Normal Cerebellar Growth by Using Three-dimensional US in the Preterm Infant from Birth to Term-corrected Age

Feasibility of Cerebellar Measurements with Phased Array Sonography through the Anterior Fontanelle in Comparison to MRI

OBJECTIVE

 Cerebral sonography (CS) through the anterior fontanelle is a neonatal brain imaging method that has become an integral part of modern neonatal bedside care for both screening and diagnostic purposes. Premature infants with cognitive delay have a reduction in cerebellar size at term corrected age on magnetic resonance imaging (MRI). We aimed to determine the level of agreement between postnatal MRI and CS for cerebellar biometry and to determine the level of agreement within one and between different examiners.

STUDY DESIGN

 Cerebellar sonography and MRI measurements of the cerebellum from 30 term infants was assessed by Bland-Altman plots. Measurements between both modalities were compared using Wilcoxon's signed rank test. A p-value < 0.01 was considered statistically significant. Intraclass correlation coefficients (ICC) for intra- and interrater reliabilities of CS measurements were calculated.

RESULTS

 There was no statistically significant difference between CS and MRI for linear measurements, but the measurements of perimeter and surface area differed significantly between the two techniques. There was a systematic bias between both modalities for most measurements except for anterior-posterior (AP) width and vermis height (VH). For measurements that were not statistically different from MRI, we found excellent intrarater ICC for the AP width, VH, and cerebellar width. The interrater ICC was excellent for the AP width and VH, but poor for the transverse cerebellar width.

CONCLUSION

 With a strict imaging protocol, cerebellar measurements of the AP width and the VH can be used as an alternative to MRI for diagnostic-screening purposes in a neonatal department where multiple clinicians perform bedside CS.

KEY POINTS

· Abnormal cerebellar growth and injuries affect neurodevelopmental outcome.. · Cerebral sonography through the anterior fontanelle is used for bedside imaging.. · Postnatal sonographic cerebellar measurements are not validated against MRI.. · Measuring vermis height and anterior-posterior width are reliable.. · Measuring transverse cerebellar width through anterior fontanelle is unreliable..

Neuroimaging in infants with congenital cytomegalovirus infection and its correlation with outcome: emphasis on white matter abnormalities

OBJECTIVE

To evaluate the association between neuroimaging and outcome in infants with congenital cytomegalovirus (cCMV), focusing on qualitative MRI and quantitative diffusion-weighted imaging of white matter abnormalities (WMAs).

METHODS

Multicentre retrospective cohort study of 160 infants with cCMV (103 symptomatic). A four-grade neuroimaging scoring system was applied to cranial ultrasonography and MRI acquired at ≤3 months. WMAs were categorised as multifocal or diffuse. Temporal-pole WMAs (TPWMAs) consisted of swollen or cystic appearance. Apparent diffusion coefficient (ADC) values were obtained from frontal, parieto-occipital and temporal white matter regions. Available follow-up MRI at ≥6 months (N=14) was additionally reviewed. Neurodevelopmental assessment included motor function, cognition, behaviour, hearing, vision and epilepsy. Adverse outcome was defined as death or moderate/severe disability.

RESULTS

Neuroimaging scoring was associated with outcome (p<0.001, area under the curve 0.89±0.03). Isolated WMAs (IWMAs) were present in 61 infants, and WMAs associated with other lesions in 30. Although TPWMAs and diffuse pattern often coexisted in infants with IWMAs (p<0.001), only TPWMAs were associated with adverse outcomes (OR 7.8; 95% CI 1.4 to 42.8), including severe hearing loss in 20% and hearing loss combined with other moderate/severe disabilities in 15%. Increased ADC values were associated with higher neuroimaging scores, WMAs based on visual assessment and IWMAs with TPWMAs. ADC values were not associated with outcome in infants with IWMAs. Findings suggestive of progression of WMAs on follow-up MRI included gliosis and malacia.

CONCLUSIONS

Categorisation of neuroimaging severity correlates with outcome in cCMV. In infants with IWMAs, TPWMAs provide a guide to prognosis.

