High resolution pituitary gland MRI at 7.0 tesla: a clinical evaluation in Cushing's disease

7T MRI for Cushing Disease: A Single-Institution Experience and Literature Review

BACKGROUND AND PURPOSE

Cushing disease is typically caused by a pituitary adenoma that frequently is small and challenging to detect on conventional MR imaging. High-field-strength 7T MR imaging can leverage increased SNR and contrast-to-noise ratios compared with lower-field-strength MR imaging to help identify small pituitary lesions. We aimed to describe our institutional experience with 7T MR imaging in patients with Cushing disease and perform a review of the literature.

MATERIALS AND METHODS

We performed a retrospective analysis of 7T MR imaging findings in patients with pathology-proved Cushing disease from a single institution, followed by a review of the literature on 7T MR imaging for Cushing disease.

RESULTS

Our institutional experience identified Cushing adenomas in 10/13 (76.9%) patients on 7T; however, only 5/13 (38.5%) lesions were discrete. Overall, the imaging protocols used were heterogeneous in terms of contrast dose as well as type of postcontrast T1-weighted sequences (dynamic, 2D versus 3D, and type of 3D sequence). From our institutional data, specific postgadolinium T1-weighted sequences were helpful in identifying a surgical lesion as follows: dynamic contrast-enhanced, 2/7 (28.6%); 2D FSE, 4/8 (50%); 3D sampling perfection with application-optimized contrasts by using different flip angle evolution (SPACE), 5/6 (83.3%); and 3D MPRAGE, 8/11 (72.7%). The literature review identified Cushing adenomas in 31/33 (93.9%) patients on 7T.

CONCLUSIONS

7T MR imaging for pituitary lesion localization in Cushing disease is a new technique with imaging protocols that vary widely. Further comparative research is needed to identify the optimal imaging technique as well as assess the benefit of 7T over lower-field-strength MR imaging.

Brain structure comparison among Parkinson disease, essential tremor, and healthy controls using 7T MRI

Both Parkinson disease (PD) and Essential tremor (ET) are movement disorders causing tremors in elderly individuals. Although PD and ET are different disease, they often present with similar initial symptoms, making their differentiation challenging with magnetic resonance imaging (MRI) techniques. This study aimed to identify structural brain differences among PD, ET, and health controls (HCs) using 7-Tesla (T) MRI. We assessed the whole-brain parcellation in gray matter volume, thickness, subcortical volume, and small regions of basal ganglia in PD (n = 18), ET (n = 15), and HCs (n = 18), who were matched for age and sex. Brain structure analysis was performed automatic segmentation through Freesurfer software. Small regions of basal ganglia were manually segmented by ITK-SNAP. Additionally, we examined the associations between clinical indicators (symptom duration, unified Parkinson diseases rating scale (UPDRS), and clinical rating scale for tremor (CRST)) and brain structure. PD showed a significant reduction in gray matter volume in the postcentral region compared to ET. ET showed a significant reduction in cerebellum volume compared to HCs. There was a negative correlation between CRST scores (B and C) and gray matter thickness in right superior frontal in ET. This study demonstrated potential of 7T MRI in differentiating brain structure differences among PD, ET, and HCs. Specific findings, such as parietal lobe atrophy in PD compared to ET and cerebellum atrophy in ET compared to HCs, the importance of advanced imaging techniques in accurately diagnosing and distinguishing between movement disorders that present with similar initial symptoms.

The diagnostic yield of inferior petrosal sinus sampling in Cushing syndrome in the era of ovine CRH shortage

PURPOSE

The ovine corticotropin-releasing hormone (oCRH) stimulation test has been routinely used in the diagnostic work-up of ACTH-dependent Cushing syndrome (CS). With oCRH currently being out-of-stock in Europe, we aimed at evaluating the diagnostic performance of inferior petrosal sinus sampling (IPSS) without oCRH stimulation.

METHODS

We compared the values of 40 patients with ACTH-dependent CS and negative MRI findings in whom ACTH was measured before and after oCRH stimulation.

RESULTS

The ratio of central-to-peripheral ACTH measurement (IPS:P) before the combined 3, 5, and 10 min of oCRH stimulation yielded diminished sensitivity (85% vs. 97%), alongside markedly decreased specificity (57% vs. 71%), as well as reduced positive and negative predictive values (90% vs. 94% and 44% vs. 83%), respectively.

CONCLUSIONS

With the current drug shortages in Europe, ACTH measurements without oCRH stimulation in IPSS cannot be recommended. Thus, we call for desmopressin or the commercially available human CRH as a potential alternative in the confirmation of ACTH excess by IPSS in equivocal MRI findings.

MRI for Cushing Disease: A Systematic Review

BACKGROUND

MR imaging is key in the diagnostic work-up of Cushing disease. The sensitivity of MR imaging in Cushing disease is not known nor is the prognostic significance of "MR imaging-negative" disease.

PURPOSE

Our aim was to determine the overall sensitivity and prognostic significance of MR imaging localization of Cushing disease.

DATA SOURCES

We performed a systematic review of the MEDLINE and PubMed databases for cohort studies reporting the sensitivity of MR imaging for the detection of adenomas in Cushing disease.

STUDY SELECTION

This study included 57 studies, comprising 5651 patients.

DATA ANALYSIS

Risk of bias was assessed using the methodological index for non-randomized studies criteria. Meta-analysis of proportions and pooled subgroup analysis were performed.

