Tract-Based Spatial Statistics in Preterm-Born Neonates Predicts Cognitive and Motor Outcomes at 18 Months

BACKGROUND AND PURPOSE

Adverse neurodevelopmental outcome is common in children born preterm. Early sensitive predictors of neurodevelopmental outcome such as MR imaging are needed. Tract-based spatial statistics, a diffusion MR imaging analysis method, performed at term-equivalent age (40 weeks) is a promising predictor of neurodevelopmental outcomes in children born very preterm. We sought to determine the association of tract-based spatial statistics findings before term-equivalent age with neurodevelopmental outcome at 18-months corrected age.

MATERIALS AND METHODS

Of 180 neonates (born at 24-32-weeks' gestation) enrolled, 153 had DTI acquired early at 32 weeks' postmenstrual age and 105 had DTI acquired later at 39.6 weeks' postmenstrual age. Voxelwise statistics were calculated by performing tract-based spatial statistics on DTI that was aligned to age-appropriate templates. At 18-month corrected age, 166 neonates underwent neurodevelopmental assessment by using the Bayley Scales of Infant Development, 3rd ed, and the Peabody Developmental Motor Scales, 2nd ed.

RESULTS

Tract-based spatial statistics analysis applied to early-acquired scans (postmenstrual age of 30-33 weeks) indicated a limited significant positive association between motor skills and axial diffusivity and radial diffusivity values in the corpus callosum, internal and external/extreme capsules, and midbrain (P < .05, corrected). In contrast, for term scans (postmenstrual age of 37-41 weeks), tract-based spatial statistics analysis showed a significant relationship between both motor and cognitive scores with fractional anisotropy in the corpus callosum and corticospinal tracts (P < .05, corrected). Tract-based spatial statistics in a limited subset of neonates (n = 22) scanned at <30 weeks did not significantly predict neurodevelopmental outcomes.

CONCLUSIONS

The strength of the association between fractional anisotropy values and neurodevelopmental outcome scores increased from early-to-late-acquired scans in preterm-born neonates, consistent with brain dysmaturation in this population.

Brain injury patterns in hypoglycemia in neonatal encephalopathy

BACKGROUND AND PURPOSE

Low glucose values are often seen in term infants with NE, including HIE, yet the contribution of hypoglycemia to the pattern of neurologic injury remains unclear. We hypothesized that MR features of neonatal hypoglycemia could be detected, superimposed on the predominant HIE injury pattern.

MATERIALS AND METHODS

Term neonates (n = 179) with NE were prospectively imaged with day-3 MR studies and had glucose data available for review. The predominant imaging pattern of HIE was recorded as watershed, basal ganglia, total, focal-multifocal, or no injury. Radiologic hypoglycemia was diagnosed on the basis of selective edema in the posterior white matter, pulvinar, and anterior medial thalamic nuclei. Clinical charts were reviewed for evidence of NE, HIE, and hypoglycemia (<46 mg/dL).

RESULTS

The predominant pattern of HIE injury imaged included 17 watershed, 25 basal ganglia, 10 total, 42 focal-multifocal, and 85 cases of no injury. A radiologic diagnosis of hypoglycemia was made in 34 cases. Compared with laboratory-confirmed hypoglycemia, MR findings had a positive predictive value of 82% and negative predictive value of 78%. Sixty (34%) neonates had clinical hypoglycemia before MR imaging. Adjusting for 5-minute Apgar scores and umbilical artery pH with logistic regression, clinical hypoglycemia was associated with a 17.6-fold higher odds of MR imaging identification (P < .001). Selective posterior white matter and pulvinar edema were most predictive of clinical hypoglycemia, and no injury (36%) or a watershed (32%) pattern of injury was seen more often in severe hypoglycemia.

CONCLUSIONS

In term infants with NE and hypoglycemia, specific imaging features for both hypoglycemia and hypoxia-ischemia can be identified.

Clinically silent preoperative brain injuries do not worsen with surgery in neonates with congenital heart disease

OBJECTIVE

Preoperative brain injury, particularly stroke and white matter injury, is common in neonates with congenital heart disease. The objective of this study was to determine the risk of hemorrhage or extension of preoperative brain injury with cardiac surgery.

