Diffusion tensor magnetic resonance imaging of the optic nerves in pediatric hydrocephalus.

OBJECTIVE: While conventional imaging can readily identify ventricular enlargement in hydrocephalus, structural changes that underlie microscopic tissue injury might be more difficult to capture. MRI-based diffusion tensor imaging (DTI) uses properties of water motion to uncover changes in the tissue microenvironment. The authors hypothesized that DTI can identify alterations in optic nerve microstructure in children with hydrocephalus. METHODS: The authors retrospectively reviewed 21 children (< 18 years old) who underwent DTI before and after neurosurgical intervention for acute obstructive hydrocephalus from posterior fossa tumors. Their optic nerve quantitative DTI metrics of mean diffusivity (MD) and fractional anisotropy (FA) were compared to those of 21 age-matched healthy controls. RESULTS: Patients with hydrocephalus had increased MD and decreased FA in bilateral optic nerves, compared to controls (p < 0.001). Normalization of bilateral optic nerve MD and FA on short-term follow-up (median 1 day) after neurosurgical intervention was observed, as was near-complete recovery of MD on long-term follow-up (median 1.8 years). CONCLUSIONS: DTI was used to demonstrate reversible alterations of optic nerve microstructure in children presenting acutely with obstructive hydrocephalus. Alterations in optic nerve MD and FA returned to near-normal levels on short- and long-term follow-up, suggesting that surgical intervention can restore optic nerve tissue microstructure. This technique is a safe, noninvasive imaging tool that quantifies alterations of neural tissue, with a potential role for evaluation of pediatric hydrocephalus.

Phase II open label pilot trial of aprepitant and palonosetron for the prevention of chemotherapy-induced nausea and vomiting (CINV) in patients receiving moderately emetogenic FOLFOX chemotherapy for the treatment of colorectal cancer.

PURPOSE: Chemotherapy-induced nausea and vomiting (CINV) causes significant morbidity among colorectal cancer patients, receiving fluorouracil, oxaliplatin, and leucovorin (FOLFOX) chemotherapy even with standard antiemetic prophylaxis. The purpose of this study is to determine if the addition of aprepitant to standard antiemetic therapy improves CINV in these patients. METHODS: Patients receiving FOLFOX for colorectal cancer were given antiemetic prophylaxis with aprepitant 125 mg orally on day 1 and 80 mg on days 2 and 3. Palonosetron 0.25 mg was given IV push on day 1 only. Dexamethasone 12 mg was administered orally on day 1 and 8 mg each morning on days 2 through 4. Assessments including emetic events, rescue doses, nutritional intake, and appetite were recorded in a patient diary which was returned to study personnel in the following cycle. RESULTS: Of the 53 patients screened, 50 were evaluable and had a complete dataset for cycle 1. For the first cycle, 74% of patients achieved a complete response (CR), 22% achieved a major response and 4% experienced treatment failure. The percentage of patients achieving a CR remained high throughout each cycle at 83, 83, and 86% for cycles 2, 3, and 4, respectively. Appetite and nutritional status remained largely unchanged throughout treatment. Adverse events occurring in more than 10% of patients included diarrhea (13.6%), fatigue (12.6%), and neutropenia (11%). CONCLUSIONS: Aprepitant added to standard antiemetic therapy appears to be an effective and safe regimen for prevention of CINV in patients receiving FOLFOX.

Diffusion-weighted MRI derived apparent diffusion coefficient identifies prognostically distinct subgroups of pediatric diffuse intrinsic pontine glioma.