DATA SYNTHESIS

Overall sensitivity was 73.4% (95% CI, 68.8%-77.7%), and the sensitivity for microadenomas was 70.6% (66.2%-74.6%). There was a trend toward greater sensitivity in more recent studies and with the use of higher-field-strength scanners. Thinner-section acquisitions and gadolinium-enhanced imaging, particularly dynamic sequences, also increased the sensitivity. The use of FLAIR and newer 3D spoiled gradient-echo and FSE sequences, such as spoiled gradient-echo sequences and sampling perfection with application-optimized contrasts by using different flip angle evolutions, may further increase the sensitivity but appear complementary to standard 2D spin-echo sequences. MR imaging detection conferred a 2.63-fold (95% CI, 2.06-3.35-fold) increase in remission for microadenomas compared with MR imaging-negative Cushing disease.

LIMITATIONS

Pooled analysis is limited by heterogeneity among studies. We could not account for variation in image interpretation and tumor characteristics.

CONCLUSIONS

Detection on MR imaging improves the chances of curative resection of adenomas in Cushing disease. The evolution of MR imaging technology has improved the sensitivity for adenoma detection. Given the prognostic importance of MR imaging localization, further effort should be made to improve MR imaging protocols for Cushing disease.

Improved Detection of Cavernous Sinus Invasion of Pituitary Macroadenomas with Ultra-High-Field 7 T MRI

To compare 7 T magnetic resonance imaging (MRI) of pituitary macroadenomas (PMA) with standard MRI and intraoperative findings regarding tumor detection, localization, size, and extension. Patients with suspected pituitary adenoma underwent pre-operative 1.5 T or 3 T and 7 T MRI; 14 patients with a PMA were included. A qualitative (lesion detection, location, cavernous sinus infiltration) and quantitative (lesion size, depth of cavernous sinus infiltration) analysis of 1.5 T, 3 T and 7 T MRI was performed and compared with intraoperative findings. Both 1.5/3 T and 7 T MRI enabled the detection of all PMAs; lesion size determination was equal. 7 T MRI enables more precise assessments of cavernous sinus infiltration of PMA (n_{correct 7T} = 78.6%, n_{correct 1.5/3T} = 64.3%). Ultra-high-field MRI is a reliable imaging modality for evaluation of PMAs providing exact information on lesion location and size. 7 T MRI yielded more accurate information on cavernous sinus infiltration with better agreement with intraoperative findings than standard MRI.

Evaluation of postcontrast images of intracranial tumors at 7T and 3T MRI: An intra-individual comparison study

AIM

This study aimed to evaluate the diagnostic value of ultrahigh-field magnetic resonance imaging (MRI) for brain tumors in clinical practice.

METHODS

Thirty patients with brain tumors underwent 7- and 3-T MRI. The performance and diagnostic confidence of 7- and 3-T MRI in the visualization of tumor details such as internal structure and feeding artery were evaluated by radiologists. Contrast-enhanced region performance and tumor detail diagnostic confidence score (DCS) were calculated and compared between 7 and 3T using Wilcoxon rank sum test.

RESULTS

In 19 with obvious enhancement and 11 cases without obvious enhancement, 7- and 3-T MRI showed similar performance. The tumors' internal structure and feeding artery were more clearly depicted by 7-T MRI (62.2% and 54.4%, respectively) than by 3-T MRI (2.2% and 6.7%, respectively). Furthermore, the mean DCSs of both internal structure and feeding artery were higher at 7T than at 3T (internal structure: 16.29 ± 9.67 vs. -5.79 ± 4.12, p = 0.028; feeding artery: 21.96 ± 6.93 vs. 4.46 ± 7.07, p = 0.028). The DCS was more significantly improved in the senior radiologist group.

CONCLUSION

Better visualization of brain tumor details and higher tumor detail diagnostic confidence can be obtained with 7-T MRI.

Ultra-high field 7 T MRI localizes regional brain volume recovery following corticotroph adenoma resection and hormonal remission in Cushing's disease: A case series

Background

Cushing's disease (CD) is defined by glucocorticoid excess secondary to the increased section of corticotropin by a pituitary adenoma. Magnetic resonance imaging (MRI) studies performed at 1.5 or 3 Tesla (T) have demonstrated correlations between regional changes in brain structure and the progression of CD. In this report, we examine the changes in brain volume following corticotroph pituitary adenoma resection using ultra-high field 7 T MRI to increase the accuracy of our volumetric analyses.

Methods

Thirteen patients were referred to the endocrinology clinic at our institution from 2017 to 2020 with symptoms of cortisol excess and were diagnosed with ACTH-dependent endogenous Cushing syndrome. Five patients had follow-up 7 T imaging at varying time points after a transsphenoidal resection.

Results

Symmetrized percent change in regional volumes demonstrated a postoperative increase in cortical volume that was relatively larger than that of cerebral white matter or subcortical gray matter (percent changes = 0.0172%, 0.0052%, and 0.0120%, respectively). In the left cerebral hemisphere, the medial orbitofrontal, lateral orbitofrontal, and pars opercularis cortical regions experienced the most robust postoperative percent increases (percent changes = 0.0166%, 0.0122%, and 0.0068%, respectively). In the right cerebral hemisphere, the largest percent increases were observed in the pars triangularis, rostral portion of the middle frontal gyrus, and superior frontal gyrus (percent changes = 0.0156%, 0.0120%, and 0.0158%).