METHODS

This dual-center prospective cohort study recruited 92 term neonates, 62 with transposition of the great arteries and 30 with single ventricle physiology, from 2 tertiary referral centers. Neonates underwent brain magnetic resonance imaging scans before and after cardiac surgery.

RESULTS

Brain injury was identified in 40 (43%) neonates on the preoperative magnetic resonance imaging scan (median 5 days after birth): stroke in 23, white matter injury in 21, and intraventricular hemorrhage in 7. None of the brain lesions presented clinically with overt signs or seizures. Preoperative brain injury was associated with balloon atrial septostomy (P = .003) and lowest arterial oxygen saturation (P = .007); in a multivariable model, only the effect of balloon atrial septostomy remained significant when adjusting for lowest arterial oxygen saturation. On postoperative magnetic resonance imaging in 78 neonates (median 21 days after birth), none of the preoperative lesions showed evidence of extension or hemorrhagic transformation (0/40 [95% confidence interval: 0%-7%]). The presence of preoperative brain injury was not a significant risk factor for acquiring new injury on postoperative magnetic resonance imaging (P = .8).

CONCLUSIONS

Clinically silent brain injuries identified preoperatively in neonates with congenital heart disease, including stroke, have a low risk of progression with surgery and cardiopulmonary bypass and should therefore not delay clinically indicated cardiac surgery. In this multicenter cohort, balloon atrial septostomy remains an important risk factor for preoperative brain injury, particularly stroke.

MR Quantification of Flow in Children with Vascular Malformations

SUMMARY

The evaluation of treatments such as embolization, stereotactic radiation, and even surgery would be enhanced by an objective method of measuring flow in feeding arteries or draining veins. We developed a non-invasive method of measuring vascular flow using cardiac gated phase contrast MR angiography (MR Q flow). The purpose of this work was to employ the same technique in a series of patients with vascular malformations of the head and neck. We selected a series of vascular malformations with simple arterial and venous architecture and significantly smaller vessel diameters than that encountered with Vein of Calen Malformations. Our aim was to determine the reproducibility of the derived flow values by using multiple velocity encoded sequences (VENC) and compare the values derived from the arterial feeders to the venous outflow data. There are inherent technical difficulties with assessing flow through multiple arterial feeders or draining veins, so the technique is most easily applied to AVMs with simple, easily defined feeding arteries or draining veins. Nonetheless, this technique is relatively straightforward to learn, rapid, cost-effective and may provide an objective means to assess therapeutic maneuvers when applied to head and neck vascular malformations.

MR Quantification of Flow in Children with Vein of Galen Malformations

SUMMARY

Vein of Galen vascular malformations are either Vein of Galen Aneurysmal malformations (VGAMs) or Vein of Galen Aneurysmal Dilatations (VGADs). VGAMs may be of the choroidal or mural type and are fistulas associated with the precursor of the vein of Galen. The treatment of VGAMs is aimed at controlling the size of the vascular shunt since it is believed that the shunt is responsible for venous hypertension, cardiac stress, delayed development and may be so large as to damage the brain. In VGAMs as noted by Berenstein and Lasjaunias. Absolute measures of flow may contribute to our understanding of CNS disease and permit objective measures of the success or failure of therapeutic interventions (5). MR phase contrast cine angiographic techniques can be employed to measure bulk flow in intracranial vessels. Vein of Galen vascular malformations are an ideal model to measure venous flow as the draining vein is large and angiographic evaluation is limited. Thus our goal was to develop an objective non-invasive method of measuring vascular flow in VGAMs and VGADs (6) . Herein we report our experience using this technique in a group of patients with Vein of Galen vascular malformations. We also hypothesized that the degree of shunting would correlate to the degree of cardiac stress and be an indicator of optimal timing for intervention. We believe that we have succeeded in our goal to develop an objective, non-invasive method of shunt quantification using velocity encoded MR sequences. This promises new insight into the hemodynamics, natural history and treatment response of vascular malformations.