While pediatric diffuse intrinsic pontine gliomas (DIPG) remain fatal, recent data have shown subgroups with distinct molecular biology and clinical behavior. We hypothesized that diffusion-weighted MRI can be used as a prognostic marker to stratify DIPG subsets with distinct clinical behavior. Apparent diffusion coefficient (ADC) values derived from diffusion-weighted MRI were computed in 20 consecutive children with treatment-naïve DIPG tumors. The median ADC for the cohort was used to stratify the tumors into low and high ADC groups. Survival, gender, therapy, and potential steroid effects were compared between the ADC groups. Median age at diagnosis was 6.6 (range 2.3-13.2) years, with median follow-up seven (range 1-36) months. There were 14 boys and six girls. Seventeen patients received radiotherapy, five received chemotherapy, and six underwent cerebrospinal fluid diversion. The median ADC of 1,295 × 10(-6) mm(2)/s for the cohort partitioned tumors into low or high diffusion groups, which had distinct median survivals of 3 and 13 months, respectively (log-rank p < 0.001). Low ADC tumors were found only in boys, whereas high ADC tumors were found in both boys and girls. Available tissue specimens in three low ADC tumors demonstrated high-grade histology, whereas one high ADC tumor demonstrated low-grade histology with a histone H3.1 K27M mutation and high-grade metastatic lesion at autopsy. ADC derived from diffusion-weighted MRI may identify prognostically distinct subgroups of pediatric DIPG.

Hedgehog-responsive candidate cell of origin for diffuse intrinsic pontine glioma.

Diffuse intrinsic pontine gliomas (DIPGs) are highly aggressive tumors of childhood that are almost universally fatal. Our understanding of this devastating cancer is limited by a dearth of available tissue for study and by the lack of a faithful animal model. Intriguingly, DIPGs are restricted to the ventral pons and occur during a narrow window of middle childhood, suggesting dysregulation of a postnatal neurodevelopmental process. Here, we report the identification of a previously undescribed population of immunophenotypic neural precursor cells in the human and murine brainstem whose temporal and spatial distributions correlate closely with the incidence of DIPG and highlight a candidate cell of origin. Using early postmortem DIPG tumor tissue, we have established in vitro and xenograft models and find that the Hedgehog (Hh) signaling pathway implicated in many developmental and oncogenic processes is active in DIPG tumor cells. Modulation of Hh pathway activity has functional consequences for DIPG self-renewal capacity in neurosphere culture. The Hh pathway also appears to be active in normal ventral pontine precursor-like cells of the mouse, and unregulated pathway activity results in hypertrophy of the ventral pons. Together, these findings provide a foundation for understanding the cellular and molecular origins of DIPG, and suggest that the Hh pathway represents a potential therapeutic target in this devastating pediatric tumor.

Cost savings realized by use of the PhaSeal(®) closed-system transfer device for preparation of antineoplastic agents.

PURPOSE: Medication cost is a major factor associated with increasing health care costs in the United States. Expenditures for prescription drugs in 2013 are estimated to be $283.7 billion. Closed system transfer devices are widely used for preparation of hazardous drugs. Reports indicate the Phaseal(®) closed system transfer device maintains sterility in vials for 7 days, suggesting the unused portion of single-use vials could be salvaged. This study was done to determine whether using a closed system transfer device to extend the beyond-use date of single-use vials of antineoplastic medications would result in a measurable cost saving. METHODS: A list of 25 drugs available in single-use vials, with a chemical stability of at least 48 hours, was compiled. Use of these agents was recorded during a 50-day period in April through June 2012. Use from a total of 296 vials of 21 antineoplastic agents was recorded. After allowing for the initial use of each vial, the mean potential percentage of drug waste was calculated to be 57.03%. RESULTS: Actual savings during the study period was $96,348.70. The pharmacy avoided nearly half of the potential waste and saved a mean of 29% of each vial. The cost-saving during the study period represents a $703,047.67 annual saving; which more than offsets the $106,556.55 the pharmacy spent for the Phaseal(®) system in 2012. CONCLUSION: In addition to being a protective measure to reduce exposure to hazardous agents, use of the Phaseal(®) system results in a reduction in drug waste, and a noticeable cost saving for antineoplastic agents.

Using bioabsorbable fixation systems in the treatment of pediatric skull deformities leads to good outcomes and low morbidity.