Development of an Ultrasound Scoring System to Describe Brain Maturation in Preterm Infants

BACKGROUND AND PURPOSE

Cerebral maturation in preterm infants predominantly occurs postnatally, necessitating the development of objective bedside markers to monitor this process. This study aimed to develop a straightforward objective Ultrasound Score of Brain Development to assess cortical development in preterm infants.

MATERIALS AND METHODS

A total of 344 serial ultrasound examinations from 94 preterm infants born at ≤ 32 weeks of gestation were analyzed to identify brain structures suitable for a scoring system.

RESULTS

Among 11 candidate structures, 3 cerebral landmarks were selected due to their correlation with gestational age: the interopercular opening (P < .001), the height of the insular cortex (P < .001), and the depth of the cingulate sulcus (P < .001). These structures can be easily visualized in a single midcoronal view in the plane through the third ventricle and the foramina of Monro. A score point from 0 to 2 was assigned to each measurement, culminating in a total score ranging from 0 to 6. The Ultrasound Score of Brain Development correlated significantly with gestational age (P < .001).

CONCLUSIONS

The proposed Ultrasound Score of Brain Development has the potential for application as an objective indicator of brain maturation in correlation with gestational age, circumventing the need to rely on individual growth trajectories and percentiles for each specific structure.

Ultrasonographic evaluation of the early brain growth pattern in very low birth weight infants

BACKGROUND

Preterm infants develop smaller brain volumes compared to term newborns. Our aim is to study early brain growth related to perinatal factors in very low birth weight infants (VLBWI).

METHODS

Manual segmentation of total brain volume (TBV) was performed in weekly 3D-ultrasonographies in our cohort of VLBWI. We studied the brain growth pattern related to term magnetic resonance image (term-MRI).

RESULTS

We found different brain growth trajectories, with smaller brain volumes and a decrease in brain growth rate in those VLBWI who would later have an abnormal term-MRI (mean TBV 190.68 vs. 213.9 cm3; P = 0.0001 and mean TBV growth rate 14.35 (±1.27) vs. 16.94 (±2.29) cm3/week; P = 0.0001). TBV in those with normal term-MRI was related to gestational age (GA), being small for gestational age (SGA), sex, and duration of parenteral nutrition (TPN) while in those with abnormal term-MRI findings it was related to GA, SGA, TPN, and comorbidities. We found a deceleration in brain growth rate in those with ≥3 comorbidities.

CONCLUSIONS

An altered brain growth pattern in VLBWI who subsequently present worst scores on term-MRI is related to GA, being SGA and comorbidities. Early ultrasonographic monitoring of TBV could be useful to detect deviated patterns of brain growth.

IMPACT STATEMENT

We describe the brain growth pattern in very low birth weight infants during their first postnatal weeks. Brain growth may be affected in the presence of certain perinatal factors and comorbidities, conditioning a deviation of the normal growth pattern. The serial ultrasound follow-up of these at-risk patients allows identifying these brain growth patterns early, which offers a window of opportunity for implementing earlier interventions.

Morphological changes in the pons and cerebellum during the first two weeks in term infants with pontine and cerebellar injury and profound neonatal asphyxia

BACKGROUND

The morphological changes in the pons and cerebellum of neonates experiencing profound asphyxia in the early period of life remain to be clarified.

PURPOSE

To assess the changes in the size of the pons and cerebellum during the first two weeks of life in term neonates with pontine and cerebellar injury caused by hypoxic-ischemic encephalopathy in comparison with a control group.

MATERIAL AND METHODS

Two groups were investigated: a group with pontine/cerebellar injury (PCI) (n = 10) demonstrated by magnetic resonance imaging (MRI) diffusion-weighted imaging; and a control group without PCI - focal-multifocal white matter injury and a normal pattern (n = 24). The anteroposterior diameter (APD) and height of the pons and cerebellar vermis, and the transverse width of the cerebellum were measured twice in the first and second weeks of life. Differences between the groups were analyzed statistically using paired and unpaired Student's t-test at a significance level of P < 0.05.

RESULTS

In the PCI group, the pontine APD and cerebellar vermian height were significantly decreased in the second week. An increase of pons and cerebellar size was evident during the first two weeks of life in the control groups.