Postvaricella angiopathy: report of a case with pathologic correlation

Varicella is a common childhood illness, and central nervous system complications occur frequently. Delayed angiopathy has been described, although there are few reports of clinicopathologic correlation. A previously well 4-year-old male is presented. He suffered varicella 2 months before presentation with extensive right middle cerebral artery (MCA) territory infarction. Cerebral angiography demonstrated an isolated 89% stenosis of the right proximal MCA. He developed cerebral edema refractory to medical treatment and progressed to transtentorial herniation. Right frontal temporoparietal craniotomies were performed with evacuation of infarcted brain tissue. Pathologic studies revealed small vessel vasculitis with lymphocytic infiltration of the vessel wall. Areas of demyelination were present within the white matter. Polymerase chain reaction for varicella was negative on brain tissue. Postvaricella angiopathy, although an uncommon complication, may affect both small and large blood vessels, with catastrophic results.

Application of a three-point method for water-fat MR imaging in children

BACKGROUND

Effective fat suppression is desirable in clinical magnetic resonance imaging. Conventional frequency selective fat suppression is dependent on accurate prescan shimming and is subject to artifacts due to magnetic field inhomogeneity. Quadrature three-point water-fat imaging with direct phase encoding is an alternative technique for fat suppression that has been previously described in adult volunteers and patients.

OBJECTIVE

To evaluate the use of three-point water-fat imaging with direct phase encoding for fat-suppressed MR scans in children.

MATERIALS AND METHODS

Sixty-two three-point water-fat imaging studies were performed in 55 children 2 months to 18 years old. T 1-weighted fat-suppressed (water) images from this sequence were compared with frequency selective fat-suppressed images obtained in 15 patients. The reliability and subjective quality of the sequence were assessed in the remaining 47 cases.

RESULTS

High-quality fat suppression was achieved in all anatomic sites studied, even where frequency selective fat-suppression failed due to magnetic susceptibility artifact. The three-point water-fat sequence was visually preferred to the frequency selective fat saturation technique in 15/15 cases.

CONCLUSION

Three-point water-fat imaging has replaced the conventional frequency selective technique for fat suppression on T 1-weighted MR imaging at our institution.

Encephalopathy complicating Henoch-Schönlein purpura: reversible MRI changes

A 10-year-old boy with Henoch-Schönlein purpura complicated by encephalopathy, transient cortical blindness, and a secondary generalized seizure is reported. Reversible changes in the posterior white and gray matter were seen on magnetic resonance imaging. Our patient illustrates uncommon neurologic manifestations of Henoch-Schönlein purpura. The nature and location of the lesions and the normalization of the patient's magnetic resonance imaging is consistent with a posterior predominant parieto-occipital encephalopathy and suggests that cerebral edema from blood-brain barrier breakdown may play a central role in the pathophysiology of the central nervous system symptomatology in some patients.

Speech, cognition, and imaging studies in congenital ocular motor apraxia

Detailed neurological, speech and language, psychological, and neuroimaging studies were carried out in eight children with the diagnosis of congenital ocular motor apraxia. The neurological examination showed clinical evidence of cerebellar vermis abnormality (hypotonia and truncal ataxia) in all cases. Neuroimaging studies suggested that the site of neuropathological disturbance of congenital ocular motor apraxia was the inferior vermis. Half of the subjects had associated speech apraxia. The most likely location of brain disturbance, which was responsible for the speech apraxia, was also an as yet undefined area of the vermis. Psychological testing consistently revealed visual-spatial difficulties. These may have been secondary to cerebellar pathology or to developmentally inappropriate sensory input caused by the abnormal saccades. Children with speech apraxia appear to be slightly more affected neurologically than those with normal speech.

Fast fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging of the brain: a comparison of multi-shot echo-planar and fast spin-echo techniques

PURPOSE

To evaluate fast spin-echo and multi-shot echo-planar fluid-attenuated inversion recovery (FLAIR) sequences in paediatric brain imaging.

MATERIALS AND METHODS

Matched images from 32 patients with suspected tumour or white matter disease were independently evaluated by two paediatric neuroradiologists. The observer preferences for image quality and lesion detection were analysed for differences between fast spin-echo FLAIR and multi-shot echo-planar FLAIR. Diagnostic quality was compared with that of fast spin-echo T2-weighted images.

