Pediatric Track Session
SCMR 22nd Annual Scientific Sessions
Accurate Pulmonary Vascular Resistance (PVR) measurements are critical for clinical decision making in congenital heart disease (CHD). CMR allows highly reproducible great vessel flow measurement. In this study, we describe the test-retest reliability of CMR and cardiac catheter (Fick principle) derived measurements of pulmonary and systemic blood flows. In addition, head-to-head comparison of PVR using CMR versus cardiac catheter derived pulmonary blood flows (Qp) was performed. CMR real-time imaging was used to guide catheterization and all measurements were obtained without the use of ionizing radiation.
Patients with CHD underwent real-time interventional CMR (iCMR) at 1.5 T. The MRWire (angled-tip Emeryglide MRWire, Nano4Imaging, Aachen, Germany) was used to aid completion of RHC and LHC. A dilute gadolinium-filled balloon-tip catheter was used for RHC and LHC/aortic pull back under real-time MRI visualization. A recently developed passive catheter tracking technique with partial saturation pulse of 40 O with flip angle of 35-45 O was used to visualize the gadolinium-filled balloon, MRWire and cardiac structures simultaneously. A series of 4 conditions were performed to evaluate for test-retest reliability. The first and second conditions were catheterization and CMR data obtained at baseline and the third and fourth conditions were retest catheter and CMR data respectively. Pearson correlation coefficients (PCC) was used to measure test-retest reliability and concordance correlation coefficients (CCC) was used to quantify agreement between cath and MRI measurements.
A total of 16 CHD (13 Male) patients participated in the iCMR reproducibility study at our institution. Median age and weight were 6.7 years and 19.6kg (range: 2-16 yrs and 9.2 - 61.6kgs). 10 patients had SV anatomy: 6 for pre-Fontan evaluation, and 4 post-Fontan patients for PLE/cyanosis evaluation. 6 patients with BiV anatomy: 3 underwent vaso-reactivity testing with inhaled Nitric Oxide, 1 underwent RV volume and branch PA stenosis evaluation and remaining 2 BiV patients had CoA.
The PCC for variables measured are shown in Figure 3. The PCC for cath derived Qp (0.890) is lower than MRI derived Qp (0.977). PCC is 0.976 for Cath PVR, while it is 0.993 for MRI PVR (PCC ≥ 0.9 = excellent reliability). There was good agreement (CCC > 0.8) for PVR between catheterization and MRI measurements at baseline (CCC 0.873) and excellent agreement (CCC > 0.9) when retested again (CCC 0.918).
MRI derived flows and resistance have higher test-retest reliability than the catheterization-derived method. Although both test-retest reliability coefficients were excellent, the PVR derived by MRI Flow technique is more reliable than that derived by Cath Fick principle.