Contact endoscopy as a novel technique for intra-operative identification of normal pituitary gland and adenoma

Intraoperative distinction of pituitary adenoma from normal gland is critical in maximizing tumor resection without compromising pituitary function. Contact endoscopy provides a noninvasive technique that allows for real-time in vivo visualization of differences in tissue vascularity. Two illustrative cases of endoscopic endonasal approaches (EEAs) for resection of pituitary adenoma illustrate the use of contact endoscopy in identifying tumor from gland and differentiating a thin section of normal gland draped over the underlying tumor, thereby allowing for safe extracapsular tumor resection. Contact endoscopy may be used as an adjunct for intraoperative, in vivo differentiation of pituitary gland and adenoma. The video can be found here: https://stream.cadmore.media/r10.3171/2021.10.FOCVID21199

Deep learning-based thin-section MRI reconstruction improves tumour detection and delineation in pre- and post-treatment pituitary adenoma

Even a tiny functioning pituitary adenoma could cause symptoms; hence, accurate diagnosis and treatment are crucial for management. However, it is difficult to diagnose a small pituitary adenoma using conventional MR sequence. Deep learning-based reconstruction (DLR) using magnetic resonance imaging (MRI) enables high-resolution thin-section imaging with noise reduction. In the present single-institution retrospective study of 201 patients, conducted between August 2019 and October 2020, we compared the performance of 1 mm DLR MRI with that of 3 mm routine MRI, using a combined imaging protocol to detect and delineate pituitary adenoma. Four readers assessed the adenomas in a pairwise fashion, and diagnostic performance and image preferences were compared between inexperienced and experienced readers. The signal-to-noise ratio (SNR) was quantitatively assessed. New detection of adenoma, achieved using 1 mm DLR MRI, was not visualised using 3 mm routine MRI (overall: 6.5% [13/201]). There was no significant difference depending on the experience of the readers in new detections. Readers preferred 1 mm DLR MRI over 3 mm routine MRI (overall superiority 56%) to delineate normal pituitary stalk and gland, with inexperienced readers more preferred 1 mm DLR MRI than experienced readers. The SNR of 1 mm DLR MRI was 1.25-fold higher than that of the 3 mm routine MRI. In conclusion, the 1 mm DLR MRI achieved higher sensitivity in the detection of pituitary adenoma and provided better delineation of normal pituitary gland than 3 mm routine MRI.

Dose to neuroanatomical structures surrounding pituitary adenomas and the effect of stereotactic radiosurgery on neuroendocrine function: an international multicenter study

OBJECTIVE Stereotactic radiosurgery (SRS) provides a safe and effective therapeutic modality for patients with pituitary adenomas. The mechanism of delayed endocrine deficits based on targeted radiation to the hypothalamic-pituitary axis remains unclear. Radiation to normal neuroendocrine structures likely plays a role in delayed hypopituitarism after SRS. In this multicenter study by the International Radiosurgery Research Foundation (IRRF), the authors aimed to evaluate radiation tolerance of structures surrounding pituitary adenomas and identify predictors of delayed hypopituitarism after SRS for these tumors. METHODS This is a retrospective review of patients with pituitary adenomas who underwent single-fraction SRS from 1997 to 2019 at 16 institutions within the IRRF. Dosimetric point measurements of 14 predefined neuroanatomical structures along the hypothalamus, pituitary stalk, and normal pituitary gland were made. Statistical analyses were performed to determine the impact of doses to critical structures on clinical, radiographic, and endocrine outcomes. RESULTS The study cohort comprised 521 pituitary adenomas treated with SRS. Tumor control was achieved in 93.9% of patients over a median follow-up period of 60.1 months, and 22.5% of patients developed new loss of pituitary function with a median treatment volume of 3.2 cm3. Median maximal radiosurgical doses to the hypothalamus, pituitary stalk, and normal pituitary gland were 1.4, 7.2, and 11.3 Gy, respectively. Nonfunctioning adenoma status, younger age, higher margin dose, and higher doses to the pituitary stalk and normal pituitary gland were independent predictors of new or worsening hypopituitarism. Neither the dose to the hypothalamus nor the ratio between doses to the pituitary stalk and gland were significant predictors. The threshold of the median dose to the pituitary stalk for new endocrinopathy was 10.7 Gy in a single fraction (OR 1.77, 95% CI 1.17–2.68, p = 0.006). CONCLUSIONS SRS for the treatment of pituitary adenomas affords a high tumor control rate with an acceptable risk of new or worsening endocrinopathy. This evaluation of point dosimetry to adjacent neuroanatomical structures revealed that doses to the pituitary stalk, with a threshold of 10.7 Gy, and doses to the normal gland significantly increased the risk of post-SRS hypopituitarism. In patients with preserved pre-SRS neuroendocrine function, limiting the dose to the pituitary stalk and gland while still delivering an optimal dose to the tumor appears prudent.

