Holocord pilocytic astrocytoma in a young woman with intracranial extension: case report and review of the MRI characteristics.

INTRODUCTION: Pilocytic astrocytoma is a low-grade glioma more frequently seen in patients <20. It is pretty uncommon in the spinal cord. Rarely, astrocytoma may involve the most or total length of the spinal cord; in that case, they are called "holo-cord astrocytoma." In this case report, we are reporting the third holo-cord pilocytic astrocytoma in an adult patient and the first with an extension to the Magendie foramen. CASE PRESENTATION: We presented a 24-year-old woman with complaints of progressively worsening neck and back pain since one year ago. The patient's MRI showed a very large intradural and intramedullary cystic lesion with a solid component within the spinal cord extending from the medulla to the conus medullaris. Partial resection of the solid part of the cervical portion of the tumor was performed. Histopathological evaluation of the resected tumor segments was compatible with grade I pilocytic astrocytoma. After one year of follow-up, neck and back pain has reduced, and neurological functions have improved. CONCLUSION: Spinal cord pilocytic astrocytoma may present as a holo-cord tumor and can rarely extend to the intracranial fossa. Although this tumor does not arise from the central canal, in this case, it was extended through the Magendie foramen. Symptoms could be subtle despite extensive cord involvement. On MRI, this tumor presents as an intramedullary holo-cord cystic lesion intermixed with a solid component with a variable enhancement of the solid component.

T2-FLAIR Mismatch: An Imaging Biomarker for Children's MYB/MYBL1-Altered Diffuse Astrocytoma or Angiocentric Glioma.

BACKGROUND AND PURPOSE: T2-FLAIR mismatch is a highly specific imaging biomarker of IDH-mutant diffuse astrocytoma in adults. It has however also been described in MYB/MYBL1-altered low grade tumors. Our aim was to assess the diagnostic power of the T2-FLAIR mismatch in IDH-mutant astrocytoma and MYB/MYBL1-altered low-grade tumors in children and correlate this mismatch with histology. MATERIALS AND METHODS: We evaluated MR imaging examinations of all pediatric patients, performed at the Princess Máxima Center for Pediatric Oncology and the University Medical Center Utrecht between January 2012 and January 2023, with the histomolecular diagnosis of IDH-mutant astrocytoma, diffuse astrocytoma MYB/MYBL1-altered, or angiocentric glioma, and the presence of T2-FLAIR mismatch was assessed. Histologically, the presence of microcysts in the tumor (a phenomenon suggested to be correlated with T2-FLAIR mismatch in IDH-mutant astrocytomas in adults) was evaluated. RESULTS: Nineteen pediatric patients were diagnosed with either IDH-mutant astrocytoma (n = 8) or MYB/MYBL1-altered tumor (n = 11: diffuse astrocytoma, MYB- or MYBL1-altered n = 8; or angiocentric glioma n = 3). T2-FLAIR mismatch was present in 11 patients, 3 (38%) in the IDH-mutant group and 8 (73%) in the MYB/MYBL1 group. No correlation was found between T2-FLAIR mismatch and the presence of microcysts or an enlarged intercellular space in either IDH-mutant astrocytoma (P = .38 and P = .56, respectively) or MYB/MYBL1-altered tumors (P = .36 and P = .90, respectively). CONCLUSIONS: In our pediatric population, T2-FLAIR mismatch was more often found in MYB/MYBL1-altered tumors than in IDH-mutant astrocytomas. In contrast to what has been reported for IDH-mutant astrocytomas in adults, no correlation was found with microcystic changes in the tumor tissue. This finding challenges the hypothesis that such microcystic changes and/or enlarged intercellular spaces in the tissue of these tumors are an important part of explaining the occurrence of the T2-FLAIR mismatch.

Differential tractography and whole brain connectometry in primary motor area gliomas resection: A feasibility study.

