (EPP) are specific markers of permanent GHD, and patients with these MRI findings show a different clinical and endocrine outcome compared to those with normal pituitary anatomy or hypoplastic pituitary alone. Furthermore, the classic triad of ectopic posterior pituitary gland, pituitary stalk hypoplasia/agenesis, and anterior pituitary gland hypoplasia is generally associated with permanent GHD. T2 DRIVE images aid in the identification of pituitary stalk without the use of contrast medium administration. Future developments in imaging techniques will undoubtedly reveal additional insights. Mutations in a number of genes encoding transcription factors - such as HESX1, SOX2, SOX3, LHX3, LHX4, PROP1, POU1F1, PITX, GLI3, GLI2, OTX2, ARNT2, IGSF1, FGF8, FGFR1, PROKR2, PROK2, CHD7, WDR11, NFKB2, PAX6, TCF7L1, IFT72, GPR161 and CDON - have been associated with pituitary dysfunction and abnormal pituitary gland development; the correlation of genetic mutations to endocrine and MRI phenotypes has improved our knowledge of pituitary development and management of patients with hypopituitarism, both in terms of possible genetic counseling, and of early diagnosis of evolving anterior pituitary hormone deficiencies.

Comparison between manual and semiautomated volumetric measurements of pituitary adenomas

Linear measurements have many limitations. The aim of this study is to compare manual and semiautomated volumetric measurements of pituitary adenomas. Magnetic resonance imaging (MRI) scans of 38 patients with pituitary adenomas were analyzed. Preoperative MRI was acquired on a 1.5 T. MRI volumes of the pituitary adenomas were obtained by two methods: manual (MA) and semiautomated (SA). The concurrent validity for SA and MA methods on 38 patients in the form of correlation coefficient was 0.97 (p < 0.0001). The intraobserver and the interobserver correlation coefficients for SA volumes were both 0.98, as for the intraobserver MA volumes were 0.98. Although the results of both methods are comparable, analysis of volumetric measurements by SA method is more time-efficient than MA segmentation. Precision in volumetric measurement techniques is likely to increase reliability of posttherapeutic monitoring of pituitary adenomas.

Height, BMI, and pituitary volume in individuals with and without isolated cleft lip and/or palate

INTRODUCTION

Individuals with isolated cleft lip and/or palate (ICLP) are often reported to be of shorter stature relative to peers, and the objective of this study was to explore the role of the pituitary in relationship to growth.

METHODS

Fifty-five males and 32 females with ICLP were compared to 121 healthy males and 158 healthy females with respect to height and BMI. Magnetic resonance imaging (MRI) scans were obtained from all ICLP participants and 47% of healthy group participants.

RESULTS

Males with ICLP were shorter than healthy males and had lower BMI. However, the trajectories for height and BMI did not differ between groups. Analyses in a separate sample of adult males suggested that height normalizes in males with ICLP in their early 30s. There were no differences in mean pituitary volume and pituitary trajectories between male groups. Females with ICLP were shorter than healthy females and also had slower growth rates. They did not differ in mean BMI or BMI trajectories. Furthermore, there were no differences in mean pituitary volume, or in pituitary trajectories.

DISCUSSION

Our findings suggest that there are no gross morphological differences in pituitary volume in individuals with ICLP, although more subtle differences may exist.