The Use of Micro Retractor in Endoscopic Endonasal Posterior Pseudocapsule Resection of Pituitary Macroadenoma. Technical Note

BackgroundThe endoscopic endonasal approach and extra-pseudocapsule resection may be the main progress in modern pituitary surgery. However, for pituitary macroadenomas, discerning the pseudocapsule in the posterior plane of the tumor may be difficult. When the anterior-inferior debulking is performed, the early subsidence of the thinning normal pituitary gland and enlarged diaphragm may obstruct the surgical dissection view.MethodWe describe the technique of using a micro retractor for the endoscopic endonasal posterior pseudocapsule resection of pituitary macroadenomas. This micro retractor that was 2 mm in width was placed at the 12 o’clock position on the nostrils, and the end was fixed in the flexible arms of the self-retaining retractor system. The head of the micro retractor elevated the herniated diaphragm sellae in order to continue the posterior pseudocapsule resection of the pituitary macroadenoma.ResultThe technique was performed very easily and no complication was observed.ConclusionThe use of this micro retractor can increase the view of the posterior margin of the adenomas to facilitate the pseudocapsule dissection.

Radiographic pituitary stalk disruption: A rare sequela of secondary empty sella syndrome

Background: This two-patient case series describes a rare sequela of postoperative empty sella syndrome (ESS) following transsphenoidal resection of pituitary macroadenomas. This is characterized by progressive hormone dysfunction, diabetes insipidus (DI), and associated MRI evidence of pituitary stalk disruption. Case Description: This phenomenon was retrospectively evaluated in a review of 2000 pituitary tumor resections performed by a single neurosurgeon (KOL). Chart review was retrospectively conducted to gather data on demographics, pituitary hormone status, tumor characteristics, and management. We identified 2 (0.1%) cases of progressive pituitary endocrine dysfunction occurring in the postoperative period associated with MRI evidence of pituitary stalk disruption within 6 weeks of discharge from the hospital. This was felt to be caused by the rapid descent of the residual normal pituitary gland down to the floor of the postoperative empty sella, causing relatively swift stalk stretching. Both patients developed DI, and one patient demonstrated increased pituitary hormone dysfunction. Conclusion: This phenomenon is a rare manifestation of postoperative ESS, secondary to surgical resection of a pituitary macroadenoma. We discuss the associated potential risk factors and strategies for avoidance in these two cases. Routine instillation of intrasellar fat in patients at risk is felt to be protective.

Visualization of incidentally imaged pituitary gland on three-dimensional arterial spin labeling of the brain

Objective: To evaluate the visualization of incidentally imaged normal pituitary gland on three-dimensional (3D) pseudo continuous arterial spin labeling (PCASL) perfusion imaging of the brain. Methods: Ninety-three patients with a normal pituitary gland who underwent 3D PCASL for suspected brain diseases were retrospectively included. Visualization of the pituitary gland on PCASL cerebral blood flow (CBF) maps was assessed independently by two observers using a three-point grading system: Grade 1, pituitary CBF ≤ CBF of the cerebral white matter (WM); Grade 2, CBF of WM < pituitary CBF ≤ CBF of the cortical gray matter (GM); and Grade 3, CBF of GM < pituitary CBF. The interobserver agreement of visual grading was determined using weighted κ statistic. The associations of visual grades with age, sex, and pituitary volume were assessed using multivariate logistic regression. Pituitary glands were divided equally into three groups (small, medium, and large) according to their volume for categorization. Results: The interobserver agreement for visual rating was excellent (weighted κ = 0.823). Of the 93 cases, Grades 1, 2, and 3 included 17 (18.3%), 41 (44.1%), and 35 cases (37.6%), respectively. Medium and large pituitary volume were significantly associated with Grade 3 visualization (p = 0.0153, OR = 4.8323; 95% CI: 1.3525, 17.2649 and p = 0.0009; OR = 9.0299; 95% CI: 2.4663, 33.0614, respectively), whereas there was no significant association for age or sex. Conclusion: The normal pituitary gland is often visualized with higher CBF than cortical GM on 3D PCASL, especially in individuals with larger pituitary volume. Advances in knowledge: Appearance of the normal pituitary gland on 3D PCASL has been documented for the first time.