OBJECTIVE: Establish the evolution of the connectome before and after resection of motor area glioma using a comparison of connectome maps and high-definition differential tractography (DifT). METHODS: DifT was done using normalized quantitative anisotropy (NQA) with DSI Studio. The quantitative analysis involved obtaining mean NQA and fractional anisotropy (FA) values for the disrupted pathways tracing the corticospinal tract (CST), and white fiber network changes over time. RESULTS: We described the baseline tractography, DifT, and white matter network changes from two patients who underwent resection of an oligodendroglioma (Case 1) and an IDH mutant astrocytoma, grade 4 (Case 2). CASE 1: There was a slight decrease in the diffusion signal of the compromised CST in the immediate postop. The NQA and FA values increased at the 1-year follow-up (0.18 vs. 0.32 and 0.35 vs. 0.44, respectively). CASE 2: There was an important decrease in the immediate postop, followed by an increase in the follow-up. In the 1-year follow-up, the patient presented with radiation necrosis and tumor recurrence, increasing NQA from 0.18 in the preop to 0.29. Fiber network analysis: whole-brain connectome comparison demonstrated no significant changes in the immediate postop. However, in the 1-year follow up there was a notorious reorganization of the fibers in both cases, showing the decreased density of connections. CONCLUSIONS: Connectome studies and DifT constitute new potential tools to predict early reorganization changes in a patient's networks, showing the brain plasticity capacity, and helping to establish timelines for the progression of the tumor and treatment-induced changes.

Follow-up report of fundus findings of tuberous sclerosis-associated retinal astrocytoma of two siblings.

A late adolescent with tuberous sclerosis (TS) presented with reduced vision in one eye to our tertiary care university hospital 4 years ago. Fundus examination revealed multiple retinal astrocytic hamartomas (RAHs) in both eyes. His younger sibling, who also had TS, was found to have RAH on retinal screening. The swept-source optical coherence tomography (SS-OCT) findings were typical of RAH. We further noted that some of the RAH lesions showed segmental whitening of the outer walls of the arterioles, which traversed through them. The segmental whitening may suggest the enveloping of normal retinal vessels by the tumour. En-face and B-scan SS-OCT angiography of patients with TS showed vascularity within the tumour. The vessels within the tumour appeared to be in continuity with the retinal vasculature. Both siblings were reviewed annually. At the end of 4 years, there was no change in visual acuity, tumour size, number, vascularity and behaviour.

Sporadic subependymal giant cell astrocytoma with somatic TSC2 mutation: A case report.

Subependymal giant cell astrocytoma (SEGA) is a rare circumscribed astrocytic glioma that occurs in approximately 25% of all tuberous sclerosis (TSC) cases. Herein, we discuss an atypical presentation of SEGA, including the genetic alterations, impact on clinical presentation, and the determinants of each medical and surgical treatment option. A 14-year-old girl presented with intermittent headache and a right intraventricular mass originating near the foramen of Monro. The tumor's proximity to critical structures necessitated maximum safe resection, which improved her symptoms. Histological findings indicated SEGA, and genetic sequencing revealed a TSC2 mutation. However, complete clinical and radiological evaluations failed to reveal TSC. Two months later, a new subependymal nodule was incidentally found. She had a recurrent left occipital horn lesion and diffuse smooth leptomeningeal enhancement with no spine drop metastases. She was administered everolimus as the tumor was considered unresectable. Subsequent imaging revealed a reduction in both residual and new lesions.

How does deep learning/machine learning perform in comparison to radiologists in distinguishing glioblastomas (or grade IV astrocytomas) from primary CNS lymphomas?: a meta-analysis and systematic review.

