Transsphenoidal resection of sellar tumors using high-field intraoperative magnetic resonance imaging

Neuronavigation-assisted pituitary neuroendocrine tumor resection: a systematic review and meta-analysis

Background

The advancement of pituitary surgery has rendered it a secure and efficient treatment method; nevertheless, the potential for incomplete tumor removal and cerebrospinal fluid (CSF) leak remains. Neuronavigation-assisted pituitary neuroendocrine tumor (PitNET) resections have been driving a rising number of attentions in recent years. However, there is currently a lack of comprehensive quantitative evaluation of the effectiveness of neuronavigation-assisted pituitary tumor resection. We aimed to assess the curative effects and complications with or without the use of an image-based neuronavigation in PitNET resection.

Methods

A systematic review and meta-analysis was performed by searching PubMed, EMBASE, Cochrane Library, Web of Science, and Scopus from inception until May 1, 2024 in English to identify any studies reporting gross total resection (GTR) or postoperative complications in patients who underwent neuronavigation-assisted PitNET resection, excluding conference abstracts and studies with fewer than five subjects. We also searched the reference lists of previous systematic reviews and other relevant publications in databases. We reviewed and analyzed the studies that investigated the operative effects and complications of neuronavigation in PitNET resection. Study quality was assessed by the Newcastle-Ottawa scale, and publication bias was evaluated by funnel plot. Review manager 5.3 was employed for meta-analysis. The results were expressed as odds ratio (OR) with 95% confidence interval (CI) of image-assisted techniques for the incidence of GTR and complications.

Results

A total of 42 publications that fulfilled the established searching criteria were obtained from the above-mentioned databases, all of which with the Newcastle-Ottawa Scale scores ≥ six ★. Among the included publications, 37 studies indicated that the OR of image-based neuronavigation was 2.29 (95% CI: 2.02-2.60, P<0.00001, I2=24%) for GTR. The other five studies compared the neuronavigation group (experimental group) and non-neuronavigation group (control group), exhibiting high heterogeneity (I2=91%). After sensitivity analysis, the results showed that the rate of the CSF leak of the neuronavigation group was slightly lower than that of the non-neuronavigation group (OR: 0.84, 95% CI: 0.73-0.97, P=0.01, I2=43%).

Conclusions

According to the existing data, neuronavigation-assisted PitNET resection can increase the rates of GTR and reduce the incidence of postoperative complications. Our results provide a reference for the selection of surgical methods for PitNET resection in future clinical practice.

Consensus guideline for the diagnosis and management of pituitary adenomas in childhood and adolescence: Part 1, general recommendations

Tumours of the anterior part of the pituitary gland represent just 1% of all childhood (aged <15 years) intracranial neoplasms, yet they can confer high morbidity and little evidence and guidance is in place for their management. Between 2014 and 2022, a multidisciplinary expert group systematically developed the first comprehensive clinical practice consensus guideline for children and young people under the age 19 years (hereafter referred to as CYP) presenting with a suspected pituitary adenoma to inform specialist care and improve health outcomes. Through robust literature searches and a Delphi consensus exercise with an international Delphi consensus panel of experts, the available scientific evidence and expert opinions were consolidated into 74 recommendations. Part 1 of this consensus guideline includes 17 pragmatic management recommendations related to clinical care, neuroimaging, visual assessment, histopathology, genetics, pituitary surgery and radiotherapy. While in many aspects the care for CYP is similar to that of adults, key differences exist, particularly in aetiology and presentation. CYP with suspected pituitary adenomas require careful clinical examination, appropriate hormonal work-up, dedicated pituitary imaging and visual assessment. Consideration should be given to the potential for syndromic disease and genetic assessment. Multidisciplinary discussion at both the local and national levels can be key for management. Surgery should be performed in specialist centres. The collection of outcome data on novel modalities of medical treatment, surgical intervention and radiotherapy is essential for optimal future treatment.

Development and prospective validation of an artificial intelligence-based smartphone app for rapid intraoperative pituitary adenoma identification

BACKGROUND

Intraoperative pathology consultation plays a crucial role in tumor surgery. The ability to accurately and rapidly distinguish tumor from normal tissue can greatly impact intraoperative surgical oncology management. However, this is dependent on the availability of a specialized pathologist for a reliable diagnosis. We developed and prospectively validated an artificial intelligence-based smartphone app capable of differentiating between pituitary adenoma and normal pituitary gland using stimulated Raman histology, almost instantly.

METHODS

The study consisted of three parts. After data collection (part 1) and development of a deep learning-based smartphone app (part 2), we conducted a prospective study that included 40 consecutive patients with 194 samples to evaluate the app in real-time in a surgical setting (part 3). The smartphone app's sensitivity, specificity, positive predictive value, and negative predictive value were evaluated by comparing the diagnosis rendered by the app to the ground-truth diagnosis set by a neuropathologist.

RESULTS

The app exhibits a sensitivity of 96.1% (95% CI: 89.9-99.0%), specificity of 92.7% (95% CI: 74-99.3%), positive predictive value of 98% (95% CI: 92.2-99.8%), and negative predictive value of 86.4% (95% CI: 66.2-96.8%). An external validation of the smartphone app on 40 different adenoma tumors and a total of 191 scanned SRH specimens from a public database shows a sensitivity of 93.7% (95% CI: 89.3-96.7%).

