The study will investigate patients with clinical suspicion for pulmonary embolism (PE) who have a contraindication to iodine based contrast. These patients normally get investigated with studies such as ultrasound and nuclear medicine studies but the fastest and preferred investigation is CT with contrast to look for filling defects in the pulmonary arteries. The investigators will assess whether gadolinium, which is currently used with MRI can be used with CT as an alternative effective contrast in diagnosis or exclusion of PE. A new type of CT scanner, a Dual Energy Scanner will be used to improve the visibility of Gadolinium contrast on CT.