BACKGROUND: Bioabsorbable fixation systems have been widely employed in pediatric patients for cranial reconstruction, obviating the complications of hardware migration and imaging artifact occurring with metallic implants. Recent concern over complications unique to bioabsorbable materials, such as inflammatory reaction and incomplete resorption, necessitates additional conclusive studies to further validate their use in pediatric neurosurgery and craniofacial surgery. Likewise, long-term follow-up in this clinical cohort has not previously been described. METHODS: We included consecutive pediatric patients under the age of 2, from Lucile Packard Children's Hospital, who underwent cranial vault reconstruction with the use of a bioabsorbable fixation system between 2003 and 2010. Hospital records were queried for patient characteristics, intraoperative data, and postoperative complications. RESULTS: Ninety-five patients with the following preoperative pathologies were analyzed: craniosynostosis (87), cloverleaf skull (5), frontonasal dysplasia (1), and frontonasal encephalocele (2). Median age was 6 months (range 1-24 months). Average case duration was 204 minutes (range 40-392 min), with median of 154 mL blood loss (range 30-500 mL). Ninety-three percent of patients had 1-4 plates implanted with 48% receiving three plates. The median number of screws used was 59 (range 0-130). The median length of hospital stay was 4 days (range 2-127 days) with an average follow-up of 22 months (five postoperative visits). The complications related to hardware implantation included swelling (1%) and broken hardware (1%), the latter of which required reoperation. DISCUSSION: The bioabsorbable fixation systems for cranial vault reconstruction in children less than 2 years of age is safe with tolerable morbidity rates.

Ventricular access devices are safe and effective in the treatment of posthemorrhagic ventricular dilatation prior to shunt placement.

Intraventricular hemorrhage of prematurity (IVH) is a diagnosis that has become more frequent in recent years. Advances in medical care have led to survival of increasingly premature infants, as well as infants with more complex medical conditions. Treatment with a ventricular access device (VAD) was reported almost 3 decades ago; however, it is unclear how effective this treatment is in the current population of premature infants. At our institution (from 2004 to present), we treat posthemorrhagic hydrocephalus (PHH) with a VAD. In order to look at safety and efficacy, we retrospectively combed the medical records of premature children, admitted to Lucile Packard Children's Hospital from January 2005 to December 2009, and identified 310 premature children with IVH. Of these, 28 children required treatment for PHH with a VAD. There were no infections associated with placement of these devices and a very low rate of other complications, such as need for repositioning (7.41%) or replacement (3.75%). Our data show that treatment with a VAD is very safe, with few complications and can be used to treat PHH in this very complex infant population.

Complete ocular paresis in a child with posterior fossa syndrome.

Posterior fossa syndrome (PFS), also known as cerebellar affective syndrome, is characterized by emotional lability and decreased speech production following injury or surgery to the cerebellum. Rarely, oculomotor dysfunction has been described in association with PFS. Here, we report a case of complete ocular paresis associated with PFS in an 11-year-old male following medulloblastoma resection.

Advances in the Treatment of Pediatric Brain Tumors.

Pediatric brain tumors are the most common solid malignancies in children. Advances in the treatment of pediatric brain tumors have come in the form of imaging, biopsy, surgical techniques, and molecular profiling. This has led the way for targeted therapies and immunotherapy to be assessed in clinical trials for the most common types of pediatric brain tumors. Here we review the latest efforts and challenges in targeted molecular therapy, immunotherapy, and newer modalities such as laser interstitial thermal therapy.

Age-dependent Intracranial Artery Morphology in Healthy Children.

PURPOSE: Evaluation of intracranial artery morphology plays an important role in diagnosing a variety of neurovascular diseases. In addition to clinical symptoms, diagnosis currently relies on qualitative rather than quantitative evaluation of vascular imaging sequences, such as magnetic resonance angiography (MRA). However, there is a paucity of literature on normal arterial morphology in the pediatric population across brain development. We aimed to quantitatively assess normal, age-related changes in artery morphology in children. METHODS: We performed retrospective analysis of pediatric MRA data obtained from a tertiary referral center. An MRA dataset from 98 children (49 boys/49 girls) aged 0.6-20 years (median = 11.5 years) with normal intracranial vasculature was retrospectively collected between 2011 and 2018. All arteries were automatically segmented to determine the vessel radius. Using an atlas-based approach, the average radius and density of arteries were measured in the three main cerebral vascular territories and the radius of five major arteries was determined at corresponding locations. RESULTS: The radii of the major arteries as well as the average artery radius and density in the different vascular territories in the brain remained constant throughout childhood and adolescence (|r| < 0.369 in all cases). CONCLUSION: This study presents the first automated evaluation of intracranial vessel morphology on MRA across childhood. Our results can serve as a framework for quantitative evaluation of cerebral vessel morphology in the setting of pediatric neurovascular diseases.

