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Growth-adjusted reference values for the main pulmonary artery-to-ascending aorta ratio derived from clinically
Ying Lyu1, Mingshu Yang2, Huaqin Bu3
1Department of Radiology, Children's Hospital of Chongqing Medical University, National Clinical Research Center for Children and Adolescents' Health and Diseases, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Child Rare Diseases in Infection and Immunity, Chongqing, China.
Insights
Pediatric main pulmonary artery-to-ascending aorta (MPA/AA) ratio is dependent on growth and should be interpreted using age-adjusted values. These age-adjusted reference values on CT scans correlate with pulmonary arterial pressure, aiding clinical decisions.
Area of Science:
- Pediatric Radiology
- Cardiovascular Imaging
- Pulmonary Hypertension
Background:
- The main pulmonary artery-to-ascending aorta (MPA/AA) ratio is a key metric in pediatric cardiovascular imaging.
- Fixed reference standards for the MPA/AA ratio are limited by normal growth-related variations in children.
- Accurate interpretation of MPA/AA ratio is crucial for diagnosing and managing pediatric pulmonary vascular conditions.
Purpose of the Study:
- To establish growth-adjusted reference values for the MPA/AA ratio in children using clinically indicated chest CT scans.
- To evaluate the applicability of these age-adjusted reference values in an independent cohort undergoing right heart catheterization (RHC).
- To provide a more accurate interpretation of MPA/AA ratio in pediatric patients, accounting for developmental changes.
Main Methods:
- Retrospective analysis of 1306 children from two pediatric centers (modeling cohort) and 175 children from an RHC cohort.
- Standardized axial measurement of MPA and ascending aorta (AA) diameters on chest CT.
- Derivation of age-adjusted reference values using generalized additive models.
- Association of age-adjusted MPA/AA values with invasively measured pulmonary arterial pressure in the RHC cohort.
Main Results:
- The MPA/AA ratio was found to be highest in early childhood, declining with growth and stabilizing in later years.
- A unified, age-based, sex-adjusted model was developed for MPA/AA ratio reference values.
- In the RHC cohort, age-adjusted MPA/AA values showed a strong association with elevated mean pulmonary arterial pressure (mPAP), with an AUC of 0.881.
Conclusions:
- The pediatric MPA/AA ratio is significantly influenced by growth and requires interpretation against age-adjusted reference values.
- Utilizing age-adjusted reference values on clinically indicated CT scans enhances consistency in interpretation.
- This imaging-based approach complements invasive hemodynamic assessment and aids in decisions regarding further evaluation.
Objectives:
To establish growth-adjusted reference values for the main pulmonary artery-to-ascending aorta (MPA/AA) ratio in children on clinically indicated chest CT and to explore their external hemodynamic applicability in an independent right heart catheterization (RHC) cohort.
Materials And Methods:
This retrospective multicenter study included a modeling cohort of 1306 children younger than 18 years from two pediatric centers and an independent RHC cohort of 175 children. Children in the modeling cohort underwent clinically indicated chest CT for conditions not expected to directly alter pulmonary arterial morphology after predefined exclusions. MPA and AA diameters were measured using a standardized axial method. Age-adjusted reference values were derived from generalized additive models for location, scale, and shape. In the RHC cohort, the primary binary analysis included 169 children older than 3 months and assessed whether reference values were associated with mPAP-defined pressure elevation.
Results:
In the modeling cohort, the median age was 6.4 years, and the median MPA/AA ratio was 1.12. The ratio was highest in early life, declined with growth, and stabilized in later childhood. The primary model was an age-based, sex-adjusted unified model. In the analyzable RHC cohort, age-adjusted MPA/AA values were associated with invasive hemodynamic status, with an area under the curve (AUC) of 0.881 (95% confidence interval, 0.830-0.932).
Conclusion:
The pediatric MPA/AA ratio is growth-dependent and should be interpreted against age-adjusted reference values rather than a fixed raw threshold. On clinically indicated CT, this approach may support more consistent interpretation while remaining complementary to invasive hemodynamic assessment.
Key Points:
Question How should the pediatric main pulmonary artery-to-ascending aorta ratio be interpreted on CT when growth-related variation limits the use of fixed reference standards? Findings In 1306 children, the main pulmonary artery-to-ascending aorta ratio declined with growth, and age-adjusted values remained associated with invasively defined pulmonary arterial pressure elevation. Clinical relevance Age-adjusted reference values provide a developmental context for pediatric main pulmonary artery-to-ascending aorta measurements on clinically indicated CT and support decisions on further hemodynamic evaluation.