BACKGROUND: Several studies have been published comparing deep learning (DL)/machine learning (ML) to radiologists in differentiating PCNSLs from GBMs with equivocal results. We aimed to perform this meta-analysis to evaluate the diagnostic accuracy of ML/DL versus radiologists in classifying PCNSL versus GBM using MRI. METHODOLOGY: The study was performed in accordance with PRISMA guidelines. Data was extracted and interpreted by two researchers with 12 and 23 years' experience, respectively, and QUADAS-2 tool was used for quality and risk-bias assessment. We constructed contingency tables to derive sensitivity, specificity accuracy, summary receiver operating characteristic (SROC) curve, and the area under the curve (AUC). RESULTS: Our search identified 11 studies, of which 8 satisfied our inclusion criteria and restricted the analysis in each study to reporting the model showing highest accuracy, with a total sample size of 1159 patients. The random effects model showed a pooled sensitivity of 0.89 [95% CI:0.84-0.92] for ML and 0.82 [95% CI:0.76-0.87] for radiologists. Pooled specificity was 0.88 [95% CI: 0.84-0.91] for ML and 0.90 [95% CI: 0.81-0.95] for radiologists. Pooled accuracy was 0.88 [95% CI: 0.86-0.90] for ML and 0.86 [95% CI: 0.78-0.91] for radiologists. Pooled AUC of ML was 0.94 [95% CI:0.92-0.96]and for radiologists, it was 0.90 [95% CI: 0.84-0.93]. CONCLUSIONS: MRI-based ML/DL techniques can complement radiologists to improve the accuracy of classifying GBMs from PCNSL, possibly reduce the need for a biopsy, and avoid any unwanted neurosurgical resection of a PCNSL.

The role of apparent diffusion coefficient in the grading of adult isocitrate dehydrogenase-mutant astrocytomas: relationship with the Ki-67 proliferation index.

BACKGROUND: The grading of adult isocitrate dehydrogenase (IDH)-mutant astrocytomas is a crucial prognostic factor. PURPOSE: To investigate the value of conventional magnetic resonance imaging (MRI) features and apparent diffusion coefficient (ADC) in the grading of adult IDH-mutant astrocytomas, and to analyze the correlation between ADC and the Ki-67 proliferation index. MATERIAL AND METHODS: The clinical and MRI data of 82 patients with adult IDH-mutant astrocytoma who underwent surgical resection and molecular genetic testing with IDH and 1p/19q were retrospectively analyzed. The conventional MRI features, ADCmin, ADCmean, and nADC of the tumors were compared using the Kruskal-Wallis single factor ANOVA and chi-square tests. Receiver operating characteristic (ROC) curves were drawn to evaluate conventional MRI and ADC accuracy in differentiating tumor grades. Pearson correlation analysis was performed to determine the correlation between ADC and the Ki-67 proliferation index. RESULTS: The difference in enhancement, ADCmin, ADCmean, and nADC among WHO grade 2, 3, and 4 tumors was statistically significant (all P <0.05). ADCmin showed the preferable diagnostic accuracy for grading WHO grade 2 and 3 tumors (AUC=0.724, sensitivity=63.4%, specificity=80%, positive predictive value (PPV)=62.0%; negative predictive value (NPV)=82.5%), and distinguishing grade 3 from grade 4 tumors (AUC=0.764, sensitivity=70%, specificity=76.2%, PPV=75.0%, NPV=71.4%). Enhancement + ADC model showed an optimal predictive accuracy (grade 2 vs. 3: AUC = 0.759; grade 3 vs. 4: AUC = 0.799). The Ki-67 proliferation index was negatively correlated with ADCmin, ADCmean, and nADC (all P <0.05), and positively correlated with tumor grade. CONCLUSION: Conventional MRI features and ADC are valuable to predict pathological grading of adult IDH-mutant astrocytomas.

Loss of methylthioadenosine phosphorylase immunoreactivity correlates with poor prognosis and elevated uptake of 11C-methionine in IDH-mutant astrocytoma.