CONCLUSIONS

The app can be readily expanded and repurposed to work on different types of tumors and optical images. Rapid recognition of normal versus tumor tissue during surgery may contribute to improved intraoperative surgical management and oncologic outcomes. In addition to the accelerated pathological assessments during surgery, this platform can be of great benefit in community hospitals and developing countries, where immediate access to a specialized pathologist during surgery is limited.

Endoscopic Sellar Defect Reconstruction with Avascular Modified Gasket Seal Technique for Sellar Tumors

Watertight repair of the skull base defect is necessary during endonasal skull base surgery to avoid postoperative CSF leak (poCSFl) and consequent intracranial complications. Various techniques have been described for reconstructing sphenoid-sellar defects with varying success rates. We have described the immediate and long-term outcomes following the reconstruction of sphenoid-sellar defects with our technique. A retrospective analysis of the patients following transsphenoidal sellar surgery underwent barrier restoring reconstruction by multi-layered (inlay-overlay) with autologous thigh fat, fascia lata, fibrin glue, knitted collagen, and absorbable gelatin sponge (modified gasket seal technique). A total of 44 patients were included in the study (n = 44). Reconstruction with modified gasket seal technique was done for all patients. 26 (59.1%) had intraoperative CSF leak (ioCSFl), and 9 (20.4%) patients had grade 3 Esposito-Kelly ioCSFl requiring adjunct short-term pressure reducing procedure (Lumbar drain) intraoperatively. 11/44 (25%) had poCSFl, 7/11 patients with poCSFl were managed conservatively, and 4/11 patients required rescue second surgery and ventriculoperitoneal shunting. 1 (2.3%) had severe meningitis and succumbed to it. Pneumocephalus was seen in 6 (13.6%). Multivariate analysis showed that revision surgery, GH-secreting tumors, and defects extending to the suprasellar region had higher chances of poCSFl (p < 0.001). All 43 alive patients had no CSF leak on long-term follow-up. The modified gasket seal technique is a viable technique for endoscopic sellar reconstruction for ioCSFl with an immediate success rate of 79.6% and 97.72% in the long term in preventing the postoperative CSF leak with a 13.6% rate of meningitis.

Impact of Intraoperative Magnetic Resonance Imaging on Short-Term and Long-Term Outcomes After Transsphenoidal Resection of Pituitary Adenoma: A Systematic Review and Meta-Analysis

BACKGROUND

Intraoperative magnetic resonance imaging (iMRI) allows for greater tumor visualization and extent of resection. It is increasingly used in transsphenoidal surgeries but its role is not yet established.

OBJECTIVE

We aimed to clarify the usefulness of iMRI in transsphenoidal surgery using direct statistical comparisons, with additional subgroup and regression analyses to investigate which patients benefit the most from iMRI use.

METHODS

Systematic searches of PubMed, Embase, and Cochrane Central were undertaken from database inception to May 2020 for published studies reporting the outcomes of iMRI use in transsphenoidal resection of pituitary adenoma.

RESULTS

Thirty-three studies reporting 2106 transsphenoidal surgeries in 2099 patients were included. Of these surgeries, 1487 (70.6%) were for nonfunctioning pituitary adenomas, whereas 619 (29.4%) were for functioning adenomas. Pooled gross total resection (GTR) was 47.6% without iMRI and 66.8% with iMRI (risk ratio [RR], 1.32; P < 0.001). Subgroup and meta-regression analyses demonstrated comparable increases in GTR between microscopic (RR, 1.35; P < 0.001) and endoscopic (RR, 1.31; P < 0.001) approaches as well as functioning and nonfunctioning adenomas (P = 0.584). The pooled rate of hypersecretion normalization was 73.0% within 3 months and 51.7% beyond 3 months postoperatively. The pooled rate of short-term and long-term improvement in visual symptoms was 96.5% and 84.9%, respectively. The incidence of postoperative surgical complications was low. The pooled reoperation rate was 3.8% across 1106 patients.

CONCLUSIONS

The use of iMRI as an adjunct significantly increases GTR for both microscopic and endoscopic resection of pituitary adenomas, with comparable benefits for both functioning and nonfunctioning adenomas. Satisfactory endocrinologic and visual outcomes were achieved.

Adjunctive Benefit of High-Field 3 Tesla MRI Guidance in Endoscopic Transsphenoidal Resection of Pituitary Adenoma

Introduction Pituitary adenomas (PAs) although benign, are difficult to resect intracranial tumors and their residues are associated with morbidity and reduced quality of life. Thus, gross total resection (GTR) is the goal for all PAs. Role of various modalities for better intraoperative visualization and thus improve resection of adenoma have been tested and each have their pros and cons. The aim of this paper is to analyze adjunctive benefit of high-field 3 Tesla intraoperative magnetic resonance imaging (iMRI) in PAs resection by endoscopic transnasal transsphenoidal surgery (eTSS).

Materials and Methods A total of 50 patients who underwent iMRI-guided eTSS were included. MRI findings in preoperative, intraoperative, and 3 months postoperative stage were compared. Adjunctive value of iMRI in improving resection rates of adenoma, postoperative endocrinological outcomes, need for adjuvant radiotherapy, and postoperative cerebrospinal fluid leak rates was assessed.

Results High-field 3 Tesla iMRI helped us to detect residues in 24 (48%) patients and iMRI-guided second look surgery increased our GTR rates from initial 52 to 80% and also helped us to identify and achieve 100% GTR in intrasellar residues and parasellar residues that were medial to medial carotid tangential line. With better resection rates, need for adjuvant radiotherapy was also reduced and only 2% received adjuvant radiotherapy. Average increase in surgical time with the use of iMRI was 38.78 minutes without any side effects pertaining to prolonged surgery.