Liposomal cytarabine for central nervous system embryonal tumors in children and young adults.

To assess the tolerability and efficacy of liposomal cytarabine (LC), an encapsulated, sustained-release, intrathecal (IT) formulation of cytosine arabinoside, in de novo and relapsed central nervous system (CNS) embryonal tumors in children and young adults. We studied retrospectively all patients less than age 30 at our institution treated consecutively with LC for medulloblastoma (MB), primitive neuroectodermal tumor (PNET), and atypical teratoid rhabdoid tumor (ATRT). Seventeen patients received LC (2 mg/kg up to 50 mg, every 2 weeks to monthly) at diagnosis of high-risk CNS embryonal tumor (2 PNET, 3 ATRT) or relapse of MB (12 MB; 9 had leptomeningeal metastases). Sixteen patients received concurrent systemic chemotherapy. A total of 108 doses were administered (IT 82, intraventricular 26) with a mean of six (range 1-16) treatments per patient. Only three administrations were associated with adverse effects of arachnoiditis or headache. None developed malignant cerebrospinal fluid (CSF) cytology while receiving LC. All the six evaluable patients with malignant CSF cytology and treated with at least two doses cleared their CSF (mean 3 doses, range 1-5). Median overall survival in relapse patients was 9.1 months. Five patients (4 de novo and 1 relapsed) remain alive in complete remission for a median 26.8 months from first LC. Liposomal cytarabine is an easily administered, well-tolerated, and active drug in patients with high-risk embryonal neoplasms. One-third of our cohort remains in remission from otherwise fatal diagnoses. Our findings warrant a phase II trial of LC in newly diagnosed or recurrent CNS embryonal tumors.

Primary pediatric skull tumors.

BACKGROUND/AIMS: To review the pathological distribution of pediatric primary skull tumors, and to determine the diagnostic value of lesion location, patient age and lesion size. METHODS: A retrospective chart review identified 51 consecutive pediatric patients with 54 primary skull tumors, treated between 2005 and 2010. RESULTS: The most common diagnoses were dermoid cysts (n = 34) and fibrous dysplasia (n = 5). While dermoid tumors could reside anywhere (sensitivity = 0.41), a midline lesion had a specificity of 0.9 and a positive predictive value of 0.88. All of the fibrous dysplasia lesions were laterally placed, with a negative predictive value (NPV) of 1. Patient age < or >5 years had a high sensitivity and NPV for dermoid cysts and fibrous dysplasia, respectively. Size appeared to be sensitive (0.91, 0.8), but not specific (0.6, 0.78), with good NPV (0.8, 0.97) when considering dermoid cysts (≤2 cm) or fibrous dysplasia (>2 cm), respectively. CONCLUSION: Dermoid cysts followed by fibrous dysplasia are the most common primary skull tumors. Lesion location, patient age and lesion size give important clues as to the diagnosis. For the majority of cases, a clinical diagnosis based on CT is sufficient for presurgical evaluation.

Loss of SMARCB1/INI1 expression in poorly differentiated chordomas.

Chordomas are malignant neoplasms that typically arise in the axial spine and primarily affect adults. When chordomas arise in pediatric patients they are more likely to display unusual histological features and aggressive behavior. We noted the absence of SMARCB1/INI1 expression by immunohistochemistry in an index case of poorly differentiated chordoma of the sacrum, leading us to further examine SMARCB1/INI1 expression as well as that of brachyury, a highly specific marker of notochordal differentiation, in 3 additional poorly differentiated chordomas of the clivus, 10 typical chordomas, and 8 atypical teratoid/rhabdoid tumors (AT/RTs). All 4 poorly differentiated chordomas and all AT/RTs lacked nuclear expression of SMARCB1/INI1, while the 10 typical chordomas maintained strong nuclear SMARCB1/INI1 immunoreactivity. All 10 typical and 4 poorly differentiated chordomas expressed brachyury; all 8 AT/RTs were brachyury immunonegative. Cytogenetic evaluation utilizing FISH probes near the SMARCB1/INI1 locus on chromosome 22q was also performed in all of the poorly differentiated chordomas in this series. Three of the four poorly differentiated chordomas had evidence for deletion of this region by FISH. Analysis of the SMARCB1/INI1 gene sequence was performed using formalin-fixed paraffin-embedded tissue in all cases and no point mutations were observed. In summary, all poorly differentiated chordomas in this series showed the absence of SMARCB1/INI1 expression, and were reliably distinguished from AT/RTs, clinically by their characteristic primary sites of origin and pathologically by strong nuclear brachyury expression. Our findings reveal a likely role for SMARCB1/INI1 in a subset of chordomas with aggressive features.

