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Craniofacial Imaging of Pediatric Patients by Ultrashort Echo-Time Bone-Selective MRI in Comparison to CT
Nada Kamona1, Jinggang J Ng2, Yohan Kim2
1Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
Insights
Ultrshort echo time (UTE) MRI shows promise for pediatric craniofacial imaging, offering good agreement with CT scans for bone structure and measurements, reducing radiation exposure concerns.
Area of Science:
- Medical Imaging
- Pediatric Radiology
- Biomedical Engineering
Background:
- Ionizing radiation from CT scans is a concern for children needing repeated craniofacial imaging.
- Low-dose CT protocols reduce but do not eliminate radiation exposure risks.
Purpose of the Study:
- To investigate the clinical feasibility of an ultrashort echo time (UTE) MRI sequence for pediatric craniofacial imaging.
- To compare the accuracy of UTE MRI with CT for visualizing bone structures and taking measurements in children.
Main Methods:
- A dual-radiofrequency, dual-echo UTE MRI sequence was used on 12 pediatric patients (aged 8-18) at 3T.
- Bright-bone images were generated to enhance bone specificity.
- Quantitative comparisons with CT included Dice similarity coefficient (DSC), Hausdorff distance (HD95), and craniometric measurements using Lin's concordance correlation coefficient (ρc).
Main Results:
- UTE MRI provided high bone contrast, suppressed soft tissues, and clearly separated bone from air sinuses.
- Skull mask overlap (DSC) and Hausdorff distance (HD95) showed good agreement between UTE MRI and CT (median DSC=0.81, median HD95=1.87 mm).
- Craniometric measurements demonstrated strong agreement (ρc=0.90-0.99) with mean absolute differences under 2 mm.
Conclusions:
- The UTE MRI sequence is clinically feasible for pediatric craniofacial imaging.
- UTE MRI shows good agreement with CT in resolving thin bone structures and craniometry.
- This technique offers a potential alternative to repeated CT scans, reducing radiation exposure in pediatric patients.
Rationale And Objectives:
The emergence of low-dose protocols for CT imaging has mitigated pediatric radiation exposure, yet ionizing radiation remains a concern for children with complex craniofacial conditions requiring repeated radiologic monitoring. In this work, the clinical feasibility of an ultrashort echo time (UTE) MRI sequence was investigated in pediatric patients.
Materials And Methods:
Twelve pediatric patients (6 female, age range 8 to 18 years) with various imaging conditions were scanned at 3T using a dual-radiofrequency, dual-echo UTE MRI sequence. Bright-bone images were generated using a weighted least-squares conjugate gradient method to enhance bone specificity. The overlap of the binary skull masks was quantified using the Dice similarity coefficient (DSC) and the 95th percentile Hausdorff distance (HD95) to evaluate the similarity between MRI and CT. To assess the anatomic accuracy of 3D skull reconstructions, six craniometric distances were recorded and the agreement between MRI- and CT-derived measurements was evaluated using Lin's concordance correlation coefficient (ρc).
Results:
The bright-bone images from UTE MRI demonstrated high bone-contrast, suppression of soft tissue, and separation from air at the sinuses. The DSC and HD95 between MRI and CT had medians of 0.81 ± 0.10 and 1.87 ± 0.32 mm, respectively. There was good agreement between MRI and CT for all craniometric distances (ρc ranging from 0.90 to 0.99) with a mean absolute difference in measurements of < 2 mm.
Conclusion:
The clinical feasibility of the UTE MRI sequence for craniofacial imaging was demonstrated in a cohort of pediatric patients, showing good agreement with CT in resolving thin bone structures and craniometry.
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