Conclusion

Cerebral volume recovery following pituitary adenoma resection is driven by changes in cortical thickness predominantly in the frontal lobe, while subcortical white and gray matter volumes increase more modestly.

Endocrinological aspects of pituitary adenoma surgery in Europe

Hormone-secreting adenomas are treated in many neurosurgical centers within Europe. The goal of the survey is to understand variance in practice management of pituitary tumors amongst neurosurgical centers. A list of departments performing pituitary surgery was created. The survey consisted of 58 questions. This study focuses on neurosurgical care of hormone-secreting adenomas. For analysis, the departments were divided into four subgroups: academic/non-academic, high-volume/low-volume, “mainly endoscopic/mainly microscopic practice” and geographical regions. Data from 254 departments from 34 countries were obtained. Most centers surgically treat 1–5 hormone-secreting adenomas per year. In prolactinomas this is the case in 194 centers, (76.4%), in GH-secreting adenomas: 133 centers, (52.4%), ACTH-secreting adenomas: 172 centers, (69.8%). Surgery as a primary treatment of prolactinomas is considered in 64 centers (25.2%). In 47 centers (18.8%), GH-secreting microadenomas are often treated pharmacologically first. Debulking surgery for an invasive GH-secreting adenoma in which hormonal remission is not a realistic goal of the surgery and the patient has no visual deficit surgery is always or mostly indicated in 156 centers (62.9%). Routine postoperative hydrocortisone replacement therapy is administered in 147 centers (58.6%). Our survey shows that in most centers, few hormone-secreting adenomas are treated per year. In about 25% of the centers, prolactinoma surgery may be regarded as first-line treatment; in about 20% of the centers, medical treatment is the first-line treatment for GH-secreting adenomas. Pretreatment for ACTH-secreting adenomas is routinely used in 21% of centers. This survey may serve as plea for neurosurgical care centralization of hormone-secreting adenomas.

Contrast-enhanced 3D-T2-weighted SPACE sequence for MRI detection and localization of adrenocorticotropin (ACTH)-secreting pituitary microadenomas

OBJECTIVE

Cushing disease is a potentially fatal endocrine disorder caused by adrenocorticotropin (ACTH)-secreting microadenomas in the pituitary gland. Accurate detection and localization of the adenomas is the key to clinical treatment. This study analysed the value of contrast-enhanced Sampling Perfection with Application-optimized Contrasts using different flip angle Evolutions (SPACE) sequence in magnetic resonance imaging (MRI) assessment of ACTH-secreting pituitary microadenomas.

DESIGN AND PATIENTS

We carried out a retrospective study in which 45 patients with ACTH-secreting pituitary microadenomas were enrolled. Dynamic contrast-enhanced (DCE) coronal T1-SE sequence was performed. A contrast-enhanced coronal SPACE sequence was added immediately after DCE MRI finished. Two independent observers assessed the tumour existence and location, then the results were compared with surgical findings.

RESULTS

Twenty-four lesions (53.3%) were detected by the DCE T1-SE sequence alone, while 35 lesions (80.0%) were detected with the addition of contrast-enhanced SPACE sequence. The sensitivity (58.5% vs. 85.3%; p < .05) and best diagnostic accuracy (62.0% vs. 84.4%; p < .05) were significantly better for addition with SPACE sequence than DCE-SE images alone in detection of ACTH-secreting pituitary microadenomas. For lesions <5 mm, the detected numbers were 4 (16.6%) versus 10 (27.8%) by DCE T1-SE sequence and combined DCE T1-SE with SPACE sequence.

CONCLUSIONS

A combination of contrast-enhanced SPACE with DCE T1-SE sequence could improve the detection of ACTH-secreting pituitary microadenomas. Contrast-enhanced SPACE sequence could be a supplementary sequence for imaging of ACTH-secreting pituitary adenomas when T1-SE sequence provides negative or equivocal findings.

Ultra-High-Field 7 T Magnetic Resonance Imaging Including Dynamic and Static Contrast-Enhanced T1-Weighted Imaging Improves Detection of Secreting Pituitary Microadenomas

OBJECTIVE

A prospective preoperative evaluation of 7 T ultra-high-field magnetic resonance imaging (MRI) in patients with suspected pituitary microadenomas for both adenoma detection and intrasellar localization compared with 3 T MRI was carried out.

MATERIALS AND METHODS

Patients underwent prospective preoperative standardized 3 and 7 T MRI. A distinct qualitative (lesion detection, intrasellar lesion location) and quantitative (lesion diameters, T1/T2 signal intensity ratio of the lesion to normal pituitary gland tissue) analysis was performed, along with an evaluation of image quality (IQ) regarding overall IQ, anatomical parameters, and artifacts; the findings of the qualitative analysis were compared with intraoperative findings and endocrinological outcomes.

RESULTS

Sixteen patients (mean age, 43 ± 16 years; 13 women) with pituitary microadenomas were included. Using 7 T MRI allowed the detection of 15 microadenomas-3 more than 3 T MRI. In addition, 7 T MRI allowed more precise lesion localization with 93.75% (15/16) agreement with intraoperative findings, compared with 75% (12/16) agreement using 3 T MRI. Lesion diameters showed no significant difference between 3 and 7 T MRI. T1 and T2 signal intensity ratio between microadenomas and normal pituitary gland tissue were higher in 7 T MRI than in 3 T MRI. The overall IQ and the IQ of each anatomical parameter of 7 T MRI were rated higher than those of 3 T MRI. No significant differences in susceptibility or head motion artifacts were observed between 3 and 7 T MRI; however, 7 T MRI was more susceptible to pulsation artifacts.