Deep Learning for Automated Delineation of Pediatric Cerebral Arteries on Pre-operative Brain Magnetic Resonance Imaging.

Introduction: Surgical resection of brain tumors is often limited by adjacent critical structures such as blood vessels. Current intraoperative navigations systems are limited; most are based on two-dimensional (2D) guidance systems that require manual segmentation of any regions of interest (ROI; eloquent structures to avoid or tumor to resect). They additionally require time- and labor-intensive processing for any reconstruction steps. We aimed to develop a deep learning model for real-time fully automated segmentation of the intracranial vessels on preoperative non-angiogram imaging sequences. Methods: We identified 48 pediatric patients (10-months to 22-years old) with high resolution (0.5-1 mm axial thickness) isovolumetric, pre-operative T2 magnetic resonance images (MRIs). Twenty-eight patients had anatomically normal brains, and 20 patients had tumors or other lesions near the skull base. Manually segmented intracranial vessels (internal carotid, middle cerebral, anterior cerebral, posterior cerebral, and basilar arteries) served as ground truth labels. Patients were divided into 80/5/15% training/validation/testing sets. A modified 2-D Unet convolutional neural network (CNN) architecture implemented with 5 layers was trained to maximize the Dice coefficient, a measure of the correct overlap between the predicted vessels and ground truth labels. Results: The model was able to delineate the intracranial vessels in a held-out test set of normal and tumor MRIs with an overall Dice coefficient of 0.75. While manual segmentation took 1-2 h per patient, model prediction took, on average, 8.3 s per patient. Conclusions: We present a deep learning model that can rapidly and automatically identify the intracranial vessels on pre-operative MRIs in patients with normal vascular anatomy and in patients with intracranial lesions. The methodology developed can be translated to other critical brain structures. This study will serve as a foundation for automated high-resolution ROI segmentation for three-dimensional (3D) modeling and integration into an augmented reality navigation platform.

Recurrence of cavernous malformations after surgery in childhood.

OBJECTIVE: Cavernous malformations (CMs) are commonly treated cerebrovascular anomalies in the pediatric population; however, the data on radiographic recurrence of pediatric CMs after surgery are limited. The authors aimed to study the clinical presentation, outcomes, and recurrence rate following surgery for a large cohort of CMs in children. METHODS: Pediatric patients (≤ 18 years old) who had a CM resected at a single institution were identified and retrospectively reviewed. Fisher's exact test of independence was used to assess differences in categorical variables. Survival curves were evaluated using the Mantel-Cox method. RESULTS: Fifty-three patients aged 3 months to 18 years underwent resection of 74 symptomatic CMs between 1996 and 2018 at a single institution. The median length of follow-up was 5.65 years. Patients most commonly presented with seizures (45.3%, n = 24) and the majority of CMs were cortical (58.0%, n = 43). Acute radiographic hemorrhage was common at presentation (64.2%, n = 34). Forty-two percent (n = 22) of patients presented with multiple CMs, and they were more likely to develop de novo lesions (71%) compared to patients presenting with a single CM (3.4%). Both radiographic hemorrhage and multiple CMs were independently prognostic for a higher risk of the patient requiring subsequent surgery. Fifty percent (n = 6) of the 12 patients with both risk factors required additional surgery within 2.5 years of initial surgery compared to none of the patients with neither risk factor (n = 9). CONCLUSIONS: Patients with either acute radiographic hemorrhage or multiple CMs are at higher risk for subsequent surgery and require long-term MRI surveillance. In contrast, patients with a single CM are unlikely to require additional surgery and may require less frequent routine imaging.

