Assessment of MR blood-oxygen-level-dependent (BOLD) cerebrovascular reactivity under general anesthesia in children with moyamoya.

BACKGROUND: Moyamoya is a progressive, non-atherosclerotic cerebral arteriopathy that may present in childhood and currently has no cure. Early diagnosis is critical to prevent a lifelong risk of neurological morbidity. Blood-oxygen-level-dependent (BOLD) MRI cerebrovascular reactivity (CVR) imaging provides a non-invasive, in vivo measure of autoregulatory capacity and cerebrovascular reserve. However, non-compliant or younger children require general anesthesia to achieve BOLD-CVR imaging. OBJECTIVE: To determine the same-day repeatability of BOLD-CVR imaging under general anesthesia in children with moyamoya. MATERIALS AND METHODS: Twenty-eight examination pairs were included (mean patient age = 7.3 ± 4.0 years). Positive and negatively reacting voxels were averaged over signals and counted over brain tissue and vascular territory. The intraclass correlation coefficient (ICC), Wilcoxon signed-rank test, and Bland-Altman plots were used to assess the variability between the scans. RESULTS: There was excellent-to-good (≥ 0.59) within-day repeatability in 18 out of 28 paired studies (64.3%). Wilcoxon signed-rank tests demonstrated no significant difference in the grey and white matter CVR estimates, between repeat scans (all p-values > 0.05). Bland-Altman plots of differences in mean magnitude of positive and negative and fractional positive and negative CVR estimates illustrated a reasonable degree of agreement between repeat scans and no systematic bias. CONCLUSION: BOLD-CVR imaging provides repeatable assessment of cerebrovascular reserve in children with moyamoya imaged under general anesthesia.

Correlative Assessment of Machine Learning-Based Cobb Angle Measurements and Human-Based Measurements in Adolescent Idiopathic and Congenital Scoliosis.

Purpose: Scoliosis is a complex spine deformity with direct functional and cosmetic impacts on the individual. The reference standard for assessing scoliosis severity is the Cobb angle which is measured on radiographs by human specialists, carrying interobserver variability and inaccuracy of measurements. These limitations may result in lack of timely referral for management at a time the scoliotic deformity progression can be saved from surgery. We aimed to create a machine learning (ML) model for automatic calculation of Cobb angles on 3-foot standing spine radiographs of children and adolescents with clinical suspicion of scoliosis across 2 clinical scenarios (idiopathic, group 1 and congenital scoliosis, group 2). Methods: We retrospectively measured Cobb angles of 130 patients who had a 3-foot spine radiograph for scoliosis within a 10-year period for either idiopathic or congenital anomaly scoliosis. Cobb angles were measured both manually by radiologists and by an ML pipeline (segmentation-based approach-Augmented U-Net model with non-square kernels). Results: Our Augmented U-Net architecture achieved a Symmetric Mean Absolute Percentage Error (SMAPE) of 11.82% amongst a combined idiopathic and congenital scoliosis cohort. When stratifying for idiopathic and congenital scoliosis individually a SMAPE of 13.02% and 11.90% were achieved, respectively. Conclusion: The ML model used in this study is promising at providing automated Cobb angle measurement in both idiopathic scoliosis and congenital scoliosis. Nevertheless, larger studies are needed in the future to confirm the results of this study prior to translation of this ML algorithm into clinical practice.

Assessment of cerebral blood flow with magnetic resonance imaging in children with sickle cell disease: A quantitative comparison with transcranial Doppler ultrasonography.

Introduction: Transcranial Doppler ultrasonography (TCD) is a clinical tool for stratifying ischemic stroke risk by identifying abnormal elevations in blood flow velocity (BFV) in the middle cerebral artery (MCA). However, TCD is not effective at screening for subtle neurologic injury such as silent cerebral infarcts. To better understand this disparity, we compared TCD measures of BFV with tissue-level cerebral blood flow (CBF) using arterial spin-labeling MRI in children with and without sickle cell disease, and correlated these measurements against clinical hematologic measures of disease severity. Methods: TCD and MRI assessment were performed in 13 pediatric sickle cell disease patients and eight age-matched controls. Using MRI measures of MCA diameter and territory weight, TCD measures of BFV in the MCA [cm/s] were converted into units of CBF [ml min-1100 g-1] for comparison. Results: There was no significant association between TCD measures of BFV in the MCA and corresponding MRI measures of CBF in patients (r = .28, p = .39) or controls (r = .10, p = .81). After conversion from BFV into units of CBF, a strong association was observed between TCD and MRI measures (r = .67, p = .017 in patients, r = .86, p = .006 in controls). While BFV in the MCA showed a lack of correlation with arterial oxygen content, an inverse association was observed for CBF measurements. Conclusions: This study demonstrates that BFV in the MCA cannot be used as a surrogate marker for tissue-level CBF in children with sickle cell disease. Therefore, TCD alone may not be sufficient for understanding and predicting subtle pathophysiology in this population, highlighting the potential clinical value of tissue-level CBF.

Diffusion tensor imaging-based assessment of white matter tracts and visual-motor outcomes in very preterm neonates.

