Susceptibility-weighted imaging in pediatric neuroimaging

Bilateral orthogonality generative acquisitions method for homogeneous T 2 * images using parallel transmission at 7 T

PURPOSE

The novel bilateral orthogonality generative acquisitions method has been developed for homogeneousT 2 * $$ {\mathrm{T}}_2^{\ast } $$ images without the effects of transmit field inhomogeneity using a parallel-transmission (pTx) system at 7 T.

THEORY AND METHODS

A new method has been introduced using four low-angle gradient-echo (GRE) acquisitions to obtain homogeneousT 2 * $$ {\mathrm{T}}_2^{\ast } $$ contrast by removing the effects of transmit field inhomogeneity in the pTx system. First, two input images are obtained in circularly polarized mode and another mode in which the first transmit channel or channel group have an additional transmit phase of π. The last two acquisitions are single-channel acquisitions for a dual-channel system or single-channel group acquisitions for more than two channels. The introduced method is demonstrated in dual-channel and eight-channel pTx systems using phantom and whole-brain in vivo experiments. Noise performance of the proposed method is also tested against the ratio of two GRE acquisitions and the TIAMO (time-interleaved acquisitions of modes) method.

RESULTS

Th new method results in more homogeneousT 2 * $$ {\mathrm{T}}_2^{\ast } $$ contrast in the final images than the compared methods, particularly in the low-intensity regions of circularly polarized-mode images for the images obtained via ratio of the two GRE acquisitions.

CONCLUSION

The introduced method is easy to implement, robust, and provides homogeneousT 2 * $$ {\mathrm{T}}_2^{\ast } $$ images of the whole brain using pTx systems with any number of channels, compared with the ratio of the two GRE images and the TIAMO method.

MR imaging and outcome in neonatal HIBD models are correlated with sex: the value of diffusion tensor MR imaging and diffusion kurtosis MR imaging

Objective

Hypoxic-ischemic encephalopathy can lead to lifelong morbidity and premature death in full-term newborns. Here, we aimed to determine the efficacy of diffusion kurtosis (DK) [mean kurtosis (MK)] and diffusion tensor (DT) [fractional anisotropy (FA), mean diffusion (MD), axial diffusion (AD), and radial diffusion (RD)] parameters for the early diagnosis of early brain histopathological changes and the prediction of neurodegenerative events in a full-term neonatal hypoxic-ischemic brain injury (HIBD) rat model.

Methods

The HIBD model was generated in postnatal day 7 Sprague-Dawley rats to assess the changes in DK and DT parameters in 10 specific brain structural regions involving the gray matter, white matter, and limbic system during acute (12 h) and subacute (3 d and 5 d) phases after hypoxic ischemia (HI), which were validated against histology. Sensory and cognitive parameters were assessed by the open field, novel object recognition, elevated plus maze, and CatWalk tests.

Results

Repeated-measures ANOVA revealed that specific brain structures showed similar trends to the lesion, and the temporal pattern of MK was substantially more varied than DT parameters, particularly in the deep gray matter. The change rate of MK in the acute phase (12 h) was significantly higher than that of DT parameters. We noted a delayed pseudo-normalization for MK. Additionally, MD, AD, and RD showed more pronounced differences between males and females after HI compared to MK, which was confirmed in behavioral tests. HI females exhibited anxiolytic hyperactivity-like baseline behavior, while the memory ability of HI males was affected in the novel object recognition test. CatWalk assessments revealed chronic deficits in limb gait parameters, particularly the left front paw and right hind paw, as well as poorer performance in HI males than HI females.

Conclusions

Our results suggested that DK and DT parameters were complementary in the immature brain and provided great value in assessing early tissue microstructural changes and predicting long-term neurobehavioral deficits, highlighting their ability to detect both acute and long-term changes. Thus, the various diffusion coefficient parameters estimated by the DKI model are powerful tools for early HIBD diagnosis and prognosis assessment, thus providing an experimental and theoretical basis for clinical treatment.