Early Diffusion Magnetic Resonance Imaging Changes in Normal-Appearing Brain in Pediatric Moyamoya Disease.

BACKGROUND: Moyamoya disease often leads to ischemic strokes visible on diffusion-weighted imaging (DWI) and T2-weighted magnetic resonance imaging (MRI) with subsequent cognitive impairment. In adults with moyamoya, apparent diffusion coefficient (ADC) is correlated with regions of steal phenomenon and executive dysfunction prior to white matter changes. OBJECTIVE: To investigate quantitative global diffusion changes in pediatric moyamoya patients prior to explicit structural ischemic damage. METHODS: We retrospectively reviewed children (<20 yr old) with moyamoya disease and syndrome who underwent bypass surgery at our institution. We identified 29 children with normal structural preoperative MRI and without findings of cortical infarction or chronic white matter ischemic changes. DWI datasets were used to calculate ADC maps for each subject as well as for 60 age-matched healthy controls. Using an atlas-based approach, the cerebral white matter, cerebral cortex, thalamus, caudate, putamen, pallidum, hippocampus, amygdala, nucleus accumbens, and brainstem were segmented in each DWI dataset and used to calculate regional volumes and ADC values. RESULTS: Multivariate analysis of covariance using the regional ADC and volume values as dependent variables and age and gender as covariates revealed a significant difference between the groups (P < .001). Post hoc analysis demonstrated significantly elevated ADC values for children with moyamoya in the cerebral cortex, white matter, caudate, putamen, and nucleus accumbens. No significant volume differences were found. CONCLUSION: Prior to having bypass surgery, and in the absence of imaging evidence of ischemic stroke, children with moyamoya exhibit cerebral diffusion changes. These findings could reflect microstructural changes stemming from exhaustion of cerebrovascular reserve.

Artificial intelligence for automatic cerebral ventricle segmentation and volume calculation: a clinical tool for the evaluation of pediatric hydrocephalus.

OBJECTIVE: Imaging evaluation of the cerebral ventricles is important for clinical decision-making in pediatric hydrocephalus. Although quantitative measurements of ventricular size, over time, can facilitate objective comparison, automated tools for calculating ventricular volume are not structured for clinical use. The authors aimed to develop a fully automated deep learning (DL) model for pediatric cerebral ventricle segmentation and volume calculation for widespread clinical implementation across multiple hospitals. METHODS: The study cohort consisted of 200 children with obstructive hydrocephalus from four pediatric hospitals, along with 199 controls. Manual ventricle segmentation and volume calculation values served as "ground truth" data. An encoder-decoder convolutional neural network architecture, in which T2-weighted MR images were used as input, automatically delineated the ventricles and output volumetric measurements. On a held-out test set, segmentation accuracy was assessed using the Dice similarity coefficient (0 to 1) and volume calculation was assessed using linear regression. Model generalizability was evaluated on an external MRI data set from a fifth hospital. The DL model performance was compared against FreeSurfer research segmentation software. RESULTS: Model segmentation performed with an overall Dice score of 0.901 (0.946 in hydrocephalus, 0.856 in controls). The model generalized to external MR images from a fifth pediatric hospital with a Dice score of 0.926. The model was more accurate than FreeSurfer, with faster operating times (1.48 seconds per scan). CONCLUSIONS: The authors present a DL model for automatic ventricle segmentation and volume calculation that is more accurate and rapid than currently available methods. With near-immediate volumetric output and reliable performance across institutional scanner types, this model can be adapted to the real-time clinical evaluation of hydrocephalus and improve clinician workflow.

Intraventricular metaplastic meningioma in a child: case report and review of the literature.

Childhood meningiomas are rare and display important differences from adult forms. We report the first case of an intraventricular metaplastic meningioma arising in a child. A 7-year-old female underwent resection of an enhancing tumor arising within the left lateral ventricle. It was composed of monomorphic cells embedded within an abundant myxoid stroma. The cells demonstrated epithelial membrane antigen and vimentin immunoreactivity. Ultrastructural analysis demonstrated intermediate filaments, complex intercellular interdigitations and desmosomes, and a diagnosis of myxoid (metaplastic) meningioma was rendered. This case reflects the higher incidence of intraventricular meningiomas in childhood and greater incidence of intraventricular meningiomas in the left lateral ventricle. Recognition of the grade I myxoid meningioma in this case is paramount since chordoid meningiomas, which share similar histologic features, are of a higher grade and worse prognosis.

