Pediatric Stroke Imaging

Abstract

Background: Pediatric stroke is a distinct clinical entity as compared with that in adults due to its unique and diverse set of etiologies. Furthermore, the role and application of diagnostic imaging has specific constraints and considerations. The intention of this article is to review these concepts in a thorough manner to offer a pediatric stroke imaging framework that providers can employ when taking care of these patients.

Methods: A comprehensive primary and secondary literature review was performed with specific attention to the common causes of pediatric stroke, appropriate use of neuroimaging, specific imaging findings, and developing techniques which may improve our ability to accurately diagnose these patients.

Results: Findings from this literature review were synthesized and summarized in order to thoroughly review the aforementioned concepts and outline the current consensus-based approach to diagnostic imaging in pediatric stroke. Furthermore, imaging findings drawn from patients seen in our institution are demonstrated to familiarize readers with pediatric stroke neuroimaging.

Conclusions: The challenges posed by pediatric stroke can be mitigated, in part, by the thoughtful application of diagnostic imaging, with the ultimate hope of improving outcomes for these vulnerable patients.

Keywords: CT; Hemorrhagic stroke; Ischemic stroke; MRI; Pediatric stroke.

Figure 1:

Proposed imaging algorithm in pediatric patients with suspected stroke. Adapted from the Paediatric Stroke Study Neuroimaging Consortium. Other MRI sequences including T1-weighted imaging, T2-weighted imaging, and arterial spin labeling perfusion techniques may also be applied to the above algorithm where appropriate. ADC = apparent diffusion coefficient; CT = computed tomography; CTA = computed tomography angiogram; DWI = diffusion weighted imaging; GRE = gradient echo; MRA = magnetic resonance angiogram; MRI = magnetic resonance imaging; SWI = susceptibility weighted imaging; TOF = time of flight.

Figure 2:

MRI in 1 year old male with single ventricle congenital heart disease status-post Glenn Procedure presenting with cardioembolic large vessel occlusion. (A) Axial DWI sequence with hyperintensity centered in the right frontoparietal region, which along with corresponding ADC map hypointensity (not shown) is indicative of infarction. (B and C) Axial GRE and SWI sequences, respectively, demonstrating blooming (i.e. hypointensity) within region of the right MCA, which is representative of intraarterial thrombus (i.e. susceptibility vessel sign) (D) Axial maximum intensity projection MRA corroborating SWI/GRE findings with an associated filling defect in the right MCA. ADC = Apparent Diffusion Coefficient; DWI = diffusion weighted imaging; GRE = gradient recall echo; MCA = middle cerebral artery; MRA = magnetic resonance angiogram; MRI = magnetic resonance imaging; SWI = susceptibility weighted imaging.

Figure 3:

MRI in pediatric patient found to have stroke within right MCA distribution. (A) Coronal maximum intensity projection MRA on day of presentation demonstrating irregularity and focal stenoses along the right M1 segment (B) Follow-up coronal maximum intensity projection MRA 1.5 years after initial presentation with resolution of MCA focal stenosis and irregularities. Patient was reported to have unspecified viral infection prior to initial presentation. These findings are suggestive of transient cerebral arteriopathy. MCA = middle cerebral artery; MRA = magnetic resonance angiogram.

Figure 4:

MRI and CTA in 7 year old female with suspected stroke. (A) Axial DWI sequence demonstrating restricted diffusion (i.e. hyperintensity) within the left paramedian midbrain consistent with infarction (B) Subsequent sagittal CTA and 3D reconstruction showing focal stenosis with aneurysmal outpouching of the left segment 3 vertebral artery. Findings were consistent with spontaneous vertebral artery dissection with associated pseudoaneurysm. DWI = diffusion weighted imaging; CTA = computed tomography angiogram; MRI = magnetic resonance imaging.

