The most appropriate diagnostic investigation in a patient presenting with chest pain and a widened mediastinum is:

d. Whilst measuring the blood pressure in all limbs raises the suspicion of aortic dissection, the most diagnostic investigation is a CT chest. Other diagnostic investigations include MRI and a trans-oesophageal echocardiogram. There are no diagnostic ECG changes associated with dissecting aortic aneurysms and liver function tests are of no use in confirming the diagnosis.