Stereotactic radiosurgery treatment of pediatric arteriovenous malformations: a PRISMA systematic review and meta-analysis

BACKGROUND

Stereotactic radiosurgery (SRS) is considered a safe definitive treatment for pediatric arteriovenous malformations (AVMs) upon indicated presentations. There are no published guidelines by the International Stereotactic Radiosurgery Society (ISRS) detailed with indications or characteristics that warrant SRS, other than the guideline that SRS is a safe and efficacious treatment for pediatric AVMs. SRS is performed using either Gamma Knife (GK) or Linear Accelerator (LINAC). This systematic review aims to uncover treatment, differences in GK and LINAC outcomes, and AVM characteristics that lead to high obliteration rates and suggest future studies to determine treatment decisions, raise obliteration rates, and lower complication rates in SRS treatment of pediatric AVMs.

METHODS

We performed a systematic review according to PRISMA guidelines across PubMed, Embase, and SCOPUS utilizing search terms related to pediatric patients, AVMS, and SRS. We collected data from the 32 full-text studies and 4 abstracts that met inclusion criteria. Subsequent pooled analysis was performed on GK vs LINAC obliteration rates, followed by sub-cohort analysis of all SRS patients with hemorrhagic presentation, Spetzler-Martin (SM) Grade, and prior procedure and their effect on obliteration rates.

RESULTS

The 36 studies reported 3425 patients, with a slight male preponderance (1662 patients, 48.5%). The obliteration analysis included 2834 patients that met follow-up criteria and contained obliteration data. The weighted mean age was 12.63 years. Pooled cohort analysis found no significant difference in obliteration proportions when comparing GK to LINAC (P = 0.7449), with an overall obliteration rate of 63% in patients with at least 1 year follow-up. The sub-cohort analysis of all patients treated with SRS revealed that presentation with AVM hemorrhage was associated with increased obliteration (CE: RR = 1.22 [95%CI = 1.09-1.35; RE: RR = 1.22, 95%CI = 10.6-1.40; prediction interval = 1.07-1.38) with low heterogeneity (I2 = 17.1%, τ2 < 0.0001, p = 0.2902). Smaller SM grade was not statistically associated with increased obliteration (CE: RR = 1.25 [95%CI = 0.87-1.81]; RE: RR = 1.84 [95%CI = 0.97-3.50]; prediction interval = 0.38-8.86) and moderate levels of heterogeneity were detected (I2 = 45.2%, τ2 = 0.2668, p = 0.1042). Procedure prior to SRS also had higher obliteration rates than no prior procedure (CE: RR = 0.77 [95%CI = 0.61-0.86]; RE: RR = 0.71 [95%CI = 0.54-0.92]; prediction interval = 0.36-1.39) with low to moderate heterogeneity (I2 = 27.6%, τ2 = 0.0.0264, p = 0.2466).

CONCLUSION

SRS is a safe and effective treatment for pediatric AVMs. This study suggests that there are no differences in obliteration between GK and LINAC, with increased obliteration in patients with hemorrhage at presentation and procedures prior to SRS treatment. Further multicenter, prospective studies are necessary to dictate future treatment decisions.

Gamma Knife radiosurgery for brain arteriovenous malformations - a single-center experience

BACKGROUND

Gamma Knife stereotactic radiosurgery (SRS) has emerged as a non-invasive and effective treatment for brain arteriovenous malformations (AVM), particularly in cases where surgical resection is not feasible. The factors influencing AVM obliteration following Gamma Knife radiosurgery remain incompletely understood and differing results across studies indicate the need for further research. This study reviews a single center's 20-year experience with Gamma Knife radiosurgery for AVMs, evaluating factors associated with successful treatment outcomes.

METHODS

A retrospective analysis was conducted on 241 patients treated with Gamma Knife SRS for intracranial AVMs at University Hospital Center Zagreb between 2004 and 2021. Patient demographics, AVM characteristics, prior treatments, radiosurgical parameters, and clinical outcomes were analyzed. AVM obliteration was assessed using MR angiography and digital subtraction angiography. Binary logistic regression and Cox regression analysis were performed to identify factors associated with treatment success and shorter time to obliteration.

RESULTS

AVM obliteration was achieved in 171 patients (71%), with a mean time to complete obliteration of 3 years. Higher prescription doses correlated with increased obliteration rates (p < 0.05), as did hemispheric AVM location (p < 0.05) while smaller nidus volumes were associated with faster obliteration times (p < 0.05). 75.5% of previously embolized AVMs achieved obliteration vs 68.2% of non-embolized AVMs, however the difference was not statistically significant. The introduction of cone beam CT angiography in treatment planning improved obliteration rates (69.1% to 75.8%), though statistical significance was not reached. The overall complication rate was 15.4%, with 5.8% experiencing post-SRS hemorrhage.