PURPOSE: The proximate localization of MTAP, which encodes methylthioadenosine phosphorylase, and CDKN2A/B on Chromosome 9q21 has allowed the loss of MTAP expression as a surrogate for homozygous deletion of CDKN2A/B. This study aimed to determine whether MTAP status correlates with clinical outcomes and 11C-methionine uptake in astrocytomas with IDH mutations. METHODS: We conducted immunohistochemistry for MTAP in 30 patients with astrocytoma, IDH-mutant who underwent 11C-methionine positron emission tomography scans prior to surgical resection. The tumor-to-normal (T/N) ratio of 11C-methionine uptake was calculated using the mean standardized uptake value (SUV) for tumor and normal brain tissues. Cox regression analysis was used for multivariate survival analysis. RESULTS: Among IDH-mutant astrocytomas, 26.7% (8/30) exhibited the loss of cytoplasmic MTAP expression, whereas 73.3% (22/30) tumors retained MTAP expression. The median progression-free survival (PFS) was significantly shorter in patients with MTAP loss than those with MTAP retention (1.88 years vs. 6.80 years, p = 0.003). The median overall survival (OS) was also shorter in patients with MTAP loss than in MTAP-retaining counterparts (5.23 years vs. 10.69 years, p = 0.019). Multivariate analysis identified MTAP status (hazard ratio (HR), 0.081) and extent of resection (HR, 0.104) as independent prognostic factors for PFS. Astrocytomas lacking cytoplasmic MTAP expression showed a significantly higher median T/N ratio for 11C-methionine uptake than tumors retaining MTAP (2.12 vs. 1.65, p = 0.012). CONCLUSION: Our study revealed that the loss of MTAP expression correlates with poor prognosis and an elevated T/N ratio of 11C-methionine uptake in astrocytoma, IDH-mutant.

Association of Clinical, Tumor, and Treatment Characteristics With Seizure Control in Patients With IDH1/2-Mutant Lower-Grade Glioma.

BACKGROUND AND OBJECTIVES: Patients with IDH1/2-mutant lower-grade glioma have a high frequency of seizures. We aimed to investigate the correlations between seizures and tumor/patient characteristics and the impact of surgery and adjuvant treatments (AT) on seizure control along the disease trajectory. METHODS: We retrospectively included patients with IDH1/2-mutant lower-grade glioma who underwent surgery at the neurosurgery divisions of the University of Turin and Milan and were treated at the Division of Neuro-Oncology of Turin. Inclusion criteria were a diagnosis according to the 2021 WHO Classification and presentation with seizures; exclusion criteria were presence of CDKN2A/B homozygous deletion, intense/ring contrast enhancement on MRI at presentation, and small tissue biopsy. We evaluated seizure freedom for 2 months after surgery, 6 months from starting observation or AT, at recurrence, and for 6 months after treatments of recurrence. RESULTS: We included 150 patients. There were 77 (51%) and 31 (21%) patients with IDH-mutant/1p19q-codeleted grade 2 and 3 oligodendroglioma and 30 (20%) and 12 (8%) with IDH-mutant grade 2 and 3 astrocytoma, respectively. Total resection was accomplished in 68 (45%). Seventy-five patients (50%) received AT while the remaining 75 were observed with MRI. After 6 months after AT, 28 of 29 patients (96.5%) displayed seizure reduction, 5 of 28 (18%) being seizure-free. 66 of 124 patients (53%) had seizures at recurrence. After 6 months after second-line treatments, 60 of 66 patients (91%) had seizure reduction, 11 (17%) being seizure-free. In multivariable analyses, grade 3 histology positively correlated with seizure freedom at 2 months after surgery (OR 3.5, 1.4-8.9, p = 0.008), 6 months after AT (OR 9.0, 1.5-54.9, p = 0.017), and 6 months after treatment of recurrence (OR 4.9, 1.5-16.5, p = 0.009). Adjuvant radiotherapy reduced seizures at recurrence in a univariate analysis (OR 0.14, 0.03-0.7, p = 0.020). Patients with seizure freedom after surgery and AT displayed longer progression-free survival (PFS) (65, 24.5-105, vs 48 months, 32-63.5, p = 0.037). DISCUSSION: This study analyzed seizure control in patients with IDH1/2-mutant lower-grade glioma across multiple time points. Grade 3 correlated with better seizure control throughout the entire disease trajectory, and seizure freedom after surgery and AT correlated with a longer PFS regardless of tumor grade. These results could serve as an external control arm in clinical trials evaluating the efficacy on seizures of antitumor agents in patients with IDH-mutant lower-grade glioma.

High-Grade Astrocytoma with Piloid Features: A Dual Institutional Review of Imaging Findings of a Novel Entity.

