Regional pulmonary perfusion using model-free analysis of contrast-enhanced MRI in meconium-aspirated piglets
Pia Ryhammer1, Michael Pedersen, Steffen Ringgaard
1Clinical Institute of Medicine, University of Aarhus, Aarhus, Denmark.
Purpose:
To investigate if dynamic contrast-enhanced MRI in lungs could add new information to pulmonary hypertension in a newborn piglet model.
Materials And Methods:
Six newborn piglets were subjected to instillation of meconium following treatment with sildenafil. Before and after both of these events, dynamic contrast-enhanced MRI was performed to determine pulmonary blood flow (PBF) using a model-free deconvolution of the dynamic signal-time curve, together with invasive measurements of mean airway pressure (PAW), cardiac output (CO), and oxygenation index (OI).
Results:
Meconium instillation caused a significant increase in PAW (P < 0.05) accompanied by a marked increase in OI, the average PBF in the four lung regions (apical-anterior, apical-posterior, distal-anterior, and distal-posterior) decreased significantly by 33% (P < 0.001), but it did not significantly affect CO. On the other hand, infusion of sildenafil caused a significant increase in CO (P < 0.01), and administration resulted mainly in an increased PBF in the distal parts of the lungs.
Conclusion:
By using dynamic contrast-enhanced MRI, we demonstrated a marked decrease in PBF following instillation of meconium, which was not followed by an equivalent decrease in CO, suggesting that measurements of CO inadequately reflect the intrapulmonary changes in the blood circulation.
Insights
Dynamic contrast-enhanced MRI revealed decreased pulmonary blood flow (PBF) in piglets after meconium instillation. This imaging technique offers insights into pulmonary hypertension beyond cardiac output measurements.
Area of Science:
- Medical Imaging
- Pediatric Cardiology
- Pulmonary Medicine
Background:
- Pulmonary hypertension in newborns poses significant clinical challenges.
- Accurate assessment of pulmonary blood flow (PBF) is crucial for managing this condition.
- Current methods may not fully capture dynamic circulatory changes in the lungs.
Purpose of the Study:
- To evaluate the utility of dynamic contrast-enhanced MRI (DCE-MRI) in assessing pulmonary hypertension.
- To investigate if DCE-MRI provides novel information in a newborn piglet model of pulmonary hypertension.
- To compare DCE-MRI findings with invasive hemodynamic measurements.
Main Methods:
- Newborn piglets underwent meconium instillation and sildenafil treatment.
- Dynamic contrast-enhanced MRI was performed before and after interventions.
- Pulmonary blood flow (PBF) was calculated using model-free deconvolution.
- Invasive measurements included mean airway pressure (PAW), cardiac output (CO), and oxygenation index (OI).
Main Results:
- Meconium instillation significantly increased PAW and OI, while decreasing PBF by 33% (P < 0.001) without affecting CO.
- Sildenafil administration significantly increased CO (P < 0.01) and PBF, particularly in distal lung regions.
- DCE-MRI demonstrated a marked decrease in PBF post-meconium, not mirrored by a similar drop in CO.
Conclusions:
- Dynamic contrast-enhanced MRI effectively visualizes reduced pulmonary blood flow in a model of neonatal pulmonary hypertension.
- DCE-MRI provides complementary information to cardiac output, highlighting intrapulmonary circulatory alterations.
- This imaging modality holds promise for a more comprehensive assessment of neonatal pulmonary vascular disease.
