Predicting pituitary adenoma consistency with preoperative magnetic resonance elastography

OBJECTIVE Pituitary adenoma is one of the most common primary intracranial neoplasms. Most of these tumors are soft, but up to 17% may have a firmer consistency. Therefore, knowing the tumor consistency in the preoperative setting could be helpful. Multiple imaging methods have been proposed to predict tumor consistency, but the results are controversial. This study aimed to evaluate the efficacy of MR elastography (MRE) in predicting tumor consistency and its potential use in a series of patients with pituitary adenomas. METHODS Thirty-eight patients with pituitary adenomas (≥ 2.5 cm) were prospectively evaluated with MRI and MRE before surgery. Absolute MRE stiffness values and relative MRE stiffness ratios, as well as the relative ratio of T1 signal, T2 signal, and diffusion-weighted imaging apparent diffusion coefficient (ADC) values were determined prospectively by calculating the ratio of those values in the tumor to adjacent left temporal white matter. Tumors were classified into three groups according to surgical consistency (soft, intermediate, and firm). Statistical analysis was used to identify the predictive value of the different radiological parameters in determining pituitary adenoma consistency. RESULTS The authors included 32 (84.21%) nonfunctional and 6 (15.79%) functional adenomas. The mean maximum tumor diameter was 3.7 cm, and the mean preoperative tumor volume was 16.4 cm3. Cavernous sinus invasion was present in 20 patients (52.63%). A gross-total resection was possible in 9 (23.68%) patients. The entire cohort’s mean absolute tumor stiffness value was 1.8 kPa (range 1.1–3.7 kPa), whereas the mean tumor stiffness ratio was 0.66 (range 0.37–1.6). Intraoperative tumor consistency was significantly correlated with absolute and relative tumor stiffness (p = 0.0087 and 0.007, respectively). Tumor consistency alone was not a significant factor for predicting gross-total resection. Patients with intermediate and firm tumors had more complications compared to patients with soft tumors (50.00% vs 12.50%, p = 0.02) and also had longer operative times (p = 0.0002). CONCLUSIONS Whereas other MRI sequences have proven to be unreliable in determining tumor consistency, MRE has been shown to be a reliable tool for predicting adenoma consistency. Preoperative knowledge of tumor consistency could be potentially useful for surgical planning, counseling about potential surgical risks, and estimating the length of operative time.

Case Report: A Case Series Using Natural Anatomical Gaps—Posterior Cervical Approach to Skull Base and Upper Craniocervical Meningiomas Without Bone Removal

Background: Removal of anteriorly located tumors of the upper cervical spine and craniovertebral junction (CVJ) is a particular surgical challenge. Extensive approaches are associated with pain, restricted mobility of neck and head and, in case of foramen magnum and clivus tumors, with retraction of brainstem and cerebellum.Methods: Four symptomatic patients underwent resection of anteriorly located upper cervical and lower clivus meningiomas without laminotomy or craniotomy using a minimally invasive posterior approach. Distances of natural gaps between C0/C1, C1/C2, and C2/C3 were measured using preoperative CT scans and intraoperative lateral x-rays.Results: In all patients, safe and complete resection was conducted by the opening of the dura between C0/C1, C1/C2, and C2/C3, respectively. There were no surgical complications. Local pain was reported as very moderate by all patients and postoperative recovery was extremely fast. All tumors had a rather soft consistency, allowing mass reduction prior to removal of the tumor capsule and were well separable from lower cranial nerves and vascular structures.Conclusion: If tumor consistency is appropriate for careful mass reduction before removal of the tumor capsule and if tumor margins are not firmly attached to crucial structures, then upper cervical, foramen magnum, and lower clivus meningiomas can be safely and completely removed through natural gaps in the CVJ region. Both prerequisites usually become clear early during surgery. Thus, this tumor entity may be planned using this minimally invasive approach and may be extended if tumor consistency turns out to be less unfavorable for resection or if crucial structures cannot be easily separated from the tumor.