Magnetic Resonance Imaging in (Near-)Term Infants with Hypoxic-Ischemic Encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is a major cause of neurological sequelae in (near-)term newborns. Despite the use of therapeutic hypothermia, a significant number of newborns still experience impaired neurodevelopment. Neuroimaging is the standard of care in infants with HIE to determine the timing and nature of the injury, guide further treatment decisions, and predict neurodevelopmental outcomes. Cranial ultrasonography is a helpful noninvasive tool to assess the brain before initiation of hypothermia to look for abnormalities suggestive of HIE mimics or antenatal onset of injury. Magnetic resonance imaging (MRI) which includes diffusion-weighted imaging has, however, become the gold standard to assess brain injury in infants with HIE, and has an excellent prognostic utility. Magnetic resonance spectroscopy provides complementary metabolic information and has also been shown to be a reliable prognostic biomarker. Advanced imaging modalities, including diffusion tensor imaging and arterial spin labeling, are increasingly being used to gain further information about the etiology and prognosis of brain injury. Over the past decades, tremendous progress has been made in the field of neonatal neuroimaging. In this review, the main brain injury patterns of infants with HIE, the application of conventional and advanced MRI techniques in these newborns, and HIE mimics, will be described.

Potential role of susceptibility-weighted imaging in the diagnosis of non-neoplastic pediatric neurological diseases

Background

This study aimed to assess the added value and current applications of SWI in the diagnosis of pediatric non-neoplastic neurological diseases, including its ability to characterize hemorrhage in various brain lesions and its important role in the evaluation of both arterial as well as venous ischemic brain lesions.

Results

Forty pediatric patients with a median age of 9 years were included in our prospective study; 23 were males and 17 females. SWI had a significantly higher detection rate than conventional MRI for traumatic brain injury (TBI) lesions, hemorrhagic lesions in acute necrotizing encephalopathy (ANEC), and cavernoma lesions (p = 0.005, p = 0.038, and p = 0.046, respectively). The sensitivity, specificity and accuracy of SWI for the detection of venous ischemic insult was 88.9%, 50%, and 76.9% respectively. SWI was significantly better than the conventional MRI (p = 0.046) for the detection of chronic ischemic brain insults and ischemic lesions with added hemorrhagic components.

Conclusion

SWI is a technique with reasonable acquisition time that could improve the diagnostic performance of MRI for the evaluation of various pediatric non-neoplastic neurological diseases.

Fetal MRI assessment of posterior fossa anomalies: A review

Prenatal ultrasound (US) is the first prenatal imaging tool for screening and evaluation of posterior fossa malformations since it is noninvasive, widely available, and safe for both mother and child. Fetal MRI is a widely used secondary technique to confirm, correct, or complement questionable US findings and plays an essential role in evaluating fetuses with suspected US findings and /or positive family history. The main sequences of fetal MRI consist of T2-weighted (T2w) ultrafast, single-shot sequences. Axial, coronal, and sagittal images are typically acquired allowing for a detailed evaluation of the posterior fossa contents. Also, various complimentary sequences, such as T1w, T2*w gradient sequences, or advanced techniques, including diffusion-weighted imaging, diffusion tensor imaging, and magnetic resonance spectroscopy, may provide additional information based on the studied malformation. Inclusion of these techniques should be done with careful risk-benefit analysis. The use of fetal MRI also aims to evaluate for associated anomalies. In addition, prenatal diagnosis of posterior fossa malformations is still a challenge but advances in knowledge in human developmental anatomy, genetic, and imaging recognition patterns have enabled us to shed some light on prognostic information that will help with the counseling of families. Finally, high-resolution late third trimester fetal MRI offers a safe alternative to early postnatal MR imaging, basically taking advantage of the uterine environment as a kind of "maternal incubator." Our goal is to discuss the spectrum of prenatal posterior fossa pathologies that can be studied by fetal MRI and their key neuroimaging features.