CONCLUSION

Infants with PCI and profound asphyxia show rapid decreases in pontine APD and cerebellar vermian height within the first two weeks of life.

Ultrasonographic Estimation of Total Brain Volume: 3D Reliability and 2D Estimation. Enabling Routine Estimation During NICU Admission in the Preterm Infant

Objectives: The aim of this study is to explore if manually segmented total brain volume (TBV) from 3D ultrasonography (US) is comparable to TBV estimated by magnetic resonance imaging (MRI). We then wanted to test 2D based TBV estimation obtained through three linear axes which would enable monitoring brain growth in the preterm infant during admission. Methods: We included very low birth weight preterm infants admitted to our neonatal intensive care unit (NICU) with normal neuroimaging findings. We measured biparietal diameter, anteroposterior axis, vertical axis from US and MRI and TBV from both MRI and 3D US. We calculated intra- and interobserver agreement within and between techniques using the intraclass correlation coefficient and Bland-Altman methodology. We then developed a multilevel prediction model of TBV based on linear measurements from both US and MRI, compared them and explored how they changed with increasing age. The multilevel prediction model for TBV from linear measures was tested for internal and external validity and we developed a reference table for ease of prediction of TBV. Results: We used measurements obtained from 426 US and 93 MRI scans from 118 patients. We found good intra- and interobserver agreement for all the measurements. US measurements were reliable when compared to MRI, including TBV which achieved excellent agreement with that of MRI [ICC of 0.98 (95% CI 0.96-0.99)]. TBV estimated through 2D measurements of biparietal diameter, anteroposterior axis, and vertical axis was comparable among both techniques. We estimated the population 95% confidence interval for the mean values of biparietal diameter, anteroposterior axis, vertical axis, and total brain volume by post-menstrual age. A TBV prediction table based on the three axes is proposed to enable easy implementation of TBV estimation in routine 2D US during admission in the NICU. Conclusions: US measurements of biparietal diameter, vertical axis, and anteroposterior axis are reliable. TBV segmented through 3D US is comparable to MRI estimated TBV. 2D US accurate estimation of TBV is possible through biparietal diameter, vertical, and anteroposterior axes.

Signal Intensity and Volume of Pituitary and Thyroid Glands in Preterm and Term Infants

BACKGROUND

Hypothalamic-pituitary-thyroid (HPT) maturation has not been extensively evaluated using neonatal MRI, even though both structures are visualized on MRI.

HYPOTHESIS

That signal intensity and volume of pituitary and thyroid (T) glands on MRI in neonates may be interrelated.

STUDY TYPE

Retrospective.

SUBJECTS

In all, 102 participants.

FIELD STRENGTH/SEQUENCE

3.0T, T₁ -weighted pointwise encoding time reduction with radial acquisition (PETRA).

ASSESSMENT

The volume of interest of the anterior pituitary (AP), posterior pituitary (PP), and T on MRI were defined on T₁ -PETRA by two radiologists, and volumes of AP (AP_vol) and thyroid (T_vol) were calculated. Gestational age (GA), chronological age (CA), GA+CA, birth weight (BW), and thyroid function were recorded. Mean and maximum signal intensities of AP, PP, and T were normalized using signals from the pons and spinal cord as follows: signal ratio of anterior pituitary/pons (AP/pons), signal ratio of posterior pituitary/pons (PP/pons), and signal ratio of thyroid/cord (T/cord) T/cord, respectively.

STATISTICAL TESTS

Correlations between signal intensity and volume measures and GA, CA, GA+CA, and BW were assessed using Pearson's correlation coefficient or Spearman's rank correlation coefficient. Thyroid function analysis and T_mean /cord, T_max /cord, and T_vol were evaluated using the Steel-Dwass test.