Ferumoxytol-enhanced MRI for surveillance of pediatric cerebral arteriovenous malformations.

OBJECTIVE: Children with intracranial arteriovenous malformations (AVMs) undergo digital DSA for lesion surveillance following their initial diagnosis. However, DSA carries risks of radiation exposure, particularly for the growing pediatric brain and over lifetime. The authors evaluated whether MRI enhanced with a blood pool ferumoxytol (Fe) contrast agent (Fe-MRI) can be used for surveillance of residual or recurrent AVMs. METHODS: A retrospective cohort was assembled of children with an established AVM diagnosis who underwent surveillance by both DSA and 3-T Fe-MRI from 2014 to 2016. Two neuroradiologists blinded to the DSA results independently assessed Fe-enhanced T1-weighted spoiled gradient recalled acquisition in steady state (Fe-SPGR) scans and, if available, arterial spin labeling (ASL) perfusion scans for residual or recurrent AVMs. Diagnostic confidence was examined using a Likert scale. Sensitivity, specificity, and intermodality reliability were determined using DSA studies as the gold standard. Radiation exposure related to DSA was calculated as total dose area product (TDAP) and effective dose. RESULTS: Fifteen patients were included in this study (mean age 10 years, range 3-15 years). The mean time between the first surveillance DSA and Fe-MRI studies was 17 days (SD 47). Intermodality agreement was excellent between Fe-SPGR and DSA (κ = 1.00) but poor between ASL and DSA (κ = 0.53; 95% CI 0.18-0.89). The sensitivity and specificity for detecting residual AVMs using Fe-SPGR were 100% and 100%, and using ASL they were 72% and 100%, respectively. Radiologists reported overall high diagnostic confidence using Fe-SPGR. On average, patients received two surveillance DSA studies over the study period, which on average equated to a TDAP of 117.2 Gy×cm2 (95% CI 77.2-157.4 Gy×cm2) and an effective dose of 7.8 mSv (95% CI 4.4-8.8 mSv). CONCLUSIONS: Fe-MRI performed similarly to DSA for the surveillance of residual AVMs. Future multicenter studies could further investigate the efficacy of Fe-MRI as a noninvasive alternative to DSA for monitoring AVMs in children.

Arterial spin labeling perfusion changes of the frontal lobes in children with posterior fossa syndrome.

OBJECTIVE: Posterior fossa syndrome (PFS) is a common complication following the resection of posterior fossa tumors in children. The pathophysiology of PFS remains incompletely elucidated; however, the wide-ranging symptoms of PFS suggest the possibility of widespread cortical dysfunction. In this study, the authors utilized arterial spin labeling (ASL), an MR perfusion modality that provides quantitative measurements of cerebral blood flow without the use of intravenous contrast, to assess cortical blood flow in patients with PFS. METHODS: A database of medulloblastoma treated at the authors' institution from 2004 to 2016 was retrospectively reviewed, and 14 patients with PFS were identified. Immediate postoperative ASL for patients with PFS and medulloblastoma patients who did not develop PFS were compared. Additionally, in patients with PFS, ASL following the return of speech was compared with immediate postoperative ASL. RESULTS: On immediate postoperative ASL, patients who subsequently developed PFS had statistically significant decreases in right frontal lobe perfusion and a trend toward decreased perfusion in the left frontal lobe compared with controls. Patients with PFS had statistically significant increases in bilateral frontal lobe perfusion after the resolution of symptoms compared with their immediate postoperative imaging findings. CONCLUSIONS: ASL perfusion imaging identifies decreased frontal lobe blood flow as a strong physiological correlate of PFS that is consistent with the symptomatology of PFS. This is the first study to demonstrate that decreases in frontal lobe perfusion are present in the immediate postoperative period and resolve with the resolution of symptoms, suggesting a physiological explanation for the transient symptoms of PFS.