CONCLUSION

Higher prescription doses correlated with improved obliteration rates, and smaller AVMs achieved faster obliteration. The use of additional imaging modalities in treatment planning possibly contributed to non-inferior obliteration rates in previously embolized AVMs.

Efficacy of radiosurgery with and without angioembolization: A subgroup analysis of effectiveness in ruptured versus unruptured arteriovenous malformations - An updated systematic review and meta-analysis

Background

Congenital arterial defects such as cerebral arteriovenous malformations (AVMs) increase brain bleeding risk. Conservative therapy, microsurgical removal, percutaneous embolization, stereotactic radiosurgery (SRS), or a combination may treat this serious disease. This study compares angioembolization with SRS to SRS alone in ruptured or unruptured brain ateriovenous malformations (BAVM) patients.

Methods

We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations for this study. Until September 2023, PubMed/Medline, Cochrane, and Clinicaltrials.gov were searched for literature. English-language studies comparing SRS alone to embolization with SRS on ruptured or non-ruptured AVMs that could not be operated on were considered. The Newcastle-Ottawa Scale assessed research study quality.

Results

Results included 46 studies with a total of 7077 participants. There was a greater obliteration rate in the SRS-only group (60.4%) than in the embolization plus SRS group (49.73%). Particularly in the SRS-only group, ruptured AVMs showed a noticeably greater obliteration rate than unruptured AVMs (P = 0.002). However, no notable differences were found in hemorrhagic events or radiation-induced changes between the two groups; however, the SRS-only group had a slightly greater, yet not statistically significant, mortality rate.

Conclusion

Our data showed that ruptured brain AVMs had a much greater obliteration rate than unruptured ones, mostly due to SRS alone, without embolization. The aggregated data showed no significant changes, whereas SRS alone decreased radiation-induced alterations and hemorrhagic rates but with increased mortality. SRS alone may have a higher risk-to-reward ratio for nidus obliteration in ruptured brain AVM patients, so it should be used without embolization, although more research is needed to determine the effects of immediate and late complications.

Prediction of Obliteration After the Gamma Knife Radiosurgery of Arteriovenous Malformations Using Hand-Crafted Radiomics and Deep-Learning Methods

INTRODUCTION

Brain arteriovenous malformations (bAVMs) are vascular abnormalities that can be treated with embolization or radiotherapy to prevent the risk of future rupture. In this study, we use hand-crafted radiomics and deep learning techniques to predict favorable vs. unfavorable outcomes following Gamma Knife radiosurgery (GKRS) of bAVMs and compare their prediction performances.

METHODS

One hundred twenty-six patients seen at one academic medical center for GKRS obliteration of bAVMs over 15 years were retrospectively reviewed. Forty-two patients met the inclusion criteria. Favorable outcomes were defined as complete nidus obliteration demonstrated on cerebral angiogram and asymptomatic recovery. Unfavorable outcomes were defined as incomplete obliteration or complications relating to the AVM that developed after GKRS. Outcome predictions were made using a random forest model with hand-crafted radiomic features and a fine-tuned ResNet-34 convolutional neural network (CNN) model. The performance was evaluated by using a ten-fold cross-validation technique.

RESULTS

The average accuracy and area-under-curve (AUC) values of the Random Forest Classifier (RFC) with radiomics features were 68.5 ±9.80% and 0.705 ±0.086, whereas those of the ResNet-34 model were 60.0 ±11.9% and 0.694 ±0.124. Four radiomics features used with RFC discriminated unfavorable response cases from favorable response cases with statistical significance. When cropped images were used with ResNet-34, the accuracy and AUC decreased to 59.3 ± 14.2% and 55.4 ±10.4%, respectively.

CONCLUSIONS

A hand-crafted radiomics model and a pre-trained CNN model can be fine-tuned on pre-treatment MRI scans to predict clinical outcomes of AVM patients undergoing GKRS with equivalent prediction performance. The outcome predictions are promising but require further external validation on more patients.

Preoperative flow analysis of arteriovenous malformations and obliteration response after stereotactic radiosurgery

OBJECTIVE

Morphological and angioarchitectural features of cerebral arteriovenous malformations (AVMs) have been widely described and associated with outcomes; however, few studies have conducted a quantitative analysis of AVM flow. The authors examined brain AVM flow and transit time on angiograms using direct visual analysis and a computer-based method and correlated these factors with the obliteration response after Gamma Knife radiosurgery.

METHODS

A retrospective analysis was conducted at a single institution using a prospective registry of patients managed from January 2013 to December 2019: 71 patients were analyzed using a visual method of flow determination and 38 were analyzed using a computer-based method. After comparison and validation of the two methods, obliteration response was correlated to flow analysis, demographic, angioarchitectural, and dosimetric data.