Conclusion High-field iMRI is a useful adjunct in assessment and improvement in extent of resection of PA by endoscopic transsphenoidal surgery. Also, it was found beneficial in preserving normal anatomical gland and, thus, reducing the need for postoperative adjuvant hormonal and radiation therapy.

The value of intraoperative MRI for resection of functional pituitary adenomas-a critical assessment of a consecutive single-center series of 114 cases

This series sought to evaluate the role of intraoperative MRI (iMRI) for resection of functional pituitary adenomas (FPAs). We retrospectively reviewed clinical data of 114 consecutive FPAs with excessive hormone secretion treated with transsphenoidal surgery and iMRI during 01/2010–12/2017. We focused on iMRI findings, extend of resection and postoperative hormonal remission. Variables of incomplete resections and persistent hormone excess were evaluated by binary regression. Patients with FPAs presented with hypercortisolism (n = 23, 20%), acromegaly (n = 56, 49%), and as prolactinomas (n = 35, 31%) resistant to medical treatment. Preoperative MRI showed 81 macroadenomas (71%) and optic system involvement in 41 cases (36%). IMRI was suggestive for residual tumor in 51 cases (45%). Re-inspection of the cavity cleared equivocal findings in 16 cases (14%). Additional tumor was removed in 22 cases (19%). Complete resection was achieved in 95 cases (83%). Postoperative morbidity was low (1.7% revision surgeries, 0.8% permanent diabetes insipidus). Overall hormonal remission-rate was 59% (hypercortisolism 78%, acromegaly 52%, prolactinoma 57%). Supra- and parasellar invasion and preoperative visual impairment were significant predictors for incomplete resections despite use of iMRI. Risk for persistent hormone excess was increased sevenfold after incomplete resections. IMRI enabled reliable identification of tumor remnants during surgery and triggered further resection in a considerable proportion of cases. Nevertheless, tumor size and invasiveness set persistent boundaries to the completeness of resections. The low rate of surgical complications could point at a less invasive iMRI-guided surgical approach while achieving a complete tumor resection was a crucial determinant for hormonal outcome.

Do We Need Intraoperative Magnetic Resonance Imaging in All Endoscopic Endonasal Pituitary Adenoma Surgery Cases? A Retrospective Study

There are previous reports investigating effectiveness of intraoperative magnetic resonance imaging (IO-MRI) in pituitary adenoma surgery but there is no clear data in the literature recommending when there is no need of intraoperative scan. This retrospective analysis was based on determining which patients does not need any IO-MRI scan following endoscopic endonasal pituitary adenoma surgery. Patients with functional or non-functional pituitary adenomas that were operated via endoscopic endonasal approach (EEA) between June 2017 and May 2019 were enrolled. Patients younger than 18 years old, patients who did not underwent IO-MRI procedure or not operated via EEA were excluded from the study. Hence, this study is designed to clarify if IO-MRI is useful in both functional and non-functional pituitary adenomas, functional adenomas did not split into subgroups. A total of 200 patients treated with pituitary adenoma were included. In Knosp Grade 0 – 2 group, primary surgeon’s opinion and IO-MRI findings were compatible in 150 patients (98.6%). In Knosp Grade 3 – 4 correct prediction were performed in 32 (66.6%) patients. When incorrectly predicted Knosp Grade 3 – 4 patients (n = 16) was analyzed, in 13 patients there were still residual tumor in cavernous sinus and in 3 patients there were no residual tumor. Fisher’s exact test showed there is a statistically significant difference of correct prediction between two different Knosp Grade groups (two-tailed P < 0.0001). Eighteen patients had a residual tumor extending to the suprasellar and parasellar regions which second most common site for residual tumor. Our findings demonstrate that there is no need of IO-MRI scan while operating adenomas limited in the sellae and not invading the cavernous sinus. However, we strongly recommend IO-MRI if there is any suprasellar and parasellar extension and/or cavernous sinus invasion.

Transsphenoidal pituitary adenoma resection: do early post-operative cortisol levels predict permanent long-term hypocortisolism?

Transsphenoidal surgery provides a minimal invasive treatment for pituitary adenoma. Our aim is to evaluate the endocrinological outcomes after adenoma resection focusing on the corticotroph function, and to identify prognostic factors for an impaired hypothalamic–pituitary–adrenal-axis function (HPA) and the reliability of postoperative early morning serum cortisol measurements. We performed a retrospective analysis of all patients treated for pituitary adenoma from April 2006 to January 2019 in our neurosurgical department. Pituitary function was assessed pre- and postoperatively as well as at 6 weeks to 12 weeks and at 1-year follow-up. Two hundred eleven patients were included. Nine percent of the patients recovered from a preoperative adrenal insufficiency, 10.4% developed a new need for hormone substitution, and a long-term deficiency of the hypothalamic–pituitary–adrenal-axis was observed in 30.9%. Cortisol measurements 5 days after surgery had a lower area under the curve (AUC) than cortisol levels detected after 6 to 12 weeks (AUC 0.740 vs. AUC 0.808) in predicting an intact corticotrope function. The cut-off value determined for cortisol measured after 6 weeks was 6.95 µg/dl (sensitivity of 94%, specificity of 68%). Postoperative early morning cortisol levels seem to be less sensitive and specific in predicting long-term corticotroph function than measurements after 6 weeks and 1 year, emphasizing the importance of endocrine follow-up testing.

