Guérin, J.

Abstract Introduction Quantitative interpretation of pediatric brain [ 18 F]-FDG PET is limited by the lack of age-matched normative reference databases, despite substantial developmental variation in cerebral glucose metabolism. This study aimed to construct a large-scale normative pediatric [ 18 F]-FDG PET database and develop an age-specific z-score mapping framework for quantitative evaluation of pediatric epilepsy. Method Pediatric brain PET data were retrospectively derived from clinically acquired whole-body or dedicated [ 18 F]-FDG PET examinations in participants 0–19 years of age without neurologic disease or visible brain abnormalities. A total of 417 PET scans from 341 participants were stratified into five developmental age groups: infancy, early childhood, middle childhood/school age, adolescence, and late adolescence. SUVR maps were generated using whole-brain atlas and brainstem reference regions. Voxel-wise t-test analyses were performed to characterize age- and sex-related metabolic differences. Age-specific voxel-wise mean and standard deviation maps were generated from the normative cohort and used to calculate age-matched hypometabolic z-score maps in 14 pediatric patients with epilepsy. The resulting abnormalities were qualitatively evaluated for concordance with epileptogenic findings identified on clinical MRI and/or PET by expert image review. Results Voxel-wise analyses demonstrated prominent age-dependent SUVR differences, particularly between infancy and older age groups. With whole-brain atlas normalization, older children showed progressively higher relative SUVR in cortical and cerebellar gray matter regions, whereas infancy showed relatively higher SUVR in the occipital cortex, white matter, thalamus, and brainstem. Brainstem normalization produced distinct developmental patterns, emphasizing higher white matter SUVR in infancy and broader gray matter differences in older groups. Sex-related differences were limited and regionally specific. Whole-brain atlas normalization showed lower variability than brainstem normalization and was selected for z-score mapping. In representative epilepsy cases, age-matched z-score maps identified focal or regional hypometabolism corresponding to malformations of cortical development, focal cortical dysplasia, mesial temporal sclerosis, nonlesional MRI cases, remote insult, tumor-related abnormalities, and Sturge-Weber syndrome. Discussion A large-scale normative pediatric [18F]-FDG PET database can support developmentally appropriate quantitative interpretation of pediatric brain PET. Age-matched z-score mapping may complement visual assessment by highlighting abnormal cerebral glucose metabolism in pediatric epilepsy, although findings should be interpreted with MRI, EEG, seizure semiology, and other presurgical data.

Aberrant internal carotid artery (ICA) is a vascular anomaly in which a segment of the ICA courses through the middle ear. The association of aberrant ICAs and pseudoaneurysm formation is not well known and can be an important finding to recognize on imaging. In this series, we present three cases of aberrant ICAs having asymmetric contour deformities consistent with pseudoaneurysms diagnosed utilizing CT of the temporal bone.

Objective Dermoid cyst (DC) is a congenital cyst with the potential to have intracranial extension (ICE). This study aims to evaluate the imaging yield and surgical outcomes of nasal, medial brow, forehead, and scalp DCs. Design Retrospective review of craniofacial DCs treated at our institution between 1992 and 2024. Results A total of 117 patients (57 females) were included. The median age at cyst detection and removal were 4.8 months (IQR 3.6-9.6) and 1.8 years (IQR 0.9-5.3), respectively. In 42 patients, parents have noticed the presence of the cyst immediately after birth. Cyst wall rupture during surgical removal was reported in 15.4%. The median follow-up time was 1.3 months (IQR 0.5-12.2). Three patients experienced recurrence. No postoperative complication was reported. The regions with the highest prevalence of ICE were the forehead, frontotemporal scalp, and nasal region. The lateral frontal/temporal scalp had a 33.3% rate of ICE. Midline forehead/scalp lesions demonstrated a higher risk of ICE compared to their lateral equivalents (54.5% vs 17.5%, P = .03). The sensitivity and specificity of magnetic resonance imaging (MRI) were 100% and 95.7%, while for computed tomography (CT scans) were 72.7% and 96.5%. The Area Under the Curve for MRI was 0.978, and for CT was 0.846. The sensitivity and specificity of ultrasound were 50% and 100%. Conclusions Midline forehead/scalp DCs are more prone to extend intracranially than lateral DCs. MRI had a higher sensitivity and specificity than CT scans in detecting ICE. Routine screening imaging should be considered in midline forehead/scalp, lateral frontal/temporal, and nasal DCs.

