Samantha E. Schoeneman

Onyx embolization of intracranial arteriovenous malformations in pediatric patients.

OBJECT The authors undertook this study to assess the safety and efficacy of Onyx embolization in the treatment of intracranial arteriovenous malformations (AVMs) in pediatric patients. METHODS All pediatric Onyx embolization of intracranial AVM cases performed consecutively at a single childrens hospital over a 5-year period were collected and evaluated. RESULTS Twenty-five patients (mean age 10.5 years) underwent a total of 38 procedures. An aggregate of 56 pedicles were embolized (mean 1.47 per session). The Spetzler-Martin grade was determined in all cases. Onyx embolization resulted in complete obliteration of the AVM in 3 cases (12%) and partial obliteration in 22 cases (88%). A total of 23 patients underwent surgical treatment. The mean preoperative AVM devascularization in these cases was 72%. One patient was treated with radiosurgery following Onyx embolization. Overall, 10 complications occurred in a total of 38 procedures (26.3%). None of the complications resulted in permanent neurological morbidity. The rate of transient neurological complications was 10.5% (4 of 38 procedures) and the rate of transient nonneurological complications was 5.3% (2 of 38 procedures). The remaining 4 complications were clinically silent (rate of 10.5%). There were no procedure-related deaths in this study population. There was no significant difference in patients with and without complications in terms of demographic characteristics, AVM grade, or embolization features (p ≥ 0.2). Deep venous drainage was associated with higher complication rates (p = 0.03). CONCLUSIONS Onyx utilization is feasible for preoperative or primary embolization in the treatment of pediatric intracranial AVMs; however, the spectrum of complications encountered is broad, and attention must be paid to the technical nuances of and indications for its use to avoid many potential dangerous effects. Although the overall complication rates were higher than expected, all were either clinically silent or had only transient clinical effects. Thus, this experience suggests that Onyx embolization can be performed safely with a low rate of permanent morbidity in pediatric patients harboring these difficult lesions.

Age‐Related Changes of Normal Cerebral and Cardiac Blood Flow in Children and Adults Aged 7 Months to 61 Years

Background Cerebral and cardiac blood flow are important to the pathophysiology and development of cerebro‐ and cardiovascular diseases. The purpose of this study was to investigate the age dependence of normal cerebral and cardiac hemodynamics in children and adults over a broad range of ages. Methods and Results Overall, 52 children (aged 0.6–17.2 years) and 30 adults (aged 19.2–60.7 years) without cerebro‐ and cardiovascular diseases were included in this study. Intracranial 4‐dimensional flow and cardiac 2‐dimensional phase‐contrast magnetic resonance imaging were performed for all participants to measure flow parameters in the major intracranial vessels and aorta. Total cerebral blood flow (TCBF), cardiac and cerebral indexes, brain volume, and global cerebral perfusion (TCBF/brain volume) were evaluated. Flow analysis revealed that TCBF increased significantly from age 7 months to 6 years (P<0.001) and declined thereafter (P<0.001). Both cardiac and cerebral indices declined with age (P<0.001). The ratio of TCBF to ascending aortic flow declined rapidly until age 18 years (P<0.001) and remained relatively stable thereafter. Age‐related changes of cerebral vascular peak velocities exhibited a trend similar to TCBF. By comparison, aortic peak velocities maintained relatively high levels in children and declined with age in adults (P<0.001). TCBF significantly correlated with brain volume in adults (P=0.005) and in 2 pediatric subgroups, aged <7 years (P<0.001) and 7 to 18 years (P=0.039). Conclusions Cerebral and cardiac flow parameters are highly associated with age. The findings collectively highlight the importance of age‐matched control data for the characterization of intracranial and cardiac hemodynamics.