Impact of intraoperative magnetic resonance imaging on gross total resection, extent of resection, and residual tumor volume in pituitary surgery: systematic review and meta-analysis

BACKGROUND

Residual tumor tissue after pituitary adenoma surgery, is linked with additional morbidity and mortality. Intraoperative magnetic resonance imaging (ioMRI) could improve resection. We aim to assess the improvement in gross total resection (GTR), extent of resection (EOR), and residual tumor volume (RV) achieved using ioMRI.

METHODS

A systematic review was carried out on PubMed/MEDLINE to identify any studies reporting intra- and postoperative (1) GTR, (2) EOR, or (3) RV in patients who underwent resection of pituitary adenomas with ioMRI. Random effects meta-analysis of the rate of improvement after ioMRI for these three surgical outcomes was intended.

RESULTS

Among 34 included studies (2130 patients), the proportion of patients with conversion to GTR (∆GTR) after ioMRI was 0.19 (95% CI 0.15-0.23). Mean ∆EOR was + 9.07% after ioMRI. Mean ∆RV was 0.784 cm3. For endoscopically treated patients, ∆GTR was 0.17 (95% CI 0.09-0.25), while microscopic ∆GTR was 0.19 (95% CI 0.15-0.23). Low-field ioMRI studies demonstrated a ∆GTR of 0.19 (95% CI 0.11-0.28), while high-field and ultra-high-field ioMRI demonstrated a ∆GTR of 0.19 (95% CI 0.15-0.24) and 0.20 (95% CI 0.13-0.28), respectively.

CONCLUSIONS

Our meta-analysis demonstrates that around one fifth of patients undergoing pituitary adenoma resection convert from non-GTR to GTR after the use of ioMRI. EOR and RV can also be improved to a certain extent using ioMRI. Endoscopic versus microscopic technique or field strength does not appear to alter the impact of ioMRI. Statistical heterogeneity was high, indicating that the improvement in surgical results due to ioMRI varies considerably by center.

10 Years' Experience of Using Low-Field Intraoperative MRI in Transsphenoidal Surgery for Pituitary Adenoma: Results of the Swiss Pituitary Registry (SwissPit)

BACKGROUND

For 20 years, several studies have reported intraoperative magnetic resonance imaging (iMRI) utility to achieve gross total resections in transsphenoidal pituitary adenoma surgery. Although few studies on low-field iMRI included >100 patients, data on hormonally active tumors remain scarce and follow-up times are <3 years. This is not sufficient to judge the long-term efficiency of the use of low-field iMRI. The aim of this retrospective study is to report the detailed outcome of iMRI-controlled transsphenoidal surgery in >200 patients during a follow-up exceeding 5 years.

METHODS

Patients undergoing surgery for pituitary adenoma by iMRI-controlled, endoscopically assisted transsphenoidal surgery at the authors' institution between 2006 and 2016 were eligible for inclusion. Data were collected in the Swiss Pituitary Registry. A Polestar 0.15T-scanner was used.

RESULTS

A total of 231 patients had surgery for 160 nonfunctioning adenomas; 28 hGH-, 27 PRL-, 10 ACTH-secreting and 6 mixed adenomas and were followed for 62 months (9-178). Additional iMRI-guided resections were possible in 54% and increased the gross total resection rate by 4% (P = 0.004). Remission rates were as follows: nonfunctioning adenoma, 53%; acromegaly, 61%; prolactinoma, 50%; Cushing disease, 90%. Tumor regrowth and recurrence was detected at a mean time of 24 and 63 months, respectively. Recovery of deficient hormone axes was detected in 22% to 27%. The risk for new postoperative hormonal deficiencies was 15%. Postoperative relieve of visual field and visual acuity deficiencies was seen in 94 (86%) and 73 (81%) patients, respectively.

CONCLUSION

Judged by long-term follow-ups of >200 nonfunctioning/functioning pituitary adenomas, the use of low-field iMRI in transsphenoidal surgery increases resection rates and sustainably influences outcomes.

The functional evaluation of pituitary in patients with a surgical resection of sellar tumours

INTRODUCTION

The aim of this study was to analyse the incidences of hypopituitarism before and after surgical resection of sellar tumours and to find the factors related to the incidences.

MATERIAL AND METHODS

From January 2009 to December 2011, 191 patients in the Department of Neurosurgery in Xiangya Hospital, who underwent the surgical resection of sellar tumours, were included in this retrospective analysis. Pre- and postoperative pituitary function assessments were performed by the detection of hormone levels. Tumour size and location were analysed by magnetic resonance imaging (MRI).

RESULTS

In total 152 (79.6%) patients had anterior pituitary hypofunction preoperatively, and 176 (92.1%) patients had anterior pituitary hypofunction postoperatively. The pre- and postoperative adrenal cortex hypofunction incidences were 83 (43.5%) and 103 (53.9%), respectively. Ninety-three (48.7%) patients had thyroid hypofunction preoperatively, and 101 (52.9%) patients had anterior pituitary hypofunction postoperatively. The pre- and postoperative hypogonadism incidences were 131 (68.6%) and 160 (83.8%), respectively. The postoperative incidences of anterior pituitary hypofunction and hypogonadism in patients with craniopharyngioma or pituitary tumours were both significantly higher than the preoperative incidences. Surgery resection methods and tumour sizes were found to be related to the incidence of postoperative hypogonadism.