Figure 5:

Brain MRI in pediatric patient with moyamoya disease. (A) Axial T2 FLAIR sequence depicting “ivy sign” with sulcal/subarachnoid hyperintensities (arrows) reflective of leptomeningeal collaterals (B and C) Axial and coronal maximum intensity projection MRA: Axial view demonstrates filling defects in the left M1 and A1 segments and narrowing of the right proximal M1 segment (arrow). Coronal view demonstrates multiple collaterals appearing with classic “puff of smoke” appearance (arrow). MRA = magnetic resonance angiogram; magnetic resonance imaging = MRI.

Figure 6:

Coronal and sagittal CTA maximum intensity projections in pediatric patient presenting with left-sided stroke. In both planes the left internal carotid artery demonstrates small continuous undulations representing the classic fibromuscular dysplasia string-of-beads sign. CTA = computed tomography angiogram.

Figure 7:

MRI in 8 year old male with history of prior hemorrhagic strokes and multifocal cavernous malformations. (A) Axial T2WI demonstrating heterogenous T2 signal in the left centrum semiovale with “popcorn” morphology (B) Axial SWI sequence demonstrating blooming (i.e. hypointensity) in the same distribution reflective of blood products (C and D) Similar appearance of pontine cavernous malformation on T2WI and SWI, respectively. MRI = magnetic resonance imaging; SWI = susceptibility-weighted imaging; T2WI = T2-weighted imaging.

Figure 8:

9 month old female presenting with seizures found to have intraparenchymal and intraventricular hemorrhage. (A) Axial CT head demonstrating hyperintense acute blood within the ventricular system and left occipital lobe consistent with hemorrhage (B) Axial GRE sequence with blooming (i.e. hypointensity) within a similar distribution. (C) Coronal maximum intensity projection MRA showing fusiform dilation of distal left posterior cerebral artery consistent with fusiform aneurysm. CT = computed tomography; GRE = gradient recall echo; MRA = magnetic resonance angiogram; MRI = magnetic resonance imaging.

Figure 9:

Axial and coronal maximum intensity projection CTA in pediatric patient with history of hemorrhagic stroke demonstrating abnormal nidus of vessels (arrows) along the distribution of the right posterior cerebral artery. This finding is consistent with arteriovenous malformation. CTA = computed tomography angiography.

Figure 10:

CT in pediatric patient presenting with suspected stroke. (A) Axial non-enhanced CT with hypodense lesion centered in the left temporal lobe suggestive of infarct related cerebral edema. Regions of hyperdensity indicate associated hemorrhage. (B) Coronal contrast enhanced CT in the same patient with left-sided mastoid opacification and an adjacent filling defect in the transverse sinus (arrow) indicative of mastoiditis related transverse sinus thrombosis. CT = computed tomography.

Figure 11:

CT of 15 year old male with history of Rasmussen’s encephalitis status-post partial left hemispherectomy due to refractory seizures with recurrent dural venous sinus thrombosis. (A) Axial non-enhanced CT with curvilinear hyperdensity within distribution of right transverse sinus (arrow) representative of the “cord sign” seen with dural venous sinus thrombosis. (B) Coronal contrast-enhanced CT demonstrating abnormal hypodensities within the right transverse and straight sinuses. Hypodensity within the straight sinus (arrow) reflective of dural venous sinus thrombosis’ “empty delta sign.” CT = computed tomography.

Figure 12:

MRI in a 5 year old male presenting with seizures and right sided weakness. (A) Axial DWI sequence with infarct in the left frontal lobe, insula, and basal ganglia (B) Axial ASL sequence with corresponding hypointensity reflective of decreased cerebral blood flow (C) Axial maximum intensity projection MRA illustrating diminutive left MCA and its branches (D) Axial black blood imaging post-contrast sequence with foci of enhancement in wall of the left MCA indicative of arterial wall inflammation. This finding was concerning for TCA.ASL = arterial spin labeling; DWI = diffusion weighted imaging; MCA = middle cerebral artery; MRA = magnetic resonance angiogram; TCA = transient cerebral arteriopathy.