Pre- and postoperative imaging and interventions for the meso-Rex bypass in children and young adults

The meso-Rex bypass is a physiological and anatomical bypass procedure for relief of extrahepatic portal vein obstruction and restoration of mesenteric venous return to the liver. Most patients who are candidates for the bypass are children or young adults with portal hypertension and hypersplenism secondary to cavernous transformation of the portal vein. Most frequently, the bypass utilizes an autologous venous graft to connect the intrahepatic left portal vein to the infrapancreatic superior mesenteric vein (SMV) re-establishing first-pass portal perfusion. We describe the preoperative imaging of the 92 bypass candidates, the surgical anatomy as reflected in postoperative imaging, and the imaging of bypass complications at our institution.Preoperative imaging with US, CT and MR is directed to demonstrate patency and size of the left portal vein and SMV, to define the extent of cavernous transformation and splanchnic collaterals, and to assess for any associated abdominal vascular or solid organ abnormalities. Postoperative imaging is aimed at diagnosing meso-Rex bypass stenosis or occlusion and the interventional management of these complications.

Safety of Blood Pool Contrast Agent Administration in Children and Young Adults

OBJECTIVE The objective of our study was to determine the adverse reaction rate associated with the administration of blood pool contrast material in children and young adults. MATERIALS AND METHODS A review of the MRI and pharmacy databases identified all patients who received gadofosveset trisodium from October 1, 2011, to June 30, 2014. Patients were classified as having been anesthetized or not anesthetized for the MRI examinations. A review of the electronic medical records identified adverse reactions recorded within 24 hours of contrast administration. The adverse reactions were graded as mild, moderate, or severe. Risk ratios were calculated between the adverse reaction rate experienced by anesthetized patients and that experience by nonanesthetized patients. RESULTS During the study period, 626 patients (mean age, 11.7 years) received 711 doses of gadofosveset trisodium; 137 adverse reactions were recorded, which yields a 19.3% (137/711) adverse reaction rate. There were 115 adverse reactions experienced by 367 anesthetized patients (31.3%): 93.0% (107/115) were mild and 7.0% (8/115) were moderate. The remaining 22 adverse reactions were experienced by 344 (6.4%) nonanesthetized patients, and 90.9% (20/22) were mild. Three nonanesthetized patients had allergiclike reactions; of these allergiclike reactions, one was mild and two were severe for a severe allergiclike reaction rate of 0.28% (2/711). Severe allergiclike reactions were treated without any adverse outcomes. Anesthetized patients were 5.7 times more likely to experience an adverse event than nonanesthetized patients; most reactions in anesthetized patients were seen after the administration of anesthesia alone. CONCLUSION Most reactions after gadofosveset trisodium administration in children and young adults are mild; however, severe allergiclike reactions occur, so policies must be in place to treat patients with adverse reactions when using this contrast agent. These data may be useful to centers considering administering gadofosveset trisodium to pediatric patients.

A semiautomatic postprocessing of liver R2* measurement for assessment of liver iron overload

PURPOSE The purpose was to propose and evaluate a semiautomatic postprocessing method to measure liver R2(⁎) values in patients with a broad range of liver iron content. MATERIALS AND METHODS Multiecho gradient echo magnetic resonance images were acquired in patients diagnosed with thalassemia or other types of congenital anemias. Liver R2(⁎) values were measured using a routine manually defined region-of-interest (mROI) method and a semiautomatic (SA) method. In the semiautomatic method, pixelwise (pSA) and averaged (aSA) signal fitting was performed on the segmented liver tissues after hepatic vessel extraction. The pixelwise fitting approach resulted in a liver R2(⁎) map with an overlay of nonfitted pixels associated with noise performance. The following aSA approach derived overall R2(⁎) by fitting the averaged signal intensities of all pixels within the liver ROI excluding vessels and nonfitted pixels. The measurement accuracy and interobserver agreement using mROI and the two semiautomatic approaches (pSA and aSA) were evaluated. RESULTS In a total of 45 exams with R2(⁎) ranging from 30 to 1500 s(-1), the R2(⁎) measurements using all three methods were overall highly correlated and concordant with each other. R2(⁎) values measured by aSA were consistently higher than those measured by mROI. At lower R2(⁎) (<1000 s(-1)), R2(⁎) values measured by pSA were consistent with aSA but higher than mROI; with increasing R2(⁎), the pSA method became less stable and underestimated R2(⁎) due to increased noise level. The interobserver agreement was higher for the aSA method compared to pSA and mROI. CONCLUSION The semiautomatic postprocessing method provides a promising tool for reliable liver R2(⁎) measurement with additional information for overall evaluation of iron distribution and measurement confidence. This method may offer the potential of reducing interoperator variability and improving diagnostic confidence in patients with liver iron overload.

