There is a progressive enlargement of the ascending aorta with age. Males have larger ascending aortas than females. The size of the normal aorta needs to be indexed to the patient’s body surface area m2 (BSA), as it is well known that larger individuals have larger aortas. Aortic size nomogram tables have been developed that show the risk of complications from aortic rupture based on size and the BSA. ( Ref 1). For example, an individual with a BSA of 1.8 m2 with an ascending aorta larger than 5.0 cm has a risk of complications from aortic dissection of 8%/year. (Ref 1)We sought to generate sex and age specific nomograms of the orthogonal and direct axial diameters of the ascending aorta that are indexed to the BSA from ungated contrast-enhanced magnetic resonance angiography (CE-MRA) exams.This was a HIPAA compliant and IRB approved retrospective study from a data set of over 113 CE-MRA examinations initially performed for the primary evaluation of suspected pulmonary embolism. The 113 subjects, (60 females: 53 males) were evenly distributed into the following age groups: (A) < 45 years; (B) 45-54; (C) 55-64; and (D) > 65 years. The CE-MRA exam was performed at 1.5T ( GE Healthcare, Waukesha, WI) using a post contrast ( gadobenate dimeglumine at 0.1mmol/kg, Bracco Diagnostics) fluoro-triggered, 3D elliptical-centric fast SPGR sequence performed pre-, during-, and post-injection. (Ref 2) Axial (Ref 3) and double-oblique (orthogonal)(Ref 4) measurements of the ascending aorta (AscA) diameter were performed directly on a PACS workstation. Measurements were made at the level of the main right pulmonary artery (Figures 1 and 2). One investigator measured the AscA three times in all 113 patients and a second investigator performed the same measurements three times in a subset of 21 patients. Inter- and intra-observer variability between measurements was quantified using Bland-Altman analysis. Plots for the aortic dimensions were generated for each age group and sex followed by the combined results for each sex plotting the aortic dimensions indexed to BSA by age.We found the inter-observer variability to be 0.34mm ± 3.365 mm (2 SD) for the axial measurements and 0.12 mm ± 3.13 (2 SD) for orthogonal measurements. While the intra-observer variability was 0.20mm ± 2.81mm (2 SD) for axial measurements and 0.58mm ± 2.61 mm (2 SD) for orthogonal measurements. The inter-test variability between the axial and orthogonal measurements showed a bias of -0.60 mm ± 2.43 mm( 2 SD) (Figure 3). The combined nomogram for all of the females with AscA dimension mm /BSA m2 shows a R2 value of 0.21 (Figure 4), while the male indexed nomogram shows a R2 value of 0.107 (Figure 5).We confirm the findings of Bireley et al (Ref 4) showing that orthogonal measurements of the AscA are less variable for a single observer than the direct axial measurements. As expected, we found that males have larger AscA dimensions than women; even after indexing to BSA. We show that there is good interobserver agreement as well as reasonable intraobserver agreement for these measurements made free hand on the PACS work station without the use of post processing to determine the aortic wall. These nomograms can serve as a basis for determining the relative importance of an individual’s aortic dimensions using non-gated breath hold CE-MRA examinations.Cardiopulmonary MRA is an off label use of gadolinium based contrast agents.