High-grade astrocytoma with piloid features (HGAP) is a recently identified brain tumor characterized by a distinct DNA methylation profile. Predominantly located in the posterior fossa of adults, HGAP is notably prevalent in individuals with neurofibromatosis type 1. We present an image-centric review of HGAP and explore the association between HGAP and neurofibromatosis type 1. Data were collected from 8 HGAP patients treated at two tertiary care institutions between January 2020 and October 2023. Demographic details, clinical records, management, and tumor molecular profiles were analyzed. Tumor characteristics, including location and imaging features on MR imaging, were reviewed. Clinical or imaging features suggestive of neurofibromatosis 1 or the presence of NF1 gene alteration were documented. The mean age at presentation was 45.5 years (male/female = 5:3). Tumors were midline, localized in the posterior fossa (n = 4), diencephalic/thalamic (n = 2), and spinal cord (n = 2). HGAP lesions were T1 hypointense, T2-hyperintense, mostly without diffusion restriction, predominantly peripheral irregular enhancement with central necrosis (n = 3) followed by mixed heterogeneous enhancement (n = 2). Two NF1 mutation carriers showed signs of neurofibromatosis type 1 before HGAP diagnosis, with one diagnosed during HGAP evaluation, strengthening the HGAP-NF1 link, particularly in patients with posterior fossa masses. All tumors were IDH1 wild-type, often with ATRX, CDKN2A/B, and NF1 gene alteration. Six patients underwent surgical resection followed by adjuvant chemoradiation. Six patients were alive, and two died during the last follow-up. Histone H3 mutations were not detected in our cohort, such as the common H3K27M typically seen in diffuse midline gliomas, linked to aggressive clinical behavior and poor prognosis. HGAP lesions may involve the brain or spine and tend to be midline or paramedian in location. Underlying neurofibromatosis type 1 diagnosis or imaging findings are important diagnostic cues.

Exploring prognostic factors and treatment strategies for long-term survival in pleomorphic xanthoastrocytoma patients.

Pleomorphic xanthoastrocytomas (PXA) are rare, accounting for < 1% of all astrocytomas. Literature on the clinical course and treatment outcomes of PXAs is limited. The study aimed to determine prognosis and treatment strategies for PXAs. Patients who had PXAs surgery between 2000-2021 were retrospectively analyzed for demographics and radiological characteristics. Initial and salvage treatment outcomes were recorded. Overall, 40 and 9 patients had grade 2 and 3 PXAs; their 5-year progression-free survival (PFS) rates were 75.8% and 37.0%, respectively (p = 0.003). Univariate analysis revealed that strong T1 enhancement (p = 0.036), infiltrative tumor margins (p < 0.001), peritumoral edema (p = 0.003), WHO grade (p = 0.005), and gross total resection (p = 0.005) affected the PFS. Multivariate analysis revealed that the WHO grade (p = 0.010) and infiltrative tumor margins (p = 0.008) influenced the PFS. The WHO grade (p = 0.027) and infiltrative tumor margins (p = 0.027) also affected the overall survival (OS). Subgroup analysis for grade 2 PXAs revealed no significant associations between adjuvant radiation therapy and the PFS and OS. This study highlighted the heterogeneous nature of PXAs and its impact on patient prognosis. Infiltrative tumor margins emerged as a key prognostic factor. Our findings have emphasized the prognostic relevance of radiological features and the need for larger studies on comprehensive management.

A 3-Year-Old Girl with Brain Imaging Findings Suggesting Arachnoid Cyst, and Biopsy Diagnosis of Extra-Axial Multicystic Pilocytic Astrocytoma.