CONCLUSION

Ultra-high-field MRI surpasses 3 T MRI in pituitary microadenoma detection and enables more precise delineation with higher correlation with intraoperative findings. Thus, 7 T sellar imaging is a promising option-especially in previously magnetic resonance-negative patients with endocrinologically confirmed hormone oversecretion-and helps reduce the need for invasive diagnostics.

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.

7-T Magnetic Resonance Imaging in the Management of Brain Tumors

This article provides an overview of the current status of ultrahigh-field 7-T magnetic resonance (MR) imaging in neuro-oncology, specifically for the management of patients with brain tumors. It includes a discussion of areas across the pretherapeutic, peritherapeutic, and posttherapeutic stages of patient care where 7-T MR imaging is currently being exploited and holds promise. This discussion includes existing technical challenges, barriers to clinical integration, as well as our impression of the future role of 7-T MR imaging as a clinical tool in neuro-oncology.

Imaging of the sellar and parasellar regions

Although a wide variety of pathologies can occur in the limited anatomic space within and surrounding the sella turcica only a few are common. This review aims to briefly summarize pituitary and parasellar anatomy and provide a focused description of the imaging features of both common and rare pituitary pathologies. Diagnoses of imaging findings with important implications for clinical management are highlighted. MR is the primary diagnostic modality for evaluation of this anatomic region. CT supplements MR in the evaluation of pathologies involving the bony sella turcica while angiography or nuclear medicine plays a limited clinical role. Despite the wide array of pathologies, imaging and basic clinical history will frequently yield a specific diagnosis or narrow differential. In certain pathologies such as hypophysitis or pituitary hyperplasia, proper imaging interpretation may obviate the need for surgical biopsy or resection. The two key elements to diagnosis in the pituitary region are localization of the abnormality and recognition of characteristic imaging features for different pathologies. Localization is particularly important in separating parasellar masses such as meningiomas, skull base tumors, carotid aneurysms, craniopharyngiomas, or sphenoid sinus tumors from pituitary masses. Imaging features are often variable and in some cases such as craniopharyngioma or epidermoid, can be almost pathognomonic. In cases of neoplastic pathology, imaging both provides diagnostic information and guides planning of surgical biopsy or resection. In most cases, biopsy or resection is performed though a trans-sphenoidal endoscopic route, and identifying invasion or the suprasellar cistern, skull base, or cavernous sinuses is critical.

Utility of 7 Tesla MRI for Preoperative Planning of Endoscopic Endonasal Surgery for Pituitary Adenomas

Objective  There is increasing interest in investigating the utility of 7 Tesla (7 T) magnetic resonance imaging (MRI) for imaging of skull base tumors. The present study quantifies visualization of tumor features and adjacent skull base anatomy in a homogenous cohort of pituitary adenoma patients. Methods  Eighteen pituitary adenoma patients were scanned at 7 T in this prospective study. All patients had reference standard-of-care clinical imaging at either 3 T (7/18, 39%) or 1.5 T (11/18, 61%). Visualization of tumor features and conspicuity of arteries and cranial nerves (CNs) was rated by an expert neuroradiologist on 7 T and clinical field strength MRI. Overall image quality and severity of image artifacts were also characterized and compared. Results  Ability to visualize tumor features did not differ between 7 T and lower field MRI. Cranial nerves III, IV, and VI were better detected at 7 T compared with clinical field strength scans. Cranial nerves III, IV, and VI were also better detected at 7 T compared with only 1.5 T, and CN III was better visualized at 7 T compared with 3 T MRI. The ophthalmic arteries and posterior communicating arteries (PCOM) were better detected at 7 T compared with clinical field strength imaging. The 7 T also provided better visualization of the ophthalmic arteries compared with 1.5 T scans. Conclusion  This study demonstrates that 7 T MRI is feasible at the skull base and identifies various CNs and branches of the internal carotid artery that were better visualized at 7 T. The 7 T MRI may offer important preoperative information that can help to guide resection of pituitary adenoma and reduce operative morbidity.

Pitfalls in Performing and Interpreting Inferior Petrosal Sinus Sampling: Personal Experience and Literature Review

CONTEXT

Inferior petrosal sinus sampling (IPSS) helps differentiate the source of ACTH-dependent hypercortisolism in patients with inconclusive biochemical testing and imaging, and is considered the gold standard for distinguishing Cushing disease (CD) from ectopic ACTH syndrome. We present a comprehensive approach to interpreting IPSS results by examining several real cases.

EVIDENCE ACQUISITION

We performed a comprehensive review of the IPSS literature using PubMed since IPSS was first described in 1977.

EVIDENCE SYNTHESIS

IPSS cannot be used to confirm the diagnosis of ACTH-dependent Cushing syndrome (CS). It is essential to establish ACTH-dependent hypercortisolism before the procedure. IPSS must be performed by an experienced interventional or neuroradiologist because successful sinus cannulation relies on operator experience. In patients with suspected cyclical CS, it is important to demonstrate the presence of hypercortisolism before IPSS. Concurrent measurement of IPS prolactin levels is useful to confirm adequate IPS venous efflux. This is essential in patients who lack an IPS-to-peripheral (IPS:P) ACTH gradient, suggesting an ectopic source. The prolactin-adjusted IPS:P ACTH ratio can improve differentiation between CD and ectopic ACTH syndrome when there is a lack of proper IPS venous efflux. In patients who have unilateral successful IPS cannulation, a contralateral source cannot be excluded. The value of the intersinus ACTH ratio to predict tumor lateralization may be improved using a prolactin-adjusted ACTH ratio, but this requires further evaluation.