CONCLUSIONS

To sum up, we found that the postoperative incidences of hypopituitarism were higher than the preoperative incidences. Tumour type, surgery resection methods, and tumour sizes were important contributing factors to the incidence of postoperative hypogonadism.

The Zurich Pituitary Score predicts utility of intraoperative high-field magnetic resonance imaging in transsphenoidal pituitary adenoma surgery

BACKGROUND

It is currently unclear if there are subsets of patients undergoing transsphenoidal surgery (TSS) in which intraoperative high-field magnetic resonance imaging (3T-iMRI) is particularly advantageous. We aimed to investigate whether a radiological grading scale predicts the utility of 3T-iMRI in pituitary adenoma (PA) TSS.

METHODS

From a prospective registry, patients who underwent endoscopic TSS for PA using 3T-iMRI were identified. Adenomas were graded using the Zurich Pituitary Score (ZPS). We assessed improvement after 3T-iMRI in terms of gross total resection (GTR), residual volume (RV), and extent of resection (EOR).

RESULTS

Among 95 patients, rates of conversion to GTR after 3T-iMRI decreased steadily from 33% for grade I to 0% for grade IV adenomas, with a statistically significant conversion rate only for grade I (p = 0.008) and grade II (p < 0.001). All grade I adenomas were completely resected after 3T-iMRI. Median RV change was statistically significant for grades I to III, but not for grade IV (p = 0.625). EOR improvement ranged from a median change of 0.0% (IQR 0.0-4.5%) for grade I to 4.4% (IQR 0.0-9.0%) for grade IV, with a significant improvement only for grades I to III (p < 0.05).

CONCLUSIONS

Interestingly, this study shows that clinical utility of 3T-iMRI is highest in the more "simple" adenomas (ZPS grades I-II) than for the more "complex" ones (ZPS grade III-IV). Grade I adenomas are amenable to GTR if 3T-iMRI is implemented. In grade III adenomas, EOR and RV can be improved to clinically relevant levels. Conversely, in grade IV adenomas, 3T-iMRI may be of limited use.

Intra-operative MRI vs endoscopy in achieving gross total resection of pituitary adenomas: a systematic review

BACKGROUND

Intraoperative magnetic resonance imaging (iMRI) is a technology that may improve rates of gross total resection (GTR) for pituitary adenomas. The endoscope is another less expensive technology, which also may maximize resection rates. A direct comparison of these approaches and their additive benefit has never been performed.

METHODS

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) standard. PubMed and Embase databases were searched for studies that examined GTR for pituitary adenoma resection with either endoscopic transsphenoidal surgery (eTSS), microscopic transsphenoidal surgery with iMRI (mTSS + iMRI), or endoscopic transsphenoidal surgery with iMRI (eTSS + iMRI).

RESULTS

Eighty-five studies that reported GTR rates in 7124 pituitary adenoma patients were identified. For all pituitary adenomas, eTSS had a pooled proportion of GTR of 68.9% (95% CI 64.7-73.0%) which was similar to that of mTSS + iMRI (GTR 68.3%; 95% CI = 59.4-76.5%) and eTSS + iMRI (GTR 70.7%; 95% CI = 56.9-89.6%). For the subgroup of pituitary macroadenomas, pooled proportions for GTR were similar between eTSS and mTSS + iMRI (eTSS: GTR 59.4%; 95% CI = 49.6-68.7% vs mTSS + iMRI: GTR 68.8%; 95% CI = 57.3-79.3%), and higher for eTSS + iMRI (81.1%; 95% CI = 75.5-86.2%). The post-operative CSF leak proportion for eTSS (4.7%; 95% CI = 3.6-5.9%) was similar to that for eTSS + iMRI (3.7%; 95% CI = 1.6-6.5%) and mTSS + iMRI (4.6%; 95% CI = 2.0-8.3%). No direct statistical comparisons could be performed.

CONCLUSION

Final GTR proportions are similar whether the surgeon uses a microscope supplemented with iMRI or endoscope with or without iMRI. The benefit of the two technologies may be complementary for macroadenomas. These findings are important to consider when comparing the efficacy of different technical strategies in the management of pituitary adenomas.

The optimal surgical techniques for pituitary tumors

In this paper, the currently used and well evaluated techniques for the surgery of pituitary tumors will be reviewed. Since the first surgical approaches to pituitary tumors more than 100 years have elapsed. Various surgical techniques have been developed, refined and standardized. Most of these tumors are to date treated via transsphenoidal approaches. Many pituitary adenomas, particularly, smaller, enclosed ones, can be completely excised and a selective adenomectomy is usually attempted. It leads to remission of hormonal oversecretion and also to recovery of pituitary function in many patients. The resection of pseudocapsule around the adenoma seems to improve the operative results further. Transcranial approaches, employing craniotomies, are still needed in some patients with pituitary adenomas and in many of those harbouring craniopharyngiomas. The operative techniques will be described and briefly commented. Moreover, the application and usefulness of several technical developments will be reviewed, such as the use of the endoscope, magnetic resonance imaging, fluorenscent dyes and neuronavigation. The use of the intraoperative Doppler probe, ultrasound and the value of intraoperative hormonal measurements will be briefly discussed. There is sufficient evidence that the best and optimal outcome in terms of tumor resection and correction of hormonal oversecretion as well as the lowest rate of complications are obtained in centers of excellence with sufficiently experienced, specialized surgeons and a high patient load.

