Aetiologies of normal CT main pulmonary arterial (PA) measurements in patients with right heart catheter (RHC) confirmed pulmonary hypertension (PH)

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1 Aetiologies of normal CT main pulmonary arterial (PA) measurements in patients with right heart catheter (RHC) confirmed pulmonary hypertension (PH) Poster No.: C-0964 Congress: ECR 2010 Type: Scientific Exhibit Topic: Chest Authors: K. L. Downey, D. V. Patel, H. Ranu, A. Dunleavy, S. Grubnic, B. P. Madden, I. Vlahos; London/UK Keywords: Computed Tomography, Pulmonary Hypertension, Pulmonary artery DOI: /ecr2010/C-0964 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 17

2 Purpose Background Pulmonary hypertension is a term defined by an increased pressure in the pulmonary arteries, veins or capillaries and a right heart catheter confirmed mean pulmonary artery pressure of more than >25mmHg at rest. [1] Pulmonary hypertension can be idiopathic or more commonly due to a range of cardiac and pulmonary disorders (Figs. 1 and 2). It is a disease that often has a poor prognosis but if diagnosed appropriately there are increasingly effective treatment options available. The diagnosis of pulmonary artery hypertension on CT is challenging. Most commonly the size of the main pulmonary artery (>3cm) or the ratio between the diameter of the main pulmonary artery and the adjacent ascending aorta (ratio greater than one) are used [2,3] to diagnose pulmonary artery hypertension on CT (Fig. 3). However, these criteria have only been validated on small sample sizes. Additionally these measurements have been found to be sensitive with high pulmonary pressures but have a weaker correlation with borderline and mildly raised pulmonary pressures and are variable in the setting of interstitial lung disease (Fig. 4). [4,5] Purpose The purpose of this study is to determine whether established CT main pulmonary artery thresholds for determination of pulmonary hypertension apply using a large tertiary referral pulmonary hypertension database and to establish the most frequent disease categories for patients with a normal pulmonary artery size in cases of known pulmonary hypertension. Indeed, many patients with pulmonary hypertension have no CT evidence of an enlarged pulmonary artery (Fig. 5). Images for this section: Page 2 of 17

3 Fig. 1: Eccentric thrombus seen in Chronic Thromboembolic Pulmonary Hypertension (CTEPH). Page 3 of 17

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5 Fig. 2: Dilated pulmonary artery in a patient with diffuse centrilobular emphysema causing pulmonary hypertension. Page 5 of 17

6 Fig. 3: Dilated pulmonary artery on axial CT Pulmonary Angiographic imaging. Note the ratio of the diameter of the pulmonary artery to the adjacent ascending aorta is greater than 1. Fig. 4: Unpredictability of pulmonary arterial size in interstitial lung disease; a case of Usual Interstitial Pneumonia (UIP) demonstrating a large pulmonary artery but the pulmonary arterial pressure was not diagnostic for pulmonary hypertension at right heart catheterisation. Page 6 of 17

7 Fig. 5: Unpredictability of pulmonary arterial size in interstitial lung disease; a case of Alpha-1 antitrypsin deficiency demonstrating a small pulmonary artery but pulmonary arterial pressure was 48mmHg at right heart catheterisation. Page 7 of 17

8 Methods and Materials Patient Population The patient population consisted of 108 consecutive patients attending St George's Hospital NHS Healthcare Trust, London, UK; a tertiary referral centre for the investigation of pulmonary hypertension. All patients underwent both CT pulmonary angiography and right heart catheterisation. The presence of pulmonary hypertension was defined as a mean pulmonary arterial pressure of more than 25mmHg diagnosed at right heart catheterisation. CT Imaging The axial diameter of the main pulmonary artery was measured as part of a wider study evaluating features of pulmonary hypertension on CT. Two experienced readers independently evaluated the dimensions of the pulmonary arterial vasculature and the figures obtained were averaged. The main pulmonary artery was considered enlarged if it was measured as greater than 30mm (Fig. 1). Main pulmonary artery measurements were correlated against mean pulmonary arterial pressure measurements within the cohort and against diagnosis categories. Causes of established pulmonary hypertension with normal pulmonary arterial measurements were also evaluated. Images for this section: Page 8 of 17