Development and Evaluation of Deep Learning-based Automated Segmentation of Pituitary Adenoma in Clinical Task

Purpose To create an automated segmentation method for the sellar region, several tools to extract invasiveness-related features, and evaluate their clinical usefulness by predicting the tumor consistency. Materials and Methods Patients included were diagnosed with pituitary adenoma at Peking Union Medical College Hospital. A deep convolutional neural network, called Gated-Shaped U-Net (GSU-Net), was created to automatically segment the sellar region into eight classes. Five MRI features were extracted from the segmentation results, including tumor diameters, volume, optic chiasma height, Knosp grading system, and degree of ICA contact. The clinical usefulness of proposed methods was evaluated by the diagnostic accuracy of the tumor consistency. Results 163 patients confirmed with pituitary adenoma were included as the first group and were randomly divided into a training dataset and test dataset (131 and 32 patients, respectively). 50 patients confirmed with acromegaly were included as the second group. The Dice coefficient of pituitary adenoma in important image slices was 0.940. The proposed methods achieved accuracies of over 80% for the prediction of five invasive-related MRI features. Methods derived from the automatic segmentation showing better performances than original methods and achieved AUCs of 0.840 and 0.920 for clinical models and radiomics models, respectively. Conclusion The proposed methods could automatically segment the sellar region and extract features with high accuracies. The outstanding performance of the prediction of the tumor consistency indicates their clinical usefulness for supporting neurosurgeons in judging patients’ conditions, predicting prognosis, and other downstream tasks during the preoperative period.

Preoperative Prediction of Meningioma Consistency via Machine Learning-Based Radiomics

ObjectivesThe aim of this study was to establish and validate a radiomics nomogram for predicting meningiomas consistency, which could facilitate individualized operation schemes-making.MethodsA total of 172 patients was enrolled in the study (train cohort: 120 cases, test cohort: 52 cases). Tumor consistency was classified as soft or firm according to Zada’s consistency grading system. Radiomics features were extracted from multiparametric MRI. Variance selection and LASSO regression were used for feature selection. Then, radiomics models were constructed by five classifiers, and the area under curve (AUC) was used to evaluate the performance of each classifiers. A radiomics nomogram was developed using the best classifier. The performance of this nomogram was assessed by AUC, calibration and discrimination.ResultsA total of 3840 radiomics features were extracted from each patient, of which 3719 radiomics features were stable features. 28 features were selected to construct the radiomics nomogram. Logistic regression classifier had the highest prediction efficacy. Radiomics nomogram was constructed using logistic regression in the train cohort. The nomogram showed a good sensitivity and specificity with AUCs of 0.861 and 0.960 in train and test cohorts, respectively. Moreover, the calibration graph of the nomogram showed a favorable calibration in both train and test cohorts.ConclusionsThe presented radiomics nomogram, as a non-invasive prediction tool, could predict meningiomas consistency preoperatively with favorable accuracy, and facilitated the determination of individualized operation schemes.

Chemotherapy-induced changes in tumor consistency can allow gross total resection of previously unresectable brainstem pilocytic astrocytoma

Background: Low-grade gliomas (LGG) are described by the World Health Organization as Grades I and II. Among LGGs, the most common primary brain tumor is pilocytic astrocytoma (PA) and carries an excellent prognosis when treated with complete surgical resection. Cases, in which this is not possible, are associated with less favorable outcomes and worse progression-free survival. Case Description: This report describes a case of a 22-year-old male, who presented with progression of a primary brainstem tumor previously treated with stereotactic radiosurgery and chemotherapy. Patient underwent surgical exploration and was diagnosed with juvenile PA, but debulking was limited by the very dense and fibrous tumor. Complete surgical resection was not possible at this time. Despite efforts to treat with chemotherapy, the patient presented a year later with clinical deterioration and severe neurologic deficits, prompting surgical re-exploration. During the second operation, the tumor was found to have undergone very significant softening in consistency, allowing for gross total resection (GTR) Conclusion: Aggressive treatment of brainstem LGG should be pursued whenever possible, given its generally favorable prognosis. Repeat microsurgical resection, even with a different approach, might be reasonable and safe. Finally, chemotherapy may be associated with changes in the tumor consistency that can render previously unresectable lesions amenable to successful aggressive resection.