The locally aggressive nature and high recurrence rate of dermatofibrosarcoma protuberans (DFSP) make it challenging to manage, especially when present on the scalp, owing to its ability to invade the underlying periosteum, bone, dura, or brain. Preoperative imaging is used to plan resection, but the true correlation between periosteal or osseous changes on imaging and the presence of tumor within the periosteum is unclear. We present our institutional experience of managing DFSP of the scalp with emphasis on the imaging used. A retrospective review of 33 patients with DFSP of the scalp treated at a tertiary center was conducted. Data on demographics, tumor characteristics, preoperative imaging (magnetic resonance imaging or computed tomography), and surgical outcomes were analyzed. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of each imaging modality were calculated. Patients underwent surgical resection at a mean age of 37.11 years and had a median follow-up of 28.34 months. Preoperative imaging was available for 26 patients (CT only: 5, MRI only: 12, CT and MRI: 9). Calvarial abnormalities were seen in 3 patients. Treatment included Mohs surgery (66.7%) and wide local excision (33.3%). In 10 patients with positive periosteal margins, bone involvement was managed by burring (7) or craniectomy (3). The sensitivity and PPV of CT for periosteal margin positivity were 25% and 100%, and for MRI were 33% and 100%, respectively. The specificity and NPV were 100% and 50% for CT, and 100% and 66% for MRI. Preoperative CT and MRI have low sensitivity and NPV but high specificity and PPV in determining depth of involvement and are essential to guiding reconstruction in DFSP of the scalp.

Purpose To document the association of CAD-related disorder (EIEE-50) with cortical visual impairment. Observations An 8-month-old Caucasian boy with whole genome sequencing confirming 2 variants in the gene CAD, who presented with severe seizures, microcephaly, hyperreflexia, hypotonia, anemia, and severe cortical visual impairment. Magnetic resonance imaging (MRI) of the brain noted thickened cortical gray matter along the right calcarine fissure as well as changes suggesting malformation of cortical development. Empiric uridine monophosphate supplementation has significantly improved seizure activity, hypotonia, and development and has led to resolution of anemia. Conclusions and Importance CAD-related disorder is treatable and may affect visual cortical development causing severe secondary cortical visual impairment, a newly described clinical manifestation.

Abstract Photon counting detector (PCD) CT represents the newest advance in CT technology, with improved radiation dose efficiency, increased spatial resolution, inherent spectral imaging capabilities, and the ability to eliminate electronic noise. Its design fundamentally differs from conventional energy integrating detector CT because photons are directly converted to electrical signal in a single step. Rather than converting X-rays to visible light and having an output signal that is a summation of energies, PCD directly counts each photon and records its individual energy information. The current commercially available PCD-CT utilizes a dual-source CT geometry, which allows 66 ms cardiac temporal resolution and high-pitch (up to 3.2) scanning. This can greatly benefit pediatric patients by facilitating high quality fast scanning to allow sedation-free imaging. The energy-resolving nature of the utilized PCDs allows “always-on” dual-energy imaging capabilities, such as the creation of virtual monoenergetic, virtual non-contrast, virtual non-calcium, and other material-specific images. These features may be combined with high-resolution imaging, made possible by the decreased size of individual detector elements and the absence of interelement septa. This work reviews the foundational concepts associated with PCD-CT and presents examples to highlight the benefits of PCD-CT in the pediatric population.

Purpose Imaging changes in the pituitary volume during pregnancy remains scantly researched. This study set out to assess the differences in total, anterior, and posterior pituitary volume in pregnant women compared to nulliparous and post-partum women. Materials and Methods A retrospective review was completed of women that had undergone MRI imaging of the brain. Patients were divided into three cohorts: pregnant, nulliparous, and post-partum (defined as being within 12 months of delivery). Anterior and posterior pituitary volumes were manually measured. Results 171 patients were included, of which 68 were pregnant, 52 were post-partum, and 51 were nulliparous. The average anterior (621.0 ± 171.6 mm 3 ) and total (705.4 ± 172.2 mm 3 ) pituitary volumes were significantly larger in pregnant patients than nulliparous women (522.6 ± 159.8 mm 3 and 624.5 ± 163.7 mm 3 , respectively) ( p = .002 and p = .01, respectively). The posterior pituitary volume was significantly smaller in pregnant women (84.4 ± 32.9 mm 3 ) compared to both post-partum (101.2 ± 42.0 mm 3 ) and nulliparous (102.0 ± 46.1 mm 3 ) women ( p = .02 for both). Conclusions The anterior and total pituitary volumes are significantly larger during pregnancy persisting into the post-partum period. The posterior pituitary volume, conversely, decreases during pregnancy, and returns to its normal size in the post-partum period.