Technological and Ideological Innovations in Endoscopic Skull Base Surgery

BACKGROUND

Endoscopic skull base surgery has evolved over the last several decades due to technological advances and operative techniques. Several innovations that are not yet mainstream may have significant impact on the future of endoscopic skull base surgery.

METHODS

Current literature pertaining to innovations in endoscopic skull base surgery was retrieved using PubMed, Embase, Web of Science, and Google Scholar.

RESULTS

Several recent innovations may play an influential role in the advancement of endoscopic skull base surgery, including fluorescent dyes such as indocyanine green fluorescence, fluorescein, and 5-aminolevulinic acid, 3-dimensional endoscopes, robotic surgery, and intraoperative magnetic resonance imaging.

CONCLUSIONS

Several technologies are under current investigation with the hope to improve future outcomes in endoscopic skull base surgery. Additional research and evolution are necessary and will require intense scrutiny before becoming standard of care.

iMRI During Transsphenoidal Surgery

A variety of intraoperative MRI (iMRI) systems are in use during transsphenoidal surgery (TSS). The variations in iMRI systems include field strengths, magnet configurations, and room configurations. Most studies report that the primary utility of iMRI during TSS lies in detecting resectable tumor residuals following maximal resection with conventional technique. Stereotaxis, neuronavigation, and complication avoidance/detection are enhanced by iMRI use during TSS. The use of iMRI during TSS can lead to increased extent of resection for large tumors. Improved remission rates from hormone-secreting tumors have also been reported with iMRI use. This article discusses the history, indications, and future directions for iMRI during TSS.

The utility of high-resolution intraoperative MRI in endoscopic transsphenoidal surgery for pituitary macroadenomas: early experience in the Advanced Multimodality Image Guided Operating suite

OBJECTIVE

Endoscopic skull base surgery has become increasingly popular among the skull base surgery community, with improved illumination and angled visualization potentially improving tumor resection rates. Intraoperative MRI (iMRI) is used to detect residual disease during the course of the resection. This study is an investigation of the utility of 3-T iMRI in combination with transnasal endoscopy with regard to gross-total resection (GTR) of pituitary macroadenomas.

METHODS

The authors retrospectively reviewed all endoscopic transsphenoidal operations performed in the Advanced Multimodality Image Guided Operating (AMIGO) suite from November 2011 to December 2014. Inclusion criteria were patients harboring presumed pituitary macroadenomas with optic nerve or chiasmal compression and visual loss, operated on by a single surgeon.

RESULTS

Of the 27 patients who underwent transsphenoidal resection in the AMIGO suite, 20 patients met the inclusion criteria. The endoscope alone, without the use of iMRI, would have correctly predicted extent of resection in 13 (65%) of 20 cases. Gross-total resection was achieved in 12 patients (60%) prior to MRI. Intraoperative MRI helped convert 1 STR and 4 NTRs to GTRs, increasing the number of GTRs from 12 (60%) to 16 (80%).

CONCLUSIONS

Despite advances in visualization provided by the endoscope, the incidence of residual disease can potentially place the patient at risk for additional surgery. The authors found that iMRI can be useful in detecting unexpected residual tumor. The cost-effectiveness of this tool is yet to be determined.

Pituitary surgery and volumetric assessment of extent of resection: a paradigm shift in the use of intraoperative magnetic resonance imaging

OBJECTIVE

The aim of this study was to quantitatively assess the role of intraoperative high-field 3-T MRI (3T-iMRI) in improving the gross-total resection (GTR) rate and the extent of resection (EOR) in endoscopic transsphenoidal surgery (TSS) for pituitary adenomas.

METHODS

Radiological and clinical data from a prospective database were retrospectively analyzed. Volumetric measurements of adenoma volumes pre-, intraoperatively, and 3 months postoperatively were performed in a consecutive series of patients who had undergone endoscopic TSS. The quantitative contribution of 3T-iMRI was measured as a percentage of the additional rate of GTR and of the EOR achieved after 3T-iMRI.

RESULTS

The cohort consisted of 50 patients (51 operations) harboring 33 nonfunctioning and 18 functioning pituitary adenomas. Mean adenoma diameter and volume were 21.1 mm (range 5–47 mm) and 5.23 cm3 (range 0.09–22.14 cm3), respectively. According to Knosp's classification, 10 cases were Grade 0; 8, Grade 1; 17, Grade 2; 12, Grade 3; and 4, Grade 4. Gross-total resection was the surgical goal (targeted [t]GTR) in 34 of 51 operations and was initially achieved in 16 (47%) of 34 at 3T-iMRI and in 30 (88%) of 34 cases after further resection. In this subgroup, the EOR increased from 91% at 3T-iMRI to 99% at the 3-month MRI (p < 0.05). In the 17 cases in which subtotal resection (STR) had been planned (tSTR), the EOR increased from 79% to 86% (p < 0.05) and GTR could be achieved in 1 case. Intrasellar remnants were present in 20 of 51 procedures at 3T-iMRI and in only 5 (10%) of 51 procedures after further resection (median volume 0.15 cm3). Overall, the use of 3T-iMRI led to further resection in 27 (53%) of 51 procedures and permitted GTR in 15 (56%) of these 27 procedures; thus, the GTR rate in the entire cohort increased from 31% (16 of 51) to 61% (31 of 51) and the EOR increased from 87% to 95% (p < 0.05).

