Relationship Between CT Head Findings and Long-term Recovery in Children with Complicated Mild Traumatic Brain Injury.

PRIMARY OBJECTIVE: Complicated mild traumatic brain injury (C-mTBI) refers to CT positive patients with clinically mild TBI. This study investigates the association between CT head findings at time of injury and recovery of paediatric patients with C-mTBI. RESEARCH DESIGN: Retrospective survey and chart review. METHODS: For paediatric patients with C-mTBI (N = 77), CT findings associated with corresponding degree and lengths of recovery from C-mTBI using logistic regression analysis. RESULTS: There was a trend that the odds of incomplete recovery at the time of survey was higher for older children than for younger children (OR = 1.14, 95% CI = 0.98-1.32, p = 0.072). There was a trend that the odds of incomplete recovery (OR = 6.26, 95% CI = 0.97-40.57, p = 0.054) and longer duration for recovery (OR = 8.14, 95% CI = 0.78-84.46, p = 0.079) was higher for children with multiple haemorrhagic contusions than those with single haemorrhagic contusion. No other imaging patterns predicted degree or length of recovery with statistical significance (p > 0.05). CONCLUSIONS: Other than the presence of multiple haemorrhagic contusions, no other pattern of imaging abnormality in paediatric C-mTBI appears to be associated with degree or length of recovery. Further studies with larger cohorts are encouraged.

Technical Note: Quantification of blood-spinal cord barrier permeability after application of magnetic resonance-guided focused ultrasound in spinal cord injury.

PURPOSE: To demonstrate that magnetic resonance-guided focused ultrasound (MRgFUS) facilitates blood-spinal cord barrier (BSCB) permeability and develop observer-independent MRI quantification of BSCB permeability after MRgFUS for spinal cord injury (SCI). METHODS: Noninjured Sprague-Dawley rats (n = 3) underwent MRgFUS and were administered Evans blue post-MRgFUS to confirm BSCB opening. Absorbance was measured by spectrophotometry and correlated with its corresponding image intensity. Rats (n = 21) underwent T8-T10 laminectomy and extradural compression of the spinal cord (23g weighted aneurysm-type clip, 1 min). The intervention group (n = 11) was placed on a preclinical MRgFUS system, administered microbubbles (Optison, 0.2 mL/kg), and received 3 MRgFUS sonications (25 ms bursts, 1 Hz pulses for 3 min, 3 acoustic W, approximately 1.0-2.1 MPa peak pressure as measured via hydrophone). The sham group (n = 10) received equivalent procedures with no sonications. T1w MRI was obtained both pre- and post-MRgFUS BSCB opening. Spinal cords were segmented manually or semiautomatically and a Pearson correlation with P ≤ 0.001 was used to correlate the two segmentation methods. MRgFUS sonication and control regions intensity values were evaluated with a paired t-test with a P ≤ 0.01. RESULTS: Semiautomatic segmentation reduced computational time by 95% and was correlated with manual segmentation (Pearson = 0.92, P < 0.001, n = 71 regions). In the noninjured rat group, Evans blue absorbance correlated with image intensity in the MRgFUS and control regions (Pearson = 0.82, P = 0.02, n = 6). In rats that underwent the SCI procedure, an increase in signal intensity in the MRgFUS targeted region relative to control was seen in all SCI rats (10.65 ± 12.4%, range: 0.96-43.9%, n = 11, P = 0.002). SCI sham MRgFUS revealed no change (0.63 ± 0.52%, 95% CI 0.320.95, n = 10). This result was significant between both groups (P = 0.003). CONCLUSION: The implemented semiautomatic segmentation procedure improved data analysis efficiency. Quantitative methods using contrast-enhanced MRI with histological validation are sensitive for detection of blood-spinal cord barrier opening induced by magnetic resonance-guided focused ultrasound.