Thanks for your health concerns, The most common cause of fatty liver infiltration is abnormal metabolism of lipids, mainly triglycerides and cholesterol, in the setting of an inflammatory state called metabolic syndrome, characterized by elevated tryglycerides, low good chlolesterol levels, most of the time obesity (not your case), and abnormal metabolism of sugars and higher than normal blood pressure. Good strict control of your lipids, blood sugars, regular physical activity, Vitamin E in some studies, and avoidance of alcohol excess are the main keys to improve this condition. Unsure why the prior CT scan did not show it; sometimes, things might actually be there but they are not commented on the final radiology report if the test was done for another reason (eg. follow up of a lung nodule) Hope this helps with your question, wish you the best health,, Dr Brenes-Salazar Mayo Clinic Minnesota