CONCLUSIONS

The use of high-definition 3T-iMRI allowed precise visualization and quantification of adenoma remnant volume. It helped to increase GTR and EOR rates in both tGTR and tSTR patient groups. Moreover, it helped to achieve low rates of intrasellar remnants. These data support the use of 3T-iMRI to achieve maximal, safe adenoma resection.

Cavernous sinus sampling in patients with Cushing's disease

OBJECT

Correct diagnosis and precise localization of adenomas in patients with Cushing's disease are essential for avoiding unsuccessful transsphenoidal pituitary exploration. In addition to the well-established inferior petrosal sinus sampling, preoperative cavernous sinus sampling (CSS) was introduced as a potentially improved way to predict adenoma lateralization. The authors present their results with CSS in a consecutive series of patients with Cushing's disease.

METHODS

During 1999–2014, transsphenoidal surgeries were consecutively performed in 510 patients with Cushing's disease. For most patients, suppression of cortisol in high-dose dexamethasone tests and stimulation of adrenocorticotropic hormone and cortisol after administration of corticotropin-releasing hormone were sufficient to prove the diagnosis of adrenocorticotropic hormone–dependent hypercortisolism. Of the 510 patients, 67 (13%) were referred to the department of neuroradiology for CSS according to the technique of Teramoto. The indications for CSS were unclear endocrine test results or negative MRI results. Data for all patients were retrospectively analyzed.

RESULTS

A central/peripheral gradient was found in 59 patients; lateralization to the left or right side was found in 51. For 8 patients with a central/peripheral gradient, no left/right gradient could be determined. For another 8 patients with equivocal test results, no central/peripheral gradient was found. No severe CSS-associated complications were encountered. Of the 51 patients who underwent transsphenoidal surgery, the predicted lateralization was proven correct for 42 (82%).

CONCLUSIONS

As MRI techniques have improved, the number of potential candidates for this invasive method has decreased in the past decade. However, because detecting minute adenomas remains problematic, CSS remains a useful diagnostic tool for patients with Cushing's disease.

Combined high-field intraoperative magnetic resonance imaging and endoscopy increase extent of resection and progression-free survival for pituitary adenomas

PURPOSE

The clinical benefit of combined intraoperative magnetic resonance imaging (iMRI) and endoscopy for transsphenoidal pituitary adenoma resection has not been completely characterized. This study assessed the impact of microscopy, endoscopy, and/or iMRI on progression-free survival, extent of resection status (gross-, near-, and sub-total resection), and operative complications.

METHODS

Retrospective analyses were performed on 446 transsphenoidal pituitary adenoma surgeries at a single institution between 1998 and 2012. Multivariate analyses were used to control for baseline characteristics, differences during extent of resection status, and progression-free survival analysis.

RESULTS

Additional surgery was performed after iMRI in 56/156 cases (35.9%), which led to increased extent of resection status in 15/156 cases (9.6%). Multivariate ordinal logistic regression revealed no increase in extent of resection status following iMRI or endoscopy alone; however, combining these modalities increased extent of resection status (odds ratio 2.05, 95% CI 1.21-3.46) compared to conventional transsphenoidal microsurgery. Multivariate Cox regression revealed that reduced extent of resection status shortened progression-free survival for near- versus gross-total resection [hazard ratio (HR) 2.87, 95% CI 1.24-6.65] and sub- versus near-total resection (HR 2.10; 95% CI 1.00-4.40). Complication comparisons between microscopy, endoscopy, and iMRI revealed increased perioperative deaths for endoscopy versus microscopy (4/209 and 0/237, respectively), but this difference was non-significant considering multiple post hoc comparisons (Fisher exact, p = 0.24).

CONCLUSIONS

Combined use of endoscopy and iMRI increased pituitary adenoma extent of resection status compared to conventional transsphenoidal microsurgery, and increased extent of resection status was associated with longer progression-free survival. Treatment modality combination did not significantly impact complication rate.

Use of high-field intraoperative magnetic resonance imaging during endoscopic transsphenoidal surgery for functioning pituitary microadenomas and small adenomas located in the intrasellar region

The usefulness of 1.5-T high-field intraoperative magnetic resonance (iMR) imaging during transsphenoidal surgery for functioning pituitary adenomas was retrospectively evaluated based on long-term endocrine remission from the records of 14 patients who underwent transsphenoidal surgery with iMR imaging for functioning pituitary microadenomas and small adenomas located in the intrasellar region. The maximum tumor diameter was 9.3 ± 2.6 mm. Patients were diagnosed with acromegaly (n = 7), prolactinoma (n = 4), and Cushing's disease (n = 3). If iMR imaging detected tumor remnants after resection, the resection cavity was reexamined and further resection was performed. Postoperative endocrine follow-up period was mean 33.7 ± 13.3 months. Tumor remnants were detected after the first resection in seven patients. Further resection was performed in five of these patients, and three achieved long-term endocrine remission. As a result, the overall long-term endocrine remission rate was 78.5% (11/14), instead of the 57.1% (8/14) that would be expected if iMR imaging had not been performed. Long-term endocrine remission had a tendency to be associated with the absence of tumor remnants on the final iMR images, but this was not significant (p = 0.09). Long-term endocrine remission was associated with presence of tumor remnants in the cavernous sinus on the final iMR images (p = 0.03). High-field iMR imaging is useful for depicting tumor remnants after resection, and increased the long-term endocrine remission rate for patients with functioning pituitary microadenomas and small adenomas.