CONCLUSION

A stepwise approach in performing and interpreting IPSS will provide clinicians with the best information from this important but delicate procedure.

Clinical 7-T MRI for neuroradiology: strengths, weaknesses, and ongoing challenges

Since the relatively recent regulatory approval for clinical use in both Europe and North America, 7-Tesla (T) MRI has been adopted for clinical practice at our institution. Based on this experience, this article reviews the unique features of 7-T MRI neuroimaging and addresses the challenges of establishing a 7-T MRI clinical practice. The underlying fundamental physics principals of high-field strength MRI are briefly reviewed. Scanner installation, safety considerations, and artifact mitigation techniques are discussed. Seven-tesla MRI case examples of neurologic diseases including epilepsy, vascular abnormalities, and tumor imaging are presented to illustrate specific applications of 7-T MRI. The advantages of 7-T MRI in conjunction with advanced neuroimaging techniques such as functional MRI are presented. Seven-tesla MRI produces more detailed information and, in some cases, results in specific diagnoses where previous 3-T studies were insufficient. Still, persistent technical issues for 7-T scanning present ongoing challenges for radiologists.

Advances in the Imaging of Pituitary Tumors

In most patients with pituitary adenomas magnetic resonance imaging (MRI) is essential to guide effective decision-making. T1- and T2-weighted sequences allow the majority of adenomas to be readily identified. Supplementary MR sequences (e.g. FLAIR; MR angiography) may also help inform surgery. However, in some patients MRI findings are 'negative' or equivocal (e.g. with failure to reliably identify a microadenoma or to distinguish postoperative change from residual/recurrent disease). Molecular imaging [e.g. ¹¹C-methionine PET/CT coregistered with volumetric MRI (Met-PET/MR^CR)] may allow accurate localisation of the site of de novo or persistent disease to guide definitive treatment (e.g. surgery or radiosurgery).

Precentral and cerebellar atrophic changes in moyamoya disease using 7-T magnetic resonance imaging

Background

Chronic repeated transient ischemic changes are one of the common symptoms of moyamoya disease that could affect cortical and subcortical atrophy.

Purpose

We aimed to assess the cortical gray matter volume and thickness, white matter subcortical volume, and clinical characteristics using 7-T magnetic resonance imaging (MRI) and MR angiography (MRA).

Material and Methods

In this case-control study, whole-brain parcellation of gray matter and subcortical volumes were manually assessed in nine patients with moyamoya disease (18 hemispheres; median age = 34 years; age range = 10–60 years) and nine healthy controls (18 hemispheres; median age = 29 years; age range = 20–62 years) matched for age and sex, who underwent both 7-T MRI and MRA. The volumes were measured using high-resolution image (<1 mm) processing based on the Desikan-Killiany-Tourville (DKT) atlas, via an automated segmentation method (FreeSurfer version 6.0).

Results

The gray matter volume of the left precentral cortex and the white matter volume of the subcortical cerebellum were lower in both hemispheres in the patients with moyamoya disease compared to the healthy controls.

Conclusion

Gray matter atrophy in the precentral cortex and cerebellar white matter were detected in this 7-T MRI volumetric analysis study of patients with moyamoya disease who experienced repeated transient ischemic changes. Cortical atrophy in precentral cortex and cerebellum could explain the transient motor weakness in patients with moyamoya disease, as one of the early findings was that patients with moyamoya disease do not have detectable infarction changes on conventional MRI images.

Outcomes of three-Tesla magnetic resonance imaging for the identification of pituitary adenoma in patients with Cushing's disease

Pituitary adenoma has been reported to be detectable in only 36-63% of Cushing's disease (CD) patients by magnetic resonance imaging (MRI). In this study, we investigate the outcomes and problems associated with tumor identification using 3-Tesla (3-T) MRI, which provides clearer images than ≤1.5-T MRI, in 115 patients who were initially diagnosed with CD. Before surgery, 31 macroadenomas (27%) and 54 microadenomas (47%) were identified by 3-T MRI, but pituitary adenoma was invisible on MRI in the remaining 30 cases (26%). The smallest tumor diameter amenable to a definitive diagnosis was 2 mm, and spoiled gradient-echo was the best sequence for diagnosing microadenomas. In 14 of 30 cases of MRI-invisible CD, the pituitary adenoma was identified during surgery. Nine of these 14 tumors that developed from outside the pituitary gland were retrospectively identified on MRI by comparison with surgical findings. The remaining 16 cases of MRI-invisible CD in which the pituitary adenoma was not identified during surgery involved partial hypophysectomy. Seven cases were hormonally remitted, but another nine cases experienced persistent disease after surgery. The sensitivity and specificity of the pituitary adenoma diagnosis in CD patients after the introduction of 3-T MRI were 80% and 100%, respectively. However, the sensitivity decreased to 72% when macroadenomas were excluded. Some adenomas associated with CD are still undetectable on 3-T MRI due to tumor size, location and intensity. However, sensitivity can be improved by monitoring tumors that develop outside the pituitary gland.

