Background: Radiography is routinely used to evaluate the pediatric and young adult pelvis and hips. Unfortunately, the 2D nature of this imaging modality is insufficient in accurately depicting and evaluating complex 3D anatomical structures. In contrast, computed tomography (CT) provides exquisite details of 3D anatomy, typically at the expense of a higher radiation dose. Recent studies have suggested that ultra-low-dose CT (ULDCT) with tin filtration may overcome this diagnostic imaging dilemma by offering high-quality CT images with reduced radiation exposure.
Objective: To compare patient-specific radiation exposure of diagnostic-quality hip ULDCTs and pelvic radiographs and thereby validate an optimized clinical protocol for hip ULDCT imaging in pediatric and young adult patients.
Materials and methods: We retrospectively searched the image archive at our large tertiary children's hospital for hip CTs and anteroposterior (AP) pelvic radiographs performed within 6 months of each other (Dec 2023 - May 2024). The inclusion criteria were (1) hip CTs performed in accordance with our established ULDCT imaging protocol and (2) AP pelvic radiographs acquired in accordance with the American College of Radiology (ACR) guidelines. To calculate the effective doses of the pelvic radiographs and hip CTs, we used the National Cancer Institute dosimetry system for Radiography and Fluoroscopy (NCIRF) and Computed Tomography (NCICT), respectively. A paired two-tailed t-test was used to compare the effective doses of the hip CTs and AP pelvic radiographs.
Results: The study cohort included 29 patients (9 males, 20 females), stratified into the pediatric group (<18 years, n=17), young adult group (18-30 years, n=12), and entire cohort, with mean ages of 10.7 (SD, 6.0), 22.3 (SD, 3.7), and 15.5 (SD, 6.9) years, respectively. The average effective doses from ULDCT were 0.33 mSv (pediatric), 0.23 mSv (young adult), and 0.29 mSv (entire cohort), not significantly different from AP pelvic radiograph doses of 0.26, 0.29, and 0.27 mSv, respectively. In contrast, cumulative radiographic doses were significantly higher at 0.73 mSv, 0.76 mSv, and 0.74 mSv.
Conclusion: ULDCT is a clinically feasible approach for pediatric and young adult hip imaging, offering diagnostic-quality CT images with substantially reduced radiation exposure (at a radiation dose level comparable to that of a single AP pelvic radiograph).
Background: Reducing acoustic noise is essential in infant brain magnetic resonance imaging (MRI) to minimize the need for sedation. Deep learning (DL)-based MRI reconstruction may enhance the image quality of the zero echo time (ZTE) silent sequence.
Objective: To evaluate the effect of DL-based reconstruction on the image quality of ZTE infant brain MRI using the feed-and-wrap technique, compared to conventional MRI with sedation.
Materials and methods: This retrospective study included 78 infants (postmenstrual age ≤16 months) who underwent brain MRI between January 2022 and December 2024. The control group underwent sedated 3-dimensional T1-weighted magnetization-prepared rapid gradient-echo (MPRAGE) imaging. The experimental group underwent unsedated inversion recovery-prepared ZTE imaging with and without DL-based reconstruction (ZTE-DL and ZTE, respectively), using the feed-and-wrap technique. Three radiologists independently rated five image quality metrics using a 5-point Likert scale. Signal uniformity was assessed by the coefficient of variation across eight brain regions. Differences among sequences were analyzed using the Mann-Whitney U test with Bonferroni correction. Interrater agreement was assessed using Cohen's kappa coefficient.
Results: ZTE-DL had the highest scores for noisiness, gray-white matter differentiation, artifacts, and overall image quality. ZTE-DL showed no significant differences from MPRAGE except for reduced noisiness, while significantly outperforming ZTE across all metrics (all P<0.017). Lesion conspicuity did not differ significantly among the groups. Interrater agreement was substantial (κ>0.6) for most metrics. Signal uniformity was greatest in ZTE-DL for gray and white matter (all P<0.001); no difference was observed between ZTE-DL and ZTE for cerebrospinal fluid (P=0.721).
Conclusion: DL-based MRI reconstruction improved ZTE image quality and provided comparable image quality to MPRAGE, potentially reducing the need for sedation in infant brain MRI.
Background: Prenatal open neural tube defect (ONTD) repair improves motor function and reduces hydrocephalus treatment by ensuring watertight closure of the defect. Hindbrain herniation (HBH) reversal is often observed postoperatively, but its association with postnatal outcomes remains unclear.
Objective: To assess HBH evolution via fetal MRI following prenatal ONTD repair, and its association with reduced hydrocephalus treatment and absence of cerebrospinal fluid (CSF) leak.