Determining the utility of intraoperative magnetic resonance imaging for transsphenoidal surgery: a retrospective study

OBJECT

Intraoperative MRI (iMRI) provides updated information for neuronavigational purposes and assessments on the status of resection during transsphenoidal surgery (TSS). The high-field technique additionally provides information about vascular structures at risk and precise information about extrasellar residual tumor, making it readily available during the procedure. The imaging, however, extends the duration of surgery. To evaluate the benefit of this technique, the authors conducted a retrospective study to compare postoperative outcome and residual tumor in patients who underwent conventional microsurgical TSS with and without iMRI.

METHODS

A total of 143 patients were assessed. A cohort of 67 patients who had undergone surgery before introduction of iMRI was compared with 76 patients who had undergone surgery since iMRI became routine in TSS at the authors' institution. Residual tumor, complications, hormone dependency, biochemical remission rates, and improvement of vision were assessed at 6-month follow-up. A volumetric evaluation of residual tumor was performed in cases of parasellar tumor extension.

RESULTS

The majority of patients in both groups suffered from nonfunctioning pituitary adenomas. At the 6-month follow-up assessment, vision improved in 31% of patients who underwent iMRI-assisted surgery versus 23% in the conventional group. One instance of postoperative intrasellar bleeding was found in the conventional group. No major complications were found in the iMRI group. Minor complications were seen in 9% of patients in the iMRI group and in 5% of those in the conventional group. No differences between groups were found for hormone dependency and biochemical remission rates. Time of surgery was significantly lower in the conventional treatment group. Overall a residual tumor was found after surgery in 35% of the iMRI group, and 41% of the conventional surgery group harbored a residual tumor. Total resection was achieved as intended significantly more often in the iMRI group (91%) than in the conventional group (73%) (p < 0.034). Patients with a planned subtotal resection showed higher mean volumes of residual tumor in the conventional group. There was a significantly lower incidence of intrasellar tumor remnants in the iMRI group than in the conventional group. Progression-free survival after 30 months was higher according to Kaplan-Meier analysis with the use of iMRI, but a statistically significant difference could not be shown.

CONCLUSIONS

The use of high-field iMRI leads to a significantly higher rate of complete resection. In parasellar tumors a lower residual volume and a significantly lower rate of intrasellar tumor remnants were shown with the technique. So far, long-term follow-up is limited for iMRI. However, after 2 years Kaplan-Meier analyses show a distinctly higher progression-free survival in the iMRI group. No significant benefit of iMRI was found for biochemical remission rates and improvement of vision. Even though the surgical time was longer with the adjunct use of iMRI, it did not increase the complication rate significantly. The authors therefore recommend routine use of high-field iMRI for pituitary surgery, if this technique is available at the particular center.

Dynamic intraoperative MRI in transsphenoidal resection of pituitary macroadenomas: a quantitative analysis

PURPOSE

To compare intraoperative dynamic contrast-enhanced (dCE) sequences with conventional CE (cCE) in the evaluation of the surgical bed after transsphenoidal removal of pituitary macroadenomas.

MATERIALS AND METHODS

Twenty-one patients with macroadenoma were selected. They all underwent intraoperative magnetic resonance imaging (iMRI) (1.5T) acquisitions during transsphenoidal resection of the tumor. For each patient, dCE and cCE images were acquired in the operating room after tumor removal. The mean values of surgical cavities volumes were measured and statistically compared through Student's t-test analysis. Informed consent to iMRI was obtained from the patients as a part of the surgical procedure. Institutional Review Board (IRB) approval was obtained.

RESULTS

No patient showed recurrence within at least 1 year of follow-up. Two patients showed residual tumor in the iMRI. Intraoperative analysis of the remaining 19 demonstrated that the mean value of the surgical cavities was significantly bigger in dCE than in cCE images (2955 mm(3) vs. 1963 mm(3) , respectively, P = 0.022).

CONCLUSION

This study demonstrated underestimation of surgical cavity by conventional iMRI, simulating residual tumor and potentially leading to unnecessary surgical revision.

Intraoperative magnetic resonance imaging during surgery for pituitary adenomas: pros and cons

Surgery for pituitary adenomas still remains a mainstay in their treatment, despite all advances in sophisticated medical treatments and radiotherapy. Total tumor excision is often attempted, but there are limitations in the intraoperative assessment of the radicalism of tumor resection by the neurosurgeon. Standard postoperative imaging is usually performed with a few months delay from the surgical intervention. The purpose of this report is to review briefly the facilities and kinds of intraoperative magnetic resonance imaging for all physician and surgeons involved in the management of pituitary adenomas on the basis of current literature. To date, there are several low- and high-field magnetic resonance imaging systems available for intraoperative use and depiction of the extent of tumor removal during surgery. Recovery of vision and the morphological result of surgery can be largely predicted from the intraoperative images. A variety of studies document that depiction of residual tumor allows targeted attack of the remnant and extent the resection. Intraoperative magnetic resonance imaging offers an immediate feedback to the surgeon and is a perfect quality control for pituitary surgery. It is also used as a basis of datasets for intraoperative navigation which is particularly useful in any kind of anatomical variations and repeat operations in which primary surgery has distorted the normal anatomy. However, setting up the technology is expensive and some systems even require extensive remodeling of the operation theatre. Intraoperative imaging prolongs the operation, but may also depict evolving problems, such as hematomas in the tumor cavity. There are several artifacts in intraoperative MR images possible that must be considered. The procedures are not associated with an increased complication rate.