Pre-operative MRI predictors of hormonal remission status post pituitary adenoma resection

INTRODUCTION

Contrast-enhanced (CE) Constructive Interference in Steady State (CISS) and Volumetric Interpolated Breath-hold Examination (VIBE) are MRI sequences used to improve the detection of pituitary adenomas and adjacent cranial nerves. The purpose of this study was to assess image quality and identify imaging predictors of postoperative hormonal remission of functioning pituitary adenomas using CE-T1 weighted image (WI), T2WI, CE-CISS, and CE-VIBE MRI sequences.

MATERIALS AND METHODS

Patients with pre-operative CE-T1WI, T2WI, CE-CISS, and CE-VIBE pituitary MRI sequences were included in this institutional retrospective review. Three raters independently reviewed randomized sequences in a blinded fashion for adenoma characteristics and parasellar invasion. Subgroup analysis of hormonal remission was performed.

RESULTS

A total of 34 functioning pituitary adenoma patients were included (average age 39.3 ± 12.2; female n = 27), 30 of which had post-operative hormonal remission (n = 34; 88.2%). Compared to CE-T1WI, CE-CISS has significantly higher number of sequences rated "good" image quality (p = 0.02). Hormone remission was associated with decreased degrees of pre-operative internal carotid artery (ICA) contact and Knosp score (p ≤ 0.02) on all sequences except for Knosp score on T2WI. On receiver operating characteristic analysis, the area under curve for differentiating endocrine remission ranged from 0.88 to 0.92 for Knosp score and 0.85-0.93 for ICA contact, depending on sequence.

CONCLUSION

Extent of pituitary adenoma cavernous sinus invasion as measured by degrees of ICA contact and Knosp score is associated with postoperative endocrine outcomes. Given improved image quality, inclusion of CE-CISS may be helpful for pre-surgical planning.

Value of pituitary gland MRI at 7 T in Cushing's disease and relationship to inferior petrosal sinus sampling: case report

Cushing's disease is caused by adrenocorticotrophic hormone (ACTH)-secreting pituitary adenomas, which are often difficult to identify on standard 1.5-T or 3-T MRI, including dynamic contrast imaging. Inferior petrosal and cavernous sinus sampling remains the gold standard for MRI-negative Cushing's disease.The authors report on a 27-year-old woman with Cushing's disease in whom the results of standard 1.5-T and 3-T MRI, including 1.5-T dynamic contrast imaging, were negative. Inferior petrosal sinus sampling showed a high central-to-peripheral ACTH ratio (148:1) as well as a right-to-left ACTH gradient (19:1), suggesting a right-sided pituitary microadenoma. The patient underwent 7-T MRI, which showed evidence of a right-sided pituitary lesion with focal hypoenhancement not visualized on 1.5-T or 3-T MRI. The patient underwent an endoscopic endonasal transsphenoidal operation, with resection of a right-sided pituitary mass. Postoperatively, she developed clinical symptoms suggestive of adrenal insufficiency and a nadir cortisol level of 1.6 μg/dl on postoperative day 3, and hydrocortisone therapy was initiated. Permanent histopathology specimens showed Crooke's hyaline change and ACTH-positive cells suggestive of an adenoma.MRI at 7 T may be beneficial in identifying pituitary microadenoma location in cases of standard 1.5-T and 3-T MRI-negative Cushing's disease. In the future, 7-T MRI may preempt inferior petrosal sinus sampling and help in cases of standard and dynamic contrast 1.5-T and 3-T MRI-negative Cushing's disease.

Clinical 7 T MRI: Are we there yet? A review about magnetic resonance imaging at ultra-high field

In recent years, ultra-high field MRI (7 T and above) has received more interest for clinical imaging. Indeed, a number of studies have shown the benefits from the application of this powerful tool not only for research purposes, but also in realms of improved diagnostics and patient management. The increased signal-to-noise ratio and higher spatial resolution compared with conventional and high-field clinical scanners allow imaging of small anatomical detail and subtle pathological findings. Furthermore, greater spectral resolution achieved at ultra-high field allows the resolution of metabolites for MR spectroscopic imaging. All these advantages have a significant impact on many neurological diseases, including multiple sclerosis, cerebrovascular disease, brain tumors, epilepsy and neurodegenerative diseases, in part because the pathology can be subtle and lesions small in these diseases, therefore having higher signal and resolution will help lesion detection. In this review, we discuss the main clinical neurological applications and some technical challenges which remain with ultra-high field MRI.

New and emerging drug therapies for Cushing's disease

INTRODUCTION

Cushing's disease is a rare systemic and disabling disease due to oversecretion of adrenocorticotrophic hormone (ACTH) resulting in excess cortisol levels. Diagnosis and treatment are difficult; despite the availability of various pharmaceutical treatment options, there is an ongoing, unmet need for even more effective treatment.

AREAS COVERED

The present review aims at providing an overview of available drugs and presenting new developments. Focusing on the pituitary as a target, the review covers compounds targeting pituitary cell signaling or cell cycle control such as heat shock protein inhibitors (e.g. silibinin), histone deacetylase inhibitors (trichostatin A, vorinostat), kinase inhibitors (gefitinib, seliciclib), and others (such as triptolide, AT-101). Levoketoconazole and osilodrostat are in clinical testing and inhibit steroidogenesis. Blockade of ACTH receptor binding at the adrenal level is explained as a theoretical drug target. Inhibition of binding of the glucocorticoid receptor in the peripheral tissue plays a minor role due to its lack of biomonitoring options.