Quantitative Susceptibility Mapping of Venous Vessels in Neonates with Perinatal Asphyxia

BACKGROUND AND PURPOSE

Cerebral venous oxygen saturation can be used as an indirect measure of brain health, yet it often requires either an invasive procedure or a noninvasive technique with poor sensitivity. We aimed to test whether cerebral venous oxygen saturation could be measured using quantitative susceptibility mapping, an MR imaging technique, in 3 distinct groups: healthy term neonates, injured term neonates, and preterm neonates.

MATERIALS AND METHODS

We acquired multiecho gradient-echo MR imaging data in 16 neonates with perinatal asphyxia and moderate or severe hypoxic-ischemic encephalopathy (8 term age: average, 40.0 [SD, 0.8]  weeks' gestational age; 8 preterm, 33.5 [SD, 2.0]  weeks' gestational age) and in 8 healthy term-age controls (39.3 [SD, 0.6] weeks, for a total of n = 24. Data were postprocessed as quantitative susceptibility mapping images, and magnetic susceptibility was measured in cerebral veins by thesholding out 99.95% of lower magnetic susceptibility values.

RESULTS

The mean magnetic susceptibility value of the cerebral veins was found to be 0.36 (SD, 0.04) ppm in healthy term neonates, 0.36 (SD, 0.06) ppm in term injured neonates, and 0.29 (SD, 0.04) ppm in preterm injured neonates. Correspondingly, the derived cerebral venous oxygen saturation values were 73.6% (SD, 2.8%), 71.5% (SD, 7.4%), and 72.2% (SD, 5.9%). There was no statistically significant difference in cerebral venous oxygen saturation among the 3 groups (P = .751).

CONCLUSIONS

Quantitative susceptibility mapping-derived oxygen saturation values in preterm and term neonates agreed well with values in past literature. Cerebral venous oxygen saturation in preterm and term neonates with hypoxic-ischemic encephalopathy, however, was not found to be significantly different between neonates or healthy controls.

Rare Abnormality of the Posterior Fossa: Unilateral İsolated Cerebellar Hypoplasia

The cerebellum abnormalities may be hypoplastic, dysplastic, or hypoplastic. It is very rare that the cerebellar hemisphere is affected unilaterally in the posterior fossa abnormalities. The reason for this effect is mostly sequela. This pathology presents with neuromotor developmental abnormalities. In this presentation, isolated left cerebellar hypoplasia is described radiologically in a 21-month-old male patient with neuromotor development defects. Dysplastic appearance was noticeable in the observable part of the left cerebellar hemisphere and folia. The cerebellar vermis could not be shaped. The right cerebellar hemisphere, other posterior fossa formations, and supratentorial area were natural. In patients with neuromuscular abnormalities, the posterior fossa is applied with care. It should be remembered that cerebellar hypoplasia and dysplasia can be unilateral.

Microcephaly, Hypotonia, and Intracranial Calcifications in an 11-Week-Old Boy

An 11-week-old unvaccinated, term Amish boy initially presented with poor feeding, microcephaly, failure to thrive, and developmental delays. His physical examination was significant for both weight and head circumference being less than the third percentile, and he was noted to have micrognathia, truncal hypotonia, and head lag. He was admitted to the pediatric hospital medicine service for further diagnostic evaluation. Laboratory studies assessing for endocrinological and metabolic etiologies yielded negative results, and imaging studies (including a chest radiograph, echocardiogram, and abdominal ultrasound) were normal. However, intracranial calcifications were noted on a head ultrasound. The etiology of his constellation of symptoms was initially thought to be infectious, but the ultimate diagnosis was not made until after discharge from the pediatric hospital medicine service.

