Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Computed Tomography and Echocardiography in Patients With Acute Pulmonary Embolism: Part 1 Correlation of Findings of Right Ventricular Enlargement Nicole Wake, MS,* Kanako K. Kumamaru, MD, PhD,w Elizabeth George, MBBS,w Arash Bedayat, MD,wz Nina Ghosh, MD,* Carlos Gonzalez Quesada, MD,y Frank J. Rybicki, MD, PhD, FAHA, FACR,w and Marie Gerhard-Herman, MD* Purpose: To evaluate the correlation between the computed tomography (CT)-derived right ventricle (RV) to left ventricle (LV) diameter ratio and the RV size determined by echocardiography in patients with acute pulmonary embolism. Materials and Methods: Consecutive CT pulmonary angiography examinations (August 2003 to May 2010) from a single, large, urban teaching hospital were retrospectively reviewed. For a cohort of 777 subjects who underwent echocardiography within 48 hours of the CT acquisition, the qualitative RV size (divided into 5 cat- egories) extracted from the echocardiography report was correlated with the CT-derived RV/LV diameter ratio. Results: There was moderate correlation (Spearman rank correla- tion coefficient = 0.54, P < 0.001) between the CT-derived RV/LV ratio and the RV size as determined by echocardiography. The correlation coefficient and the concordance rate were inversely related to the time difference between the acquisitions of the 2 modalities. Conclusions: CT and echocardiography findings to assess the RV size after acute pulmonary embolism have moderate correlation. Key Words: computed tomography pulmonary angiography, transthoracic echocardiography, pulmonary embolism, correlation, right ventricular enlargement (J Thorac Imaging 2013;00:000–000) A cute pulmonary embolism (PE) is a common diagnosis with a wide spectrum of clinical presentations and outcomes. 1–3 It is important to determine which patients with PE are at a high risk for poor outcomes and which of them would be most likely to benefit from aggressive therapy such as thrombolysis. Right ventricular dysfunc- tion is a frequent consequence of PE and is a marker for increased risk of mortality in patients with acute PE. 4,5 Computed tomography pulmonary angiography (CTPA) is the current reference standard imaging test to confirm the clinical suspicion of acute PE. 6,7 In addition to providing diagnostic information, CTPA can also be used to identify high-risk patients. The right ventricle (RV) to left ventricle (LV) 8 diameter ratio, which is used as an indicator of RV enlargement, can be measured using axial images or reconstructed 4-chamber views 9–11 or can be determined subjectively. 12 Although CTPA can evaluate the RV size, echo- cardiography has been accepted as a first-line method for identifying RV function in order to provide prognostic data for patients with acute PE. 5,13 Echocardiography data regarding RV dysfunction in published studies include RV dilatation, RV hypokinesis, increased RV/LV diameter ratios, increased velocity of the tricuspid regurgitation jet, paradoxical interventricular septal motion during systole, or shortening of the pulmonic valve systolic flow. 8,14–17 To our knowledge, CTPA and echocardiography assessments of RV size have not been correlated in a large population of patients with acute PE. Thus, the relationship and potential differences between the 2 modalities are not clear. The purpose of this study was to test the hypothesis that there is high correlation between the CT-derived RV/LV ratio and the RV size as determined by echocardiography. MATERIALS AND METHODS Study Population The institutional human research committee approved this HIPAA-compliant retrospective study; informed con- sent was waived. All 1744 consecutive CTPA examinations positive for acute PE performed at a single, large, urban, teaching hospital between August 2003 and May 2010 were reviewed. If there were multiple episodes of acute PE in a subject, only the latest episode was included in the study. Of this cohort, 804 subjects underwent echocardiography within 48 hours either before or after the CTPA acquisition. If there were multiple echocardiography examinations within 48 hours, the echocardiography examination per- formed closest in time (either before or after) to the CTPA was selected for further analysis. Twenty-seven of these initial 804 subjects were excluded from further analysis. In 9 subjects, the CT images did not adequately depict the RV/ LV diameter ratio, and an additional 18 subjects were excluded because the echocardiography report categorized the RV size as indeterminate. The remaining 777 subjects formed the study cohort. CTPA Image Acquisition All CTPA examinations were performed in the cra- niocaudal direction with 16-, 64-, or 128-slice multidetector From the *Department of Medicine, Cardiovascular Division; wAp- plied Imaging Science Laboratory, Department of Radiology; yDepartment of Medicine, Brigham and Women’s Hospital & Harvard Medical School, Boston; and zDepartment of Radiology, University of Massachusetts Medical School, Worcester, MA. The authors declare no conflicts of interest. Reprints: Frank J. Rybicki, MD, PhD, FAHA, FACR, Applied Imaging Science Laboratory, Department of Radiology, Brigham and Women’s Hospital & Harvard Medical School, 75 Francis Street, Boston, MA 02115 (e-mail: frybicki@partners.org). Copyright r 2013 by Lippincott Williams & Wilkins ORIGINAL ARTICLE J Thorac Imaging  Volume 00, Number 00, ’’ 2013 www.thoracicimaging.com | 1