Endovascular Management of Pediatric High-Flow Vertebro-Vertebral Fistula with Reversed Basilar Artery Flow: A Case Report and Review of the Literature

Vertebral artery arteriovenous fistula (VAVF) is mostly known as a post-traumatic and/or iatrogenic arteriovenous complication. However, spontaneous high-flow VAVF associated with flow reversal in the basilar artery has not been reported in children. We describe a unique asymptomatic presentation of a spontaneous high-flow VAVF associated with flow reversal in the basilar artery in a pediatric patient. The literature for classification, pathophysiology, treatment strategies, and post-procedural complications is also reviewed.

Juvenile Pilocytic Astrocytoma in Association with Arteriovenous Malformation

Pilocytic astrocytomas are highly vascular, relatively common primary brain tumors in the pediatric population, but their association with a true arteriovenous malformation (AVM) is extremely rare. We describe an eight-year-old girl with a right supratentorial juvenile pilocytic astrocytoma (WHO grade I) with an angiographically documented AVM entangled in the tumor mass who presented with intracranial hemorrhage due to a ruptured anterior choroidal artery pseudoaneurysm encased in the lesion. The AVM nidus as well as the hemorrhage site was embolized with Onyx. A literature review revealed only one previous report of a true intermixture of these two lesions. We hypothesize whether the association of vascular malformations and primary brain tumors are merely coincidental or if they point to the existence of a distinct entity and/or a common etiologic factor.

Complex Alterations of Intracranial 4-Dimensional Hemodynamics in Vein of Galen Aneurysmal Malformations During Staged Endovascular Embolization

BACKGROUND: Vein of Galen aneurysmal malformations (VGAMs) are rare congenital cerebral arteriovenous shunts often treated by staged endovascular embolization early in life. Treatment-induced changes in intracranial hemodynamics and their impact on the clinical management of VGAM patients remain unclear. OBJECTIVE: To evaluate hemodynamic alterations in the cerebral arterial and venous network in pediatric patients with VGAMs during staged embolizations. METHODS: Serial 4-dimensional flow magnetic resonance imaging (21 scans) was performed in 6 VGAM patients (3 female; mean age, 2.1 ± 4.0 years) undergoing staged embolization. Time-integrated pathlines were used to visualize 3-dimensional blood flow changes in intracranial arterial and venous systems. Total cerebral arterial inflow (flow in bilateral internal carotid arteries plus basilar artery), arteriovenous shunt flow, and blood flow in other major cerebral arteries (middle cerebral artery; posterior cerebral artery) were quantified for all patients. RESULTS: Intracranial 3-dimensional blood flow visualization demonstrated marked reduction of arteriovenous shunting and distinct hemodynamic alterations after embolization. From baseline to endpoint embolization, total cerebral arterial inflow dropped by 40.2% (from 22.70 ± 6.54 mL/s to 13.57 ± 4.87 mL/s), corresponding to arteriovenous shunt flow reduction of 73.5% (from 9.69 ± 6.16 mL/s to 2.57 ± 3.79 mL/s). In addition, the ipsilateral posterior cerebral artery/middle cerebral artery flow ratio decreased by 86.9% (from 4.20 ± 6.28 to 0.55 ± 0.23). CONCLUSION: Hemodynamic alterations in VGAMs after embolization can be visualized and quantified using 4-dimensional flow magnetic resonance imaging. Cerebral arterial inflow and arteriovenous shunt flow reduction and complex flow redistribution after embolization illustrate the potential of 4-dimensional flow magnetic resonance imaging to better evaluate the efficacy of interventions and monitor treatment effects. ABBREVIATIONS: 2-D, 2-dimensional 3-D, 3-dimensional 4-D, 4-dimensional AVM, arteriovenous malformation BA, basilar artery ICA, internal carotid artery MCA, middle cerebral artery PCA, posterior cerebral artery TS, transverses sinuses VENC, velocity encoding VGAM, Vein of Galen aneurysmal malformation