Value of susceptibility-weighted MR imaging (SWI) in the detection of developmental venous anomaly

Background

Developmental venous anomaly (DVA) is probably the most common anomaly of the intracranial vasculature. DVAs consist of multiple, radially oriented dilated medullary veins that converge into a transcerebral vein. Susceptibility-weighted imaging (SWI) is a high spatial resolution 3D gradient-echo MRI sequence with phase post-processing that accentuates the paramagnetic properties of blood products such as deoxyhemoglobin, intracellular methemoglobin, and hemosiderin. Its high sensitivity to hemorrhagic particles by means of susceptibility dephasing effects within the veins allow for the accurate detection, grading, and monitoring of brain venous anomalies. In this review, we evaluated the prevalence of the brain DVAs identified by SWI in many patients who had undergone magnetic resonance imaging (MRI) with contrast administration. All images were independently reviewed by two radiologists who were blinded to other MR imaging finding. It is hoped that as SWI becomes more widely available, it will provide additional diagnostic and prognostic information that will improve the care and outcome of patients with DVAs.

Results

A total of 29 DVAs were observed with its prevalence 2.8%. The DVA caputs had mostly deep localization in about 44.8% of our DVA cases. SWI proved excellent demonstration of DVAs with the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were significantly higher than the other non-contrast MR sequences. On SWI, DVA is delineated as a signal void lesion with the normal cerebral veins.

Conclusion

Susceptibility-weighted imaging (SWI) is valuable in the diagnosis of DVA and should be included in routine MR assessment of the brain.

Neuroimaging Findings of Organic Acidemias and Aminoacidopathies

Although individual cases of inherited metabolic disorders are rare, overall they account for a substantial number of disorders affecting the central nervous system. Organic acidemias and aminoacidopathies include a variety of inborn errors of metabolism that are caused by defects in the intermediary metabolic pathways of carbohydrates, amino acids, and fatty acid oxidation. These defects can lead to the abnormal accumulation of organic acids and amino acids in multiple organs, including the brain. Early diagnosis is mandatory to initiate therapy and prevent permanent long-term neurologic impairments or death. Neuroimaging findings can be nonspecific, and metabolism- and genetics-based laboratory investigations are needed to confirm the diagnosis. However, neuroimaging has a key role in guiding the diagnostic workup. The findings at conventional and advanced magnetic resonance imaging may suggest the correct diagnosis, help narrow the differential diagnosis, and consequently facilitate early initiation of targeted metabolism- and genetics-based laboratory investigations and treatment. Neuroimaging may be especially helpful for distinguishing organic acidemias and aminoacidopathies from other more common diseases with similar manifestations, such as hypoxic-ischemic injury and neonatal sepsis. Therefore, it is important that radiologists, neuroradiologists, pediatric neuroradiologists, and clinicians are familiar with the neuroimaging findings of organic acidemias and aminoacidopathies. ^©RSNA, 2018.

Conventional MRI

Conventional magnetic resonance imaging (MRI) allows for a detailed noninvasive visualization/examination of posterior fossa structures and represents a fundamental step in the diagnostic workup of many cerebellar disorders. In the first part of this chapter methodologic issues, like the correct choice of hardware (magnets, coils), pro and cons of the different MRI sequences, and patient management during the examination are discussed. In the second part, the MRI anatomy of the cerebellum, as noted on the various conventional MRI sequences, as well as a detailed description of cerebellar maturational processes from birth to childhood and into adulthood, are reported. Volumetric studies on the cerebellar growth based on three-dimensional MRI sequences are also presented. Moreover, we briefly discuss two main topics regarding conventional MRI of the cerebellum that have generated some debate in recent years: the differentiation between cerebellar atrophy, hypoplasia, and pontocerebellar hypoplasia, and signal changes of dentate nuclei after repetitive gadolinium-based contrast injections. The advantages and benefits of advanced neuroimaging techniques, including ¹H magnetic resonance spectroscopy, diffusion-weighted imaging, diffusion tensor imaging, and perfusion-weighted imaging are discussed in the last section of the chapter.

