Background/Objectives: There is an increasing need for cross-sectional imaging in pediatric patients with congenital heart disease. This patient group is highly sensitive to ionizing radiation. The purpose of this article was to evaluate differences in radiation dose and image quality between a first-generation photon-counting (PC)-CT system and a 256-slice single-source energy-integrating detector (EID)-CT in these patients. Methods: We retrospectively assessed effective dose, CT dose index-volume (CTDI_vol), dose length product (DLP), and image quality of all prospectively electrocardiography-gated CTs of the thorax in all patients < 18 years of age examined between February 2021 and August 2024 (n = 43). Two independent observers subjectively scored image quality, vascular contrast, and noise on a 5-point Likert scale. In addition, we assessed the signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) quantitatively. Results: All dose parameters were significantly lower in the PC-CT (n = 27) versus the EID-CT (n = 16) group (mean effective dose: 0.8 ± 0.64 versus 2.2 ± 0.88 mSv, p < 0.001; mean CTDI_vol: 1.22 ± 0.96 versus 4.8 ± 1.08 mGy, p < 0.001; mean DLP: 30.7 ± 31.9 versus 73.7 ± 50.7 mGy*cm, p < 0.001). Overall subjective image quality and contrast were rated higher in the PC-CT group (p = 0.046 and < 0.001, respectively). Quantitative CNR was significantly higher in the PC-CT group (mean 39.1 ± 12.9 versus 26.2 ± 10.8, p = 0.002). Conclusions: PC-CT enables high-quality examinations for the evaluation of congenital heart disease with a highly significant dose reduction compared with a 256-slice single-source EID-CT.

Background/Objectives: Pediatric patients with solid tumors (non-lymphoma) require adequate staging prior to and during therapy. ¹⁸F-FDG-PET/CT is commonly used for the detection of tumorous lesions, with the drawback of exposure to ionizing radiation. Whole-body MRI (WB-MRI) can be considered as a complementary method according to clinical guidelines. The main objective of this study was to assess the diagnostic performance of the aforementioned methods for the detection of metastases, both separately and in combination. Methods: We retrospectively assessed sensitivity and specificity of ¹⁸F-FDG-PET/CT, WB-MRI, and the combination of both methods for the detection of lymph node and distant metastases in pediatric patients with solid tumors. Results: A total of 21 patients who underwent both ¹⁸F-FDG-PET/CT and WB-MRI were included in this study. We found 109 confirmed metastatic lesions in 1322 body regions. Sensitivity and specificity for the whole collective were 63.4%/99.3% for ¹⁸F-FDG-PET/CT, 91.3%/98.6% for WB-MRI, and 100%/98.2% for the combination of both methods. In 11 therapy-naïve patients, both ¹⁸F-FDG-PET/CT and WB-MRI exhibited a sensitivity of 84.7%, while specificity was 98.8% for ¹⁸F-FDG-PET/CT and 98.5% for WB-MRI. The combination of both methods led to a significant increase in sensitivity to 100% in both therapy-naïve patients and patients under chemotherapy (both p < 0.001), while specificity remained high (97.7%/98.7%). Conclusions: ¹⁸F-FDG-PET/CT in combination with WB-MRI showed a higher sensitivity for the detection of metastases in solid malignant pediatric tumors than either of the methods alone. Thus, the combination allows for the most accurate staging.

Background/Objectives: Vascular involvement has been described in mucopolysaccharidosis type IVa (MPS IVa), but the morphology of the aorta and carotid arteries has not been comprehensively characterized. This study aimed to quantitatively assess aortic and carotid artery tortuosity and kinking using contrast-enhanced three-dimensional (3D) magnetic resonance (MR) angiography. Methods: In this retrospective exploratory comparative imaging study, six patients with confirmed MPS IVa underwent clinically indicated 3D MR angiography of the aorta and supraaortic vessels; two were excluded due to motion artifacts, leaving four patients for analysis. Two radiologists independently assessed vascular kinking and tortuosity. For comparison, 12 age- and sex-matched polytrauma patients without documented vascular abnormalities were retrospectively evaluated using computed tomography angiography. Results: All four patients with MPS IVa showed multiple kinking sites of the descending aorta and increased tortuosity of the common and internal carotid arteries. Aortic tortuosity indices ranged from 2.01 to 2.68. Carotid tortuosity indices were also increased, particularly in the internal carotid arteries. Compared with controls, all assessed tortuosity indices were consistently higher in patients with MPS IVa (exploratory p = 0.001). Despite multiple aortic kinking sites, no marked anatomical luminal narrowing was observed. Conclusions: This exploratory study provides quantitative evidence of differences in aortic and carotid geometry between a small, highly selected MPS IVa cohort and external imaging controls. Larger studies using harmonized imaging protocols and longitudinal follow-up are needed to assess prevalence, disease-specific causation and clinical significance of these findings.