Abstract 18835: Semi-quantitative Estimation Of Systemic To Pulmonary Collateral Flow In Patients With Superior Cavopulmonary Connections Using Magnetic Resonance Angiography During Lower Extremity Gadolinium Injection: Correlation With Direct Flow Measurement
Introduction: We recently described the novel quantification of systemic to pulmonary collateral flow (SPCF) in patients with superior cavopulmonary connections (SCPC) by cardiac magnetic resonance (CMR) velocity mapping by subtracting pulmonary artery from pulmonary vein (PV) flow. Semi-quantification of the collateral flow by CMR angiography (MRA) may be helpful for further validation and to guide therapy.
Hypothesis: In patients with SCPC, degree of lung field and PV enhancement on the systemic arterial (SA) phase of high speed 3D MRA during lower extremity (LE) injection predicts the fractional contribution of SPCF to total pulmonary blood flow (Qp=PV flow).
Methods: We retrospectively reviewed 16 SCPC patients with a LE injection 3-D MRA (TWIST, Siemens) and quantification of SPCF expressed as SPCF/Qp. Coronal maximum intensity projection stacks were imported into ImageJ (NIH) for segmentation of each lung into upper and lower lobes, as well as any visualized PV, taking care to exclude overlying structures. Intensity curves were extracted, and the SA enhancement (SPCF) to post-superior vena cava enhancement ratio (SA/SVC) calculated for each lung lobe and visualized PV.
Results: Significant correlation was seen between SPCF/Qp and SA/SVC enhancement ratios for both lung lobes (r=0.73, p<0.01, see figure) and PV's (r=0.76, p<0.01). It also allowed for regional localization of collateral flow. In all 16 pts, SPCF was directed predominately to the upper lobes. The 13 pts with bilateral upper PV enhancement on the SA phase had a mean SPCF/Qp ratio of 0.50 (range 0.37 to 0.68) compared to a mean ratio of 0.20 (range 0.10-0.34) for the 3 without (p<0.001).
Conclusions: LE injection during 3D MRA with high temporal resolution is useful in directly visualizing SPCF in patients with SCPC physiology and semi-quantification correlates with measured SPCF. This is potentially a useful tool for guiding and assessing percutaneous embolization of collateral vessels.
- © 2010 by American Heart Association, Inc.