EXPERT OPINION

In our opinion, further research and drug development of pituitary-directed targets are necessary. Combination therapies may exert synergistic effects and allow for smaller and better tolerated doses, but more experience and data are needed to guide such treatment schemes.

Visualizing the Human Subcortex Using Ultra-high Field Magnetic Resonance Imaging

With the recent increased availability of ultra-high field (UHF) magnetic resonance imaging (MRI), substantial progress has been made in visualizing the human brain, which can now be done in extraordinary detail. This review provides an extensive overview of the use of UHF MRI in visualizing the human subcortex for both healthy and patient populations. The high inter-subject variability in size and location of subcortical structures limits the usability of atlases in the midbrain. Fortunately, the combined results of this review indicate that a large number of subcortical areas can be visualized in individual space using UHF MRI. Current limitations and potential solutions of UHF MRI for visualizing the subcortex are also discussed.

Key clinical benefits of neuroimaging at 7T

The growing interest in ultra-high field MRI, with more than 35.000 MR examinations already performed at 7T, is related to improved clinical results with regard to morphological as well as functional and metabolic capabilities. Since the signal-to-noise ratio increases with the field strength of the MR scanner, the most evident application at 7T is to gain higher spatial resolution in the brain compared to 3T. Of specific clinical interest for neuro applications is the cerebral cortex at 7T, for the detection of changes in cortical structure, like the visualization of cortical microinfarcts and cortical plaques in Multiple Sclerosis. In imaging of the hippocampus, even subfields of the internal hippocampal anatomy and pathology may be visualized with excellent spatial resolution. Using Susceptibility Weighted Imaging, the plaque-vessel relationship and iron accumulations in Multiple Sclerosis can be visualized, which may provide a prognostic factor of disease. Vascular imaging is a highly promising field for 7T which is dealt with in a separate dedicated article in this special issue. The static and dynamic blood oxygenation level-dependent contrast also increases with the field strength, which significantly improves the accuracy of pre-surgical evaluation of vital brain areas before tumor removal. Improvement in acquisition and hardware technology have also resulted in an increasing number of MR spectroscopic imaging studies in patients at 7T. More recent parallel imaging and short-TR acquisition approaches have overcome the limitations of scan time and spatial resolution, thereby allowing imaging matrix sizes of up to 128×128. The benefits of these acquisition approaches for investigation of brain tumors and Multiple Sclerosis have been shown recently. Together, these possibilities demonstrate the feasibility and advantages of conducting routine diagnostic imaging and clinical research at 7T.

7.0 Tesla MRI tractography in patients with trigeminal neuralgia

7.0 Tesla (T) high-resolution diffusion tensor imaging (DTI) can supply information on changing microstructures in cranial nerves. We investigated DTI parameters and the feasibility of DTI criteria for diagnosing trigeminal neuralgia (TN). In this study, 14 patients (28 hemispheres) of mean age 49.0 years (range, 31-64) with TN underwent DTI using 7.0 TMRI. We compared fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) of affected-side and unaffected-side trigeminal nerves using DTI. We examined associations between DTI parameters and clinical characteristics for patients with TN. In patients with TN, affected sides showed significantly decreased FA and significantly increased MD, and RD compared with unaffected sides of trigeminal nerves. Nuclei were not significantly different among patients with TN. Barrow Neurological Institute (BNI) pain scores did not correlate with affected sides. 7.0 T DTI was useful for detecting neurovascular compression in patients with TN. The increased signal-to-noise ratio provided by 7 T MRI should be advantageous for increasing spatial resolution to detect microstructure changes to trigeminal nerves in patients with TN.

Has acromegaly been diagnosed earlier?

PURPOSE

We investigated whether acromegaly has been diagnosed earlier at the Niigata Medical and Dental University Hospital.

METHODS

Patients with acromegaly (n = 81) who underwent their first transsphenoidal surgery from 2006 to 2015 were reviewed. Two groups were compared: those who underwent surgery between 2006 and 2010 (n = 35) and those who underwent surgery between 2011 and 2015 (n = 46). We compared clinical features and serum levels of the growth hormone (GH) and insulin-like growth factor-1 (IGF-1), hypertension (HT) and diabetes mellitus (DM) prevalence between the two groups.

RESULTS

Compared with the early group, microadenomas (<10 mm) were more prevalent in the late group (0% vs. 15.2%, p < .05). Serum IGF-1 standard deviation score (SDS) was significantly lower in the late group (8.57 ± 2.50 vs. 6.44 ± 2.30, p < .001). In both groups, mean IGF-1 SDS was significantly lower in patients without DM than in those with DM (6.9 ± 2.6 vs. 8.3 ± 2.4, p = .02). Logistic regression analysis showed that serum GH and IGF-1 levels were significantly higher in patients with DM than in those without DM.

CONCLUSION

Regarding operated cases of GH-producing pituitary adenoma, acromegaly clinical manifestations tended to be milder at diagnosis in later years of the decade, and acromegaly was diagnosed at lower IGF-1 levels and in smaller lesions. Further study is mandatory for the generalization of this trend.

First Application of 7-T Magnetic Resonance Imaging in Endoscopic Endonasal Surgery of Skull Base Tumors

BACKGROUND

Successful endoscopic endonasal surgery for the resection of skull base tumors is reliant on preoperative imaging to delineate pathology from the surrounding anatomy. The increased signal-to-noise ratio afforded by 7-T MRI can be used to increase spatial and contrast resolution, which may lend itself to improved imaging of the skull base. In this study, we apply a 7-T imaging protocol to patients with skull base tumors and compare the images with clinical standard of care.