The use of neuroimaging for assessing disorders of pituitary development

Magnetic resonance imaging (MRI) is the radiological examination method of choice for evaluating hypothalamo-pituitary-related endocrine disease and is considered essential in the assessment of patients with suspected hypothalamo-pituitary pathology. Physicians involved in the care of such patients have, in MRI, a valuable tool that can aid them in determining the pathogenesis of their patients' underlying pituitary conditions. Indeed, the use of MRI has led to an enormous increase in our knowledge of pituitary morphology, improving, in particular, the differential diagnosis of hypopituitarism. Specifically, MRI allows detailed and precise anatomical study of the pituitary gland by differentiating between the anterior and posterior pituitary lobes. MRI recognition of pituitary hyperintensity in the posterior part of the sella, now considered a marker of neurohypophyseal functional integrity, has been the most striking finding in the diagnosis and understanding of certain forms of 'idiopathic' and permanent growth hormone deficiency (GHD). Published data show a number of correlations between pituitary abnormalities as observed on MRI and a patient's endocrine profile. Indeed, several trends have emerged and have been confirmed: (i) a normal MRI or anterior pituitary hypoplasia generally indicates isolated growth hormone deficiency that is mostly transient and resolves upon adult height achievement; (ii) patients with multiple pituitary hormone deficiencies (MPHD) seldom show a normal pituitary gland; and (iii) the classic triad of ectopic posterior pituitary, pituitary stalk hypoplasia/agenesis and anterior pituitary hypoplasia is more frequently reported in MPHD patients and is generally associated with permanent GHD. Pituitary abnormalities have also been reported in patients with hypopituitarism carrying mutations in several genes encoding transcription factors. Establishing endocrine and MRI phenotypes is extremely useful for the selection and management of patients with hypopituitarism, both in terms of possible genetic counselling and in the early diagnosis of evolving anterior pituitary hormone deficiencies. Going forward, neuroimaging techniques are expected to progressively expand and improve our knowledge and understanding of pituitary diseases.

Pituitary iron and volume imaging in healthy controls

BACKGROUND AND PURPOSE

Patients with transfusional iron overload develop iron deposits in the pituitary gland, which are associated with volume loss and HH. The purpose of this study was to characterize R2 and volumetric data in a healthy population for diagnostic use in patients with transfusional iron overload.

MATERIALS AND METHODS

One hundred healthy controls without iron overload between the ages of 2 and 48 were recruited to have MR imaging of the brain to assess their pituitary R2 and volume. Pituitary R2 was assessed with a 8-echo spin-echo sequence, and pituitary volumes, by a 3D spoiled gradient-echo sequence with 1-mm(3) resolution. A 2-component continuous piecewise linear approximation was used for creating volumetric and R2 nomograms. Equations were generated from regression relationships for convenient z-score calculation.

RESULTS

Pituitary R2 rose weakly with age (r(2) = 0.19, P < .0001). Anterior and total pituitary volumes increased steadily up to 18 years of age, after which volume slightly decreased. Females had larger pituitary glands, most likely representing their larger lactotroph population.

CONCLUSIONS

From these data, a clinician can calculate the z scores for R2 and pituitary volume in patients with iron overload. Normal ranges are well-differentiated from values previously associated with endocrine disease in transfusional siderosis; this finding suggests that preclinical iron overload can be recognized and appropriately treated.

Sensory Neurons of the Human Brachial Plexus

BACKGROUND:

Extensive neuron death following peripheral nerve trauma is implicated in poor sensory recovery. Translational research for experimentally proven neuroprotective drugs requires knowledge of the numbers and distribution of sensory neurons in the human upper limb and a novel noninvasive clinical measure of neuron loss.

OBJECTIVE:

To compare optical fractionation and volumetric magnetic resonance imaging (MRI) of dorsal root ganglia (DRG) in histological quantification and objective clinical assessment of human brachial plexus sensory neurons.

METHODS:

Bilateral C5-T1 DRG were harvested from 5 human cadavers for stereological volume measurement and sensory neuron counts (optical fractionator). MRI scans were obtained from 14 healthy volunteers for volumetric analysis of C5-T1 DRG.

RESULTS:

The brachial plexus is innervated by 425 409 (standard deviation 15 596) sensory neurons with a significant difference in neuron counts and DRG volume between segmental levels (P &lt; .001), with C7 ganglion containing the most. DRG volume correlated with neuron counts (r = 0.75, P &lt; .001). Vertebral artery pulsation hindered C5 and 6 imaging, yet high-resolution MRI of C7, C8, and T1 DRG permitted unbiased volume measurement. In accord with histological analysis, MRI confirmed a significant difference between C7, C8, and T1 DRG volume (P &lt; .001), interindividual variability (CV = 15.3%), and sex differences (P = .04). Slight right-left sided disparity in neuron counts (2.5%, P = .04) was possibly related to hand dominance, but no significant volume disparity existed.

