Additional Study Information: If your doctor has found that you have an aneurysm, penetrating atherosclerotic ulcer (PAU), intramural hematoma (IMH), or chronic uncomplicated type B dissection (UTBAD) of the aorta, you might be eligible for a research study evaluating the safety and efficacy of the RelayBranch Thoracic Stent-Graft System as treatment for your thoracic aortic disease. The RelayBranch Thoracic Stent-Graft System is an investigational device, meaning that it has not yet been approved for the market by the Food and Drug Administration (FDA) for use or sale on the market. Patients who wish to join this study must sign and date an informed consent form, and will be asked to undergo the tests and procedures below to screen for eligibility to participate. If the following tests were already performed as per standard of care prior to regular surgical treatment, they will not need to be administered again. These tests include medical history assessment, physical examination (including assessment of neurological functions), CT (Computed Tomography) scan (an X-Ray type picture) of your aneurysm and blood vessels, pregnancy test for females of childbearing potential to confirm non-pregnant status, additional tests as required by your study doctor. Except for the neurological assessment, all tests described above are part of your standard of care treatment and would be done with or without your interest of participation in this study. If you enroll in the study, you will be one of approximately 5 subjects at Columbia University Irving Medical Center and one of 30 total participants at sites across the nation.