Materials and methods: This retrospective study included fetuses who underwent prenatal ONTD repair via laparotomy-assisted fetoscopic or open-hysterotomy techniques. Preoperative and 6-week postoperative fetal MRIs were reviewed by two blinded experts using a modified Sutton classification. HBH reversal was categorized as complete (cerebellum above the foramen magnum), partial (improved but still below the foramen magnum), or absent (no change). Associations with hydrocephalus treatment and CSF leak were analyzed using logistic regression, adjusting for potential confounders. A P-value <0.05 was considered statistically significant.
Results: One hundred forty-six fetuses (fetoscopic, 112; open-hysterotomy, 34) were included. The median gestational age at repair was 25.1 weeks (range, 21.3-26.4). At 6 weeks, 103/146 (70.5%) achieved complete HBH reversal, 17/146 (11.6%) had partial reversal, and 26/146 (17.8%) showed no reversal. CSF leak was significantly lower in complete HBH reversal (3/103 (2.9%)) compared to the partial/no reversal group (14/43 (32.6%), P<0.01), with a 12.33-fold increased risk (95% CI (2.55-45.31), P<0.01) for CSF leak in the latter group. Hydrocephalus treatment was lower in complete HBH reversal (18/86 (20.9%)) versus partial/no reversal (25/36 (69.4%), P<0.01), with a 5.58-fold increased risk (95% CI (2.98-24.74), P<0.01).
Conclusion: Complete HBH reversal occurred in 70.5% after prenatal ONTD repair and was associated with lower risks of CSF leak and hydrocephalus. Fetal MRI at 6 weeks post-surgery is a reliable prognostic indicator for assessing repair integrity and hydrocephalus risk.
Background: Magnetic resonance urography (MRU) with diuretic injection is increasingly used to evaluate pediatric ureteropelvic junction obstruction, providing anatomical and functional information without ionizing radiation.
Objective: To analyze the increase in anteroposterior diameter of the renal pelvis following furosemide injection during MRU to determine a diagnostic cutoff. To assess whether this increase supports etiological diagnosis and whether magnetic resonance imaging (MRI) reliably detects crossing vessels.
Materials and methods: We retrospectively included all children who underwent surgery for ureteropelvic junction obstruction at our institution between January 2010 and January 2023 and had preoperative MRU. For each patient, the increase in renal pelvis diameter after furosemide injection during MRU was measured on the obstructed and contralateral healthy sides. Measurements were compared to determine a pathological cutoff. The change in renal pelvis diameter was also compared according to etiology (intrinsic vs. extrinsic). The association between crossing vessels identified on MRI and intraoperative findings was also assessed.
Results: Seventy patients (median age 9) were included. The increase in renal pelvis diameter was significantly greater on the obstructed side compared to the contralateral side (P < 0.001). The optimal cutoff for predicting obstruction was 6 mm (sensitivity 68.6%, specificity 87.1%). No significant difference was found in the change in renal pelvis diameter according to etiology (P = 0.86). The association between crossing vessels identified on MRI and during surgery was significant (P < 0.001).
Conclusion: An increase greater than 6 mm in renal pelvis diameter after furosemide injection during MRU could represent an additional diagnostic criterion for pediatric ureteropelvic junction obstruction.
Background: Hemophagocytic lymphohistiocytosis is a non-malignant immune regulation disorder, with activation of uncontrolled inflammatory processes and multiorgan damage; primary hemophagocytic lymphohistiocytosis is genetic.
Objectives: To analyze clinical and brain magnetic resonance imaging features in children with familial hemophagocytic lymphohistiocytosis.
Materials and methods: This retrospective study included 28 children with molecularly confirmed hemophagocytic lymphohistiocytosis. Clinical and laboratory manifestations at initial presentation and upon reactivation were recorded. Routine brain magnetic resonance imaging scans were reviewed and severity scores were calculated for different molecular types.
Results: Eleven (39.4%) children presented with neurological symptoms, 13 (46.4%) with developmental delays, and four with altered levels of consciousness. Lesions predominated in white matter (39.3% subcortical, 35.7% periventricular, and 7.1% central), although 25% had gray matter involvement; 78.6% of the cases presented with cerebral volume loss. Brain stem, cerebellar, and meningeal involvement were observed in 14.3%, 25%, and 7.1%, respectively. The most common mutations were in UNC13D (53.6%), PRF (21.4%), RAB27A (17.9%), and STBXP2 (7.1%); of the children with these mutations, neurological symptoms were observed in 20%, 50%, 80%, and 50%, respectively. Central nervous system reactivation was more prevalent in patients with RAB27A mutations (60%). White matter changes were noted in 16.7% of PRF cases, predominantly involving central regions, whereas 80% of RAB27A cases exhibited periventricular white matter abnormalities. RAB27A mutations were associated with higher white matter severity scores, whereas UNC13D mutations had higher cerebral atrophy scores.
Conclusion: Variable imaging manifestations were observed in familial hemophagocytic lymphohistiocytosis, with white matter involvement predominating. Patients with RAB27A mutations had more frequent clinical and imaging-based neurological involvement.