Microhemorrhage identified on 3.0 T MR susceptibility-weighted imaging for prognosis of viral encephalitis

OBJECTIVE

To evaluate the relationship of microhemorrhage on susceptibility-weighted imaging (SWI) with the severity of clinical symptoms and the prognosis of viral encephalitis.

MATERIALS AND METHODS

Thirty patients with clinically diagnosed viral encephalitis were divided into three groups according to the Glasgow Coma Scale (GCS) and the condition of recovery namely, Group I (n = 12): Glasgow Coma Scale (GCS)≥13 and recovered with no sequelae; Group II (n = 11): GCS 9-12 and recovered with some sequelae; Group III (n = 7): GCS 3-8 and recovered with more severe sequelae. The microhemorrhage detectability on SWI and conventional MR imaging in these three groups was compared and their correlations with different seriousness of clinical symptoms and prognosis were analyzed.

RESULTS

There was a significant difference in microhemorrhage volume among different MR sequences (p < 0.05). SWI was more sensitive to detect microhemorrhage than conventional MR imaging techniques. Microhemorrhages on SWI were significantly different among the three groups (p < 0.01). The volume of microhemorrhage on SWI was well correlated with the degree of clinical symptoms and the prognosis of viral encephalitis.

CONCLUSION

SWI can be used to detect microhemorrhage in patients with viral encephalitis. Assessment of microhemorrhage with SWI can provide useful information for the prognosis evaluation of viral encephalitis.

Does the Addition of a "Black Bone" Sequence to a Fast Multisequence Trauma MR Protocol Allow MRI to Replace CT after Traumatic Brain Injury in Children?

BACKGROUND AND PURPOSE

Head CT is the current neuroimaging tool of choice in acute evaluation of pediatric head trauma. The potential cancer risks of CT-related ionizing radiation should limit its use in children. We evaluated the role of MR imaging, including a "black bone" sequence, compared with CT in detecting skull fractures and intracranial hemorrhages in children with acute head trauma.

MATERIALS AND METHODS

We performed a retrospective evaluation of 2D head CT and brain MR imaging studies including the black bone sequence of children with head trauma. Two experienced pediatric neuroradiologists in consensus created the standard of reference. Another pediatric neuroradiologist blinded to the diagnosis evaluated brain MR images and head CT images in 2 separate sessions. The presence of skull fractures and intracranial posttraumatic hemorrhages was evaluated. We calculated the sensitivity and specificity of CT and MR imaging with the black bone sequence in the diagnosis of skull fractures and intracranial hemorrhages.

RESULTS

Twenty-eight children (24 boys; mean age, 4.89 years; range, 0-15.5 years) with head trauma were included. MR imaging with the black bone sequence revealed lower sensitivity (66.7% versus 100%) and specificity (87.5% versus 100%) in identifying skull fractures. Four of 6 incorrectly interpreted black bone MR imaging studies showed cranial sutures being misinterpreted as skull fractures and vice versa.

CONCLUSIONS

Our preliminary results show that brain MR imaging complemented by a black bone sequence is a promising nonionizing alternative to head CT for the assessment of skull fractures in children. However, accuracy in the detection of linear fractures in young children and fractures of aerated bone remains limited.

Pediatric Cerebellar Tumors: Emerging Imaging Techniques and Advances in Understanding of Genetic Features

Cerebellar tumors are the most common group of solid tumors in children. MR imaging provides an important role in characterization of these lesions, surgical planning, and postsurgical surveillance. Preoperative imaging can help predict the histologic subtype of tumors, which can provide guidance for surgical planning. Beyond histology, pediatric brain tumors are undergoing new classification schemes based on genetic features. Intraoperative MR imaging has emerged as an important tool in the surgical management of pediatric brain tumors. Effective understanding of the imaging features of pediatric cerebellar tumors can benefit communication with neurosurgeons and neuro-oncologists and can improve patient management.