A Potential Impact of SARS-CoV-2 on Pituitary Glands and Pituitary Neuroendocrine Tumors

Introduction: Angiotensin-converting enzyme 2 (ACE2) is the receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The effects of SARS-CoV-2 on normal pituitary glands function or pituitary neuroendocrine tumors (PitNETs) have not yet been elucidated. Thus, the present study aimed to investigate the potential risks of SARS-CoV-2 infection on the impairment of pituitary glands and the development of PitNETs.Methods: PitNETs tissues were obtained from 114 patients, and normal pituitary gland tissues were obtained from the autopsy. The mRNA levels of ACE2 and angiotensin II receptor type 1 (AGTR1) were examined by quantitative real-time PCR. Immunohistochemical staining was performed for ACE2 in 69 PitNETs and 3 normal pituitary glands. The primary tumor cells and pituitary cell lines (MMQ, GH3 and AtT-20/D16v-F2) were treated with diminazene aceturate (DIZE), an ACE2 agonist, with various dose regimens. The pituitary hormones between 43 patients with SARS-CoV-2 infection were compared with 45 healthy controls.Results: Pituitary glands and the majority of PitNET tissues showed low/negative ACE2 expression at both the mRNA and protein levels, while AGTR1 showed high expression in normal pituitary and corticotroph adenomas. ACE2 agonist increased the secretion of ACTH in AtT-20/D16v-F2 cells through downregulating AGTR1. The level of serum adrenocorticotropic hormone (ACTH) was significantly increased in COVID-19 patients as compared to normal controls (p<0.001), but was dramatically decreased in critical cases as compared to non-critical patients (p=0.003).Conclusion: This study revealed a potential impact of SARS-CoV-2 infection on corticotroph cells and adenomas.

Morphological Study on Magnetic Resonance Imaging of the Normal Pituitary Gland in Nepalese Population: Age and Sex-Related Changes

Introduction: The pituitary gland is the master endocrine gland that secretes important hormones and controls other glands. Its size, shape and volume vary with age and sex and also in various pathological conditions. This study was conducted to identify the size, shape and volume of the normal pituitary gland in different age groups of both genders using Magnetic Resonance Imaging (MRI).Methods: A retrospective study of the brain MRI Images of 203 patients was done in the Radiology and Imaging department of Pokhara Academy of Health Sciences, Nepal. Anterior-posterior dimension, transverse dimension, height and shape of the pituitary gland were noted and volume was calculated. Descriptive analysis and relationship of pituitary parameters with age and sex were assessed using ANOVA and Chi-square tests.Results: The pituitary height and volume was maximum in the 11-20years age group. Similarly, the mean height and volume of the pituitary gland in female patients of each age group were greater than that of male patients in the same age group. The inferential analysis revealed significant differences for mean pituitary height and volume with age but not with gender. The upper surface convexity was maximum in the age group 11-20years.Conclusion: The study has shown a clear trend with regards to the morphology of the pituitary gland with the age and sex of the individual highlighting the size, shape and volume of the pituitary gland should be taken into consideration while evaluating the glands for any neuroendocrine disorders.

Limited utility of 5-ALA optical fluorescence in endoscopic endonasal skull base surgery: a multicenter retrospective study

OBJECTIVEIncomplete resection of skull base pathology may result in local tumor recurrence. This study investigates the utility of 5-aminolevulinic acid (5-ALA) fluorescence during endoscopic endonasal approaches (EEAs) to increase visibility of pathologic tissue.METHODSThis retrospective multicenter series comprises patients with planned resection of an anterior skull base lesion who received preoperative 5-ALA at two tertiary care centers. Diagnostic use of a blue light endoscope was performed during EEA for all cases. Demographic and tumor characteristics as well as fluorescence status, quality, and homogeneity were assessed for each skull base pathology.RESULTSTwenty-eight skull base pathologies underwent blue-light EEA with preoperative 5-ALA, including 15 pituitary adenomas (54%), 4 meningiomas (14%), 3 craniopharyngiomas (11%), 2 Rathke’s cleft cysts (7%), as well as plasmacytoma, esthesioneuroblastoma, and sinonasal squamous cell carcinoma. Of these, 6 (21%) of 28 showed invasive growth into surrounding structures such as dura, bone, or compartments of the cavernous sinus. Tumor fluorescence was detected in 2 cases (7%), with strong fluorescence in 1 tuberculum sellae meningioma and vague fluorescence in 1 pituicytoma. In all other cases fluorescence was absent. Faint fluorescence of the normal pituitary gland was seen in 1 (7%) of 15 cases. A comparison between the particular tumor entities as well as a correlation between invasiveness, WHO grade, Ki-67, and positive fluorescence did not show any significant association.CONCLUSIONSWith the possible exception of meningiomas, 5-ALA fluorescence has limited utility in the majority of endonasal skull base surgeries, although other pathology may be worth investigating.