RESULTS

Images of a diagnostic quality equivalent to that of fast spin-echo T2-weighted images were achieved with both FLAIR techniques. Grey and white matter differentiation and cerebrospinal fluid (CSF) nulling were significantly better on fast spin-echo FLAIR sequences. CSF flow artefact was reduced on multi-shot echo-planar FLAIR. There was no difference in lesion detection. Fast spin-echo FLAIR images were visually preferred at the expense of longer imaging time.

CONCLUSION

Fast FLAIR techniques are complementary to fast spin-echo T2-weighted sequences in imaging of the paediatric brain. We find that the fast spin-echo FLAIR sequence is preferable to the multi-shot echo-planar technique.

Congenital ocular motor apraxia: imaging findings

PURPOSE

To determine the frequency of cerebellar and cerebral abnormalities on brain imaging studies in children with congenital ocular motor apraxia.

METHODS

Brain imaging studies were performed in 19 children with typical congenital ocular motor apraxia who were in the care of a visual impairment program at a children's hospital. Independent clinical review categorized the subjects as having partial (n = 10) or expanded (n = 9) congenital ocular motor apraxia on the basis of extent of associated speech or neurodevelopmental problems. Fifteen CT studies and 13 MR examinations of the brain performed in these children were reviewed independently by two pediatric neuroradiologists. Radiologic findings were agreed on by consensus.

RESULTS

Cerebellar abnormalities were found in 12 of 19 cases. The cerebellar vermis was small in 10 children. A small cerebellar vermis was the only abnormality in five of 10 children with partial congenital ocular motor apraxia and in two of nine children with expanded congenital ocular motor apraxia. Among seven children with a small vermis examined with high-resolution MR imaging, the inferior portion of the vermis was preferentially involved in each case. Of these seven subjects, none of four with partial congenital ocular motor apraxia but two of three with expanded congenital ocular motor apraxia had an abnormality of the superior portion of the vermis. Miscellaneous supratentorial lesions affecting both gray and white matter were found in six subjects. Five of the 19 children had normal imaging findings.

CONCLUSION

Inferior vermian hypoplasia is the most common abnormality in children with congenital ocular motor apraxia.

Hydrocephalus, mineralizing angiopathy, hypercholesterolemia, and hyperlipoprotein (a)

A boy born at 34 weeks gestation with initially normal development presented with acute hydrocephalus at 22 months. Subsequently his development has been slow and complicated clinically by epilepsy. Upon extensive investigation, he has been found to have extremely elevated lipoprotein(a) levels, hypercholesterolemia (familial), and lesions of the cortex and meninges. Radiologic studies have disclosed a mineralizing angiopathy.

Duplication of 9P and hyperplasia of the choroid plexus: a pathologic, radiologic, and molecular cytogenetics study

Duplication of the short arm of chromosome 9 is a rare constitutional abnormality, and the presence of pathologically confirmed hyperplasia of the choroid plexus in one of two cases, and a choroid plexus papilloma in another, raises the possibility of a relationship between the 9p abnormality and abnormal growth of the choroid plexus. Molecular cytogenetic analysis using fluorescence in situ hybridization was used for detection of chromosome 9-derived material in various formalin-fixed choroid plexus abnormalities. Extra copies of chromosome 9-derived material was found in the hyperplastic choroid plexus and in a choroid plexus carcinoma. These findings suggest that there may be an association between duplication of chromosome 9 material and abnormal development of the choroid plexus.

Comparison of stimulable phosphor technology and conventional screen-film technology in pediatric scoliosis

One hundred consecutive patients being investigated for scoliosis were studied using a double cassette containing a conventional film screen and a stimulable phosphor plate. The images were separated, randomised and scored thrice by three radiologists for anatomic structure visualisation. The exposure to the plate and film and repeat rate were measured. Scoliosis angles were comparable on both sets of images, however, visualisation of vertebrae, vertebral end plates, pedicles, spinous processes and other structures were significantly improved (p < 0.0001). Intra- and inter-observer reliability was high with good intraclass correlation. There was a 40% potential exposure reduction, and retakes were decreased from 3 to 0%. We conclude that stimulable phosphor images give better anatomic structure visualisation with potential radiation exposure reduction and lower repeat rate.