Background: Requests for secondary interpretation of imaging examinations adds clinical work and generates additional charges.
Objective: To understand the impact of secondary interpretations of pediatric nuclear medicine examinations at a quaternary academic center.
Materials and methods: In this IRB approved study, we retrospectively reviewed nuclear medicine examinations submitted for secondary interpretation by a pediatric radiologist with a nuclear medicine focus at our institution between 08/2019 and 08/2024. A single reviewer compared the primary and secondary reports to identify discrepancies that would likely impact clinical management, and discrepancies were confirmed by additional reviewers. Pediatric hematology/oncology faculty (n=29) and fellows (n=18) at our institution were surveyed to understand requests for, and the impact of, secondary interpretations. Results are summarized with descriptive statistics.
Results: Three hundred fifty-eight examinations (median patient age=8 years) were included, 237 were 18F-FDG PET body scans, 97 were 123I-MIBG scans, and 24 were other examinations. Secondary interpretations yielded meaningful changes in 17% (60/358). Of these, 20% (12/60) changed from negative/normal to positive, 20% (12/60) changed from positive to negative/normal, and 57% (34/60) included additional positive findings/diagnoses. Sixteen survey responses (34%; n=16/47 response rate) were received, with providers indicating that secondary interpretations were clinically useful even when they agreed with the primary impression.
Conclusion: Secondary interpretation of pediatric nuclear medicine examinations by pediatric radiologists with nuclear medicine focus resulted in changes that have potential impact on clinical management in 17% of cases. Secondary interpretations completely changed the impression regarding the presence or absence of malignant disease in 40% of these cases. Referring providers identified benefit in secondary interpretations even when they confirmed the primary impression.
Background: Hyperechoic ependyma is a known ultrasound finding in preterm infants with intraventricular hemorrhage but its prognostic implications remain uncertain.
Objective: To evaluate whether hyperechoic ependyma identified on head ultrasound in preterm neonates is associated with intraventricular hemorrhage severity, post-hemorrhagic hydrocephalus of prematurity, multiloculated hydrocephalus, and other complications.
Materials and methods: This retrospective single-center study included 184 preterm neonates (<37 weeks' gestation) who underwent early (≤10 days) and/or late (>10 days) head ultrasound in the neonatal intensive care unit (NICU). Hyperechoic ependyma was identified by consensus between two radiologists. Logistic regression was used to assess associations with intraventricular hemorrhage grade, ventriculomegaly, shunt-dependent hydrocephalus, multiloculated hydrocephalus, and periventricular leukomalacia, including magnetic resonance imaging (MRI) correlation.
Results: Hyperechoic ependyma was observed in 14/184 neonates (7.6%), more often on late ultrasound. It was strongly associated with intraventricular hemorrhage, particularly high-grade intraventricular hemorrhage (P<0.0001). While linked to higher rates of shunt dependency and periventricular leukomalacia, it was an independent predictor only for multiloculated hydrocephalus (OR≈11.3, P=0.021), after adjusting for intraventricular hemorrhage grade.
Conclusion: Hyperechoic ependyma is associated with high-grade intraventricular hemorrhage and is an independent risk factor for multiloculated hydrocephalus. This sonographic finding may reflect underlying ependymal inflammation or injury and could serve as an early imaging marker for complex hydrocephalus in preterm infants.
Primary vertebral tumors in children are rare but clinically significant due to their potential for neurological compromise, spinal instability, and growth-related deformities. These lesions encompass a wide histologic spectrum, ranging from benign entities, such as osteoid osteoma and osteoblastoma, to aggressive malignancies like Ewing sarcoma and osteosarcoma. Despite their rarity, timely and accurate diagnosis is essential, as delays can result in irreversible neurological deficits. Imaging is fundamental across the clinical continuum, from detection and characterization to treatment planning and post-therapeutic monitoring. Conventional radiography remains a common first-line tool, although limited in sensitivity for early or subtle findings. Computed tomography (CT) is particularly useful for evaluating cortical integrity and detecting tumor mineralization, findings that are especially relevant in lesions such as osteoid osteoma, where CT also plays a key role in planning and guiding percutaneous treatment. Magnetic resonance imaging (MRI), the modality of choice, offers superior soft tissue contrast and is essential for assessing bone marrow involvement and adjacent neural structures. Advanced MRI techniques, such as diffusion-weighted imaging (DWI) and dynamic contrast-enhanced studies, further enhance lesion characterization and may help predict response to treatment. Minimally invasive techniques, including image-guided biopsy, radiofrequency ablation, and cryoablation, have expanded the therapeutic techniques, particularly for benign lesions. This review provides a comprehensive overview of the classification and imaging features of pediatric spinal bone tumors, with emphasis on the strengths and limitations of each modality and the evolving role of interventional radiology in diagnosis and treatment.
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