BACKGROUND Arachnoid cysts and pilocytic astrocytomas are distinct intracranial entities with differing clinical presentations, origins, and management strategies. Arachnoid cysts are benign fluid-filled sacs associated with congenital or acquired causes, while pilocytic astrocytomas are low-grade brain tumors, primarily affecting pediatric and young adult populations, originating from astrocytes. However, diagnosing pilocytic astrocytomas can be challenging due to their radiological features, sometimes resembling more common intracranial lesions, such as arachnoid cysts. This case underscores the need for vigilance and a multidisciplinary approach when confronted with neuroimaging findings that diverge from typical patterns. CASE REPORT We present a case of a 3-year-old girl who presented with persistent headaches, vomiting, and difficulty walking. Initial radiological assessment suggested an arachnoid cyst, given the patient's symptoms and imaging characteristics. Subsequently, the patient underwent a craniotomy, with intraoperative findings revealing a cystic lesion without a solid mural nodule, which was excised completely. Postoperatively, histopathological examination confirmed a diagnosis of extra-axial pilocytic astrocytoma. The patient's symptoms resolved, and she was discharged without neurological deficits. CONCLUSIONS Diagnosing extra-axial pilocytic astrocytomas presents challenges, due to their radiological similarities with more common intracranial lesions, like arachnoid cysts. This case underscores the importance of histopathological examination to confirm the diagnosis accurately. Surgical resection remains the primary treatment for extra-axial pilocytic astrocytomas, often resulting in a favorable prognosis.

Resection of an Intradural Intramedullary C7-T1 Tumor: Technical Nuances and Complication Management.

Primary spinal cord tumors are relatively rare, comprising approximately 4%-16% of all tumors originating from the central nervous system. These tumors are anatomically separable into 2 broad categories: intradural intramedullary and intradural extramedullary. Intramedullary tumors are composed predominantly of gliomas (infiltrative astrocytoma) and ependymomas.1-4 The primary treatment approach for these tumors is surgical resection, aiming to preserve neurologic function.5-9 In Video 1, the authors showcase a step-by-step approach for microsurgical resection of a primary spinal ependymoma, with emphasis on microsurgical technique and utility of adjunct equipment, such as intraoperative ultrasound and neuromonitoring.10,11 The patient consented to the procedure.

Comparison of diagnostic performance of radiologist- and AI-based assessments of T2-FLAIR mismatch sign and quantitative assessment using synthetic MRI in the differential diagnosis between astrocytoma, IDH-mutant and oligodendroglioma, IDH-mutant and 1p/19q-codeleted.

PURPOSE: This study aimed to compare assessments by radiologists, artificial intelligence (AI), and quantitative measurement using synthetic MRI (SyMRI) for differential diagnosis between astrocytoma, IDH-mutant and oligodendroglioma, and IDH-mutant and 1p/19q-codeleted and to identify the superior method. METHODS: Thirty-three cases (men, 14; women, 19) comprising 19 astrocytomas and 14 oligodendrogliomas were evaluated. Four radiologists independently evaluated the presence of the T2-FLAIR mismatch sign. A 3D convolutional neural network (CNN) model was trained using 50 patients outside the test group (28 astrocytomas and 22 oligodendrogliomas) and transferred to evaluate the T2-FLAIR mismatch lesions in the test group. If the CNN labeled more than 50% of the T2-prolonged lesion area, the result was considered positive. The T1/T2-relaxation times and proton density (PD) derived from SyMRI were measured in both gliomas. Each quantitative parameter (T1, T2, and PD) was compared between gliomas using the Mann-Whitney U-test. Receiver-operating characteristic analysis was used to evaluate the diagnostic performance. RESULTS: The mean sensitivity, specificity, and area under the curve (AUC) of radiologists vs. AI were 76.3% vs. 94.7%; 100% vs. 92.9%; and 0.880 vs. 0.938, respectively. The two types of diffuse gliomas could be differentiated using a cutoff value of 2290/128 ms for a combined 90th percentile of T1 and 10th percentile of T2 relaxation times with 94.4/100% sensitivity/specificity with an AUC of 0.981. CONCLUSION: Compared to the radiologists' assessment using the T2-FLAIR mismatch sign, the AI and the SyMRI assessments increased both sensitivity and objectivity, resulting in improved diagnostic performance in differentiating gliomas.

Bilateral thalamic high-grade astrocytomas in an early-adolescent child: A case report.

An early-adolescent girl presented with incoordination, headache, vomiting and dysphonia. MRI brain demonstrated diffuse increased T2 and FLAIR signal in bilateral thalami, consistent with anaplastic astrocytomas. A stereotactic burr-hole biopsy provided frozen tissues sections demonstrating an IDH-1 wildtype astrocytoma (anaplastic grade III according to prior WHO classification 2016-21). Chemoradiotherapy was commenced. Bilateral thalamic high-grade astrocytomas are very rare in the paediatric population and require timely diagnosis and interdisciplinary management. CT and MR imaging help point towards this diagnosis in the correct clinical context.