METHODS

Images were acquired at 7 T on 11 patients with skull base lesions. Two neuroradiologists evaluated clinical 1.5-, 3-, and 7-T scans for detection of intracavernous cranial nerves and internal carotid artery (ICA) branches. Detection rates were compared. Images were used for surgical planning and uploaded to a neuronavigation platform and used to guide surgery.

RESULTS

Image analysis yielded improved detection rates of cranial nerves and ICA branches at 7 T. The 7-T images were successfully incorporated into preoperative planning and intraoperative neuronavigation.

CONCLUSIONS

Our study represents the first application of 7-T MRI to the full neurosurgical workflow for endoscopic endonasal surgery. We detected higher rates of cranial nerves and ICA branches at 7-T MRI compared with 3- and 1.5-T MRI, and found that integration of 7 T into surgical planning and guidance was feasible. These results suggest a potential for 7-T MRI to reduce surgical complications. Future studies comparing standardized 7-, 3-, and 1.5-T MRI protocols in a larger number of patients are warranted to determine the relative benefit of 7-T MRI for endonasal endoscopic surgical efficacy.

Pituitary magnetic resonance imaging in Cushing's disease

Adrenocorticotropin-secreting pituitary tumor represents about 10 % of pituitary adenomas and at the time of diagnosis most of them are microadenomas. Transsphenoidal surgery is the first-line treatment of Cushing's disease and accurate localization of the tumor within the gland is essential for selectively removing the lesion and preserving normal pituitary function. Magnetic resonance imaging is the best imaging modality for the detection of pituitary tumors, but adrenocorticotropin-secreting pituitary microadenomas are not correctly identified in 30-50 % of cases, because of their size, location, and enhancing characteristics. Several recent studies were performed with the purpose of better localizing the adrenocorticotropin-secreting microadenomas through the use in magnetic resonance imaging of specific sequences, reduced contrast medium dose and high-field technology. Therefore, an improved imaging technique for pituitary disease is mandatory in the suspect of Cushing's disease. The aims of this paper are to present an overview of pituitary magnetic resonance imaging in the diagnosis of Cushing's disease and to provide a magnetic resonance imaging protocol to be followed in case of suspicion adrenocorticotropin-secreting pituitary adenoma.

Suction Filter in Endoscopic Endonasal Surgery: A Technical Note

BACKGROUND

The collection of the greatest possible amount of pathologic tissue is of paramount importance in neurosurgery to achieve the most accurate histopathologic diagnosis, to perform all of the necessary biomolecular tests on the pathologic specimen, and to collect biological material for basic or translational science studies. This problem is particularly relevant in pituitary surgery because of the possible small size and soft consistency of tumors, which make them suitable for removal through suction, reducing the amount of available pathologic tissue. To solve this issue, we adopted a filter connected to the suction tube, which allows the surgeon to collect all of the tissue aspirated during surgery.

METHODS

Our experience of 1734 endoscopic endonasal procedures, performed adopting this device since 1998 to December 2015, has been revised to assess its advantages and limitations.

RESULTS

This system is easy-to-use, does not impair the surgical maneuvers, and does not add any relevant cost to the surgery. The tissue collected through the filter proved useful for diagnostic histologic and biomolecular analyses and for research purposes, without any relevant artifacts as a result of this method of collection.

CONCLUSIONS

The use of a filter has allowed us to obtain the greatest amount possible of pathologic tissue at each surgery. This surgical material has revealed to be helpful both for diagnostic and basic science purposes. The use of the filter has proven to be of particular importance for microadenomas, soft tumors, and supradiaphragmatic or skull base lesions with heterogeneous features, improving the accuracy of histopathologic diagnosis.

Dynamic computed tomography of the pituitary gland using a single slice scanner in dogs with pituitary-dependent hypercortisolism

Selective removal of the pituitary adenoma has not been advocated in dogs with pituitary-dependent hypercortisolism because the pituitary adenoma is usually not visualized on routine computed tomography (CT). Dynamic pituitary CT scanning is aimed at the detection of the pituitary flush and, indirectly, at the presence and position of the adenoma. The first aim of this retrospective study was to compare findings of a multiple slice dynamic scanning protocol with those of a single slice dynamic protocol using a single slice CT scanner. The second aim was to compare the CT findings with surgical findings, and surgical findings with histopathological findings. Computed tomography with single and multiple slice dynamic scanning protocols was performed in 86 dogs with pituitary-dependent hypercortisolism. Thirty dogs underwent transsphenoidal hypophysectomy and pituitary specimens were collected as tumor, normal, mixed and neurohypophyseal samples and processed for histology. The pituitary flush was not detected more frequent in multiple slice dynamic scanning series than in single slice dynamic scanning series. However, in non-enlarged pituitaries, the flush was seen significantly more frequently than in enlarged pituitaries. Prediction of the nature of the tissue during hypophysectomy by the surgeon was inconclusive. In conclusion, when using a single slice CT scanner, both single or multiple slice dynamic scanning protocols can be used for localization of the neurohypophyseal flush, and, indirectly, the adenoma. However, based on this study, the aim of surgery in dogs with pituitary-dependent hypercortisolism remains total adenohypophysectomy, and when the neurophypophysis is recognized, it may be left in situ.