Prenatal Cerebellar Disruptions: Neuroimaging Spectrum of Findings in Correlation with Likely Mechanisms and Etiologies of Injury

There is increasing evidence that the cerebellum is susceptible to prenatal infections and hemorrhages and that congenital morphologic anomalies of the cerebellum may be caused by disruptive (acquired) causes. Starting from the neuroimaging pattern, this report describes a spectrum of prenatal cerebellar disruptions including cerebellar agenesis, unilateral cerebellar hypoplasia, cerebellar cleft, global cerebellar hypoplasia, and vanishing cerebellum in Chiari type II malformation. The neuroimaging findings, possible causative disruptive events, and clinical features of each disruption are discussed. Recognition of cerebellar disruptions and their differentiation from cerebellar malformations is important in terms of diagnosis, prognosis, and genetic counselling.

Susceptibility-Based Neuroimaging: Standard Methods, Clinical Applications, and Future Directions

The evaluation of neuropathologies using MRI methods that leverage tissue susceptibility have become standard practice, especially to detect blood products or mineralization. Additionally, emerging MRI techniques have the ability to provide new information based on tissue susceptibility properties in a robust and quantitative manner. This paper discusses these advanced susceptibility imaging techniques and their clinical applications.

Cerebellar disruptions and neurodevelopmental disabilities

The vulnerability of the cerebellum during prenatal life to disruptive events such as hemorrhage and infection leads to a wide variety of morphological abnormalities. This review discusses various prenatal cerebellar disruptions including cerebellar agenesis, unilateral cerebellar hypoplasia, cerebellar cleft, global cerebellar hypoplasia, and vanishing cerebellum in Chiari type II malformation. For each entity, we discuss the definition, potential pathomechanism, clinical findings including neurocognitive and behavioral problems, neuroimaging features, and management. Accurate recognition of cerebellar disruptions and their differentiation from malformations is important in terms of diagnosis, prognosis, and genetic counselling.

Pediatric Cerebellar Tumors: Emerging Imaging Techniques and Advances in Understanding of Genetic Features

Cerebellar tumors are the most common group of solid tumors in children. MR imaging provides an important role in characterization of these lesions, surgical planning, and postsurgical surveillance. Preoperative imaging can help predict the histologic subtype of tumors, which can provide guidance for surgical planning. Beyond histology, pediatric brain tumors are undergoing new classification schemes based on genetic features. Intraoperative MR imaging has emerged as an important tool in the surgical management of pediatric brain tumors. Effective understanding of the imaging features of pediatric cerebellar tumors can benefit communication with neurosurgeons and neuro-oncologists and can improve patient management.

Conventional and advanced (DTI/SWI) neuroimaging findings in pediatric oligodendroglioma

PURPOSE

Oligodendroglioma are rare pediatric brain tumors. The literature about neuroimaging findings is scant. A correct presurgical diagnosis is important to plan the therapeutic approach. Here, we evaluated the conventional and advanced neuroimaging features in our cohort of pediatric oligodendrogliomas and discuss our findings in the context of the current literature.

METHODS

Clinical histories were reviewed for tumor grading, neurologic manifestation, treatment, and clinical status at the last follow-up. Neuroimaging studies were retrospectively evaluated for tumor morphology and characteristics on conventional and advanced magnetic resonance imaging (MRI).

RESULTS

Five children with oligodendroglioma were included in this study. Four children were diagnosed with a low-grade oligodendroglioma. The location of the tumors included the frontal and temporal lobe in two cases each and the fronto-parietal lobe in one. In all oligodendrogliomas, tumor margins appeared sharp. In the high-grade oligodendroglioma, a cystic and partially hemorrhagic component was seen. In all children, the tumor showed a T1-hypointense and T2-hyperintense signal. The signal intensity on fluid attenuation inversion recovery (FLAIR) images was hyperintense in four and mixed hypo-hyperintense in one child. The anaplastic oligodendroglioma showed postcontrast enhancement and decreased diffusion while the low-grade oligodendrogliomas showed increased diffusion. One low-grade oligodendroglioma showed calcifications on susceptibility weighted imaging.

