Background: Thoracic aortic aneurysms are often an accidental finding and result from a degenerative process. Medical therapy includes pharmacological control of arterial hypertension and smoking cessation, that slows the growth of aneurysms. An association between the dilatation of the ascending and abdominal aorta has been already reported. The aim of the study was to identify possible demographic and clinical factors that may implicate further imaging diagnostics in patients with ascending aorta dilatation. Methods: There were 181 (93 (53%) males and 88 (47%) females) patients with a median age of 54 (41–62) years who underwent cardiac magnetic resonance due to non-vascular diseases, were enrolled into retrospective analysis. Results: Multivariable analysis revealed ascending aorta dilatation (odds ratios (OR) = 7.45, 95% confidence interval (CI): 1.98–28.0, p = 0.003) and co-existence of coronary artery disease (OR = 8.68, 95% CI: 2.15–35.1, p = 0.002) as significant predictors for thoracic descending aorta dilatation. In patients with abdominal aorta dilatation, the multivariable analysis showed a predictive value of ascending aortic dilatation (OR = 14.8, 95% CI: 2.36–92.8, p = 0.004) and age (OR = 1.04, 95% CI: 1.00–1.08, p = 0.027). In addition, cut-off values were established for age groups determining the risk of thoracic aorta dilatation over 49 years and abdominal aorta dilatation over 54 years. Conclusions: The results of our analysis showed predictive factors, including ascending aorta dilatation and co-existence of coronary artery disease, particularly over 49 years of age for thoracic, while ascending aorta dilatation and age, particularly over 54 years, for abdominal aorta dilatation. These features may be considered to increase clinical vigilance in patients with aortic diameter abnormalities.