CONCLUSION:

Neuron counts for the human brachial plexus are presented. These correlate with histological DRG volumes and concur with volumetric MRI results in human volunteers. Volumetric MRI of C7-T1 DRG is a legitimate noninvasive proxy measure of sensory neurons for clinical study.

Comparison of three methods for the estimation of the pituitary gland volume using magnetic resonance imaging: a stereological study

Stereological techniques using point counting and planimetry have been used to estimate pituitary gland volume. However, many studies have estimated pituitary gland volume by the mathematical approach the elliptic formula. The objective of the current study was to determine pituitary gland volume using stereological methods and elliptic formula on magnetic resonance imaging (MRI). In this study, pituitary gland volumes were estimated in a total of 28 subjects (22 females, 6 males,) who were free of any pituitary or neurological symptoms and signs. The mean ± SD pituitary gland volumes for the point counting, planimetry and elliptic formulae groups were 582.14 ± 140.16 mm³, 610.08 ± 133.17 mm³, and 432.82 ± 147.38 mm³, respectively. The mean CE for the pituitary gland volume estimates derived from the point counting technique was 8.07%. No significant difference was found between point counting and planimetric methods for the pituitary gland volume (P > 0.05). In addition, there was a 26.14 and 29.71% underestimation of pituitary volume as measured by the elliptic formula compared to the point counting and planimetric techniques, respectively. From these results, it can be concluded that stereological techniques are unbiased, efficient and reliable methods and are ideally suitable for in vivo examination of MRI data for pituitary gland volume estimation. Hence, we suggest that estimating pituitary gland volume using MRI study and stereology may be clinically relevant for pituitary surgeons for the investigation of the structure and function of the pituitary gland.

Volumetric magnetic resonance imaging of dorsal root ganglia for the objective quantitative assessment of neuron death after peripheral nerve injury

Prevention of neuron death after peripheral nerve injury is vital to regaining adequate cutaneous innervation density and quality of sensation, and while experimentally proven neuroprotective therapies exist, there lacks suitable clinical outcome measures for translational research. Axotomized dorsal root ganglia (DRG) histologically exhibit volume reduction in proportion to the amount of neuronal death within them. Hence, this study evaluated the validity of using magnetic resonance imaging (MRI) to quantify DRG volume as a proxy measure of cell death. A high-resolution 3D MRI sequence was developed for volumetric quantification of the L4 DRG in the rat sciatic nerve model. An unoperated "control" group (n=4), and a "nerve transection" group (n=6), 4 weeks after axotomy, were scanned. Accuracy and validity of the technique were evaluated by comparison with morphological quantification of DRG volume and stereological counts of surviving neurons (optical fractionator). The technique was precise (coefficient of variation=4.3%), highly repeatable (9% variability), and sensitive (mean 15.0% volume reduction in axotomized ganglia detected with statistical significance: p<0.01). MRI showed strong and highly significant correlation with morphological measures of DRG volume loss (r=0.90, p<0.001), which in turn correlated well with neuron loss (r=0.75, p<0.05). MRI similarly exhibited direct correlation with neuron loss (r=0.67, p<0.05) with consistent agreement. MRI volumetric quantification of DRG is therefore a valid in vivo measure of neuron loss. As a non-invasive, objective measure of neuronal death after nerve trauma this technique has potential as a diagnostic modality and a quantitative tool for clinical studies of neuroprotective agents.

Hypothalamic-pituitary magnetic resonance imaging in growth hormone deficiency

The accurate analysis of the hypothalamic-pituitary area is essential in the diagnosis of endocrine-related diseases. High-quality magnetic resonance imaging represents the examination modality of choice in the evaluation of hypothalamic-pituitary morphology. Indeed, the advent of molecular biology and neuroimaging techniques has led to significant progress in the understanding of the pathogenesis of disorders affecting the pituitary gland, specifically by demonstrating a clear phenotype-genotype relationship. Animal studies, along with the correlation of a particular genetic profile to certain endocrine and magnetic resonance imaging phenotypes in humans, have yielded great insights into pituitary development. Today, there is convincing evidence to support the hypothesis that marked magnetic resonance imaging differences in pituitary morphology indicate a variety of disorders that affect anterior pituitary gland organogenesis and function with a variety of diverse prognoses.