CONCLUSION

Conventional MRI findings of pediatric oligodendrogliomas are nonspecific. Advanced MRI sequences may differentiate (1) low-grade and high-grade pediatric oligodendrogliomas and (2) pediatric oligodendrogliomas and other brain tumors.

Prenatal cerebellar hemorrhage: fetal and postnatal neuroimaging findings and postnatal outcome

BACKGROUND

Despite significant progress in fetal neuroimaging techniques, only a few well-documented examples of prenatal cerebellar hemorrhages are available in the literature. In the majority of these individuals, the diagnosis of prenatal cerebellar hemorrhages led to termination of pregnancy or death occurred in utero; data about postnatal outcome of children with prenatal diagnosis of cerebellar hemorrhages are scant. We describe fetal and postnatal neuroimaging findings and the neurodevelopmental outcome of a child with a large cerebellar hemorrhage that occurred at approximately 27 weeks' gestation.

METHOD

Data about neurological features and neurodevelopmental outcome were collected from the clinical history and follow-up examination. All pre- and postnatal MRI data were qualitatively evaluated for infra- and supratentorial abnormalities.

RESULTS

Fetal MRI at 27 weeks' gestation showed a T1-hyperintense and T2-hypointense lesion within the cerebellum suggestive of bilateral cerebellar hemorrhages with extension into the adjacent subarachnoid, subdural, and intraventricular spaces. The prenatal cerebellar hemorrhage was possibly related to maternal sepsis. Postnatal MRI showed encephalomalacic changes involving the vermis and both cerebellar hemispheres. Neurodevelopmental follow-up at 15 months of age was concerning for global developmental delay and significant right esotropia.

CONCLUSION

This child illustrates (1) the role of prenatal neuroimaging in the diagnosis of fetal cerebellar hemorrhages, (2) the significance of cerebellar involvement for neurodevelopment, and (3) the importance of the collection of postnatal outcome data in children with prenatal diagnosis of cerebellar hemorrhage.

Susceptibility-weighted imaging in pediatric arterial ischemic stroke: a valuable alternative for the noninvasive evaluation of altered cerebral hemodynamics

BACKGROUND AND PURPOSE

SWI provides information about blood oxygenation levels in intracranial vessels. Prior reports have shown that SWI focusing on venous drainage can provide noninvasive information about the degree of brain perfusion in pediatric arterial ischemic stroke. We aimed to evaluate the influence of the SWI venous signal pattern in predicting stroke evolution and the development of malignant edema in a large cohort of children with arterial ischemic stroke.

MATERIALS AND METHODS

A semiquantitative analysis of venous signal intensity on SWI and diffusion characteristics on DTI was performed in 16 vascular territories. The mismatch between areas with SWI-hypointense venous signal and restricted diffusion was correlated with stroke progression on follow-up. SWI-hyperintense signal was correlated with the development of malignant edema.

RESULTS

We included 24 children with a confirmed diagnosis of pediatric arterial ischemic stroke. Follow-up images were available for 14/24 children. MCA stroke progression on follow-up was observed in 5/6 children, with 2/8 children without mismatch between areas of initial SWI hypointense venous signal and areas of restricted diffusion on DTI. This mismatch showed a statistically significant association (P = .03) for infarct progression. Postischemic malignant edema developed in 2/10 children with and 0/14 children without SWI-hyperintense venous signal on initial SWI (P = .07).

CONCLUSIONS

SWI-DTI mismatch predicts stroke progression in pediatric arterial ischemic stroke. SWI-hyperintense signal is not useful for predicting the development of malignant edema. SWI should be routinely added to the neuroimaging diagnostic protocol of pediatric arterial ischemic stroke.