CT Scan Does Not Differentiate Patients with Hepatopulmonary Syndrome from Other Patients with Liver Disease

Abstract

BackgroundHepatopulmonary syndrome (HPS) is defined by liver dysfunction, intrapulmonary vascular dilatations, and impaired oxygenation. The gold standard for detection of intrapulmonary vascular dilatations in HPS is contrast echocardiography. However, two small studies have suggested that patients with HPS have larger segmental pulmonary arterial diameters than both normal subjects and normoxemic subjects with cirrhosis, when measured by CT. We sought to compare CT imaging-based pulmonary vasodilatation in patients with HPS, patients with liver dysfunction without HPS, and matching controls on CT imaging.MethodsWe performed a retrospective cohort study at two quaternary care Canadian HPS centers. We analyzed CT thorax scans in 23 patients with HPS, 29 patients with liver dysfunction without HPS, and 52 gender- and age-matched controls. We measured the artery-bronchus ratios (ABRs) in upper and lower lung zones, calculated the “delta ABR” by subtracting the upper from the lower ABR, compared these measurements between groups, and correlated them with clinically relevant parameters (partial pressure of arterial oxygen, alveolar-arterial oxygen gradient, macroaggregated albumin shunt fraction, and diffusion capacity). We repeated measurements in patients with post-transplant CTs.ResultsPatients had significantly larger lower zone ABRs and delta ABRs than controls (1.20 +/- 0.19 versus 0.98 +/- 0.10, p<0.01; and 0.12 +/- 0.17 versus -0.06 +/- 0.10, p<0.01, respectively). However, there were no significant differences between liver disease patients with and without HPS, nor any significant correlations between CT measurements and clinically relevant parameters. There were no significant changes in ABRs after liver transplantation (14 patients).ConclusionsBasilar segmental artery-bronchus ratios are larger in patients with liver disease than in normal controls, but this vasodilatation is no more severe in patients with HPS. CT does not distinguish patients with HPS from those with uncomplicated liver disease.

Hepatopulmonary syndrome has low prevalence of pulmonary vascular abnormalities on chest computed tomography

“…Moreover, consistent with previous reports [10], ABR and PaO 2 were not correlated. Chen et al [10] compared patients with HPS and those with liver dysfunction without HPS, reporting no difference in ABR. Our study reinforces the hypothesis that dilatation of muscularized pulmonary arterioles is a consequence of the hyperdynamic circulatory state of cirrhosis mediated by vasoactive substances.…”

“…The mean ABRs in our and other studies [7–10] are within the normal range reported for healthy patients (0.98; 95% CI: 0.7, 1.26) [17]. Moreover, consistent with previous reports [10], ABR and PaO 2 were not correlated. Chen et al [10] compared patients with HPS and those with liver dysfunction without HPS, reporting no difference in ABR.…”

“…Our study reinforces the hypothesis that dilatation of muscularized pulmonary arterioles is a consequence of the hyperdynamic circulatory state of cirrhosis mediated by vasoactive substances. Intrapulmonary vascular dilatations constitute a distinct anatomic abnormality located distal to these vessels [10].…”

“…Two subsequent studies in individuals with cirrhosis and HPS reported an increased CT diameter of the peripheral pulmonary vasculature compared with both healthy controls and patients with normoxemic cirrhosis [8,9]. In contrast, another study reported evidence of peripheral pulmonary artery dilatation on CT in patients with liver disease compared with healthy controls, but no differences between patients with liver disease with or without HPS [10].…”

Cardiac Imaging in Liver Transplantation Candidates: Current Knowledge and Future Perspectives

“…Echocardiography with contrast agents [101], angiography [102] and CMR [103] have been used for such measurement but their specificity is questionable as transit time is also affected by cardiac output [104]. CT angiography may be used to diagnose focal atrioventricular shunts [96] but it's accuracy for HPS diagnosis remains to be assessed as small studies have shown conflicting results [105,106].…”