Use of Onyx for endovascular embolization of pediatric spinal perimedullary (Type IV) fistula: Case report

Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA Neurointerventional Surgery, Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA Neurointerventional Surgery, Department of Neurosurgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA Division of Neurosurgery, Ann & Robert H. Lurie Children’s Hospital of Chicago, Northwestern University Feinberg School of Medicine, Chicago, IL, USA Department of Medical Imaging, Ann & Robert H. Lurie Children’s Hospital of Chicago, IL, USA

E-004 Endovascular Embolisation of Spinal Perimedullary (Type IV) Fistula Using Ethylene Vinyl Alcohol Copolymer (Onyx): Is It Safe in Children?

Purpose Several endovascular embolic agents have been utilised for permanent obliteration of perimedullary spinal arteriovenous fistulas (sAVFs) in children; however, endovascular embolisation using ethylene vinyl alcohol copolymer (Onyx) has not been widely described in treatment of this type of spinal lesion in children. We describe the usefulness of Onyx in endovascular embolisation of paediatric high-flow perimedullary sAVFs. Case Report Case 1: During evaluation of a 7-year-old boy presenting with abdominal pain, incidental intraspinal vascular abnormalities were detected on a contrast-enhanced CT abdomen/pelvis study. Subsequent MRI revealed dilated vascular flow voids predominantly along the ventral surface of the spinal cord extending from the lower thoracic level to the cauda equina appearing to be intradural but extramedullary and suggestive of a perimedullary sAVF. The patient had been completely asymptomatic. Physical examination was normal except for an audible bruit in the lower back by auscultation. Case 2: A 17-year-old boy with a history of a cervico-spinal arteriovenous malformation presented with right lower extremity pain and progressive ambulatory disturbance. On physical examination he was noted to have considerable right lower extremity weakness associated with sensory deficits (mRS score: 4). Imaging Findings Case 1: Spinal digital subtraction angiography (DSA) demonstrated a high flow intradural AVF at the L3–4 level supplying from an extremely hypertrophied anterior spinal artery arising from the left T9 intercostal, classified as perimedullary AVF (subtype B). Using detachable platinum coils and Onyx 18, progressive embolisation of the fistula was initiated in the efferent recipient vein with embolic reflux proximally across the fistulous site and into the distal afferent components of the three major feeding arteries for obliteration. Postembolisation spinal DSA one week later revealed a second separate perimedullary AVF subtype A supplied by the PSA which was resected surgically due to the small calibre of the posterior spinal artery supplying this AVF. Case 2: Spinal DSA demonstrated a high-flow dorsal perimedullary sAVF (subtype C) at C7-T1 level with a large recipient venous varix invaginating into the substance of the cervical cord posteriorly. The lesion was supplied from the PSA and the recipient varix drained superiorly into the dorsal longitudinal spinal veins exiting via the petrosal veins, superior petrosal sinuses, and sigmoid sinuses respectively. Embolisation of the AVF was performed utilising Onyx 34 to occlude the proximal venous efferent, with controlled reflux into the fistulous site and distal afferent of several arterial feeders. The patient achieved significant clinical improvement after one year (mRS score: 2). Conclusion Although the safety of Onyx in individuals less than 18 years of age has not been yet well established, our initial results in a study on various types of CNS vascular malformations demonstrated that Onyx embolisation could be performed with high degree of safety and efficacy in children. To the best of our knowledge, use of Onyx in perimedullary sAVF embolisation in the paediatric population has been reported in only 3 cases. We believe Onyx embolisation could be performed with high degree of safety and efficacy in treatment of spinal perimedullary AVFs in children. Disclosures A. Honarmand: None. M. Soltanolkotabi: None. S. Ansari: None. S. Schoeneman: None. B. Patel: None. M. Hurley: None. T. Tomita: None. A. Shaibani: None.