Neuroradiological findings in three cases of pontocerebellar hypoplasia type 9 due to AMPD2 mutation: typical MRI appearances and pearls for differential diagnosis.

Pontocerebellar hypoplasia type 9 (PCH9) is a rare autosomal recessive neurodegenerative disorder with prenatal onset caused by mutations in adenosine monophosphate deaminase 2 (AMPD2). PCH9 patients demonstrate severe neurodevelopmental delay with early onset and typical magnetic resonance imaging (MRI) findings consisting in: pontine hypoplasia or atrophy with dragonfly cerebellar atrophy appearance on coronal images, reduction in size of the pons and middle cerebellar peduncles, abnormal midbrain describing a figure of "8" on axial images, diffuse loss of cerebral white matter with striking periventricular leukomalacia (PVL), and absence or extreme thinning of the corpus callosum. A review of the literature on PCH9 shows that the MRI phenotype observed in the series herein presented is similar to the eleven cases of PCH9 previously reported. Finally, the main radiological elements which differentiate this diagnosis from other PCH subtypes are described.

Current concepts in radiologic assessment of pediatric brain tumors during treatment, part 1.

Pediatric brain tumors differ from those in adults by location, phenotype and genotype. In addition, they show dissimilar imaging characteristics before and after treatment. While adult brain tumor treatment effects are primarily assessed on MRI by measuring the contrast-enhancing components in addition to abnormalities on T2-weighted and fluid-attenuated inversion recovery images, these methods cannot be simply extrapolated to pediatric central nervous system tumors. A number of researchers have attempted to solve the problem of tumor assessment during treatment in pediatric neuro-oncology; specifically, the Response Assessment in Pediatric Neuro-Oncology (RAPNO) working group was recently established to deal with the distinct challenges in evaluating treatment-related changes on imaging, but no established criteria are available. In this article we review the current methods to evaluate brain tumor therapy and the numerous challenges that remain. In part 1, we examine the role of T2-weighted imaging and fluid-attenuated inversion recovery sequences, contrast enhancement, volumetrics and diffusion imaging techniques. We pay particular attention to several specific pediatric brain tumors, such as optic pathway glioma, diffuse midline glioma and medulloblastoma. Finally, we review the best means to assess leptomeningeal seeding.

Do Lacunar Infarcts Have Different Aetiologies? Risk Factor Profiles of Lacunar Infarcts in Deep White Matter and Basal Ganglia: The Second Manifestations of ARTerial Disease-Magnetic Resonance Study.

BACKGROUND: Evidence suggests that lacunar infarcts have different etiologies, possibly related to their anatomical location and vascular territory. We investigated the risk factor profiles of patients with new lacunar infarcts in the basal ganglia and deep white matter. METHODS: Within the Second Manifestations of ARTerial disease-Magnetic Resonance study, a prospective cohort on brain changes on MRI in patients with symptomatic atherosclerotic disease, 679 patients (57 ± 9 years) had vascular screening and MRI at baseline and after a mean follow-up of 3.9 years. We investigated the association between vascular risk factors at baseline and appearance of new lacunar infarcts in the basal ganglia and deep white matter at follow-up. RESULTS: New lacunar infarcts appeared in 44 patients in the basal ganglia and in 37 patients in the deep white matter. In multivariable analysis, older age, history of cerebrovascular disease, and baseline white matter hyperintensity (WMH) volume were associated with increased risk of new lacunar infarcts in both locations. Hyperhomocysteinemia was associated with increased risk of lacunar infarcts in the basal ganglia (relative risk [RR] 2.0; 95% CI 1.0-4.2), whereas carotid stenosis >70% (RR 2.5; 95% CI 1.2-5.0), smoking (per 10 pack-year: RR 1.1; 95% CI 1.0-1.3), hypertension (RR 3.4; 95% CI 1.2-9.7), and progression of WMH volume (RR 2.4; 95% CI 1.1-5.2) were associated with increased risk of lacunar infarcts in the deep white matter. CONCLUSIONS: The different risk factor profiles for new lacunar infarcts in basal ganglia and deep white matter indicate different etiologies. The independent association between progression of WMH and new deep white matter lacunar infarcts suggest a common etiology for these radiological abnormalities.