INTRODUCTION: The purpose of this study was to assess the impact of brain injury on white matter development and long-term outcomes in very preterm (VPT) neonates. METHODS: Eighty-five VPT neonates (born <32/40 weeks gestational age (GA)) scanned within 2 weeks of birth were divided into three groups based on the presence of perinatal cerebral injury: (i) no injury, (ii) mild/moderate injury and (iii) severe injury. Diffusion tensor imaging (DTI) was acquired for each neonate and fractional anisotropy (FA), and diffusivity measures were calculated in the posterior limb of the internal capsule (PLIC) and optic radiation (OR). At 2 and 4 years of age, 41 and 44 children were assessed for motor and visual-motor abilities. Analyses determined the relation between GA and DTI measures, injury groups and DTI measures as well as developmental assessments. RESULTS: GA was related to all DTI measures within the PLIC bilaterally, FA in the OR bilaterally and AD in the left OR. The severely injured group had significantly different DTI measures in the left PLIC compared to the other two groups, independent of lateralization of lesions. Group differences in the left OR were also found, due to higher incidence of the white matter injury in the left hemisphere. No differences were found between groups and outcome measures at 2 and 4 years, with the exception of destructive periventricular venous haemorrhagic infarction (PVHI). CONCLUSIONS: DTI measures of the PLIC and OR were affected by injury in VPT neonates. These findings seen shortly after birth did not always translate into long-term motor and visual-motor impairments suggesting compensatory mechanisms.

Factors impacting same-day cancellation of outpatient pediatric magnetic resonance imaging under anesthesia.

BACKGROUND: Studies of elective surgical procedures indicate that cancellation is common and preventable. Little is known about cancellation of anesthesia-supported elective diagnostic imaging. OBJECTIVE: To describe the reasons for same-day cancellation of MRI studies performed under sedation or anesthesia and identify patient characteristics associated with cancellations. MATERIALS AND METHODS: This case-control study was carried out in a university-affiliated tertiary care children's hospital. Cases were defined as elective outpatient MRI studies booked under anesthesia that were cancelled after the patient had arrived in the radiology department in 2009. Matched controls were identified by selecting the same day and time 1 week before or after the cancelled case. Main outcome measures included demographics, MRI study characteristics, and social and medical factors. RESULTS: There were 111 outpatient anesthesia-supported MRI studies cancelled on the same day as the assessment (cancellation rate: 4.5%), of which 74.6% were related to family and patient factors, while 22% were related to system factors. Cancelled cases involved patients who lived in lower median income quintile neighborhoods compared to controls (2 vs. 3; P = 0.0007; odds ratio [OR] 3.81; 95% confidence interval [CI] 1.18-12.34). Those who traveled a greater median distance (in kilometers) were less likely to be cancelled (18.8 vs. 27.1, P = 0.0035). Although cancelled patients had a lower mean number of total medical services (2.5 vs. 3.0; P = 0.03; OR = 0.78; 95% CI 0.62-0.98), current medical factors (past 12 months) did not impact cancellations. CONCLUSION: Same-day cancellations of anesthesia-supported MRI studies are not uncommon, and the main predictor of cancellation seems to be socioeconomic rather than medical.

Assessment of cerebrovascular reactivity using real-time BOLD fMRI in children with moyamoya disease: a pilot study.

PURPOSE: This pilot study aims to test the reliability and clinical validity of the assessment of cerebrovascular reactivity (CVR) with real-time blood-oxygen-level-dependent (BOLD) fMRI (rtCVR) in comparison with standard off-line processing in children with moyamoya disease. METHODS: Eight consecutive pediatric patients with moyamoya cerebral arteriopathy underwent BOLD fMRI CVR studies either on a 1.5-T or on a 3-T scanner with breath-holding techniques in six patients and under general anesthesia (GA) in three patients. One patient had undergone CVR study initially without and later with GA, and another had undergone CVR study before and after a revascularization procedure. The off-line and real-time processing of the data was done, and the results were compared for general quality and adequacy of the study (scale 0-3, 3 being the best) and for the presence or absence of abnormal reactivity and the location, pattern, and extent of abnormal reactivity. RESULTS: A total of 20 CVR series each was studied on real-time functional MRI and off-line analysis (eight patients, ten sessions, two series per session). All eight sessions done under GA were rated as quality class 3 (100 %), whereas only 5 of the 12 (41.7 %) studies with breath-holding technique were considered to be of best quality (class 3). In comparison to the off-line processing, the overall sensitivity of the rtCVR technique was 90 % with a specificity of 100 %. CONCLUSIONS: rtCVR assessment in children with moyamoya disease is feasible, and the results are comparable to that of standard off-line analysis. The results from off-line analysis are only available, at the earliest, several hours after the MRI has been completed. rtCVR can overcome this difficulty and may be equally reliable.

Radiologic assessment of brain arteriovenous malformations: what clinicians need to know.

Brain arteriovenous malformations (AVMs) are abnormal vascular connections within the brain that are presumably congenital in nature. There are several subgroups, the most common being glomerular type brain AVMs, with fistulous type AVMs being less common. A brain AVM may also be a part of more extensive disease (eg, cerebrofacial arteriovenous metameric syndrome). When intracranial pathologic vessels are encountered at cross-sectional imaging, other diagnoses must also be considered, including large developmental venous anomalies, malignant dural arteriovenous fistulas, and moyamoya disease, since these entities are known to have different natural histories and require different treatment options. Several imaging findings in brain AVMs have an impact on decision making with respect to clinical management; the most important are those known to be associated with risk of future hemorrhage, including evidence of previous hemorrhage, intranidal aneurysms, venous stenosis, deep venous drainage, and deep location of the nidus. Other imaging findings that should be included in the radiology report are secondary effects caused by brain AVMs that may lead to nonhemorrhagic neurologic deficits, such as venous congestion, gliosis, hydrocephalus, or arterial steal.