LIVER,P ANCREAS, AND BILIARY TRACT:CLINICAL RESEARCH Evaluation of Intrapulmonary Vascular Dilatations With High-Resolution Computed Thorax Tomography in Patients With Hepatopulmonary Syndrome Deniz Ko ¨ksal, MD,* Sabite Kac xar, MD,† Aydın S x. Ko ¨ksal, MD,† Omac x Tu ¨fekc xiog ˘lu, MD,‡ Fahrettin Ku ¨c xu ¨kay, MD,§ Sarper O ¨ kten, MD,§ Nurgu ¨l S xas xmaz, MD,† Kemal Arda, MD,§ and Burhan S xahin, MD† Goals: We aimed to determine the role of thorax high-resolution computed tomography (HRCT) in demonstrating the pulmonary vaso- dilatation in patients with hepatopulmonary syndrome (HPS). Background: Traditionally, the presence of intrapulmonary vascu- lar dilatations can be detected by using one of the three diagnostic modalities: contrast-enhanced echocardiography, technetium 99 m- labeled macroaggregated albumin scan, and pulmonary angiography. Study: The study group included 10 patients with HPS (Group 1), 12 patients with normoxemic cirrhosis (Group 2), and 12 healthy con- trols (Group 3). All of the subjects underwent conventional and HRCT of thorax. The diameters of pulmonary trunk, main pulmonary arteries, and right lower lobe basal segmental arteries were measured. The ratios of right lower lobe basal segmental pulmonary artery to bron- chus diameter were calculated. Results: The mean diameters of the main pulmonary trunk, right and left main pulmonary arteries were not different between the groups. Mean diameters of right lower lobe basal segmental pulmonary arteries were significantly higher in Group 1 compared with Group 2 (P = 0.01) and Group 3 (P = 0.002). Mean right lower lobe basal segmental pulmonary artery to bronchus ratios were significantly higher in Group 1 compared with Group 2 (P = 0.03) and Group 3 (P , 0.001). Group 2 had significantly higher pulmonary artery to bronchus ratios than Group 3 (P , 0.001). Conclusions: Thorax HRCT may be helpful in the diagnosis of HPS by demonstrating the dilated peripheral pulmonary vessels or increased pulmonary artery to bronchus ratios in patients with liver disease and hypoxemia. Key Words: liver cirrhosis, hepatopulmonary syndrome, vasodila- tation, high-resolution computed tomography (J Clin Gastroenterol 2006;40:77–83) H epatopulmonary syndrome (HPS) is a well-recognized extrahepatic manifestation of liver disease, with a reported incidence of 13% to 47%. 1,2 It is defined as the triad of liver disease, a widened age-corrected alveolar-arterial oxygen gra- dient (AAG) while breathing room air with or without hypox- emia, and evidence of intrapulmonary vascular dilatations. 3–5 The diagnosis of HPS depends on documenting the presence of intrapulmonary vascular dilatations in a hypox- emic patient with chronic liver disease. Pathologically, intra- pulmonary vascular dilatations have been defined by postmortem micro-opaque gelatin suspension injections into the pulmo- nary arterial bed, which have shown dilated precapillaries, direct arteriovenous communications, and dilated pleural vessels. 6,7 Vasodilatation of precapillaries is associated with excess perfusion for a given ventilation (ventilation-perfusion mismatch), limitation of diffusion (incomplete penetration of oxygen through dilated vessels abut alveoli), and true ana- tomic shunts (direct arteriovenous communications that bypass gas exchange units). The resulting effect on arterial oxy- genation ranges from an asymptomatic increase in AAG to severe hypoxemia. 8 The contribution of pleural based vascular dilatations to the degree of hypoxemia is unclear. 6 Traditionally, the presence of intrapulmonary vascular dilatations can be detected by using one of the three diagnostic modalities: contrast-enhanced echocardiography (CEE), tech- netium 99m-labeled macroaggregated albumin (MAA) scan, and pulmonary angiography. 5 In this study, we conducted a prospective trial to determine the role of high-resolution com- puted tomography (HRCT) of thorax in demonstrating the pul- monary vasodilatation in patients with HPS. MATERIALS AND METHODS Patients The study group consisted of 22 patients with cirrhosis and portal hypertension, and 12 healthy controls. Group 1 included 10 patients with HPS. The diagnosis of HPS was based on an increased age-corrected AAG and a delayed posi- tive CEE. Group 2 included 12 patients with nonhypoxemic cirrhosis. Age-corrected AAG and CEE of these patients were normal. Group 3 included 12 randomly selected healthy con- trols who had undergone conventional and HRCT of thorax. Received for publication April 21, 2005; accepted June 22, 2005. From the *Department of Chest Diseases, Atatu ¨rk Chest Diseases and Chest Surgery Education and Research Hospital; and the Departments of †Gastroenterology, ‡Cardiology, and §Radiology, Tu ¨rkiye Yu ¨ksek _ Ihtisas Hospital, Ankara, Turkey. Reprints: Deniz Ko ¨ksal, MD, Feneryolu sokak 5/21, 06010 Etlik, Ankara, Turkey (e-mail: deniz_koksal@yahoo.com). Copyright Ó 2005 by Lippincott Williams & Wilkins J Clin Gastroenterol  Volume 40, Number 1, January 2006 77 Copyright ' Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.