Assessing Pulmonary Perfusion in Emphysema Automated Quantification of Perfused Blood Volume in Dual-Energy CTPA

Objectives: The objective of this study was to determine whether
automated quantification of lung perfused blood volume (PBV) in
dual-energy computed tomographic pulmonary angiography (DE-CTPA)
can be used to assess the severity and regional distribution of
pulmonary hypoperfusion in emphysema. Materials and Methods: We
retrospectively analyzed 40 consecutive patients (mean age, 67 13]
years) with pulmonary emphysema, who have no cardiopulmonary
comorbidities, and a DE-CTPA negative for pulmonary embolism.
Automated quantification of global and regional pulmonary PBV was
performed using the syngo Dual Energy application (Siemens
Healthcare). Similarly, the global and regional degrees of
parenchymal hypodensity were assessed automatically as the
percentage of voxels with a computed tomographic density less than
-900 Hounsfield unit. Emphysema severity was rated visually, and
pulmonary function tests were obtained by chart review, if
available. Results: Global PBV generated by automated
quantification of pulmonary PBV in the DE-CTPA data sets showed a
moderately strong but highly significant negative correlation with
residual volume in percentage of the predicted residual volume (r =
-0.62; P = 0.002; n = 23) and a positive correlation with forced
expiratory volume in 1 second in percentage of the predicted forced
expiratory volume in 1 second (r = 0.67; P < 0.001; n = 23).
Global PBV values strongly correlated with diffusing lung capacity
for carbon monoxide (r = 0.80; P < 0.001; n = 15). Pulmonary PBV
values decreased with visual emphysema severity (r = -0.46, P =
0.003, n = 40). Moderate negative correlations were found between
global PBV values and parenchymal hypodensity both in a per-patient
(r = -0.63; P G 0.001; n = 40) and per-region analyses (r = -0.62;
P < 0.001; n = 40). Conclusions: Dual-energy computed
tomographic pulmonary angiography allows simultaneous assessment of
lung morphology, parenchymal density, and pulmonary PBV. In
patients with pulmonary emphysema, automated quantification of
pulmonary PBV in DE-CTPA can be used for a quick,
reader-independent estimation of global and regional pulmonary
perfusion, which correlates with several lung function parameters.