Quantitative susceptibility mapping as a measure of cerebral oxygenation in neonatal piglets.

Prominence of cerebral veins using susceptibility weighted magnetic resonance imaging (SWI) has been used as a qualitative indicator of cerebral venous oxygenation (CvO2). Quantitative susceptibility mapping (QSM) adds more precision to the assessment of CvO2, but has not been applied to neonatal hypoxic ischemic injury (HII). We proposed to study QSM measures of venous susceptibility and their correlation with direct measures of brain oxygenation and cerebral blood flow (CBF) in the neonatal piglet. The association of QSM intravascular cerebral venous susceptibility, with brain tissue O2 tension, CBF, cortical tissue oxyhemoglobin saturation, and the partial pressure of oxygen in arterial blood measurement during various oxygenation states was determined by linear regression. Compared to normoxia, venous susceptibility in the straight sinus increased 56.8 ± 25.4% during hypoxia, while decreasing during hyperoxia (23.5 ± 32.9%) and hypercapnia (23.3 ± 73.1%), which was highly correlated to all other measures of oxygenation (p < 0.0001) but did not correlate to CBF (p = 0.82). These findings demonstrate a strong relationship between venous susceptibility and brain tissue O2 tension. Our results suggest that QSM-derived venous susceptibility is sensitive to cerebral oxygenation status across various oxygenation states.

Craniocervical Dissociation in Pediatric Patients: Pearls and Pitfalls of Diagnosis and Management.

AIMS: The aims of this study were to document the injury pattern in pediatric traumatic craniocervical dissociation (CCD) and identify features of survivors. METHODS: Pediatric traumatic CCDs, diagnosed between January 2004 and July 2016, were reviewed. Survivors and nonsurvivors were compared. Categorical and continuous variables were analyzed with Fisher exact and t tests, respectively. RESULTS: Twenty-seven children were identified; 10 died (37%). The median age was 60 months (ranges, 6-109 months [survivors], 2-98 months [nonsurvivors]). For survivors, the median follow-up was 13.4 months (range, 1-109 months). The median time to mortality was 1.5 days (range, 1-7 days). The injury modality was motor vehicle collision in 18 (67%), pedestrian struck in 8 (30%), and 1 shaken infant (3%). For nonsurvivors, CCD was equally diagnosed by plain radiograph and head/cervical spine computed tomography scan. For survivors, CCD was diagnosed by computed tomography in 7 (41%), magnetic resonance imaging in 10 (59%), and none by radiograph. Seven diagnosed by magnetic resonance imaging (41%) had nondiagnostic initial imaging but persistent neck pain. Magnetic resonance imaging was obtained and was diagnostic of CCD in all 7 (P < 0.01). Survivors required significantly less cardiopulmonary resuscitation (P < 0.01), had lower Injury Severity Scores (P < 0.01), higher Glasgow Coma Scale scores (P < 0.01), and shorter transport times (P < 0.01). Significantly more involved in motor vehicle collisions survived (P = 0.04). Nine (53%) had no disability at follow-up evaluation. CONCLUSIONS: In pediatric CCD, high-velocity mechanism, cardiac arrest, high Injury Severity Score, and low Glasgow Coma Scale score are associated with mortality. If CCD is correctly managed in the absence of cardiac arrest or traumatic brain or spinal cord injury, children may survive intact.

Prognostic Value of Brain Magnetic Resonance Imaging in Neonatal Hypoxic-Ischemic Encephalopathy: A Meta-analysis.

OBJECTIVE: To quantify the prognostic value of neonatal brain magnetic resonance imaging (MRI) in neonatal hypoxic-ischemic encephalopathy. METHODS: Meta-analysis of studies with ≥35-week neonates with hypoxic-ischemic encephalopathy who underwent brain MRI within age 4 weeks and had neurodevelopmental follow-up for at least 12 months. RESULTS: An abnormal neonatal brain MRI was more frequent among patients with unfavorable neurodevelopmental outcome: odds ratio = 18.2 (95% confidence interval: 9.4-34.9), P <.0001. The prognostic value of neonatal brain MRI in moderate hypoxic-ischemic encephalopathy had an odds ratio of 17.7 (95% confidence interval: 5.3-59.3) and in severe hypoxic-ischemic encephalopathy, the odds ratio was 125.0 (95% confidence interval: 2.0-7917.1). Therapeutic hypothermia did not change the prognostic value of neonatal brain MRI (odds ratio for hypothermia, 14.0 [95% confidence interval: 3.1-63.6], vs no hypothermia, 18.1 [95% confidence interval: 10.0-33.1], P = .7525). CONCLUSION: Neonatal brain MRI provides prognostic information on outcome beyond early infancy in hypoxic-ischemic encephalopathy and therapeutic hypothermia does not change its prognostic value.

Cerebral Microhemorrhage: A Frequent Magnetic Resonance Imaging Finding in Pediatric Patients after Cardiopulmonary Bypass.

OBJECTIVES: This study was undertaken to estimate the incidence and burden of cerebral microhemorrhage (CM) in patients with heart disease who underwent cardiopulmonary bypass (CPB), as detected on susceptibility-weighted imaging (SWI), a magnetic resonance (MR) sequence that is highly sensitive to hemorrhagic products. MATERIALS AND METHODS: With Institutional Review Board waiver of consent, MR imaging (MRI) of a cohort of 86 consecutive pediatric patients with heart failure who underwent heart transplantation evaluation were retrospectively reviewed for CM. A nested case-control study was performed. The CPB group consisted of 23 pediatric patients with heart failure from various cardiac conditions who underwent CPB. The control group was comprised of 13 pediatric patients with similar cardiac conditions, but without CPB history. Ten patients in the CPB group were female (age: 5 days to 16 years at the time of the CPB and 6 days to 17 years at the time of the MRI). The time interval between the CPB and MRI ranged from 11 days to 4 years and 5 months. Six patients in the control group were female, age range of 2 days to 6 years old. The number of CM on SWI was counted by three radiologists (PK, EK and DK). The differences in number of CM between groups were tested for significance using Mann-Whitney U-test, α = 0.05. Using the univariate analysis of variance model, the differences in number of CM between groups were also tested with adjustment for age at MRI. RESULTS: There are statistically significant differences in CM on SWI between the CPB group and control group with more CM were observed in the CPB group without and with adjustment for age at MRI (P < 0.001). CONCLUSIONS: Exposure of CPB is associated with increased prevalence and burden of CM among pediatric patients with heart failure.

Cerebral Misery Perfusion on Susceptibility Weighted Imaging in Acute Carotid Dissection.

The cerebral vasculature incorporates several fail-safes that must be breached before an irreversible ischemic event takes place. In particular, when autoregulatory vasodilatation fails secondary to falling cerebral perfusion pressure (CPP; stage I hemodynamic failure), increases in the oxygen extraction fraction work to maintain the cerebral metabolic rate of oxygen. Previously, failure of this mechanism, stage II hemodynamic failure, or misery perfusion, has been imaged via positron emission tomography/computed tomography (PET/CT). Current susceptibility-weighted sequences (SWI) allow for more efficient imaging of this physiology. In this case, we identify an incident of reversible ischemia caused by spontaneous carotid artery dissection using a combination of diffusion weighted imaging (DWI) and SWI. The level of hemodynamic failure identified by the imaging sequences elevated the urgency of neurointervention, expediting the patient's arrival to the neurointerventional table and thus avoiding impending irreversible ischemia.