Abstract 11686: Assessing Pulmonary Perfusion Reserve in Patients With Chronic Obstructive Lung Disease Using MRI, a Pilot Study

Abstract

Background: Patients with COPD are associated with reduced lung perfusion. However, little is known about their pulmonary vascular reserve. In this study we sought to investigate the lung perfusion reserve using lung perfusion quantitation by MRI.

Methods: Twenty seven volunteers were prospectively recruited and divided into 3 groups based on pulmonary function test (PFT), normal, borderline and abnormal defined by actual FEV1/FVC ≥76%, 71%-75% and ≤70%, respectively. All underwent MRI in a 1.5T scanner. Dynamic images of the lung were acquired in 3 parallel coronal views using saturation recovery steady state free precession sequence during gadolinium DTPA infusion (0.01 mmol/kg). Following rest imaging stress lung perfusion images were acquired during adenosine infusion (140µg/kg/min) using the same imaging protocol. A total of 324 lung sections were quantitatively analyzed using a custom model-independent deconvolution program. All subjects underwent PFT prior to MRI.

Results: Average age was 51±18 years and 21 (78%) were male. The average cardiac output increased from 4.9 L/min at rest to 8.0 L/min (p<0.001) during adenosine infusion while the average lung perfusion increased from 85±28 ml/100ml/min at rest to 161±77 ml/100ml/min during adenosine infusion (p=0.005). In the 3 groups defined by the PFT average FEV1/FVC was 84±5 (N=16), 74±5 (N=6) and 59±11 (N=5) for normal, borderline and abnormal groups (p<0.001), respectively. There was a graded decrease of rest lung perfusion in the 3 PFT groups, 95±23 ml/100ml/min, 80±27 ml/100ml/min and 55±23 ml/100ml/min (p=0.003), respectively. While a perfusion augmentation was achieved with adenosine in all 3 groups at 187±75 ml/100ml/min, 151±60 ml/100ml/min and 89±54 ml/100ml/min (p=0.01), respectively, there was a trend with the highest perfusion reserve ratio in normal (2.1) followed by borderline group (1.9) and with the least in the abnormal PFT group (1.6) (p=0.258).

Conclusion: With adenosine challenge the absolute lung perfusion was increased by about 2 folds on average. Reduced lung perfusion was associated with impaired PFT at rest and during stress. Our findings suggest that quantitative assessment of pulmonary perfusion reserve is feasible using lung perfusion quantitation by MRI.