Prevention of postshunting ventricular asymmetry by transseptal placement of ventricular catheters. A randomized study

Ventricular asymmetry is common after ventricular shunting, and occasionally isolation of the contralateral ventricle necessitates a second shunt. The following study was performed to determine whether contralateral placement of the ventricular catheter via ultrasound-guided perforation of the septum pellucidum would decrease the incidence of postshunting ventricular asymmetry which might predispose to symptomatic isolation of a lateral ventricle. Fifty-eight children with hydrocephalus and an open fontanel, who were having a ventriculo-peritoneal shunt via a parieto-occipital approach, were randomized to have the ventricular catheter tip placed into either the ipsilateral or the contralateral frontal horn. Ventricular asymmetry occurred in 23% of the patients with contralateral versus 54% with ipsilateral placement (chi 2 = 5.53; p = 0.019). In 7 patients with contralateral placement, in whom a special catheter with two sets of holes was used, such that holes were located in both ventricles, no shunt-related ventricular asymmetry occurred. In 2 children with ipsilateral placement, a second shunt was required for a symptomatic isolated lateral ventricle. Perforation of the septum pellucidum with placement of the ventricular catheter in the contralateral ventricle, using a specially designed catheter with two sets of holes, may decrease the incidence of postshunting ventricular asymmetry and symptomatic isolation of a lateral ventricle.

Surgical implications of cerebral dysgenesis

Cerebral dysgenesis encompasses varied disorders of brain development. Based on the understanding of these conditions provided by histopathologists, embryologists, radiologists and developmental pediatricians, surgeons are able to appropriately assist in the care of these patients. The surgeon can offer assessment of the ventriculomegaly that commonly accompanies cerebral dysgenesis in addition to providing methods to control hydrocephalus, to reconstruct cranial and facial malformations and to remove dysfunctional tissue. For most patients, surgical intervention is only one of the many factors that determine developmental prognosis. Based on the foundation built by other specialists, this review discusses cerebral dysgenesis from the perspective of historical and current surgical interventions.

Ruptured intracranial aneurysm presenting as cerebral infarction in a young child

We describe a 15-month-old girl who presented with an acute hemiplegia. The sequence of events appears to have been clinically silent subarachnoid hemorrhage, vasospasm, infarction and a second lethal hemorrhage 3 months later. The old infarction was seen on computed tomography during her second illness. Autopsy confirmed the presence of a recent rupture of an intracranial aneurysm and old hemorrhage. In addition there was an unusual fibroblastic proliferation in the aneurysm wall. This case demonstrates that clinically silent subarachnoid hemorrhage, vasospasm and infarction can occur as complications of aneurysms, even in very young children.

Methotrexate leukoencephalopathy mimicking cerebral abscess on CT brain scan

A case is reported of methotrexate leukoencephalopathy presenting as an intracerebral rim-enhancing mass lesion of CT scan. The implications of this rare presentation of methotrexate leukoencephalopathy for therapy are discussed.

Sonography and CT in staging nonseminomatous testicular tumors

The usefulness of sonography and computed tomography (CT) in the clinical staging of nonseminomatous testes tumors was examined by retrospectively reviewing the clinical staging of 57 patients. Twenty-five patients had sonographic examinations; two were considered inadequate and there were no false-positive results. Understaging occurred in 13% (3/23), while the negative predictive value for sonography was 73% (8/11). CT was performed on 29 patients; no patients were overstaged and only one examination was inadequate due to technical reasons. Understaging occurred in 18% (5/28), and CT had a negative predictive value of 67% (8/12). A subgroup of 18 patients having both sonography and CT was examined, and each staging procedure had a 22% false-negative and a 0 false-positive rate. Twenty-seven lymphangiograms, 28 excretory urograms, and 49 tumor marker determinations were also performed on this patient population, and their false-negative rates were 35%, 78%, and 61%, respectively. False-positive rates of 30% for lymphangiograms, 6% for tumor markers, and 0 for excretory urograms were also obtained. On the basis of these results, sonography and CT are equivalent and superior examinations that have a high degree of accuracy (90%) in predicting bulky metastatic disease, either stage B3 or C disease. All patients would have received appropriate therapy if both examinations were carried out. However, this same goal could have been achieved with greater cost efficiency by initial sonographic screening, followed by CT in only those patients with negative or inadequate sonographic examinations.