RESULTS

AP_mean /pons correlated positively with GA (ρ = 0.62, P < 0.001) and BW (ρ = 0.74, P < 0.001), and negatively with CA (ρ = -0.86, P < 0.001) and GA+CA (ρ = -0.46, P < 0.001). PP_mean /pons correlated positively with GA (ρ = 0.49, P < 0.001) and BW (ρ = 0.63, P < 0.001), and negatively with CA (ρ = -0.70, P < 0.001) and GA+CA (r = -0.38, P < 0.001). T_mean /cord correlated positively with GA (ρ = 0.48, P < 0.001) and BW (ρ = 0.55, P < 0.001), and negatively with CA (ρ = -0.59, P < 0.001) and GA+CA (ρ = -0.22, P = 0.03). AP_vol correlated positively with GA (ρ = 0.68, P < 0.001) and BW (ρ = 0.73, P < 0.001), and negatively with CA (ρ = -0.72, P < 0.001). T_vol correlated positively with GA (ρ = 0.50, P < 0.001) and BW (ρ = 0.61, P < 0.001), and negatively with CA (ρ = -0.54, P < 0.001). AP_mean /pons correlated positively with T_mean /cord (ρ = 0.61, P < 0.001).

DATA CONCLUSION

Signal and volume of pituitary and thyroid glands correlated positively with GA and BW, and negatively with CA in neonates.

LEVEL OF EVIDENCE

4 TECHNICAL EFFICACY STAGE: 5.

Linear growth of corpus callosum and cerebellar vermis in very-low-birth-weight preterm infants

BACKGROUND/PURPOSE

Impaired growth of the corpus callosum (CC) and cerebellar vermis (CV) is associated with poorer neurodevelopmental outcomes in preterm infants. However, references on the postnatal growth rate of the CC and CV by sonography are limited. The aim of this study is to assess the normal linear growth of CC and CV using a serial cranial ultrasound.

METHODS

We prospectively enrolled preterm infants with very low birth weight from September 2008 to December 2009 after excluding those with congenital anomalies or diseases affecting the brain parenchyma. Serial sonographic measurements of the CC and CV were performed according to the standard protocol. Scheduled comprehensive neurodevelopmental evaluations were performed till the corrected age of 2 years. We excluded those with significant brain damages or poor neurodevelopmental outcomes in the final analysis. The growth rate was estimated using the loess smoothing curve and linear regression analysis.

RESULTS

Among the 86 enrolled neonates, 14 with significant brain damage and 8 with poor neurodevelopmental outcomes were excluded from the final analysis. The growth rate of the CC length was 1.72 (95% confidence interval [CI]: 1.24-2.20) and 0.57 (95% CI: 0.33-0.80) mm per week before and after the postmenstrual age of 30.5 weeks, respectively. The growth rate of the CV length was 0.78 (95% CI: 0.68-0.89) mm per week.

CONCLUSION

We proposed reference values of the normal linear growth rate of the CC and CV lengths in very-low-birth-weight preterm infants using the serial cranial ultrasound.

Lipid/PLGA Hybrid Microbubbles as a Versatile Platform for Noninvasive Image-Guided Targeted Drug Delivery

Microbubbles (MBs) have recently emerged as promising theranostic carriers for ultrasound contrast imaging and drug delivery. However, conventional lipid-based MBs have a poor drug encapsulation efficiency, and polymer-based MBs show a weak capability in contrast imaging and ultrasound-triggered drug release. Here, we developed a novel type of multiporous lipid/PLGA hybrid MBs (lipid/PLGA MBs) that solved the dilemma of MBs as imaging agents and drug carriers. The lipid/PLGA MBs were designed through regulating the elasticity of the bubble shells using lipids to incorporate into the PLGA shells and ammonium bicarbonate as a gas-generating agent. The softened shells and the porous bubble structure make them be able to generate stronger harmonic signals and be more vulnerable to ultrasound irradiation, leading to their excellent performance in ultrasound contrast imaging and ultrasound-triggered MB destruction in vitro and in vivo. By using doxorubicin (Dox) as a model drug, the Dox-loaded lipid/PLGA MBs (Dox-lipid/PLGA MBs) were prepared and achieved a high drug encapsulation efficiency. The real-time tracking of drug delivery and on-command controlled drug release by ultrasound were successfully realized in the tumor-bearing mice. A significantly enhanced tumor growth inhibition effect could be observed when using Dox-lipid/PLGA MBs combined with ultrasound irradiation, compared with free Dox and Dox-lipid/PLGA MBs without ultrasound. Our study provides an innovative multifunctional platform of MBs for ultrasound contrast imaging and drug delivery applications.