Presurgical somatostatin receptor ligands treatment does not affect tumor consistency in GH-secreting pituitary macroadenomas

Purpose: To evaluate whether pre-surgical treatment using long-acting somatostatin receptor ligands (SRL) may change pituitary tumor consistency and improve surgical outcome in GH-secreting pituitary macroadenomas. Methods: Retrospective study of 40 patients with GH-secreting pituitary macroadenomas operated for the first time by endoscopic transsphenoidal approach. Tumor consistency was evaluated intraoperatively and then correlated with histopathological fibrosis parameters and surgical outcomes. Surgical remission was reported based on the 2010 criteria. Results: The mean tumor size of GH-secreting macroadenomas was of 16.9±8.2mm and 25 were invasive pituitary adenomas (PAs). Presurgical treatment with long-acting SRL was performed in 17 patients (11 lanreotide, 6 octreotide). The cure rate was higher in those patients pre-treated with monthly doses ≥30mg of octreotide or ≥90mg of lanreotide than in those treated with lower doses or untreated (8/11 vs 11/29, P=0.049). However, although the proportion of soft tumors increased as higher doses of SRL were considered in the pre-treated group, no statistical significance was reached, even when the highest approved monthly doses were used (6/6 vs 23/34, P=0.102). Moreover, we found that the remission rate was similar between fibrous and soft tumors (P=0.873) and also of surgical complications (P=0.859), despite of the higher prevalence of Knosp>2 (P=0.035) and very large PA (P=0.025) in fibrous tumors than in soft tumors. Conclusions: Although presurgical treatment with high doses of SRL was associated with a 2.2-fold greater chance of surgical remission, this benefit was not related with changes in tumor consistency induced by the presurgical treatment.

Endoscopic Transnasal Resection of Midline Skull Base Meningiomas: Tumor Consistency and Surgical Outcomes

Background The endoscopic transnasal approach (ETA) has proven to be of great value in the resection of midline skull base meningiomas when compared with traditional approaches. Our objective was to assess tumor consistency in relation to surgical outcomes for midline meningiomas (MMs) resected using ETA. Methods Radiological preoperative features, including the tumor to cerebellar peduncle T2-weighted magnetic resonance imaging (MRI) ratio (TCTI), were evaluated. The intraoperative consistency assessment was performed by the surgeon, which determined if the tumor was soft (resectable by suction) or firm (required a cavitation ultrasonic aspirator). Surgical resection and postoperative complications were evaluated in relation to tumor consistency. Results Twenty patients were evaluated; 6 were classified as firm and 14 were classified as soft. The mean TCTI ratio was 1.7 and the median was 1.7 (range: 1.3–2.4). Three firm tumors had a ratio of <1.6. All soft tumors had a ratio of ≥1.6 with three outliers. Additionally, 66.7% of patients with firm tumors had complications compared with 35.7% of patients with soft tumors. Only 33.3% of firm tumors underwent gross total resection (GTR) in comparison to 79.0% of tumors with a soft consistency. Conclusion In our analysis, we found that tumor consistency was significantly related to short-term surgical outcomes in MMs resected using the ETA. The TCTI ratio was found to be the most reliable predictor with a sensitivity of 76.9% and a specificity of 40.0%. Our findings suggest that traditional cranial approaches should be considered as the first surgical option for managing firm MMs.

Safety and Efficacy of Preoperative Embolization in Patients with hypervascularized Meningioma

Objective: Preoperative embolization of meningiomas can facilitate their resection when they are difficult to remove. In this study, we retrospectively reviewed our experience of embolization using particulate embolic material and coil to clarify the therapeutic efficacy, safety, and risk of complication. Methods: We reviewed 50 patients who underwent embolization with particulate embolic material or with N-butyl cyanoacrylate (NBCA)followed by surgical resection. For a total of 50 procedures of preoperative embolization. We analyzed the following clinical data: age, sex, tumor size pathology, complications related to embolization, and surgeon’s opinion on the intraoperative ease of debulking and blood transfusion. Embolization was performed mainly from the branches of the external carotid artery and branches of the vertebral artery. Results: No allogenic blood transfusions were needed for any patients. The surgeon had the opinion that whitening and softening of the tumor allowed for easy debulking during decompression of the tumor in most of the patients. Transient cranial nerve palsy was seen in one patient. One allergic complication occurred. Conclusion: Preoperative embolization could give us an advantage in surgery for meningioma. The procedure reduces intraoperative blood loss and operating time by softening the tumor consistency. However, we must pay attention to the possibility of embolic complications and keep the preparation of emergency craniotomy, particularly in patients with large meningiomas. Keywords: Meningioma; Embolization; Resection; Endovascular treatment; Preoperative embolization;