RESULTS

The mean AVM volume was 3.84 cm3 (range 0.64-19.8 cm3), 32 AVMs (45%) were in critical functional locations, and the mean margin radiosurgical dose was 18.8 Gy (range 16-22 Gy). Twenty-seven AVMs (38%) were classified as high flow, 37 (52%) as moderate flow, and 7 (10%) as low flow. Complete obliteration was achieved in 44 patients (62%) at the time of the study; the mean time to obliteration was 28 months for low-flow, 34 months for moderate-flow, and 47 months for high-flow AVMs. Univariate and multivariate analyses of factors predicting obliteration included AVM nidus volume, age, and flow. Adverse radiation effects were identified in 5 patients (7%), and 67 patients (94%) remained free of any functional deterioration during follow-up.

CONCLUSIONS

AVM flow analysis and categorization in terms of transit time are useful predictors of the probability of and the time to obliteration. The authors believe that a more quantitative understanding of flow can help to guide stereotactic radiosurgery treatment and set accurate outcome expectations.

Treatment of Intracranial Tumors With Stereotactic Radiosurgery: Short-Term Results From Cuba

Background Although international publications on radiosurgery have increased exponentially, reports of heterogeneous series treated with linear accelerator (LINAC) are scarce. Since most intracranial tumors are irregular in size and not spherical, LINACs (Elekta Precise®, Elekta AB, Sweden), fitted with a multi-leaf collimator, allow for precise stereotactic radiosurgery for the entire tumor. Aim To evaluate the effects of LINAC on an outpatient basis with patients diagnosed with various intracranial malignancies. Methodology A retrospective observational study of a series of cases of patients with intracranial lesions treated at the Institute of Oncology and Radiobiology using LINAC was carried out from October 2019 to May 2021 to evaluate the therapeutic results of radiosurgery in patients with intracranial tumors. Results A total of 22 lesions in 20 patients were treated with LINAC. The average age of the patients was 49.7, and the male-female ratio was 1:2. The cases consisted were mostly vestibular schwannoma (7 lesions), metastases from breast cancer (3 lesions), and tuberculum sellae meningioma (2 lesions). The prescription dose covered 99% of the planning target volume in 16 lesions (72.7%) and 100% in six lesions (27.3%) (prescription volume). In meningiomas and schwannomas, doses between 12 and 14 Gy were used, in plasmacytoma 13 Gy, in pilocytic astrocytoma 14 Gy, in cavernoma 15 Gy, in breast cancer metastasis between 18 and 20 Gy, and in lung cancer metastasis 22 Gy. When evaluating local control, 11 patients exhibited stable findings at the six-month control while 10 had partial regression, and a single patient had total regression. Minor complications such as perilesional edema, facial paresthesia, facial paralysis, and transient alopecia were observed in eight of the patients. Conclusions Patients with extra-axial, low-grade malignancy, and posterior fossa lesions were predominant in the studied population. Radiosurgery treatment is associated with good local control of the treated lesions. Complications are infrequent, mild, and predominated by perilesional edema.

State of the Art and Future Direction in Diagnosis, Molecular Biology, Genetics, and Treatment of Brain Arteriovenous Malformations

Brain arteriovenous malformations (bAVMs) are uncommon and represent a heterogeneous group of lesions. Although these 2 facts have delayed research on this topic, knowledge about the pathophysiology, diagnosis, and treatment of bAVMs has evolved in recent years. We conducted a review of the literature to update the knowledge about diagnosis, molecular biology, genetic, pathology, and treatment by searching for the following terms: "Epidemiology AND Natural History," "risk of hemorrhage," "intracranial hemorrhage," "diagnosis," "angiogenesis," "molecular genetics," "VEGF," "KRAS," "radiosurgery," "endovascular," "microsurgery," or "surgical resection." Our understanding of bAVMs has significantly evolved in recent years. The latest investigations have helped in defining some molecular pathways involved in the pathology of bAVM. Although there is still more to learn and discover, describing these pathways will allow the creation of targeted treatments that could improve the prognosis of patients with bAVMs.

A Ruptured Spetzler and Martin Grade V Arteriovenous Malformation in a Child Treated With Radiotherapy Followed by Embolization: A Case Report and Literature Review

Treatment of ruptured high-grade Spetzler-Martin (S&M) arteriovenous malformation (AVM) is challenging and requires a multidisciplinary treatment approach. Here, we report a case of ruptured giant callosal Grade V AVM in a child initially treated with stereotactic radiotherapy followed by endovascular embolization with Onyx; a management approach recently described in a few reports on the “postradiosurgical embolization” method. Complete obliteration was achieved 20 months after stereotactic radiotherapy and embolization. In this article, we discuss the usefulness and significance of postradiosurgical embolization, particularly for high-grade AVMs. To our knowledge, this is the first case with a giant Spetzler-Martin Grade V AVM treated with a postradiosurgical embolization method.