<prompt> Which of the following describes the Westermark sign in Pulmonary Thromboembolism?Peripheral Wedge shaped infarctPulmonary OligemiaProminence of Main Pulmonary AeryProminence of Descending Rt Pulmonary aery  <response>: Sign in Pulmonary Thromboembolism: Fleischner sign: enlarged pulmonary aery Hampton hump:peripheral wedge of airspace opacity and implies lung infarction Westermark sign:regional oligemia and highest positive predictive value. Palla sign: enlarged right descending pulmonary aery Chang sign: dilated right descending pulmonary aery with sudden cut-of 