9 Fig. 1: Measurement of pulmonary artery diameter on axial CT Pulmonary Angiographic imaging. Page 9 of 17

10 Results The pulmonary arterial pressure measurements of 108 patients with confirmed pulmonary hypertension by right heart catheterisation ranged from 25-69mmHg with a mean pressure of 37.4mmHg. Axial main pulmonary arterial measurements demonstrated a moderate correlation in those with pulmonary hypertension using Spearman's rank correlation coefficient analysis where r = 0.47 (p = 0.01) (Fig. 1). The patients with pulmonary hypertension were categorised into 6 disease groups according to diagnosis - Pulmonary (n = 30), Chronic thromboembolic pulmonary hypertension (CTEPH) (n = 21), Left heart disease e.g. Mitral valve disease, left ventricular failure (n = 35), Shunts (n = 2), Idiopathic (n = 8) and Mixed (n = 12) (Fig. 2). The Spearman correlation strength ( ) and slope ( ) varied widely across these disease groups (Fig. 3). The sensitivity of an enlarged pulmonary artery on axial CT imaging in patients with pulmonary hypertension was only 62% (Fig. 4). Of those patients with a normal pulmonary artery size, 43.9% had a left cardiac precipitating cause for pulmonary arterial hypertension (Fig. 5). Indeed, the proportion of patients with left heart disease induced pulmonary hypertension that had a normal pulmonary arterial size (51.4%) was significantly higher than all other groups (31.5%, p<0.05 Chi-square test). Analysis of variance (ANOVA) between the different aetiological groups demonstrated no significant difference in pulmonary arterial pressures. Images for this section: Page 10 of 17

11 Fig. 1: A scatterplot demonstrating the relationship between pulmonary artery diameter (mm) and mean pulmonary arterial pressure (mmhg). Page 11 of 17

12 Fig. 2: A pie chart demonstrating disease groups in patients with pulmonary hypertension. Page 12 of 17

13 Fig. 3: Trends of pulmonary artery diameter against mean pulmonary artery pressure grouped by disease category. Page 13 of 17

14 Fig. 4: A pie chart of disease groups in patients with an enlarged pulmonary artery. Page 14 of 17

15 Fig. 5: A pie chart of disease groups in patients with a normal pulmonary artery diameter. Page 15 of 17

16 Conclusion Conclusions 1. The correlation of CT determined pulmonary arterial size and pulmonary arterial pressure measurements is only moderate and varies according to aetiology. 2. The sensitivity of a main pulmonary artery threshold of 30mm is low. 3. Patients with pulmonary hypertension and a main pulmonary artery of normal size are most likely to have a left cardiac precipitating cause. References 1. Mcgoon M, Gutterman D, Steen V et al. Screening, early detection, and diagnosis of pulmonary arterial hypertension: ACCP evidence-based clinical practice guidelines. Chest 2004;126:14S-34S. 2. Kuriyama K, Gamsu G and Stern RG, et al. CT-determined pulmonary artery diameters in predicting pulmonary hypertension. Invest Radiol 1984;19: Edwards PD, Bull RK, Coulden R. CT measurement of main pulmonary artery diameter. Br J Radiol 1998;71: Deveraj A, Wells AU, Meister MG, et al. The effect of diffuse pulmonary fibrosis on the reliability of CT signs of pulmonary hypertension. Radiology 2008;249: Zisman DA, Karlamangla AS, Ross DJ, et al. High-resolution chest CT findings do not predict the presence of pulmonary hypertension in advanced idiopathic pulmonary fibrosis. Chest 2007;132: Personal Information Correspondence address: kate.downey@me.com Page 16 of 17

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