Isolated subependymal giant cell astrocytoma (SEGA) in the absence of clinical tuberous sclerosis: two case reports and literature review.

PURPOSE: Subependymal giant cell astrocytoma (SEGA) is a WHO grade I pediatric glioma arising in 5-15% of patients with tuberous sclerosis (TSC). Rare cases of isolated SEGA without TSC have been described. The etiology, genetic mechanisms, natural history, and response to treatment of these lesions are currently unknown. We describe two such cases of isolated SEGA with follow-up. METHODS: Retrospective review was performed at a single institution to describe the clinical course of pathology-confirmed SEGA in patients with germline testing negative for TSC mutations. RESULTS: Two cases of isolated SEGA were identified. Genetic analysis of the tumor specimen was available for one, which revealed an 18 base pair deletion in TSC1. Both cases were managed with surgical resection, one with preoperative embolization. In spite of a gross total resection, one patient experienced recurrence after three years. Treatment with an mTOR inhibitor led to a significant interval reduction of the mass on follow-up MRI. The patient tolerated the medication well for 6 years and is now off of treatment for 2 years with a stable lesion. CONCLUSION: Cases of SEGA outside of the context of TSC are exceedingly rare, with only 48 cases previously described. The genetic mechanisms and treatment response of these lesions are poorly understood. To date, these lesions appear to respond well to mTOR inhibitors and may behave similarly to SEGAs associated with TSC. However, given that experience is extremely limited, these cases should be followed long term to better understand their natural history and treatment response.

A novel MRI-based deep learning networks combined with attention mechanism for predicting CDKN2A/B homozygous deletion status in IDH-mutant astrocytoma.

OBJECTIVES: To develop a high-accuracy MRI-based deep learning method for predicting cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B) homozygous deletion status in isocitrate dehydrogenase (IDH)-mutant astrocytoma. METHODS: Multiparametric brain MRI data and corresponding genomic information of 234 subjects (111 positives for CDKN2A/B homozygous deletion and 123 negatives for CDKN2A/B homozygous deletion) were obtained from The Cancer Imaging Archive (TCIA) and The Cancer Genome Atlas (TCGA) respectively. Two independent multi-sequence networks (ResFN-Net and FN-Net) are built on the basis of ResNet and ConvNeXt network combined with attention mechanism to classify CDKN2A/B homozygous deletion status using MR images including contrast-enhanced T1-weighted imaging (CE-T1WI) and T2-weighted imaging (T2WI). The performance of the network is summarized by three-way cross-validation; ROC analysis is also performed. RESULTS: The average cross-validation accuracy (ACC) of ResFN-Net is 0.813. The average cross-validation area under curve (AUC) of ResFN-Net is 0.8804. The average cross-validation ACC and AUC of FN-Net is 0.9236 and 0.9704, respectively. Comparing all sequence combinations of the two networks (ResFN-Net and FN-Net), the sequence combination of CE-T1WI and T2WI performed the best, and the ACC and AUC were 0.8244, 0.8975 and 0.8971, 0.9574, respectively. CONCLUSIONS: The FN-Net deep learning networks based on ConvNeXt network achieved promising performance for predicting CDKN2A/B homozygous deletion status of IDH-mutant astrocytoma. CLINICAL RELEVANCE STATEMENT: A novel deep learning network (FN-Net) based on preoperative MRI was developed to predict the CDKN2A/B homozygous deletion status. This network has the potential to be a practical tool for the noninvasive characterization of CDKN2A/B in glioma to support personalized classification and treatment planning. KEY POINTS: • CDKN2A/B homozygous deletion status is an important marker for glioma grading and prognosis. • An MRI-based deep learning approach was developed to predict CDKN2A/B homozygous deletion status. • The predictive performance based on ConvNeXt network was better than that of ResNet network.